Merge pull request 'Build for Minecraft 26.1, 26.2 and 26.3' (#8) from mc-26 into master

Reviewed-on: #8

README.md

@@ -5,15 +5,57 @@ A player emote library for Saturn Client, with limb bending.
 ## Layout
 
 - `core/`: Minecraft-independent animation model (`Bone`, `BoneTransform`, `Pose`, `Animation`,
-  `AnimationPlayer`). Plain Java 21 with JUnit tests. Published as `org.saturnclient:emotes-core`.
+  `AnimationPlayer`), keyframes and easings, the Emotecraft JSON loader and the `EmoteRegistry`.
+  Plain Java 21 plus Jackson, with JUnit tests. Published as `org.saturnclient:emotes-core`.
 - `src/main/`: the Fabric mod that puts poses on player models. It's built once per Minecraft
   version with [Stonecutter](https://stonecutter.kikugie.dev/) and published as
-  `org.saturnclient:emotes-fabric:<version>+<mc>`, with `core` bundled inside the jar.
-- `src/testmod/`: a dev-only tester mod that is never published. It adds `/emotes play <name>`,
-  `/emotes stop` and `/emotes info`. Press F5 to see yourself.
+  `org.saturnclient:emotes-fabric:<version>+<mc>`, with `core` and Jackson 2.17.0 (the version Saturn
+  Client ships) bundled inside the jar.
+- `src/testmod/`: a dev-only tester mod that is never published. It loads Saturn's emotes into the
+  library's registry and keeps its own hand-written test animations in a separate registry.
+  `/emotes play <id>` plays a registered emote, `/emotes test <name>` a test animation, and there's
+  `/emotes stop` and `/emotes info`. Press F5 to see yourself. It also has a Fabric client gametest
+  that creates a world and screenshots each animation from the front and side, into
+  `versions/<mc>/build/run/clientGameTest/screenshots/`.
+- `tools/capture/`: a Python tool that measures an emote from a store page's 3D preview and writes
+  it as Emotecraft JSON. See its README.
+- `tools/emotecraft/convert.py`: converts Emotecraft's binary `.emotecraft` files to Emotecraft JSON
+  (standard-library Python).
 
-Supported versions: 1.21.4 to 1.21.11, the same range as Saturn Client. Each version's Fabric API
-version is set in `stonecutter.properties.toml`. The code uses Mojang mappings.
+Supported versions: 1.21.4 to 1.21.11, 26.1 (and its hotfixes), 26.2 and 26.3. Each version's
+Fabric API version is set in `stonecutter.properties.toml`. The code uses Mojang mappings, which
+26.1+ ships as its own names, so `loom-back-compat` applies the remapping Loom for 1.21.x and the
+plain one for 26.x. 26.x builds need Java 25; Gradle downloads it when it isn't installed.
+
+## Using it
+
+```java
+// At startup: load emotes (Emotecraft / player-animation-lib JSON) into the registry.
+try (InputStream in = MyMod.class.getResourceAsStream("/assets/mymod/player_animations/facepalm.json")) {
+    Emotes.registry().loadEmotecraft("facepalm", in);
+}
+
+Emotes.play(player.getUUID(), "facepalm");   // false if there's no such emote
+Emotes.play(player.getUUID(), animation);    // or any Animation, e.g. written in code
+Emotes.stop(player.getUUID());
+Emotes.playing(player.getUUID());            // Optional<AnimationPlayer>
+```
+
+Emotes work for any player you can see, run on game ticks, and a non-looping one stops by itself.
+`Emotes.registry().all()` lists the emotes with their name, description and author, for an emote wheel.
+
+An `Animation` returns a `Pose` for a time in ticks: a `BoneTransform` (offset in model pixels,
+pitch/yaw/roll in radians, bend and bend axis) for any of `ROOT` (the whole player), `HEAD`, `BODY`,
+`RIGHT_ARM`, `LEFT_ARM`, `RIGHT_LEG` and `LEFT_LEG`. Bones it doesn't set keep their vanilla pose.
+`KeyframeAnimation` builds one from keyframes and `Easing`s.
+
+`EmotecraftLoader` follows player-animation-lib's reader: absolute part pivots become offsets,
+`body` (and `torso` before format version 3) is the whole player in blocks, angles are degrees unless
+`"degrees": false`, `turn` adds whole turns, and loops jump back to `returnTick` after `endTick`.
+Emotecraft's two-segment bends become our curved ones: a limb's bend changes sign, the torso's
+doesn't, and a bend on the whole player bends the torso. Scale channels, `easingArg` and blending
+with the vanilla pose aren't supported yet (issue #4). Binary `.emotecraft` files can be converted to
+JSON first with `tools/emotecraft/convert.py`.
 
 ## How it hooks in
 
@@ -22,22 +64,48 @@ version is set in `stonecutter.properties.toml`. The code uses Mojang mappings.
    and the armor layers both go through this method, so armor follows the pose.
 
 Both hook points exist unchanged in every supported version. Version-specific code goes behind
-Stonecutter comments:
+Stonecutter comments, like the vertex accessors in `BentCubeRenderer`:
 
 ```java
 //? if >=1.21.9 {
-import net.minecraft.client.renderer.entity.state.AvatarRenderState;
+return new float[] { vertex.x(), vertex.y(), vertex.z(), vertex.u(), vertex.v() };
 //?} else
-/*import net.minecraft.client.renderer.entity.state.PlayerRenderState;*/
+/*return new float[] { vertex.pos().x(), vertex.pos().y(), vertex.pos().z(), vertex.u(), vertex.v() };*/
 ```
 
-Bending (`BoneTransform.bend` / `bendAxis`) is part of the model but isn't rendered yet.
+## Bending
+
+Each limb bends along a single axis (`BoneTransform.bend`, `bendAxis`). It works like the cloak
+renderer: build a spine, put a ring of shared vertices along it, and draw the faces between the rings.
+
+- `LimbBend` (core) runs the spine along a cubic Bézier (`Bezier`). The control points are the rigid
+  "upper half, joint, lower half" shape, and `sharpness` goes from a round curve (0) to a tight joint
+  (1). The spine is cut into one ring per texture row (12 per limb), spaced evenly by arc length, so
+  the limb keeps its length. Each ring moves its cross-section rigidly, so neighbouring pieces share
+  vertices and the mesh stays closed.
+- `QuadSplitter` (core) cuts each vanilla face into strips at the rings and splits its UVs to match.
+  The texture is unchanged apart from the cuts.
+- `ModelPartMixin` swaps in `BentCubeRenderer` for any part with a bend. That renderer deforms
+  vanilla's own cubes, so slim arms, sleeves, pants and armor all work. Overlays and armor use the
+  limb's spine, not their own inflated box, so they stay attached.
+
+Axis 0 folds towards the front (-Z) and PI/2 towards +X, in the limb's own space. Knees fold back,
+so they use axis PI.
+
+The torso is anchored at the hips instead of its pivot (`LimbBend.anchoredAtEnd`), so the legs stay
+attached and the chest leans. The head and arms are siblings of the body in the vanilla model, so
+`PoseApplier` carries them: their pivots follow the bent torso, and they turn with its ring there
+(`LimbBend.angleAt`). An arm carried by a forward lean swings back like a diver's, so emotes that want
+hanging arms tilt them forward by about the lean (see the `twerk` test animation).
+
+Held items still attach to the unbent arm, and the cape doesn't follow the torso yet.
 
 ## Commands
 
 ```sh
 ./gradlew :core:test                      # core unit tests
 ./gradlew :1.21.11:runTestmodClient       # launch the game with the tester (run dir: ./run)
+./gradlew :1.21.11:runClientGameTest      # screenshot each test animation, then quit
 ./gradlew :1.21.4:compileTestmodJava      # quick compile check for one version
 ./gradlew buildAll                        # every version's jar → build/libs/<version>/
 GITEA_TOKEN=... ./gradlew publish         # publish core + every version to Gitea
@@ -48,8 +116,8 @@ version whose code is uncommented in `src/`. Switch versions with the Stonecutte
 or the `Set active project to <v>` Gradle task. Run `Reset active project` before committing, so
 the tree is committed with `vcsVersion` (1.21.11) active.
 
-Loom 1.18 needs a Java 25 JVM to run Gradle, so the build is pinned to Loom 1.17 until the
-toolchain moves. Minecraft 26.x will need that upgrade.
+Loom 1.18 needs a Java 25 JVM to run Gradle, so the build is pinned to Loom 1.17, which builds
+26.x as well (with a Java 25 toolchain for those versions only).
 
 ## Publishing
 

build.gradle.kts

@@ -22,7 +22,8 @@ val testmod: SourceSet = sourceSets.create("testmod") {
 }
 
 loom {
-    createRemapConfigurations(testmod)
+    // The testmod's mod* configurations; 26.1+ has nothing to remap, and loomx aliases them there.
+    if (!loomx.isUnobfuscated) createRemapConfigurations(testmod)
 
     mods {
         register("saturn_emotes") { sourceSet(sourceSets.main.get()) }
@@ -33,6 +34,13 @@ loom {
         options.put("mark-corresponding-synthetics", "1") // Names lambdas, useful for mixins
     }
 
+    runConfigs.all {
+        preferGradleTask = true
+        generateRunConfig = true
+        runDirectory = rootProject.file("run") // Shared by every version
+        jvmArguments.add("-Dmixin.debug.export=true")
+    }
+
     runs {
         // ./gradlew :<mc>:runTestmodClient launches the game with the tester mod loaded.
         register("testmodClient") {
@@ -40,13 +48,15 @@ loom {
             name = "Testmod Client"
             source(testmod)
         }
-    }
 
-    runConfigs.all {
-        preferGradleTask = true
-        generateRunConfig = true
-        runDirectory = rootProject.file("run") // Shared by every version
-        jvmArguments.add("-Dmixin.debug.export=true")
+        // ./gradlew :<mc>:runClientGameTest screenshots the test animations, then quits.
+        register("clientGameTest") {
+            client()
+            name = "Client Game Test"
+            source(testmod)
+            vmArg("-Dfabric.client.gametest")
+            runDir = "build/run/clientGameTest"
+        }
     }
 }
 
@@ -61,11 +71,20 @@ dependencies {
     modImplementation("net.fabricmc:fabric-loader:${property("deps.fabric_loader")}")
     fapi("fabric-api-base", "fabric-lifecycle-events-v1")
 
-    // The core is Minecraft-independent; ship it inside the mod jar.
+    // The core is Minecraft-independent; ship it inside the mod jar, with the Jackson it reads emotes
+    // with (the version Saturn Client ships too, so the game only loads one).
     api(project(":core"))
     include(project(":core"))
+    for (module in listOf("jackson-databind", "jackson-core", "jackson-annotations")) {
+        include("com.fasterxml.jackson.core:$module:2.17.0")
+    }
 
-    "modTestmodImplementation"(fabricApi.module("fabric-command-api-v2", sc.properties["deps.fabric_api"]))
+    for (module in listOf("fabric-command-api-v2", "fabric-client-gametest-api-v1")) {
+        "modTestmodImplementation"(fabricApi.module(module, sc.properties["deps.fabric_api"]))
+    }
+    // Single modules don't bring their Fabric API dependencies (which differ between versions),
+    // so the tester runs with all of Fabric API.
+    "modTestmodRuntimeOnly"("net.fabricmc.fabric-api:fabric-api:${sc.properties.get<String>("deps.fabric_api")}")
 }
 
 java {

core/build.gradle.kts

@@ -11,6 +11,9 @@ repositories {
 }
 
 dependencies {
+    // Same version Saturn Client ships, so only one copy ends up in the game.
+    implementation("com.fasterxml.jackson.core:jackson-databind:2.17.0")
+
     testImplementation(platform("org.junit:junit-bom:5.13.4"))
     testImplementation("org.junit.jupiter:junit-jupiter")
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")

core/src/main/java/org/saturnclient/emotes/core/Animation.java

@@ -14,4 +14,12 @@ public interface Animation {
     default boolean loops() {
         return false;
     }
+
+    /**
+     * Where a looping animation starts again after reaching {@link #length()}, in ticks. The part
+     * before it plays once, like an intro.
+     */
+    default float loopStart() {
+        return 0;
+    }
 }

core/src/main/java/org/saturnclient/emotes/core/AnimationPlayer.java

@@ -18,11 +18,19 @@ public final class AnimationPlayer {
     public float time(long tick, float partialTick) {
         float elapsed = Math.max(0, tick - startTick + partialTick);
         float length = animation.length();
-        if (animation.loops() && length > 0) {
-            return elapsed % length;
-        }
+        if (!animation.loops()) {
             return Math.min(elapsed, length);
         }
+        if (elapsed < length) {
+            return elapsed;
+        }
+        float loopStart = animation.loopStart();
+        float loopLength = length - loopStart;
+        if (loopLength <= 0) {
+            return length;
+        }
+        return loopStart + (elapsed - length) % loopLength;
+    }
 
     public boolean isFinished(long tick) {
         return !animation.loops() && tick - startTick >= animation.length();

core/src/main/java/org/saturnclient/emotes/core/Bone.java

@@ -2,7 +2,14 @@ package org.saturnclient.emotes.core;
 
 /** The parts of the player model an animation can move. */
 public enum Bone {
+    /**
+     * The whole player. Offsets are in model pixels (Y down, like the other bones), and rotations turn
+     * the whole model around its middle, 12.8 pixels below the neck (0.7 blocks above the feet). Used
+     * for flips, spins and jumps.
+     */
+    ROOT,
     HEAD,
+    /** The torso. It bends from the hips; see {@code LimbBend#anchoredAtEnd}. */
     BODY,
     RIGHT_ARM,
     LEFT_ARM,

core/src/main/java/org/saturnclient/emotes/core/Emote.java

@@ -0,0 +1,9 @@
+package org.saturnclient.emotes.core;
+
+/**
+ * An animation with the details a player sees, like in an emote wheel.
+ *
+ * @param id identifies the emote, for example in network messages ("facepalm")
+ */
+public record Emote(String id, String name, String description, String author, Animation animation) {
+}

core/src/main/java/org/saturnclient/emotes/core/EmoteRegistry.java

@@ -0,0 +1,47 @@
+package org.saturnclient.emotes.core;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import org.saturnclient.emotes.core.format.EmotecraftLoader;
+
+/** Emotes by ID, in the order they were added. Safe to use from any thread. */
+public final class EmoteRegistry {
+    private final Map<String, Emote> emotes = new LinkedHashMap<>();
+
+    /** Adds the emote, replacing any with the same ID. */
+    public synchronized Emote register(Emote emote) {
+        emotes.put(emote.id(), emote);
+        return emote;
+    }
+
+    /** Reads an emote in Emotecraft's JSON format and registers it under {@code id}. */
+    public Emote loadEmotecraft(String id, InputStream json) throws IOException {
+        return register(EmotecraftLoader.load(id, json));
+    }
+
+    public synchronized Optional<Emote> get(String id) {
+        return Optional.ofNullable(emotes.get(id));
+    }
+
+    public synchronized List<Emote> all() {
+        return List.copyOf(emotes.values());
+    }
+
+    public synchronized List<String> ids() {
+        return new ArrayList<>(emotes.keySet());
+    }
+
+    public synchronized boolean remove(String id) {
+        return emotes.remove(id) != null;
+    }
+
+    public synchronized void clear() {
+        emotes.clear();
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/bend/Bezier.java

@@ -0,0 +1,51 @@
+package org.saturnclient.emotes.core.bend;
+
+import java.util.List;
+
+/** A Bézier curve of any degree, evaluated with De Casteljau's algorithm. */
+public final class Bezier {
+    private final Vec3[] points;
+
+    public Bezier(List<Vec3> controlPoints) {
+        if (controlPoints.size() < 2) {
+            throw new IllegalArgumentException("A Bézier curve needs at least two control points");
+        }
+        this.points = controlPoints.toArray(Vec3[]::new);
+    }
+
+    public static Bezier of(Vec3... controlPoints) {
+        return new Bezier(List.of(controlPoints));
+    }
+
+    public int degree() {
+        return points.length - 1;
+    }
+
+    public List<Vec3> controlPoints() {
+        return List.of(points);
+    }
+
+    /** The point at {@code t} in [0, 1]. */
+    public Vec3 point(float t) {
+        return deCasteljau(points, t);
+    }
+
+    /** The first derivative at {@code t}: the tangent, scaled by the curve's speed. */
+    public Vec3 derivative(float t) {
+        Vec3[] hodograph = new Vec3[points.length - 1];
+        for (int i = 0; i < hodograph.length; i++) {
+            hodograph[i] = points[i + 1].sub(points[i]).scale(degree());
+        }
+        return deCasteljau(hodograph, t);
+    }
+
+    private static Vec3 deCasteljau(Vec3[] controlPoints, float t) {
+        Vec3[] work = controlPoints.clone();
+        for (int level = work.length - 1; level > 0; level--) {
+            for (int i = 0; i < level; i++) {
+                work[i] = work[i].lerp(work[i + 1], t);
+            }
+        }
+        return work[0];
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/bend/LimbBend.java

@@ -0,0 +1,261 @@
+package org.saturnclient.emotes.core.bend;
+
+/**
+ * Bends one limb along a single axis, the way an elbow or knee folds.
+ *
+ * <p>Coordinates are the limb's model space in pixels: the limb hangs along +Y from {@code start}
+ * to {@code end}, and its front faces -Z. At rest, the spine runs down the limb's center (x = z = 0).
+ * When bent, the spine follows a cubic Bézier curve whose control polygon is the rigid "upper half,
+ * joint, lower half" shape, so the upper and lower halves stay nearly straight and the joint curves.
+ *
+ * <p>The spine is split into {@code segments} rings, spaced evenly by arc length so the limb keeps its
+ * length and each piece covers the same texture rows as before. Each ring moves its cross-section
+ * rigidly, so neighbouring pieces share their vertices and the mesh stays closed however far it bends.
+ *
+ * <p>A limb is normally anchored at {@code start}, its pivot. The torso is anchored at {@code end}
+ * instead: the hips stay on the legs and the upper half leans (see {@link #anchoredAtEnd}).
+ */
+public final class LimbBend {
+    /** Samples used to measure the curve's arc length. */
+    private static final int ARC_SAMPLES = 64;
+
+    private final float start;
+    private final float length;
+    /** Whether the fixed end is {@code end}. Then everything is mirrored along Y around the middle. */
+    private final boolean anchoredAtEnd;
+    private final int segments;
+    private final float angle;
+    /** Unit bend direction D in the XZ plane, and the rotation axis n = Y × D. */
+    private final float dirX, dirZ;
+    private final float axisX, axisZ;
+
+    /** Ring centers and their rotation around n, for rings 0..segments. */
+    private final float[] ringX, ringY, ringZ, ringAngle;
+
+    /**
+     * @param start     top of the limb (its pivot end), along Y
+     * @param end       bottom of the limb, along Y
+     * @param angle     how far the lower half folds, in radians
+     * @param axis      direction the limb folds towards, as an angle around the limb: 0 folds to the
+     *                  front (-Z) and PI/2 folds to +X
+     * @param sharpness 0 for a long, round curve (a quadratic Bézier) up to 1 for a tight joint
+     * @param segments  number of pieces the limb is divided into
+     */
+    public LimbBend(float start, float end, float angle, float axis, float sharpness, int segments) {
+        this(start, end, angle, axis, sharpness, segments, false);
+    }
+
+    /**
+     * Like {@link #LimbBend(float, float, float, float, float, int)}, but {@code end} stays in place and
+     * the half towards {@code start} folds. Axis 0 still folds towards the front.
+     */
+    public static LimbBend anchoredAtEnd(float start, float end, float angle, float axis, float sharpness,
+            int segments) {
+        return new LimbBend(start, end, angle, axis, sharpness, segments, true);
+    }
+
+    private LimbBend(float start, float end, float angle, float axis, float sharpness, int segments,
+            boolean anchoredAtEnd) {
+        if (end <= start) {
+            throw new IllegalArgumentException("end must be below start");
+        }
+        if (segments < 1) {
+            throw new IllegalArgumentException("segments must be at least 1");
+        }
+        this.start = start;
+        this.length = end - start;
+        this.anchoredAtEnd = anchoredAtEnd;
+        this.segments = segments;
+        this.angle = angle;
+        this.dirX = (float) Math.sin(axis);
+        this.dirZ = (float) -Math.cos(axis);
+        // n = Y × D = (0, 1, 0) × (dirX, 0, dirZ)
+        this.axisX = dirZ;
+        this.axisZ = -dirX;
+
+        ringX = new float[segments + 1];
+        ringY = new float[segments + 1];
+        ringZ = new float[segments + 1];
+        ringAngle = new float[segments + 1];
+
+        if (isStraight()) {
+            for (int i = 0; i <= segments; i++) {
+                ringY[i] = start + length * i / segments;
+            }
+            return;
+        }
+        buildRings(spine(Math.max(0, Math.min(1, sharpness))));
+    }
+
+    /** Whether the limb is (close enough to) unbent. Straight limbs can be drawn as they are. */
+    public boolean isStraight() {
+        return Math.abs(angle) < 1e-4f;
+    }
+
+    public int segments() {
+        return segments;
+    }
+
+    /** Top of the limb along Y (its pivot end), as given to the constructor. */
+    public float start() {
+        return start;
+    }
+
+    /** Bottom of the limb along Y (the hand or foot end), as given to the constructor. */
+    public float end() {
+        return start + length;
+    }
+
+    /** Y positions where the limb is cut into pieces, not counting its ends. */
+    public float[] cuts() {
+        float[] cuts = new float[segments - 1];
+        for (int i = 1; i < segments; i++) {
+            cuts[i - 1] = start + length * i / segments;
+        }
+        return cuts;
+    }
+
+    private Bezier spine(float sharpness) {
+        float half = length / 2;
+        Vec3 top = new Vec3(0, start, 0);
+        Vec3 joint = new Vec3(0, start + half, 0);
+        Vec3 lower = new Vec3(dirX * (float) Math.sin(angle), (float) Math.cos(angle), dirZ * (float) Math.sin(angle));
+        Vec3 bottom = joint.add(lower.scale(half));
+        // At sharpness 0 this is the quadratic (top, joint, bottom) raised to a cubic.
+        float pull = 2f / 3 + sharpness / 3;
+        return Bezier.of(top, top.lerp(joint, pull), bottom.lerp(joint, pull), bottom);
+    }
+
+    private void buildRings(Bezier curve) {
+        // Arc length table, so rings can be spaced evenly along the curve.
+        float[] ts = new float[ARC_SAMPLES + 1];
+        float[] lengths = new float[ARC_SAMPLES + 1];
+        Vec3 previous = curve.point(0);
+        for (int i = 1; i <= ARC_SAMPLES; i++) {
+            ts[i] = (float) i / ARC_SAMPLES;
+            Vec3 point = curve.point(ts[i]);
+            lengths[i] = lengths[i - 1] + point.sub(previous).length();
+            previous = point;
+        }
+        // The curve cuts the corner, so it's shorter than the limb. Scale it about the top to fit.
+        float scale = length / lengths[ARC_SAMPLES];
+        Vec3 top = curve.point(0);
+        Vec3 dir = new Vec3(dirX, 0, dirZ);
+
+        int sample = 0;
+        for (int i = 0; i <= segments; i++) {
+            float target = lengths[ARC_SAMPLES] * i / segments;
+            while (sample < ARC_SAMPLES - 1 && lengths[sample + 1] < target) {
+                sample++;
+            }
+            float span = lengths[sample + 1] - lengths[sample];
+            float f = span > 0 ? (target - lengths[sample]) / span : 0;
+            float t = ts[sample] + (ts[sample + 1] - ts[sample]) * f;
+
+            Vec3 center = top.add(curve.point(t).sub(top).scale(scale));
+            Vec3 tangent = curve.derivative(t);
+            ringX[i] = center.x();
+            ringY[i] = center.y();
+            ringZ[i] = center.z();
+            ringAngle[i] = (float) Math.atan2(tangent.dot(dir), tangent.y());
+        }
+    }
+
+    /**
+     * Moves a point from the straight limb onto the bent one. Points above or below the limb follow
+     * the end rings' tangents, so overlay layers and armor that stick out past the limb stay attached.
+     *
+     * @param out receives the bent position as {x, y, z}
+     */
+    public void bendPoint(float x, float y, float z, float[] out) {
+        if (anchoredAtEnd) {
+            bendPointFromStart(x, mirror(y), z, out);
+            out[1] = mirror(out[1]);
+        } else {
+            bendPointFromStart(x, y, z, out);
+        }
+    }
+
+    /** Rotates a direction (a face normal) the same way {@link #bendPoint} rotates points at {@code atY}. */
+    public void bendDirection(float atY, float nx, float ny, float nz, float[] out) {
+        if (anchoredAtEnd) {
+            rotate(nx, -ny, nz, angleFromStart(mirror(atY)), out);
+            out[1] = -out[1];
+        } else {
+            rotate(nx, ny, nz, angleFromStart(atY), out);
+        }
+    }
+
+    /**
+     * How far the limb has turned at {@code y}, as a rotation around {@link #axis()} by this angle.
+     * Parts attached to the limb at {@code y} (like the head and arms on the torso) turn by this much.
+     */
+    public float angleAt(float y) {
+        // Mirroring along Y turns a rotation around a horizontal axis the other way.
+        return anchoredAtEnd ? -angleFromStart(mirror(y)) : angleFromStart(y);
+    }
+
+    /** The unit axis the limb turns around. It's horizontal, at right angles to the bend direction. */
+    public Vec3 axis() {
+        return new Vec3(axisX, 0, axisZ);
+    }
+
+    private float mirror(float y) {
+        return 2 * start + length - y;
+    }
+
+    private void bendPointFromStart(float x, float y, float z, float[] out) {
+        float along = (y - start) / length * segments;
+        int ring;
+        float f;
+        float extra = 0;
+        if (along <= 0) {
+            ring = 0;
+            f = 0;
+            extra = y - start;
+        } else if (along >= segments) {
+            ring = segments - 1;
+            f = 1;
+            extra = y - (start + length);
+        } else {
+            ring = Math.min((int) along, segments - 1);
+            f = along - ring;
+        }
+
+        float cx = lerp(ringX[ring], ringX[ring + 1], f);
+        float cy = lerp(ringY[ring], ringY[ring + 1], f);
+        float cz = lerp(ringZ[ring], ringZ[ring + 1], f);
+        float a = lerp(ringAngle[ring], ringAngle[ring + 1], f);
+
+        // The cross-section offset (x, extra, z) rotates with the ring. Past the ends, "extra"
+        // carries on along the end tangent.
+        rotate(x, extra, z, a, out);
+        out[0] += cx;
+        out[1] += cy;
+        out[2] += cz;
+    }
+
+    private float angleFromStart(float y) {
+        float along = Math.max(0, Math.min(segments, (y - start) / length * segments));
+        int ring = Math.min((int) along, segments - 1);
+        return lerp(ringAngle[ring], ringAngle[ring + 1], along - ring);
+    }
+
+    /** Rodrigues' rotation of v around the bend axis n by {@code a}. */
+    private void rotate(float x, float y, float z, float a, float[] out) {
+        float cos = (float) Math.cos(a);
+        float sin = (float) Math.sin(a);
+        // n = (axisX, 0, axisZ)
+        float crossX = -axisZ * y;
+        float crossY = axisZ * x - axisX * z;
+        float crossZ = axisX * y;
+        float dot = axisX * x + axisZ * z;
+        out[0] = x * cos + crossX * sin + axisX * dot * (1 - cos);
+        out[1] = y * cos + crossY * sin;
+        out[2] = z * cos + crossZ * sin + axisZ * dot * (1 - cos);
+    }
+
+    private static float lerp(float a, float b, float t) {
+        return a + (b - a) * t;
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/bend/QuadSplitter.java

@@ -0,0 +1,71 @@
+package org.saturnclient.emotes.core.bend;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Cuts the faces of a box into horizontal strips so they can bend.
+ *
+ * <p>A quad is four vertices of {x, y, z, u, v}. Faces that run along Y (the sides of a limb) are cut
+ * at every Y in {@code cuts}, and each strip's UVs are interpolated along the face, so the strips
+ * together cover the same texture as the original face. Flat faces (the limb's ends) are kept as they
+ * are. Strips keep the original winding.
+ */
+public final class QuadSplitter {
+    private static final float EPSILON = 1e-4f;
+
+    private QuadSplitter() {
+    }
+
+    public static List<float[][]> split(float[][] quad, float[] cuts) {
+        float minY = Float.MAX_VALUE;
+        float maxY = -Float.MAX_VALUE;
+        for (float[] vertex : quad) {
+            minY = Math.min(minY, vertex[1]);
+            maxY = Math.max(maxY, vertex[1]);
+        }
+        if (maxY - minY < EPSILON) {
+            return List.<float[][]>of(quad);
+        }
+
+        // Each vertex's partner is its neighbour at the other end of the face's vertical edge.
+        int[] partner = new int[4];
+        for (int i = 0; i < 4; i++) {
+            int next = (i + 1) % 4;
+            int prev = (i + 3) % 4;
+            partner[i] = Math.abs(quad[next][1] - quad[i][1]) > EPSILON ? next : prev;
+        }
+
+        List<Float> bounds = new ArrayList<>();
+        bounds.add(minY);
+        for (float cut : cuts) {
+            if (cut > minY + EPSILON && cut < maxY - EPSILON) {
+                bounds.add(cut);
+            }
+        }
+        bounds.add(maxY);
+
+        List<float[][]> strips = new ArrayList<>(bounds.size() - 1);
+        for (int s = 0; s + 1 < bounds.size(); s++) {
+            float top = bounds.get(s);
+            float bottom = bounds.get(s + 1);
+            float[][] strip = new float[4][];
+            for (int i = 0; i < 4; i++) {
+                float[] from = quad[i];
+                float[] to = quad[partner[i]];
+                float target = from[1] < to[1] ? top : bottom;
+                strip[i] = lerp(from, to, (target - from[1]) / (to[1] - from[1]));
+            }
+            strips.add(strip);
+        }
+        return strips;
+    }
+
+    private static float[] lerp(float[] a, float[] b, float t) {
+        float[] out = new float[a.length];
+        for (int i = 0; i < a.length; i++) {
+            out[i] = a[i] + (b[i] - a[i]) * t;
+        }
+        return out;
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/bend/Vec3.java

@@ -0,0 +1,39 @@
+package org.saturnclient.emotes.core.bend;
+
+/** A small immutable 3D vector, in model pixels. */
+public record Vec3(float x, float y, float z) {
+    public static final Vec3 ZERO = new Vec3(0, 0, 0);
+
+    public Vec3 add(Vec3 o) {
+        return new Vec3(x + o.x, y + o.y, z + o.z);
+    }
+
+    public Vec3 sub(Vec3 o) {
+        return new Vec3(x - o.x, y - o.y, z - o.z);
+    }
+
+    public Vec3 scale(float s) {
+        return new Vec3(x * s, y * s, z * s);
+    }
+
+    public Vec3 lerp(Vec3 o, float t) {
+        return new Vec3(x + (o.x - x) * t, y + (o.y - y) * t, z + (o.z - z) * t);
+    }
+
+    public float dot(Vec3 o) {
+        return x * o.x + y * o.y + z * o.z;
+    }
+
+    public Vec3 cross(Vec3 o) {
+        return new Vec3(y * o.z - z * o.y, z * o.x - x * o.z, x * o.y - y * o.x);
+    }
+
+    public float length() {
+        return (float) Math.sqrt(dot(this));
+    }
+
+    public Vec3 normalize() {
+        float length = length();
+        return length < 1e-7f ? ZERO : scale(1 / length);
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/format/Easing.java

@@ -0,0 +1,116 @@
+package org.saturnclient.emotes.core.format;
+
+import java.util.Locale;
+
+/**
+ * Easing curves between keyframes (see easings.net). Each maps progress through a segment, from 0
+ * to 1, to how far the value has moved.
+ */
+public enum Easing {
+    LINEAR,
+    /** Holds the earlier keyframe's value until the next one. */
+    CONSTANT,
+    INSINE, OUTSINE, INOUTSINE,
+    INQUAD, OUTQUAD, INOUTQUAD,
+    INCUBIC, OUTCUBIC, INOUTCUBIC,
+    INQUART, OUTQUART, INOUTQUART,
+    INQUINT, OUTQUINT, INOUTQUINT,
+    INEXPO, OUTEXPO, INOUTEXPO,
+    INCIRC, OUTCIRC, INOUTCIRC,
+    INBACK, OUTBACK, INOUTBACK,
+    INELASTIC, OUTELASTIC, INOUTELASTIC,
+    INBOUNCE, OUTBOUNCE, INOUTBOUNCE;
+
+    private static final double BACK = 1.70158;
+    private static final double BACK_INOUT = BACK * 1.525;
+
+    /**
+     * Reads an Emotecraft easing name. Case and underscores don't matter, and the optional "EASE"
+     * prefix is dropped ("EASEINOUTQUAD" and "inOutQuad" both work). Unknown names are linear.
+     */
+    public static Easing fromName(String name) {
+        if (name == null) {
+            return LINEAR;
+        }
+        String key = name.toUpperCase(Locale.ROOT).replace("_", "");
+        if (key.startsWith("EASE")) {
+            key = key.substring(4);
+        }
+        try {
+            return valueOf(key);
+        } catch (IllegalArgumentException e) {
+            return LINEAR;
+        }
+    }
+
+    public float apply(float progress) {
+        double t = Math.max(0, Math.min(1, progress));
+        return (float) switch (this) {
+            case LINEAR -> t;
+            case CONSTANT -> t < 1 ? 0 : 1;
+            case INSINE -> 1 - Math.cos(t * Math.PI / 2);
+            case OUTSINE -> Math.sin(t * Math.PI / 2);
+            case INOUTSINE -> -(Math.cos(Math.PI * t) - 1) / 2;
+            case INQUAD -> in(t, 2);
+            case OUTQUAD -> out(t, 2);
+            case INOUTQUAD -> inOut(t, 2);
+            case INCUBIC -> in(t, 3);
+            case OUTCUBIC -> out(t, 3);
+            case INOUTCUBIC -> inOut(t, 3);
+            case INQUART -> in(t, 4);
+            case OUTQUART -> out(t, 4);
+            case INOUTQUART -> inOut(t, 4);
+            case INQUINT -> in(t, 5);
+            case OUTQUINT -> out(t, 5);
+            case INOUTQUINT -> inOut(t, 5);
+            case INEXPO -> t == 0 ? 0 : Math.pow(2, 10 * t - 10);
+            case OUTEXPO -> t == 1 ? 1 : 1 - Math.pow(2, -10 * t);
+            case INOUTEXPO -> t == 0 || t == 1 ? t
+                    : t < 0.5 ? Math.pow(2, 20 * t - 10) / 2 : (2 - Math.pow(2, -20 * t + 10)) / 2;
+            case INCIRC -> 1 - Math.sqrt(1 - t * t);
+            case OUTCIRC -> Math.sqrt(1 - (t - 1) * (t - 1));
+            case INOUTCIRC -> t < 0.5 ? (1 - Math.sqrt(1 - 4 * t * t)) / 2
+                    : (Math.sqrt(1 - Math.pow(-2 * t + 2, 2)) + 1) / 2;
+            case INBACK -> (BACK + 1) * t * t * t - BACK * t * t;
+            case OUTBACK -> 1 + (BACK + 1) * Math.pow(t - 1, 3) + BACK * Math.pow(t - 1, 2);
+            case INOUTBACK -> t < 0.5
+                    ? Math.pow(2 * t, 2) * ((BACK_INOUT + 1) * 2 * t - BACK_INOUT) / 2
+                    : (Math.pow(2 * t - 2, 2) * ((BACK_INOUT + 1) * (t * 2 - 2) + BACK_INOUT) + 2) / 2;
+            case INELASTIC -> t == 0 || t == 1 ? t
+                    : -Math.pow(2, 10 * t - 10) * Math.sin((t * 10 - 10.75) * (2 * Math.PI / 3));
+            case OUTELASTIC -> t == 0 || t == 1 ? t
+                    : Math.pow(2, -10 * t) * Math.sin((t * 10 - 0.75) * (2 * Math.PI / 3)) + 1;
+            case INOUTELASTIC -> t == 0 || t == 1 ? t
+                    : t < 0.5 ? -(Math.pow(2, 20 * t - 10) * Math.sin((20 * t - 11.125) * (2 * Math.PI / 4.5))) / 2
+                    : Math.pow(2, -20 * t + 10) * Math.sin((20 * t - 11.125) * (2 * Math.PI / 4.5)) / 2 + 1;
+            case INBOUNCE -> 1 - bounce(1 - t);
+            case OUTBOUNCE -> bounce(t);
+            case INOUTBOUNCE -> t < 0.5 ? (1 - bounce(1 - 2 * t)) / 2 : (1 + bounce(2 * t - 1)) / 2;
+        };
+    }
+
+    private static double in(double t, int power) {
+        return Math.pow(t, power);
+    }
+
+    private static double out(double t, int power) {
+        return 1 - Math.pow(1 - t, power);
+    }
+
+    private static double inOut(double t, int power) {
+        return t < 0.5 ? Math.pow(2, power - 1) * Math.pow(t, power) : 1 - Math.pow(-2 * t + 2, power) / 2;
+    }
+
+    private static double bounce(double t) {
+        double n = 7.5625;
+        double d = 2.75;
+        if (t < 1 / d) {
+            return n * t * t;
+        } else if (t < 2 / d) {
+            return n * (t -= 1.5 / d) * t + 0.75;
+        } else if (t < 2.5 / d) {
+            return n * (t -= 2.25 / d) * t + 0.9375;
+        }
+        return n * (t -= 2.625 / d) * t + 0.984375;
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/format/EmotecraftLoader.java

@@ -0,0 +1,179 @@
+package org.saturnclient.emotes.core.format;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Map;
+
+import org.saturnclient.emotes.core.Bone;
+import org.saturnclient.emotes.core.Emote;
+import org.saturnclient.emotes.core.format.KeyframeAnimation.Channel;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+/**
+ * Reads emotes in Emotecraft's JSON format, following player-animation-lib's reader:
+ *
+ * <pre>
+ * { "version": 1, "name": ..., "description": ..., "author": ...,
+ *   "emote": { "isLoop": ..., "returnTick": ..., "endTick": ..., "stopTick": ..., "degrees": ...,
+ *              "moves": [ { "tick": 10, "easing": "INOUTQUAD", "turn": 0,
+ *                           "rightArm": { "pitch": -1.9, "bend": -0.9 } }, ... ] } }
+ * </pre>
+ *
+ * <p>Parts are {@code head}, {@code torso}, {@code rightArm}, {@code leftArm}, {@code rightLeg},
+ * {@code leftLeg} and {@code body} (the whole player, {@link Bone#ROOT}). Before format version 3,
+ * {@code torso} also means the whole player. Axes are {@code x}, {@code y}, {@code z}, {@code pitch},
+ * {@code yaw}, {@code roll}, {@code bend} and {@code axis}. Values are converted to this library's
+ * conventions:
+ * <ul>
+ * <li>Part positions are absolute pivots (the right arm rests at x = -5, y = 2), so the rest pivot is
+ * subtracted to get an offset.</li>
+ * <li>Whole-player positions are in blocks with Y up, and its rotations are around the world axes
+ * before Minecraft flips the model, so X, Y, pitch and yaw change sign.</li>
+ * <li>Emotecraft bends limbs the other way, so a limb's {@code bend} changes sign. The torso's doesn't:
+ * ours is anchored at the hips, which already turns it round, so the two agree (a positive bend with
+ * axis 0 leans forward in both).</li>
+ * <li>The whole player can't bend. In Emotecraft its {@code bend} and {@code axis} bend the torso,
+ * so they go to {@link Bone#BODY}.</li>
+ * <li>Angles are in degrees unless {@code "degrees": false}.</li>
+ * <li>{@code turn} adds whole turns to the move's angles, for spins and flips.</li>
+ * <li>Looping emotes jump back to {@code returnTick} after {@code endTick}, and only loop when they
+ * have a {@code returnTick}.</li>
+ * </ul>
+ *
+ * <p>Not supported: {@code scaleX}/{@code scaleY}/{@code scaleZ}, {@code easingArg}, and the blend with
+ * the vanilla pose before the first keyframe and between {@code endTick} and {@code stopTick} (the
+ * first and last keyframes are held instead).
+ */
+public final class EmotecraftLoader {
+    private static final ObjectMapper MAPPER = new ObjectMapper();
+
+    private static final Map<String, Bone> PARTS = Map.of(
+            "body", Bone.ROOT,
+            "head", Bone.HEAD,
+            "torso", Bone.BODY, // Bone.ROOT before version 3
+
+            "rightArm", Bone.RIGHT_ARM,
+            "leftArm", Bone.LEFT_ARM,
+            "rightLeg", Bone.RIGHT_LEG,
+            "leftLeg", Bone.LEFT_LEG);
+
+    private static final Map<String, Channel> AXES = Map.of(
+            "x", Channel.X,
+            "y", Channel.Y,
+            "z", Channel.Z,
+            "pitch", Channel.PITCH,
+            "yaw", Channel.YAW,
+            "roll", Channel.ROLL,
+            "bend", Channel.BEND,
+            "axis", Channel.BEND_AXIS);
+
+    /** Emotecraft's rest pivots, {x, y, z} in model pixels. */
+    private static final Map<Bone, float[]> REST_PIVOTS = Map.of(
+            Bone.RIGHT_ARM, new float[] { -5, 2, 0 },
+            Bone.LEFT_ARM, new float[] { 5, 2, 0 },
+            Bone.RIGHT_LEG, new float[] { -1.9f, 12, 0.1f },
+            Bone.LEFT_LEG, new float[] { 1.9f, 12, 0.1f });
+
+    private static final float FULL_TURN = (float) (2 * Math.PI);
+
+    private EmotecraftLoader() {
+    }
+
+    public static Emote load(String id, InputStream json) throws IOException {
+        return read(id, MAPPER.readTree(json));
+    }
+
+    public static Emote load(String id, String json) throws IOException {
+        return read(id, MAPPER.readTree(json));
+    }
+
+    private static Emote read(String id, JsonNode root) throws IOException {
+        JsonNode emote = root.path("emote");
+        JsonNode moves = emote.path("moves");
+        if (!moves.isArray()) {
+            throw new IOException("Emote " + id + " has no \"emote.moves\" array");
+        }
+        int version = root.path("version").asInt(1);
+        boolean degrees = bool(emote.path("degrees"), true);
+
+        KeyframeAnimation.Builder animation = KeyframeAnimation.builder()
+                .easeBefore(bool(emote.path("easeBeforeKeyframe"), false));
+        float lastTick = 0;
+        for (JsonNode move : moves) {
+            float tick = (float) move.path("tick").asDouble();
+            lastTick = Math.max(lastTick, tick);
+            Easing easing = Easing.fromName(move.path("easing").asText(null));
+            float turn = (float) move.path("turn").asDouble(0) * FULL_TURN;
+
+            for (Map.Entry<String, Bone> part : PARTS.entrySet()) {
+                JsonNode axes = move.get(part.getKey());
+                if (axes == null || !axes.isObject()) {
+                    continue;
+                }
+                Bone bone = part.getKey().equals("torso") && version < 3 ? Bone.ROOT : part.getValue();
+                for (Map.Entry<String, Channel> axis : AXES.entrySet()) {
+                    JsonNode value = axes.get(axis.getKey());
+                    if (value != null && value.isNumber()) {
+                        Channel channel = axis.getValue();
+                        boolean bend = channel == Channel.BEND || channel == Channel.BEND_AXIS;
+                        Bone target = bone == Bone.ROOT && bend ? Bone.BODY : bone;
+                        float converted = convert(target, channel, value.floatValue(), degrees, turn);
+                        animation.keyframe(target, channel, tick, converted, easing);
+                    }
+                }
+            }
+        }
+
+        float endTick = (float) emote.path("endTick").asDouble(lastTick);
+        if (bool(emote.path("isLoop"), false) && emote.has("returnTick")) {
+            // endTick itself plays before jumping back.
+            float returnTick = (float) emote.path("returnTick").asDouble();
+            animation.length(endTick + 1).loop(returnTick <= endTick ? returnTick : 0);
+        } else {
+            animation.length((float) emote.path("stopTick").asDouble(endTick));
+        }
+
+        return new Emote(id, text(root.path("name"), id), text(root.path("description"), ""),
+                text(root.path("author"), ""), animation.build());
+    }
+
+    private static float convert(Bone bone, Channel channel, float value, boolean degrees, float turn) {
+        return switch (channel) {
+            case X, Y, Z -> {
+                if (bone == Bone.ROOT) {
+                    // Blocks to pixels, and into model space, where X and Y point the other way.
+                    yield channel == Channel.Z ? value * 16 : -value * 16;
+                }
+                float[] rest = REST_PIVOTS.get(bone);
+                yield rest == null ? value : value - rest[channel.ordinal()];
+            }
+            case PITCH, YAW, ROLL -> {
+                float radians = angle(value, degrees, turn);
+                yield bone == Bone.ROOT && channel != Channel.ROLL ? -radians : radians;
+            }
+            case BEND -> bone == Bone.BODY ? angle(value, degrees, turn) : -angle(value, degrees, turn);
+            case BEND_AXIS -> angle(value, degrees, turn);
+        };
+    }
+
+    private static float angle(float value, boolean degrees, float turn) {
+        return (degrees ? (float) Math.toRadians(value) : value) + turn;
+    }
+
+    /** Emotecraft writes booleans both as JSON booleans and as "true"/"false" strings. */
+    private static boolean bool(JsonNode node, boolean fallback) {
+        if (node.isBoolean()) {
+            return node.booleanValue();
+        }
+        if (node.isTextual()) {
+            return Boolean.parseBoolean(node.textValue());
+        }
+        return fallback;
+    }
+
+    private static String text(JsonNode node, String fallback) {
+        return node.isTextual() ? node.textValue() : fallback;
+    }
+}

core/src/main/java/org/saturnclient/emotes/core/format/KeyframeAnimation.java

@@ -0,0 +1,165 @@
+package org.saturnclient.emotes.core.format;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Map;
+
+import org.saturnclient.emotes.core.Animation;
+import org.saturnclient.emotes.core.Bone;
+import org.saturnclient.emotes.core.BoneTransform;
+import org.saturnclient.emotes.core.Pose;
+
+/**
+ * An animation made of keyframes: for each bone, each {@link Channel} has its own list of values at
+ * given ticks, and values in between follow the segment's {@link Easing}.
+ *
+ * <p>A bone with any keyframes gets a full {@link BoneTransform} each frame. Its channels without
+ * keyframes are 0. Bones without keyframes keep their vanilla pose. Before a channel's first keyframe
+ * and after its last one, it holds that keyframe's value.
+ */
+public final class KeyframeAnimation implements Animation {
+    /** The fields of a {@link BoneTransform}, in the same units. */
+    public enum Channel {
+        X, Y, Z, PITCH, YAW, ROLL, BEND, BEND_AXIS
+    }
+
+    public record Keyframe(float tick, float value, Easing easing) {
+    }
+
+    private final Map<Bone, Map<Channel, Keyframe[]>> tracks;
+    private final float length;
+    private final boolean loops;
+    private final float loopStart;
+    private final boolean easeBefore;
+
+    private KeyframeAnimation(Builder builder) {
+        this.tracks = new EnumMap<>(Bone.class);
+        builder.keyframes.forEach((bone, channels) -> {
+            Map<Channel, Keyframe[]> sorted = new EnumMap<>(Channel.class);
+            channels.forEach((channel, keyframes) -> sorted.put(channel, sortedUnique(keyframes)));
+            tracks.put(bone, sorted);
+        });
+        this.length = builder.length;
+        this.loops = builder.loops;
+        this.loopStart = builder.loopStart;
+        this.easeBefore = builder.easeBefore;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    @Override
+    public float length() {
+        return length;
+    }
+
+    @Override
+    public boolean loops() {
+        return loops;
+    }
+
+    @Override
+    public float loopStart() {
+        return loopStart;
+    }
+
+    /** The keyframes of one channel, sorted by tick, or an empty array. */
+    public Keyframe[] keyframes(Bone bone, Channel channel) {
+        Map<Channel, Keyframe[]> channels = tracks.get(bone);
+        Keyframe[] keyframes = channels == null ? null : channels.get(channel);
+        return keyframes == null ? new Keyframe[0] : keyframes.clone();
+    }
+
+    @Override
+    public Pose sample(float tick) {
+        Pose.Builder pose = Pose.builder();
+        float[] values = new float[Channel.values().length];
+        for (Map.Entry<Bone, Map<Channel, Keyframe[]>> track : tracks.entrySet()) {
+            Arrays.fill(values, 0);
+            for (Map.Entry<Channel, Keyframe[]> channel : track.getValue().entrySet()) {
+                values[channel.getKey().ordinal()] = valueAt(channel.getValue(), tick);
+            }
+            pose.set(track.getKey(), new BoneTransform(values[0], values[1], values[2], values[3], values[4],
+                    values[5], values[6], values[7]));
+        }
+        return pose.build();
+    }
+
+    private float valueAt(Keyframe[] keyframes, float tick) {
+        if (tick <= keyframes[0].tick()) {
+            return keyframes[0].value();
+        }
+        for (int i = 0; i + 1 < keyframes.length; i++) {
+            Keyframe from = keyframes[i];
+            Keyframe to = keyframes[i + 1];
+            if (tick < to.tick()) {
+                float progress = (tick - from.tick()) / (to.tick() - from.tick());
+                Easing easing = easeBefore ? to.easing() : from.easing();
+                return from.value() + (to.value() - from.value()) * easing.apply(progress);
+            }
+        }
+        return keyframes[keyframes.length - 1].value();
+    }
+
+    /** Sorts by tick. Of several keyframes on the same tick, the last one added wins. */
+    private static Keyframe[] sortedUnique(List<Keyframe> keyframes) {
+        List<Keyframe> sorted = new ArrayList<>(keyframes);
+        sorted.sort(Comparator.comparingDouble(Keyframe::tick)); // Stable, so the added order is kept
+        List<Keyframe> unique = new ArrayList<>(sorted.size());
+        for (Keyframe keyframe : sorted) {
+            if (!unique.isEmpty() && unique.get(unique.size() - 1).tick() == keyframe.tick()) {
+                unique.set(unique.size() - 1, keyframe);
+            } else {
+                unique.add(keyframe);
+            }
+        }
+        return unique.toArray(Keyframe[]::new);
+    }
+
+    public static final class Builder {
+        private final Map<Bone, Map<Channel, List<Keyframe>>> keyframes = new EnumMap<>(Bone.class);
+        private float length;
+        private boolean loops;
+        private float loopStart;
+        private boolean easeBefore;
+
+        private Builder() {
+        }
+
+        public Builder keyframe(Bone bone, Channel channel, float tick, float value, Easing easing) {
+            keyframes.computeIfAbsent(bone, b -> new EnumMap<>(Channel.class))
+                    .computeIfAbsent(channel, c -> new ArrayList<>())
+                    .add(new Keyframe(tick, value, easing));
+            return this;
+        }
+
+        /** Length in ticks. A looping animation repeats from {@code loopStart} after this. */
+        public Builder length(float length) {
+            this.length = length;
+            return this;
+        }
+
+        public Builder loop(float loopStart) {
+            this.loops = true;
+            this.loopStart = loopStart;
+            return this;
+        }
+
+        /**
+         * Whether a segment uses the easing of the keyframe it moves towards. By default it uses the
+         * easing of the keyframe it starts from, like Emotecraft's original format.
+         */
+        public Builder easeBefore(boolean easeBefore) {
+            this.easeBefore = easeBefore;
+            return this;
+        }
+
+        public KeyframeAnimation build() {
+            return new KeyframeAnimation(this);
+        }
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/AnimationPlayerTest.java

@@ -57,4 +57,34 @@ class AnimationPlayerTest {
         AnimationPlayer player = new AnimationPlayer(headSpin(20, false), 100);
         assertEquals(0f, player.time(90, 0), 1e-6);
     }
+
+    @Test
+    void loopsRestartFromLoopStart() {
+        Animation withIntro = new Animation() {
+            @Override
+            public Pose sample(float tick) {
+                return Pose.builder().set(Bone.HEAD, BoneTransform.rotation(0, tick, 0)).build();
+            }
+
+            @Override
+            public float length() {
+                return 20;
+            }
+
+            @Override
+            public boolean loops() {
+                return true;
+            }
+
+            @Override
+            public float loopStart() {
+                return 5;
+            }
+        };
+        AnimationPlayer player = new AnimationPlayer(withIntro, 0);
+        assertEquals(3, player.time(3, 0), 1e-6); // intro plays once
+        assertEquals(19, player.time(19, 0), 1e-6);
+        assertEquals(5, player.time(20, 0), 1e-6); // then 5..20 repeats
+        assertEquals(7, player.time(37, 0), 1e-6);
+    }
 }

core/src/test/java/org/saturnclient/emotes/core/EmoteRegistryTest.java

@@ -0,0 +1,71 @@
+package org.saturnclient.emotes.core;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+class EmoteRegistryTest {
+    private static Emote emote(String id) {
+        return new Emote(id, id, "", "", new Animation() {
+            @Override
+            public Pose sample(float tick) {
+                return Pose.EMPTY;
+            }
+
+            @Override
+            public float length() {
+                return 1;
+            }
+        });
+    }
+
+    @Test
+    void findsEmotesById() {
+        EmoteRegistry registry = new EmoteRegistry();
+        Emote wave = registry.register(emote("wave"));
+        assertSame(wave, registry.get("wave").orElseThrow());
+        assertTrue(registry.get("dab").isEmpty());
+    }
+
+    @Test
+    void keepsTheOrderEmotesWereAdded() {
+        EmoteRegistry registry = new EmoteRegistry();
+        registry.register(emote("b"));
+        registry.register(emote("a"));
+        registry.register(emote("c"));
+        assertEquals(List.of("b", "a", "c"), registry.ids());
+    }
+
+    @Test
+    void replacesEmotesWithTheSameId() {
+        EmoteRegistry registry = new EmoteRegistry();
+        registry.register(emote("wave"));
+        Emote replacement = registry.register(emote("wave"));
+        assertEquals(1, registry.all().size());
+        assertSame(replacement, registry.get("wave").orElseThrow());
+    }
+
+    @Test
+    void removesEmotes() {
+        EmoteRegistry registry = new EmoteRegistry();
+        registry.register(emote("wave"));
+        assertTrue(registry.remove("wave"));
+        assertFalse(registry.remove("wave"));
+    }
+
+    @Test
+    void loadsEmotecraftFiles() throws IOException {
+        EmoteRegistry registry = new EmoteRegistry();
+        try (InputStream in = getClass().getResourceAsStream("/emotes/cry.json")) {
+            registry.loadEmotecraft("cry", in);
+        }
+        assertEquals("T_T", registry.get("cry").orElseThrow().description());
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/bend/BezierTest.java

@@ -0,0 +1,47 @@
+package org.saturnclient.emotes.core.bend;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class BezierTest {
+    private static void assertVec(Vec3 expected, Vec3 actual) {
+        assertEquals(expected.x(), actual.x(), 1e-5);
+        assertEquals(expected.y(), actual.y(), 1e-5);
+        assertEquals(expected.z(), actual.z(), 1e-5);
+    }
+
+    @Test
+    void passesThroughEndpoints() {
+        Bezier curve = Bezier.of(new Vec3(0, 0, 0), new Vec3(1, 2, 0), new Vec3(3, 2, 1), new Vec3(4, 0, 2));
+        assertVec(new Vec3(0, 0, 0), curve.point(0));
+        assertVec(new Vec3(4, 0, 2), curve.point(1));
+    }
+
+    @Test
+    void quadraticMidpoint() {
+        Bezier curve = Bezier.of(new Vec3(0, 0, 0), new Vec3(1, 2, 0), new Vec3(2, 0, 0));
+        // B(0.5) = 0.25 P0 + 0.5 P1 + 0.25 P2
+        assertVec(new Vec3(1, 1, 0), curve.point(0.5f));
+    }
+
+    @Test
+    void endTangentsFollowControlPolygon() {
+        Bezier curve = Bezier.of(new Vec3(0, 0, 0), new Vec3(0, 1, 0), new Vec3(1, 1, 0), new Vec3(2, 1, 0));
+        // B'(0) = n (P1 - P0), B'(1) = n (P3 - P2)
+        assertVec(new Vec3(0, 3, 0), curve.derivative(0));
+        assertVec(new Vec3(3, 0, 0), curve.derivative(1));
+    }
+
+    @Test
+    void derivativeMatchesFiniteDifference() {
+        Bezier curve = Bezier.of(new Vec3(0, 0, 0), new Vec3(1, 3, -1), new Vec3(2, -1, 4), new Vec3(5, 2, 0));
+        float t = 0.37f;
+        float h = 1e-3f;
+        Vec3 numeric = curve.point(t + h).sub(curve.point(t - h)).scale(1 / (2 * h));
+        Vec3 exact = curve.derivative(t);
+        assertEquals(exact.x(), numeric.x(), 1e-2);
+        assertEquals(exact.y(), numeric.y(), 1e-2);
+        assertEquals(exact.z(), numeric.z(), 1e-2);
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/bend/LimbBendTest.java

@@ -0,0 +1,175 @@
+package org.saturnclient.emotes.core.bend;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class LimbBendTest {
+    private static final float HALF_PI = (float) (Math.PI / 2);
+
+    /** An arm: pivot at the shoulder, box from y = -2 to 10. */
+    private static LimbBend arm(float angle, float axis) {
+        return new LimbBend(-2, 10, angle, axis, 0.5f, 12);
+    }
+
+    private static float[] bend(LimbBend bend, float x, float y, float z) {
+        float[] out = new float[3];
+        bend.bendPoint(x, y, z, out);
+        return out;
+    }
+
+    private static float distance(float[] a, float[] b) {
+        float dx = a[0] - b[0], dy = a[1] - b[1], dz = a[2] - b[2];
+        return (float) Math.sqrt(dx * dx + dy * dy + dz * dz);
+    }
+
+    @Test
+    void zeroBendLeavesPointsInPlace() {
+        LimbBend straight = arm(0, 0);
+        assertTrue(straight.isStraight());
+        assertArrayEquals(new float[] { 1.5f, 7, -2 }, bend(straight, 1.5f, 7, -2), 1e-5f);
+    }
+
+    @Test
+    void cutsDivideTheLimbEvenly() {
+        float[] cuts = arm(1, 0).cuts();
+        assertEquals(11, cuts.length);
+        assertEquals(-1, cuts[0], 1e-5);
+        assertEquals(9, cuts[10], 1e-5);
+    }
+
+    @Test
+    void topStaysAttachedToThePivot() {
+        LimbBend bend = arm(HALF_PI, 0);
+        assertArrayEquals(new float[] { 2, -2, 2 }, bend(bend, 2, -2, 2), 1e-4f);
+    }
+
+    @Test
+    void spineKeepsItsLength() {
+        LimbBend bend = arm(HALF_PI, 0);
+        float total = 0;
+        float[] previous = bend(bend, 0, -2, 0);
+        for (int i = 1; i <= 12; i++) {
+            float[] point = bend(bend, 0, -2 + i, 0);
+            total += distance(previous, point);
+            previous = point;
+        }
+        // Rings are chords of the curve, so they come out a hair shorter than its arc.
+        assertEquals(12, total, 0.05);
+    }
+
+    @Test
+    void forwardBendMovesTheHandForward() {
+        // Axis 0 folds towards -Z, the front of the model.
+        float[] hand = bend(arm(HALF_PI, 0), 0, 10, 0);
+        assertTrue(hand[2] < -4, "hand should be in front, z = " + hand[2]);
+        assertEquals(0, hand[0], 1e-4);
+    }
+
+    @Test
+    void axisTurnsTheBendDirection() {
+        float[] hand = bend(arm(HALF_PI, HALF_PI), 0, 10, 0);
+        assertTrue(hand[0] > 4, "hand should be towards +X, x = " + hand[0]);
+        assertEquals(0, hand[2], 1e-4);
+    }
+
+    @Test
+    void endPointsFollowTheLowerHalf() {
+        // Past the bottom of the limb, points carry on along the forearm, which points forward at 90°.
+        LimbBend bend = arm(HALF_PI, 0);
+        float[] bottom = bend(bend, 0, 10, 0);
+        float[] below = bend(bend, 0, 11, 0);
+        assertEquals(0, below[1] - bottom[1], 0.05);
+        assertEquals(-1, below[2] - bottom[2], 0.05);
+    }
+
+    @Test
+    void ringsMoveRigidly() {
+        // Every point on one ring keeps its distance from the ring's center.
+        LimbBend bend = arm(1.2f, 0.7f);
+        float[] center = bend(bend, 0, 4, 0);
+        float[] corner = bend(bend, 2, 4, -2);
+        assertEquals(Math.sqrt(8), distance(center, corner), 1e-4);
+    }
+
+    @Test
+    void neighbouringPiecesShareVertices() {
+        // A vertex on a cut is reached the same way from the piece above and the piece below.
+        LimbBend bend = arm(2, 0);
+        float[] fromAbove = bend(bend, 2, 3.99999f, 2);
+        float[] fromBelow = bend(bend, 2, 4.00001f, 2);
+        assertEquals(0, distance(fromAbove, fromBelow), 1e-3);
+    }
+
+    @Test
+    void normalsRotateWithTheLimb() {
+        // The front face's normal (-Z) points up (-Y) on the forearm after a 90° forward bend.
+        float[] normal = new float[3];
+        arm(HALF_PI, 0).bendDirection(10, 0, 0, -1, normal);
+        assertArrayEquals(new float[] { 0, -1, 0 }, normal, 1e-3f);
+    }
+
+    /** A torso: box from y = 0 (neck) to 12 (hips), anchored at the hips. */
+    private static LimbBend torso(float angle, float axis) {
+        return LimbBend.anchoredAtEnd(0, 12, angle, axis, 0.5f, 12);
+    }
+
+    @Test
+    void torsoKeepsItsHipsInPlace() {
+        assertArrayEquals(new float[] { 3, 12, -1 }, bend(torso(1, 0), 3, 12, -1), 1e-4f);
+    }
+
+    @Test
+    void torsoLeansForward() {
+        // Axis 0 still means forward: the neck moves to the front (-Z) and down (+Y).
+        float[] neck = bend(torso(HALF_PI, 0), 0, 0, 0);
+        assertTrue(neck[2] < -4, "neck should be in front, z = " + neck[2]);
+        assertTrue(neck[1] > 4, "neck should drop, y = " + neck[1]);
+    }
+
+    @Test
+    void torsoKeepsItsLength() {
+        LimbBend bend = torso(HALF_PI, 0);
+        float total = 0;
+        float[] previous = bend(bend, 0, 0, 0);
+        for (int i = 1; i <= 12; i++) {
+            float[] point = bend(bend, 0, i, 0);
+            total += distance(previous, point);
+            previous = point;
+        }
+        assertEquals(12, total, 0.05);
+    }
+
+    @Test
+    void attachedPartsTurnWithTheRing() {
+        // The offset from a ring's center to a point on it turns by angleAt around axis.
+        for (LimbBend bend : new LimbBend[] { arm(1.3f, 0.4f), torso(1.3f, 0.4f) }) {
+            for (float y : new float[] { -2, 0, 4, 10, 12 }) {
+                float[] center = bend(bend, 0, y, 0);
+                float[] point = bend(bend, 1, y, -2);
+                float[] expected = rotate(new float[] { 1, 0, -2 }, bend.axis(), bend.angleAt(y));
+                assertArrayEquals(expected,
+                        new float[] { point[0] - center[0], point[1] - center[1], point[2] - center[2] }, 1e-3f);
+            }
+        }
+    }
+
+    @Test
+    void torsoNormalsTurnWithTheRing() {
+        // A forward lean tips the front face (-Z) of the chest towards the ground (+Y).
+        float[] normal = new float[3];
+        torso(HALF_PI, 0).bendDirection(0, 0, 0, -1, normal);
+        assertArrayEquals(new float[] { 0, 1, 0 }, normal, 1e-3f);
+    }
+
+    /** Rodrigues' rotation of v around the unit axis n. */
+    private static float[] rotate(float[] v, Vec3 n, float angle) {
+        Vec3 vec = new Vec3(v[0], v[1], v[2]);
+        float cos = (float) Math.cos(angle);
+        float sin = (float) Math.sin(angle);
+        Vec3 r = vec.scale(cos).add(n.cross(vec).scale(sin)).add(n.scale(n.dot(vec) * (1 - cos)));
+        return new float[] { r.x(), r.y(), r.z() };
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/bend/QuadSplitterTest.java

@@ -0,0 +1,67 @@
+package org.saturnclient.emotes.core.bend;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+class QuadSplitterTest {
+    // Front face of a 4 x 12 limb from y = 0 to 12, texture rows 20 to 32.
+    private static final float[][] FRONT = {
+            { 2, 0, -2, 8, 20 },
+            { -2, 0, -2, 4, 20 },
+            { -2, 12, -2, 4, 32 },
+            { 2, 12, -2, 8, 32 },
+    };
+
+    private static final float[] CUTS = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
+
+    @Test
+    void splitsSideFacesIntoOneStripPerSegment() {
+        List<float[][]> strips = QuadSplitter.split(FRONT, CUTS);
+        assertEquals(12, strips.size());
+        assertArrayEquals(new float[] { 2, 5, -2, 8, 25 }, strips.get(5)[0], 1e-5f);
+        assertArrayEquals(new float[] { -2, 6, -2, 4, 26 }, strips.get(5)[2], 1e-5f);
+    }
+
+    @Test
+    void stripsCoverTheFaceWithoutGaps() {
+        List<float[][]> strips = QuadSplitter.split(FRONT, CUTS);
+        for (int i = 0; i + 1 < strips.size(); i++) {
+            // The bottom edge of one strip is the top edge of the next.
+            assertArrayEquals(strips.get(i)[3], strips.get(i + 1)[0], 1e-5f);
+            assertArrayEquals(strips.get(i)[2], strips.get(i + 1)[1], 1e-5f);
+        }
+    }
+
+    @Test
+    void keepsFlatFaces() {
+        float[][] top = {
+                { 2, 0, -2, 4, 16 },
+                { -2, 0, -2, 8, 16 },
+                { -2, 0, 2, 8, 20 },
+                { 2, 0, 2, 4, 20 },
+        };
+        List<float[][]> strips = QuadSplitter.split(top, CUTS);
+        assertEquals(1, strips.size());
+        assertSame(top, strips.get(0));
+    }
+
+    @Test
+    void overlaysThatStickOutGetShorterEndStrips() {
+        // A sleeve inflated by 0.25 runs from -0.25 to 12.25.
+        float[][] sleeve = {
+                { 2.25f, -0.25f, -2.25f, 48, 36 },
+                { -2.25f, -0.25f, -2.25f, 44, 36 },
+                { -2.25f, 12.25f, -2.25f, 44, 48 },
+                { 2.25f, 12.25f, -2.25f, 48, 48 },
+        };
+        List<float[][]> strips = QuadSplitter.split(sleeve, CUTS);
+        assertEquals(12, strips.size());
+        assertEquals(-0.25f, strips.get(0)[0][1], 1e-5);
+        assertEquals(1, strips.get(0)[3][1], 1e-5);
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/format/EasingTest.java

@@ -0,0 +1,44 @@
+package org.saturnclient.emotes.core.format;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class EasingTest {
+    @Test
+    void everyEasingStartsAtZeroAndEndsAtOne() {
+        for (Easing easing : Easing.values()) {
+            assertEquals(0, easing.apply(0), 1e-5, easing.name());
+            assertEquals(1, easing.apply(1), 1e-5, easing.name());
+        }
+    }
+
+    @Test
+    void symmetricEasingsAreHalfwayAtTheMiddle() {
+        for (Easing easing : new Easing[] { Easing.LINEAR, Easing.INOUTSINE, Easing.INOUTQUAD, Easing.INOUTCUBIC,
+                Easing.INOUTQUART, Easing.INOUTQUINT, Easing.INOUTEXPO, Easing.INOUTCIRC }) {
+            assertEquals(0.5, easing.apply(0.5f), 1e-5, easing.name());
+        }
+    }
+
+    @Test
+    void inIsSlowAtFirstAndOutIsFast() {
+        assertEquals(0.25, Easing.INQUAD.apply(0.5f), 1e-6);
+        assertEquals(0.75, Easing.OUTQUAD.apply(0.5f), 1e-6);
+    }
+
+    @Test
+    void constantHoldsUntilTheEnd() {
+        assertEquals(0, Easing.CONSTANT.apply(0.99f), 1e-6);
+    }
+
+    @Test
+    void readsEmotecraftNames() {
+        assertEquals(Easing.INOUTQUAD, Easing.fromName("INOUTQUAD"));
+        assertEquals(Easing.INOUTQUAD, Easing.fromName("EASEINOUTQUAD"));
+        assertEquals(Easing.OUTSINE, Easing.fromName("easeOutSine"));
+        assertEquals(Easing.INBOUNCE, Easing.fromName("in_bounce"));
+        assertEquals(Easing.LINEAR, Easing.fromName("wobbly"));
+        assertEquals(Easing.LINEAR, Easing.fromName(null));
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/format/EmotecraftLoaderTest.java

@@ -0,0 +1,149 @@
+package org.saturnclient.emotes.core.format;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.junit.jupiter.api.Test;
+import org.saturnclient.emotes.core.Bone;
+import org.saturnclient.emotes.core.BoneTransform;
+import org.saturnclient.emotes.core.Emote;
+
+/** Loads the emotes Saturn Client ships (copied into test resources). */
+class EmotecraftLoaderTest {
+    private static Emote load(String id) throws IOException {
+        try (InputStream in = EmotecraftLoaderTest.class.getResourceAsStream("/emotes/" + id + ".json")) {
+            return EmotecraftLoader.load(id, in);
+        }
+    }
+
+    private static Emote inline(String moves, String emoteFields) throws IOException {
+        return EmotecraftLoader.load("test", "{\"emote\": {" + emoteFields + "\"moves\": [" + moves + "]}}");
+    }
+
+    private static BoneTransform bone(Emote emote, Bone bone, float tick) {
+        return emote.animation().sample(tick).get(bone).orElseThrow();
+    }
+
+    @Test
+    void loadsEveryShippedEmote() throws IOException {
+        for (String id : new String[] { "back_flip", "cry", "facepalm", "front_flip", "giga_chad", "tpose" }) {
+            Emote emote = load(id);
+            assertEquals(id, emote.id());
+            assertFalse(emote.animation().sample(emote.animation().length() / 2).isEmpty(), id);
+        }
+    }
+
+    @Test
+    void readsDetails() throws IOException {
+        Emote emote = load("facepalm");
+        assertEquals("facepalm", emote.name());
+        assertEquals("just facepalm", emote.description());
+        assertEquals("dsty", emote.author());
+    }
+
+    @Test
+    void readsTiming() throws IOException {
+        // facepalm: plays once until stopTick 61.
+        Emote facepalm = load("facepalm");
+        assertFalse(facepalm.animation().loops());
+        assertEquals(61, facepalm.animation().length(), 1e-6);
+
+        // cry: loops back to returnTick 5 after playing endTick 60.
+        Emote cry = load("cry");
+        assertTrue(cry.animation().loops());
+        assertEquals(61, cry.animation().length(), 1e-6);
+        assertEquals(5, cry.animation().loopStart(), 1e-6);
+
+        // back_flip writes isLoop as the string "false".
+        assertFalse(load("back_flip").animation().loops());
+    }
+
+    @Test
+    void turnsPivotsIntoOffsets() throws IOException {
+        // tpose's arms start at their rest pivots (x = ±5, y = 2), which is no offset.
+        BoneTransform arm = bone(load("tpose"), Bone.RIGHT_ARM, 0);
+        assertEquals(0, arm.x(), 1e-5);
+        assertEquals(0, arm.y(), 1e-5);
+        assertEquals(0, arm.z(), 1e-5);
+    }
+
+    @Test
+    void flipsTheBendDirection() throws IOException {
+        // cry bends the elbows by -0.96 in Emotecraft terms: towards the face.
+        assertEquals(0.96f, bone(load("cry"), Bone.RIGHT_ARM, 30).bend(), 0.01);
+    }
+
+    @Test
+    void keepsTheTorsoBendAndGivesItTheWholeBodysBend() throws IOException {
+        // A positive torso bend at axis 0 leans forward in both, so it keeps its sign (Get the Griddy
+        // leans forward with a bend of +0.4).
+        Emote torso = EmotecraftLoader.load("torso",
+                "{\"version\": 3, \"emote\": {\"degrees\": false, \"moves\": [{\"tick\": 0, \"torso\": {\"bend\": 0.4}}]}}");
+        assertEquals(0.4f, bone(torso, Bone.BODY, 0).bend(), 1e-6);
+
+        // Emotecraft's whole-body bend bends the torso; the whole player can't bend.
+        Emote body = inline("{\"tick\": 0, \"body\": {\"bend\": 0.4, \"axis\": 0.2, \"pitch\": 0.1}}", "\"degrees\": false, ");
+        assertEquals(0.4f, bone(body, Bone.BODY, 0).bend(), 1e-6);
+        assertEquals(0.2f, bone(body, Bone.BODY, 0).bendAxis(), 1e-6);
+        assertEquals(0, bone(body, Bone.ROOT, 0).bend(), 1e-6);
+        assertEquals(-0.1f, bone(body, Bone.ROOT, 0).pitch(), 1e-6);
+    }
+
+    @Test
+    void mapsTheWholeBodyToRoot() throws IOException {
+        // front_flip turns "body" pitch to -2π by tick 15, which is a forward flip: +2π around model X.
+        Emote flip = load("front_flip");
+        assertEquals(2 * Math.PI, bone(flip, Bone.ROOT, 15).pitch(), 0.01);
+    }
+
+    @Test
+    void treatsTheTorsoAsTheWholeBodyBeforeVersion3() throws IOException {
+        // back_flip has no version (so 1) and flips with "torso".
+        assertEquals(-2 * Math.PI, bone(load("back_flip"), Bone.ROOT, 70).pitch(), 0.01);
+        assertTrue(load("back_flip").animation().sample(40).get(Bone.BODY).isEmpty());
+
+        String move = "{\"tick\": 0, \"torso\": {\"pitch\": 1}}";
+        Emote version3 = EmotecraftLoader.load("v3",
+                "{\"version\": 3, \"emote\": {\"degrees\": false, \"moves\": [" + move + "]}}");
+        assertEquals(1, bone(version3, Bone.BODY, 0).pitch(), 1e-6);
+    }
+
+    @Test
+    void convertsRootOffsetsFromBlocks() throws IOException {
+        Emote emote = inline("{\"tick\": 0, \"body\": {\"x\": 1, \"y\": 0.5, \"z\": 0.25}}", "");
+        BoneTransform root = bone(emote, Bone.ROOT, 0);
+        assertEquals(-16, root.x(), 1e-5);
+        assertEquals(-8, root.y(), 1e-5);
+        assertEquals(4, root.z(), 1e-5);
+    }
+
+    @Test
+    void anglesAreInDegreesUnlessSaidOtherwise() throws IOException {
+        Emote emote = inline("{\"tick\": 0, \"head\": {\"pitch\": 90}}", "");
+        assertEquals(Math.PI / 2, bone(emote, Bone.HEAD, 0).pitch(), 1e-5);
+        Emote radians = inline("{\"tick\": 0, \"head\": {\"pitch\": 1.5}}", "\"degrees\": false,");
+        assertEquals(1.5, bone(radians, Bone.HEAD, 0).pitch(), 1e-5);
+    }
+
+    @Test
+    void onlyLoopsWithAReturnTick() throws IOException {
+        assertFalse(inline("{\"tick\": 0, \"head\": {\"yaw\": 1}}", "\"isLoop\": true, \"endTick\": 10,")
+                .animation().loops());
+    }
+
+    @Test
+    void addsTurns() throws IOException {
+        Emote emote = inline("{\"tick\": 0, \"turn\": 1, \"head\": {\"yaw\": 0.5}}", "\"degrees\": false,");
+        assertEquals(0.5 + 2 * Math.PI, bone(emote, Bone.HEAD, 0).yaw(), 1e-5);
+    }
+
+    @Test
+    void rejectsFilesWithoutMoves() {
+        assertThrows(IOException.class, () -> EmotecraftLoader.load("broken", "{\"emote\": {}}"));
+    }
+}

core/src/test/java/org/saturnclient/emotes/core/format/KeyframeAnimationTest.java

@@ -0,0 +1,80 @@
+package org.saturnclient.emotes.core.format;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+import org.saturnclient.emotes.core.Bone;
+import org.saturnclient.emotes.core.BoneTransform;
+import org.saturnclient.emotes.core.format.KeyframeAnimation.Channel;
+
+class KeyframeAnimationTest {
+    private static BoneTransform head(KeyframeAnimation animation, float tick) {
+        return animation.sample(tick).get(Bone.HEAD).orElseThrow();
+    }
+
+    @Test
+    void interpolatesBetweenKeyframes() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.PITCH, 0, 0, Easing.LINEAR)
+                .keyframe(Bone.HEAD, Channel.PITCH, 10, 1, Easing.LINEAR)
+                .length(10).build();
+        assertEquals(0.25f, head(animation, 2.5f).pitch(), 1e-6);
+    }
+
+    @Test
+    void segmentsUseTheEasingOfTheKeyframeTheyStartFrom() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.PITCH, 0, 0, Easing.INQUAD)
+                .keyframe(Bone.HEAD, Channel.PITCH, 10, 1, Easing.LINEAR)
+                .length(10).build();
+        assertEquals(0.25f, head(animation, 5).pitch(), 1e-6);
+    }
+
+    @Test
+    void easeBeforeUsesTheEasingOfTheNextKeyframe() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.PITCH, 0, 0, Easing.INQUAD)
+                .keyframe(Bone.HEAD, Channel.PITCH, 10, 1, Easing.LINEAR)
+                .easeBefore(true).length(10).build();
+        assertEquals(0.5f, head(animation, 5).pitch(), 1e-6);
+    }
+
+    @Test
+    void holdsTheFirstAndLastValues() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.YAW, 5, 1, Easing.LINEAR)
+                .keyframe(Bone.HEAD, Channel.YAW, 10, 2, Easing.LINEAR)
+                .length(20).build();
+        assertEquals(1, head(animation, 0).yaw(), 1e-6);
+        assertEquals(2, head(animation, 15).yaw(), 1e-6);
+    }
+
+    @Test
+    void channelsWithoutKeyframesAreZeroAndBonesWithoutKeyframesAreLeftAlone() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.YAW, 0, 1, Easing.LINEAR)
+                .length(10).build();
+        assertEquals(0, head(animation, 0).pitch(), 1e-6);
+        assertTrue(animation.sample(0).get(Bone.BODY).isEmpty());
+    }
+
+    @Test
+    void laterKeyframesOnTheSameTickWin() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.ROLL, 5, 1, Easing.LINEAR)
+                .keyframe(Bone.HEAD, Channel.ROLL, 5, 3, Easing.LINEAR)
+                .length(10).build();
+        assertEquals(1, animation.keyframes(Bone.HEAD, Channel.ROLL).length);
+        assertEquals(3, head(animation, 5).roll(), 1e-6);
+    }
+
+    @Test
+    void keyframesCanBeAddedOutOfOrder() {
+        KeyframeAnimation animation = KeyframeAnimation.builder()
+                .keyframe(Bone.HEAD, Channel.PITCH, 10, 1, Easing.LINEAR)
+                .keyframe(Bone.HEAD, Channel.PITCH, 0, 0, Easing.LINEAR)
+                .length(10).build();
+        assertEquals(0.5f, head(animation, 5).pitch(), 1e-6);
+    }
+}

core/src/test/resources/emotes/cry.json

@@ -0,0 +1,305 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "cry",
+  "description": "T_T",
+  "author": "dsty",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 60,
+    "stopTick": 61,
+    "isLoop": true,
+    "returnTick": 5,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.34134695
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.22808763
+        }
+      },
+      {
+        "tick": 25,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.21269174
+        }
+      },
+      {
+        "tick": 35,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.32248768
+        }
+      },
+      {
+        "tick": 45,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.0874397
+        }
+      },
+      {
+        "tick": 55,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.17582592
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.21476103
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -6.320644E-4
+        }
+      },
+      {
+        "tick": 25,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.029434478
+        }
+      },
+      {
+        "tick": 35,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.039604172
+        }
+      },
+      {
+        "tick": 45,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.037607383
+        }
+      },
+      {
+        "tick": 55,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.050604735
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.00930274
+        }
+      },
+      {
+        "tick": 25,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0010032838
+        }
+      },
+      {
+        "tick": 35,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.009209918
+        }
+      },
+      {
+        "tick": 45,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.012478679
+        }
+      },
+      {
+        "tick": 55,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.031160546
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.8700758
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.4349194
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.4970688
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.9622451
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.9203311
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": 0.6307226
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -0.2971223
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -0.8864816
+        }
+      }
+    ]
+  }
+}

core/src/test/resources/emotes/facepalm.json

@@ -0,0 +1,389 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "facepalm",
+  "description": "just facepalm",
+  "author": "dsty",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 60,
+    "stopTick": 61,
+    "isLoop": false,
+    "returnTick": 2,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.067995355
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.14453278
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.11871816
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.19018666
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.20064461
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.060454715
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.086299464
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.087619215
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.083825104
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.036273066
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0041144555
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.12942825
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.050149817
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.08701207
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.08676299
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -3.8523226
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -3.8523226
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.0664942
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.074402
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.074402
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.02932
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.02932
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.47555572
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.5093512
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.5093512
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.38563538
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.38563538
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.20147677
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.20521602
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.3274244
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.30787703
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.40478125
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.49199954
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.54730254
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.52019864
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.0
+        }
+      }
+    ]
+  }
+}

core/src/test/resources/emotes/front_flip.json

@@ -0,0 +1,697 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "front_flip",
+  "description": "Parkour!!!!1",
+  "author": "DKinchik",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 17,
+    "stopTick": 18,
+    "isLoop": false,
+    "returnTick": 1,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.7020477
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.7020477
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "x": -1.9
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "x": -1.9
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "y": 11.169379
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "z": -0.39214998
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "z": 0.1
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "z": 0.1
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -1.9707682
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -1.9707682
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.3665518
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.3665518
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.0793308
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.0793308
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "x": 1.9
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "x": 1.9
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "y": 10.861001
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "z": -0.5082285
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "z": -0.1
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "z": -0.1
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -1.9850811
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -1.9850811
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "x": 0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "x": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "y": -0.061333913
+        }
+      },
+      {
+        "tick": 7,
+        "easing": "OUTQUAD",
+        "body": {
+          "y": 0.48852682
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "CONSTANT",
+        "body": {
+          "y": 0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "y": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 7,
+        "easing": "OUTQUAD",
+        "body": {
+          "pitch": -2.8362873
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "CONSTANT",
+        "body": {
+          "pitch": -6.2831855
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "yaw": 0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "yaw": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "body": {
+          "bend": -0.0
+        }
+      }
+    ]
+  }
+}

core/src/test/resources/emotes/tpose.json

@@ -0,0 +1,354 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "tpose",
+  "description": "MENACING",
+  "author": "stephanieisdumb",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 80,
+    "stopTick": 81,
+    "isLoop": true,
+    "returnTick": 20,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -6.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -6.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.0704756
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": 0.059108086
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.61077195
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.008776078
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.6060502
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 1.5707964
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 1.5765934
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 1.5707964
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -1.3806202
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 6.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 6.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.0045553
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.010133168
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": 0.44322997
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": 0.038214765
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -0.5571526
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -1.5707964
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -1.5692185
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -1.5707964
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -1.3810014
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": 0.0
+        }
+      }
+    ]
+  }
+}

settings.gradle.kts

@@ -9,6 +9,8 @@ pluginManagement {
 }
 
 plugins {
+    // Downloads the Java toolchain a version needs (Java 25 for 26.1+) when it isn't installed.
+    id("org.gradle.toolchains.foojay-resolver-convention") version "1.0.0"
     id("dev.kikugie.stonecutter") version "0.9.8"
     // Picks the right Loom variant per Minecraft version (remapping for 1.21.x, plain for 26.1+).
     id("dev.kikugie.loom-back-compat") version "0.4.2"
@@ -17,7 +19,7 @@ plugins {
 stonecutter {
     create(rootProject) {
         // Same range as Saturn Client. Per-version dependencies live in stonecutter.properties.toml.
-        versions("1.21.4", "1.21.5", "1.21.6", "1.21.7", "1.21.8", "1.21.9", "1.21.10", "1.21.11")
+        versions("1.21.4", "1.21.5", "1.21.6", "1.21.7", "1.21.8", "1.21.9", "1.21.10", "1.21.11", "26.1", "26.2", "26.3")
         vcsVersion = "1.21.11"
     }
 }

src/main/java/org/saturnclient/emotes/fabric/BendTransforms.java

@@ -0,0 +1,32 @@
+package org.saturnclient.emotes.fabric;
+
+import org.joml.Quaternionf;
+import org.saturnclient.emotes.core.bend.LimbBend;
+import org.saturnclient.emotes.core.bend.Vec3;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+
+/** Pose stack helpers for attaching things to bent limbs. */
+public final class BendTransforms {
+    private BendTransforms() {
+    }
+
+    /**
+     * Moves whatever is drawn next from the straight limb onto the bent one, as if it were fixed to the
+     * limb at {@code y} (model pixels, in the limb's space). This is the same rigid move the ring at
+     * {@code y} makes, so anything attached there stays attached the way the mesh does. The pose stack
+     * must already be in the limb's space, i.e. after {@code ModelPart.translateAndRotate}.
+     */
+    public static void attachAt(PoseStack poseStack, LimbBend bend, float y) {
+        float[] center = new float[3];
+        bend.bendPoint(0, y, 0, center);
+        Vec3 axis = bend.axis();
+        poseStack.translate(center[0] / 16, center[1] / 16, center[2] / 16);
+        Quaternionf rotation = new Quaternionf().rotationAxis(bend.angleAt(y), axis.x(), axis.y(), axis.z());
+        //? if >=26.3 {
+        /*poseStack.rotate(rotation);
+        *///?} else
+        poseStack.mulPose(rotation);
+        poseStack.translate(0, -y / 16, 0);
+    }
+}

src/main/java/org/saturnclient/emotes/fabric/BentCubeRenderer.java

@@ -0,0 +1,66 @@
+package org.saturnclient.emotes.fabric;
+
+import java.util.List;
+
+import org.joml.Matrix4f;
+import org.joml.Vector3f;
+import org.saturnclient.emotes.core.bend.LimbBend;
+import org.saturnclient.emotes.core.bend.QuadSplitter;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.blaze3d.vertex.VertexConsumer;
+
+import net.minecraft.client.model.geom.ModelPart;
+
+/**
+ * Draws a part's cubes bent. Each vanilla face is cut into strips at the bend's rings (UVs split with
+ * it), and every vertex is moved onto the bent limb. Vertices that were shared stay shared, so the
+ * mesh has no gaps, and the texture is the same as vanilla apart from the cuts.
+ */
+public final class BentCubeRenderer {
+    private BentCubeRenderer() {
+    }
+
+    public static void render(List<ModelPart.Cube> cubes, LimbBend bend, PoseStack.Pose pose,
+            VertexConsumer consumer, int light, int overlay, int color) {
+        Matrix4f matrix = pose.pose();
+        float[] cuts = bend.cuts();
+        float[] bent = new float[3];
+        Vector3f position = new Vector3f();
+        Vector3f normal = new Vector3f();
+
+        for (ModelPart.Cube cube : cubes) {
+            for (ModelPart.Polygon polygon : cube.polygons) {
+                ModelPart.Vertex[] vertices = polygon.vertices();
+                float[][] quad = new float[vertices.length][];
+                for (int i = 0; i < vertices.length; i++) {
+                    quad[i] = vertex(vertices[i]);
+                }
+
+                for (float[][] strip : QuadSplitter.split(quad, cuts)) {
+                    // The strip's normal turns with the ring at its middle. End caps are flat, so theirs
+                    // turns with the end they're at.
+                    float stripY = (strip[0][1] + strip[2][1]) / 2;
+                    bend.bendDirection(stripY, polygon.normal().x(), polygon.normal().y(), polygon.normal().z(),
+                            bent);
+                    pose.transformNormal(normal.set(bent[0], bent[1], bent[2]), normal);
+
+                    for (float[] vertex : strip) {
+                        bend.bendPoint(vertex[0], vertex[1], vertex[2], bent);
+                        matrix.transformPosition(bent[0] / 16, bent[1] / 16, bent[2] / 16, position);
+                        consumer.addVertex(position.x(), position.y(), position.z(), color, vertex[3], vertex[4],
+                                overlay, light, normal.x(), normal.y(), normal.z());
+                    }
+                }
+            }
+        }
+    }
+
+    /** {x, y, z, u, v} in model pixels. */
+    private static float[] vertex(ModelPart.Vertex vertex) {
+        //? if >=1.21.9 {
+        return new float[] { vertex.x(), vertex.y(), vertex.z(), vertex.u(), vertex.v() };
+        //?} else
+        /*return new float[] { vertex.pos().x(), vertex.pos().y(), vertex.pos().z(), vertex.u(), vertex.v() };*/
+    }
+}

src/main/java/org/saturnclient/emotes/fabric/Emotes.java

@@ -7,6 +7,8 @@ import java.util.concurrent.ConcurrentHashMap;
 
 import org.saturnclient.emotes.core.Animation;
 import org.saturnclient.emotes.core.AnimationPlayer;
+import org.saturnclient.emotes.core.Emote;
+import org.saturnclient.emotes.core.EmoteRegistry;
 import org.saturnclient.emotes.core.Pose;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -17,9 +19,10 @@ import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents;
 /** Client-side entry point: which player is playing which animation. */
 public final class Emotes implements ClientModInitializer {
     public static final String MOD_ID = "saturn_emotes";
-    public static final String VERSION = /*$ mod_version*/ "0.1.0";
+    public static final String VERSION = /*$ mod_version*/ "0.1.2";
     public static final Logger LOGGER = LoggerFactory.getLogger(MOD_ID);
 
+    private static final EmoteRegistry REGISTRY = new EmoteRegistry();
     private static final Map<UUID, AnimationPlayer> PLAYING = new ConcurrentHashMap<>();
     private static long tick;
 
@@ -31,11 +34,27 @@ public final class Emotes implements ClientModInitializer {
         });
     }
 
+    /** The emotes {@link #play(UUID, String)} looks up. Load or register emotes into it at startup. */
+    public static EmoteRegistry registry() {
+        return REGISTRY;
+    }
+
     /** Starts {@code animation} on the player, replacing whatever they were playing. */
     public static void play(UUID player, Animation animation) {
         PLAYING.put(player, new AnimationPlayer(animation, tick));
     }
 
+    /**
+     * Starts the registered emote {@code id} on the player.
+     *
+     * @return false if no emote has that ID, in which case nothing changes
+     */
+    public static boolean play(UUID player, String id) {
+        Optional<Emote> emote = REGISTRY.get(id);
+        emote.ifPresent(e -> play(player, e.animation()));
+        return emote.isPresent();
+    }
+
     public static void stop(UUID player) {
         PLAYING.remove(player);
     }

src/main/java/org/saturnclient/emotes/fabric/PoseApplier.java

@@ -1,8 +1,13 @@
 package org.saturnclient.emotes.fabric;
 
+import org.joml.Quaternionf;
+import org.joml.Vector3f;
 import org.saturnclient.emotes.core.Bone;
 import org.saturnclient.emotes.core.BoneTransform;
 import org.saturnclient.emotes.core.Pose;
+import org.saturnclient.emotes.core.bend.LimbBend;
+import org.saturnclient.emotes.core.bend.Vec3;
+import org.saturnclient.emotes.fabric.access.BendablePart;
 
 import net.minecraft.client.model.HumanoidModel;
 import net.minecraft.client.model.geom.ModelPart;
@@ -12,17 +17,47 @@ import net.minecraft.client.model.geom.ModelPart;
  * jacket, pants) are children of the base parts, so they follow automatically.
  */
 public final class PoseApplier {
+    /** How tightly joints curve, from 0 (round) to 1 (tight). See {@link LimbBend}. */
+    private static final float SHARPNESS = 0.5f;
+
     private PoseApplier() {
     }
 
+    /** Where {@link Bone#ROOT} turns around, in model pixels below the neck (0.7 blocks above the feet). */
+    private static final float ROOT_PIVOT_Y = 12.8f;
+
     public static void apply(HumanoidModel<?> model, Pose pose) {
-        for (var entry : pose.bones().entrySet()) {
-            apply(part(model, entry.getKey()), entry.getValue());
+        pose.get(Bone.ROOT).ifPresent(transform -> applyRoot(model.root(), transform));
+
+        LimbBend bodyBend = null;
+        for (Bone bone : Bone.values()) {
+            if (bone == Bone.ROOT) {
+                continue;
+            }
+            ModelPart part = part(model, bone);
+            BoneTransform transform = pose.get(bone).orElse(null);
+            if (transform != null) {
+                apply(part, transform);
+            }
+            // Models are shared between entities, so bends from the last one drawn must be cleared.
+            LimbBend bend = bend(bone, transform);
+            ((BendablePart) (Object) part).saturnEmotes$setBend(bend);
+            if (bone == Bone.BODY) {
+                bodyBend = bend;
+            }
+        }
+
+        // The torso bends from the hips, so whatever hangs off its upper half moves with it.
+        if (bodyBend != null && !bodyBend.isStraight()) {
+            carry(model.body, bodyBend, model.head);
+            carry(model.body, bodyBend, model.rightArm);
+            carry(model.body, bodyBend, model.leftArm);
         }
     }
 
     private static ModelPart part(HumanoidModel<?> model, Bone bone) {
         return switch (bone) {
+            case ROOT -> model.root();
             case HEAD -> model.head;
             case BODY -> model.body;
             case RIGHT_ARM -> model.rightArm;
@@ -40,6 +75,72 @@ public final class PoseApplier {
         part.xRot = transform.pitch();
         part.yRot = transform.yaw();
         part.zRot = transform.roll();
-        // TODO: bend (transform.bend(), transform.bendAxis()) needs a custom mesh.
+    }
+
+    /**
+     * The root part turns around its own pivot, which is at the neck. Move it so the model turns around
+     * its middle instead: a point p ends up at offset + pivot + R (p - pivot).
+     */
+    private static void applyRoot(ModelPart root, BoneTransform transform) {
+        root.xRot = transform.pitch();
+        root.yRot = transform.yaw();
+        root.zRot = transform.roll();
+        Vector3f pivot = new Vector3f(0, ROOT_PIVOT_Y, 0);
+        Vector3f turned = rotation(root).transform(new Vector3f(pivot));
+        root.x += transform.x() + pivot.x - turned.x;
+        root.y += transform.y() + pivot.y - turned.y;
+        root.z += transform.z() + pivot.z - turned.z;
+    }
+
+    private static LimbBend bend(Bone bone, BoneTransform transform) {
+        if (transform == null || transform.bend() == 0) {
+            return null;
+        }
+        // Vanilla player limbs, in each part's own space. Armor uses the same ranges so it bends with
+        // the limb instead of along its own (inflated) box. One segment per texture row, so each piece
+        // keeps a whole row of pixels.
+        float bend = transform.bend();
+        float axis = transform.bendAxis();
+        return switch (bone) {
+            case ROOT, HEAD -> null;
+            case RIGHT_ARM, LEFT_ARM -> new LimbBend(-2, 10, bend, axis, SHARPNESS, 12);
+            case RIGHT_LEG, LEFT_LEG -> new LimbBend(0, 12, bend, axis, SHARPNESS, 12);
+            // The hips stay on the legs and the chest leans.
+            case BODY -> LimbBend.anchoredAtEnd(0, 12, bend, axis, SHARPNESS, 12);
+        };
+    }
+
+    /**
+     * Moves {@code part} (a sibling of the body in the model) as if it were attached to the bent torso
+     * at its pivot: its pivot follows the torso and it turns with the torso's ring there.
+     */
+    private static void carry(ModelPart body, LimbBend bend, ModelPart part) {
+        Quaternionf bodyRotation = rotation(body);
+
+        // The part's pivot in the torso's own space.
+        Vector3f pivot = bodyRotation.transformInverse(
+                new Vector3f(part.x - body.x, part.y - body.y, part.z - body.z));
+        float[] bent = new float[3];
+        bend.bendPoint(pivot.x, pivot.y, pivot.z, bent);
+        Vector3f moved = bodyRotation.transform(new Vector3f(bent[0], bent[1], bent[2]));
+        part.x = body.x + moved.x;
+        part.y = body.y + moved.y;
+        part.z = body.z + moved.z;
+
+        // The ring's turn happens in the torso's space, so bring it into model space around the part's
+        // own rotation.
+        Vec3 axis = bend.axis();
+        Quaternionf turn = new Quaternionf().rotationAxis(bend.angleAt(pivot.y), axis.x(), axis.y(), axis.z());
+        Quaternionf result = new Quaternionf(bodyRotation).mul(turn).mul(new Quaternionf(bodyRotation).conjugate())
+                .mul(rotation(part));
+        Vector3f euler = result.getEulerAnglesZYX(new Vector3f());
+        part.xRot = euler.x;
+        part.yRot = euler.y;
+        part.zRot = euler.z;
+    }
+
+    /** The rotation ModelPart.translateAndRotate applies. */
+    private static Quaternionf rotation(ModelPart part) {
+        return new Quaternionf().rotationZYX(part.zRot, part.yRot, part.xRot);
     }
 }

src/main/java/org/saturnclient/emotes/fabric/access/BendablePart.java

@@ -0,0 +1,13 @@
+package org.saturnclient.emotes.fabric.access;
+
+import org.jetbrains.annotations.Nullable;
+import org.saturnclient.emotes.core.bend.LimbBend;
+
+/** Mixed into ModelPart. A part with a bend draws its cubes bent instead of rigid. */
+public interface BendablePart {
+    @Nullable
+    LimbBend saturnEmotes$getBend();
+
+    /** Sets the bend on this part and all its children (overlay layers like sleeves). */
+    void saturnEmotes$setBend(@Nullable LimbBend bend);
+}

src/main/java/org/saturnclient/emotes/fabric/mixin/FirstPersonHandMixin.java

@@ -0,0 +1,30 @@
+package org.saturnclient.emotes.fabric.mixin;
+
+import org.saturnclient.emotes.fabric.access.BendablePart;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.llamalad7.mixinextras.sugar.Local;
+
+import net.minecraft.client.model.geom.ModelPart;
+//? if >=1.21.9 {
+import net.minecraft.client.renderer.entity.player.AvatarRenderer;
+//?} else
+/*import net.minecraft.client.renderer.entity.player.PlayerRenderer;*/
+
+/**
+ * The first-person arm is drawn from the same shared model without calling setupAnim, so it would
+ * keep whatever bend the last third-person player drawn left on it. It should never be bent.
+ */
+//? if >=1.21.9 {
+@Mixin(AvatarRenderer.class)
+//?} else
+/*@Mixin(PlayerRenderer.class)*/
+public class FirstPersonHandMixin {
+    @Inject(method = "renderHand", at = @At("HEAD"))
+    private void saturnEmotes$straightenArm(CallbackInfo ci, @Local(argsOnly = true) ModelPart arm) {
+        ((BendablePart) (Object) arm).saturnEmotes$setBend(null);
+    }
+}

src/main/java/org/saturnclient/emotes/fabric/mixin/HumanoidModelMixin.java

@@ -1,6 +1,5 @@
 package org.saturnclient.emotes.fabric.mixin;
 
-import org.saturnclient.emotes.core.Pose;
 import org.saturnclient.emotes.fabric.PoseApplier;
 import org.saturnclient.emotes.fabric.access.EmotePoseHolder;
 import org.spongepowered.asm.mixin.Mixin;
@@ -21,9 +20,7 @@ public class HumanoidModelMixin {
             method = "setupAnim(Lnet/minecraft/client/renderer/entity/state/HumanoidRenderState;)V",
             at = @At("TAIL"))
     private void saturnEmotes$applyPose(HumanoidRenderState state, CallbackInfo ci) {
-        Pose pose = ((EmotePoseHolder) state).saturnEmotes$getPose();
-        if (!pose.isEmpty()) {
-            PoseApplier.apply((HumanoidModel<?>) (Object) this, pose);
-        }
+        // Always applied, even for an empty pose, so bends left over from another entity get cleared.
+        PoseApplier.apply((HumanoidModel<?>) (Object) this, ((EmotePoseHolder) state).saturnEmotes$getPose());
     }
 }

src/main/java/org/saturnclient/emotes/fabric/mixin/ModelPartMixin.java

@@ -0,0 +1,60 @@
+package org.saturnclient.emotes.fabric.mixin;
+
+import java.util.List;
+import java.util.Map;
+
+import org.jetbrains.annotations.Nullable;
+import org.saturnclient.emotes.core.bend.LimbBend;
+import org.saturnclient.emotes.fabric.BentCubeRenderer;
+import org.saturnclient.emotes.fabric.access.BendablePart;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.blaze3d.vertex.VertexConsumer;
+
+import net.minecraft.client.model.geom.ModelPart;
+
+@Mixin(ModelPart.class)
+public class ModelPartMixin implements BendablePart {
+    @Shadow
+    @Final
+    private List<ModelPart.Cube> cubes;
+
+    @Shadow
+    @Final
+    private Map<String, ModelPart> children;
+
+    @Unique
+    private @Nullable LimbBend saturnEmotes$bend;
+
+    @Override
+    public @Nullable LimbBend saturnEmotes$getBend() {
+        return saturnEmotes$bend;
+    }
+
+    @Override
+    public void saturnEmotes$setBend(@Nullable LimbBend bend) {
+        if (bend == null && saturnEmotes$bend == null) {
+            return;
+        }
+        saturnEmotes$bend = bend;
+        for (ModelPart child : children.values()) {
+            ((BendablePart) (Object) child).saturnEmotes$setBend(bend);
+        }
+    }
+
+    @Inject(method = "compile", at = @At("HEAD"), cancellable = true)
+    private void saturnEmotes$compileBent(PoseStack.Pose pose, VertexConsumer consumer, int light, int overlay,
+            int color, CallbackInfo ci) {
+        if (saturnEmotes$bend != null && !saturnEmotes$bend.isStraight()) {
+            BentCubeRenderer.render(cubes, saturnEmotes$bend, pose, consumer, light, overlay, color);
+            ci.cancel();
+        }
+    }
+}

src/main/java/org/saturnclient/emotes/fabric/mixin/PlayerModelMixin.java

@@ -0,0 +1,46 @@
+package org.saturnclient.emotes.fabric.mixin;
+
+import org.saturnclient.emotes.core.bend.LimbBend;
+import org.saturnclient.emotes.fabric.BendTransforms;
+import org.saturnclient.emotes.fabric.access.BendablePart;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.llamalad7.mixinextras.sugar.Local;
+import com.mojang.blaze3d.vertex.PoseStack;
+
+import net.minecraft.client.model.HumanoidModel;
+import net.minecraft.client.model.geom.ModelPart;
+import net.minecraft.world.entity.HumanoidArm;
+//? if >=1.21.11 {
+import net.minecraft.client.model.player.PlayerModel;
+//?} else
+/*import net.minecraft.client.model.PlayerModel;*/
+
+/**
+ * Held items are placed at the hand of the straight arm. PlayerModel overrides translateToHand (for
+ * slim arms) without calling HumanoidModel's, so this has to hook PlayerModel's own.
+ */
+@Mixin(PlayerModel.class)
+public class PlayerModelMixin {
+    //? if >=1.21.9 {
+    @Unique
+    private static final String TRANSLATE_TO_HAND = "translateToHand(Lnet/minecraft/client/renderer/entity/state/AvatarRenderState;Lnet/minecraft/world/entity/HumanoidArm;Lcom/mojang/blaze3d/vertex/PoseStack;)V";
+    //?} else
+    /*@Unique private static final String TRANSLATE_TO_HAND = "translateToHand(Lnet/minecraft/world/entity/HumanoidArm;Lcom/mojang/blaze3d/vertex/PoseStack;)V";*/
+
+    /** Moves the item from the hand of the straight arm to the hand of the bent one. */
+    @Inject(method = TRANSLATE_TO_HAND, at = @At("TAIL"))
+    private void saturnEmotes$followBentArm(CallbackInfo ci, @Local(argsOnly = true) HumanoidArm arm,
+            @Local(argsOnly = true) PoseStack poseStack) {
+        HumanoidModel<?> model = (HumanoidModel<?>) (Object) this;
+        ModelPart part = arm == HumanoidArm.LEFT ? model.leftArm : model.rightArm;
+        LimbBend bend = ((BendablePart) (Object) part).saturnEmotes$getBend();
+        if (bend != null && !bend.isStraight()) {
+            BendTransforms.attachAt(poseStack, bend, bend.end());
+        }
+    }
+}

src/main/resources/saturn_emotes.mixins.json

@@ -3,9 +3,12 @@
   "package": "org.saturnclient.emotes.fabric.mixin",
   "compatibilityLevel": "${java}",
   "client": [
+    "FirstPersonHandMixin",
     "HumanoidModelMixin",
     "LivingEntityRenderStateMixin",
-    "LivingEntityRendererMixin"
+    "LivingEntityRendererMixin",
+    "ModelPartMixin",
+    "PlayerModelMixin"
   ],
   "injectors": {
     "defaultRequire": 1

src/testmod/java/org/saturnclient/emotes/testmod/EmotesGameTest.java

@@ -0,0 +1,121 @@
+package org.saturnclient.emotes.testmod;
+
+import org.saturnclient.emotes.core.EmoteRegistry;
+import org.saturnclient.emotes.fabric.Emotes;
+
+import net.fabricmc.fabric.api.client.gametest.v1.FabricClientGameTest;
+import net.fabricmc.fabric.api.client.gametest.v1.context.ClientGameTestContext;
+import net.fabricmc.fabric.api.client.gametest.v1.context.TestSingleplayerContext;
+import net.minecraft.client.CameraType;
+import net.minecraft.client.Minecraft;
+
+/**
+ * Screenshots each test animation at set points, from the front, the side and behind.
+ * Run with {@code ./gradlew :<mc>:runClientGameTest}. Screenshots land in
+ * {@code versions/<mc>/build/run/clientGameTest/screenshots/}.
+ */
+public final class EmotesGameTest implements FabricClientGameTest {
+    private static final String MINECRAFT = /*$ minecraft*/ "1.21.11";
+
+    /** What to play, the tick to screenshot it at, and the angles to look from (0 is the front). */
+    private static final Shot[] SHOTS = {
+            Shot.test("tpose", 10, 0, 90),
+            Shot.test("bend", 20, 0, 90),
+            Shot.test("flap", 15, 0, 90),
+            Shot.test("squat", 20, 0, 90),
+            Shot.test("bow", 20, 0, 90),
+            // Top and bottom of the bounce.
+            Shot.test("twerk", 16, 0, 90, 150),
+            Shot.test("twerk", 4, 0, 90, 150),
+            // Saturn's emotes, loaded from Emotecraft JSON into the library's registry.
+            Shot.emote("facepalm", 40, 0, 90),
+            Shot.emote("cry", 30, 0, 90),
+            Shot.emote("tpose", 30, 0),
+            Shot.emote("front_flip", 9, 90),
+            Shot.emote("back_flip", 30, 90),
+            Shot.emote("back_flip", 50, 90),
+            Shot.emote("giga_chad", 60, 0, 90),
+    };
+
+    /** A test animation or a registered emote, named apart in screenshots since IDs can repeat. */
+    private record Shot(EmoteRegistry registry, String prefix, String id, int tick, float... angles) {
+        static Shot test(String id, int tick, float... angles) {
+            return new Shot(TestAnimations.REGISTRY, "test-", id, tick, angles);
+        }
+
+        static Shot emote(String id, int tick, float... angles) {
+            return new Shot(Emotes.registry(), "", id, tick, angles);
+        }
+    }
+
+    @Override
+    public void runTest(ClientGameTestContext context) {
+        try (TestSingleplayerContext singleplayer = context.worldBuilder().create()) {
+            //? if >=26.2 {
+            /*singleplayer.getConnection().waitForChunksRender();
+            *///?} else if >=26.1 {
+            /*singleplayer.getClientLevel().waitForChunksRender();
+            *///?} else
+            singleplayer.getClientWorld().waitForChunksRender();
+            context.runOnClient(client -> {
+                setHudHidden(client, true);
+                client.options.setCameraType(CameraType.THIRD_PERSON_FRONT);
+            });
+            context.waitTicks(20);
+
+            for (Shot shot : SHOTS) {
+                context.runOnClient(client -> Emotes.play(client.player.getUUID(),
+                        shot.registry().get(shot.id()).orElseThrow().animation()));
+                context.waitTicks(shot.tick());
+                for (float angle : shot.angles()) {
+                    screenshot(context, shot.prefix() + shot.id() + "-t" + shot.tick() + "-" + (int) angle, angle);
+                }
+                context.runOnClient(client -> Emotes.stop(client.player.getUUID()));
+            }
+
+            // A held item should come out of the fist on the bent forearm.
+            singleplayer.getServer().runCommand("give @a diamond_sword");
+            context.runOnClient(client -> Emotes.play(client.player.getUUID(),
+                    TestAnimations.REGISTRY.get("hold").orElseThrow().animation()));
+            context.waitTicks(10);
+            screenshot(context, "hold-0", 0);
+            screenshot(context, "hold-90", 90);
+
+            // The first-person arm shares the model, so it must not keep the bend from the frame above.
+            // Vanilla only draws the arm with an empty hand, and hiding the GUI hides it too.
+            singleplayer.getServer().runCommand("clear @a");
+            context.waitTicks(2);
+            context.runOnClient(client -> {
+                setHudHidden(client, false);
+                client.options.setCameraType(CameraType.FIRST_PERSON);
+            });
+            // Give the hand time to come back up after the item change.
+            context.waitTicks(20);
+            context.takeScreenshot(MINECRAFT + "-hold-firstperson");
+            context.runOnClient(client -> {
+                Emotes.stop(client.player.getUUID());
+                setHudHidden(client, true);
+            });
+        }
+    }
+
+    private static void setHudHidden(Minecraft client, boolean hidden) {
+        // From 26.2 the HUD can only be toggled.
+        //? if >=26.2 {
+        /*if (client.gui.hud.isHidden() != hidden) {
+            client.gui.hud.toggle();
+        }
+        *///?} else
+        client.options.hideGui = hidden;
+    }
+
+    /** Turns the body (not the camera) by {@code turn} degrees, then takes a screenshot. */
+    private static void screenshot(ClientGameTestContext context, String name, float turn) {
+        context.runOnClient(client -> {
+            float body = client.player.getYRot() + turn;
+            client.player.setYBodyRot(body);
+            client.player.yBodyRotO = body;
+        });
+        context.takeScreenshot(MINECRAFT + "-" + name);
+    }
+}

src/testmod/java/org/saturnclient/emotes/testmod/EmotesTestmod.java

@@ -1,11 +1,20 @@
 package org.saturnclient.emotes.testmod;
 
+//? if >=26.1 {
+/*import static net.fabricmc.fabric.api.client.command.v2.ClientCommands.argument;
+import static net.fabricmc.fabric.api.client.command.v2.ClientCommands.literal;
+*///?} else {
 import static net.fabricmc.fabric.api.client.command.v2.ClientCommandManager.argument;
 import static net.fabricmc.fabric.api.client.command.v2.ClientCommandManager.literal;
+//?}
 
-import java.util.TreeSet;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+import java.util.Optional;
 
-import org.saturnclient.emotes.core.Animation;
+import org.saturnclient.emotes.core.Emote;
+import org.saturnclient.emotes.core.EmoteRegistry;
 import org.saturnclient.emotes.fabric.Emotes;
 import org.spongepowered.asm.mixin.MixinEnvironment;
 
@@ -18,46 +27,70 @@ import net.fabricmc.fabric.api.client.command.v2.FabricClientCommandSource;
 import net.minecraft.network.chat.Component;
 
 /**
- * Dev-only tester. In game: {@code /emotes play <name>}, {@code /emotes stop}, {@code /emotes info}.
+ * Dev-only tester. In game: {@code /emotes play <id>} plays an emote from the library's registry
+ * (Saturn's emotes, loaded here), {@code /emotes test <name>} plays one of the testmod's own
+ * {@link TestAnimations}, and there's {@code /emotes stop} and {@code /emotes info}.
  * Switch to third person (F5) to see yourself.
  */
 public final class EmotesTestmod implements ClientModInitializer {
     private static final String MINECRAFT = /*$ minecraft*/ "1.21.11";
+    /** Saturn Client's emotes, in Emotecraft's format, from assets/saturn_emotes_testmod/player_animations. */
+    static final List<String> EMOTECRAFT_EMOTES = List.of("back_flip", "cry", "facepalm", "front_flip",
+            "giga_chad", "tpose");
 
     @Override
     public void onInitializeClient() {
         // Applies every mixin now, so a broken target crashes at startup instead of in a world.
         MixinEnvironment.getCurrentEnvironment().audit();
         Emotes.LOGGER.info("Mixin audit passed on Minecraft {}", MINECRAFT);
+        loadEmotes();
 
         ClientCommandRegistrationCallback.EVENT.register((dispatcher, registryAccess) -> dispatcher.register(
                 literal("emotes")
-                        .then(literal("play").then(argument("name", StringArgumentType.word())
+                        .then(literal("play").then(argument("id", StringArgumentType.word())
                                 .suggests((ctx, builder) -> {
-                                    TestAnimations.ALL.keySet().forEach(builder::suggest);
+                                    Emotes.registry().ids().forEach(builder::suggest);
                                     return builder.buildFuture();
                                 })
-                                .executes(EmotesTestmod::play)))
+                                .executes(ctx -> play(ctx, Emotes.registry(), "id"))))
+                        .then(literal("test").then(argument("name", StringArgumentType.word())
+                                .suggests((ctx, builder) -> {
+                                    TestAnimations.REGISTRY.ids().forEach(builder::suggest);
+                                    return builder.buildFuture();
+                                })
+                                .executes(ctx -> play(ctx, TestAnimations.REGISTRY, "name"))))
                         .then(literal("stop").executes(ctx -> {
                             Emotes.stop(ctx.getSource().getPlayer().getUUID());
                             return 1;
                         }))
                         .then(literal("info").executes(ctx -> {
                             ctx.getSource().sendFeedback(Component.literal("Saturn Emotes " + Emotes.VERSION
-                                    + " on Minecraft " + MINECRAFT + ". Animations: "
-                                    + String.join(", ", new TreeSet<>(TestAnimations.ALL.keySet()))));
+                                    + " on Minecraft " + MINECRAFT + ". Emotes: "
+                                    + String.join(", ", Emotes.registry().ids()) + ". Test animations: "
+                                    + String.join(", ", TestAnimations.REGISTRY.ids())));
                             return 1;
                         }))));
     }
 
-    private static int play(CommandContext<FabricClientCommandSource> ctx) {
-        String name = StringArgumentType.getString(ctx, "name");
-        Animation animation = TestAnimations.ALL.get(name);
-        if (animation == null) {
-            ctx.getSource().sendError(Component.literal("Unknown animation: " + name));
+    private static void loadEmotes() {
+        for (String id : EMOTECRAFT_EMOTES) {
+            String path = "/assets/saturn_emotes_testmod/player_animations/" + id + ".json";
+            try (InputStream in = EmotesTestmod.class.getResourceAsStream(path)) {
+                Emotes.registry().loadEmotecraft(id, in);
+            } catch (IOException | NullPointerException e) {
+                Emotes.LOGGER.error("Couldn't load emote {}", id, e);
+            }
+        }
+    }
+
+    private static int play(CommandContext<FabricClientCommandSource> ctx, EmoteRegistry registry, String argument) {
+        String id = StringArgumentType.getString(ctx, argument);
+        Optional<Emote> emote = registry.get(id);
+        if (emote.isEmpty()) {
+            ctx.getSource().sendError(Component.literal("Unknown: " + id));
             return 0;
         }
-        Emotes.play(ctx.getSource().getPlayer().getUUID(), animation);
+        Emotes.play(ctx.getSource().getPlayer().getUUID(), emote.get().animation());
         return 1;
     }
 }

src/testmod/java/org/saturnclient/emotes/testmod/TestAnimations.java

@@ -1,18 +1,24 @@
 package org.saturnclient.emotes.testmod;
 
 import java.util.Map;
+import java.util.TreeMap;
 import java.util.function.Function;
 
 import org.saturnclient.emotes.core.Animation;
 import org.saturnclient.emotes.core.Bone;
+import org.saturnclient.emotes.core.Emote;
+import org.saturnclient.emotes.core.EmoteRegistry;
 import org.saturnclient.emotes.core.BoneTransform;
 import org.saturnclient.emotes.core.Pose;
 
-/** Hand-written animations for checking that poses reach the model on every version. */
+/**
+ * Hand-written animations for checking that poses reach the model on every version. They live in the
+ * testmod's own registry, separate from the library's {@code Emotes.registry()}.
+ */
 final class TestAnimations {
     private static final float HALF_PI = (float) (Math.PI / 2);
 
-    static final Map<String, Animation> ALL = Map.of(
+    private static final Map<String, Animation> ALL = Map.of(
             // Right arm raised, waving side to side. Tests rotation.
             "wave", of(40, true, t -> Pose.builder()
                     .set(Bone.RIGHT_ARM, BoneTransform.rotation((float) Math.PI, 0,
@@ -33,18 +39,108 @@ final class TestAnimations {
                         .set(Bone.LEFT_ARM, new BoneTransform(0, drop, 0, 0, 0, 0, 0, 0))
                         .build();
             }),
-            // Arms forward with elbows folding in and out. Bend isn't rendered yet.
+            // Arms forward with elbows folding in and out. Tests bending towards the front.
             "bend", of(40, true, t -> {
                 float bend = HALF_PI * 0.5f * (1 - (float) Math.cos(t / 40f * 2 * Math.PI));
                 return Pose.builder()
                         .set(Bone.RIGHT_ARM, BoneTransform.rotation(-HALF_PI, 0, 0).withBend(bend, 0))
                         .set(Bone.LEFT_ARM, BoneTransform.rotation(-HALF_PI, 0, 0).withBend(bend, 0))
                         .build();
-            }));
+            }),
+            // Arms out to the sides with elbows folding down. Tests the bend axis.
+            "flap", of(30, true, t -> {
+                float bend = HALF_PI * 0.5f * (1 - (float) Math.cos(t / 30f * 2 * Math.PI));
+                return Pose.builder()
+                        .set(Bone.RIGHT_ARM, BoneTransform.rotation(0, 0, HALF_PI).withBend(bend, HALF_PI))
+                        .set(Bone.LEFT_ARM, BoneTransform.rotation(0, 0, -HALF_PI).withBend(bend, -HALF_PI))
+                        .build();
+            }),
+            // Thighs forward and knees folding back, past 90°. Tests legs, pants and sharp bends.
+            "squat", of(40, true, t -> {
+                float depth = 0.5f * (1 - (float) Math.cos(t / 40f * 2 * Math.PI));
+                BoneTransform leg = BoneTransform.rotation(-1.2f * depth, 0, 0)
+                        .withBend(2.2f * depth, (float) Math.PI);
+                return Pose.builder()
+                        .set(Bone.RIGHT_LEG, leg)
+                        .set(Bone.LEFT_LEG, leg)
+                        .build();
+            }),
+            // Chest leaning forward from the hips, head and arms carried with it. Tests the torso.
+            "bow", of(40, true, t -> {
+                float lean = HALF_PI * 0.5f * (1 - (float) Math.cos(t / 40f * 2 * Math.PI));
+                return Pose.builder()
+                        .set(Bone.BODY, BoneTransform.IDENTITY.withBend(lean, 0))
+                        .build();
+            }),
+            // Right arm forward with the forearm folded up, as if showing off a sword. Tests held items.
+            "hold", of(20, true, t -> Pose.builder()
+                    .set(Bone.RIGHT_ARM, BoneTransform.rotation(-0.9f, 0, 0).withBend(1.4f, 0))
+                    .build()),
+            "twerk", of(8, true, TestAnimations::twerk));
 
     private TestAnimations() {
     }
 
+    static final EmoteRegistry REGISTRY = new EmoteRegistry();
+
+    static {
+        new TreeMap<>(ALL).forEach((id, animation) ->
+                REGISTRY.register(new Emote(id, id, "Test animation", "Saturn Emotes testmod", animation)));
+    }
+
+    /**
+     * Squatting with knees out and hips pushed back, bouncing the hips about 2.5 times a second. The
+     * torso tips forward around the hips and bends backwards, so the lower back arches in (not a
+     * hunched back) and the chest comes up. The arch deepens at the top of each bounce.
+     */
+    private static Pose twerk(float t) {
+        // 0 at the bottom of the bounce, 1 at the top.
+        float up = 0.5f * (1 - (float) Math.cos(t / 8f * 2 * Math.PI));
+
+        float thighPitch = -1.1f + 0.15f * up;
+        float knee = 1.75f - 0.3f * up;
+        float splay = 0.55f;
+        // How far the torso tips forward at the hips, and how much of that the arch takes back by the
+        // chest. The chest ends up leaning forward by tilt - arch.
+        float tilt = 1.4f;
+        float arch = 0.4f + 0.3f * up;
+
+        // Lower everything by as much as the bent legs got shorter, and push the hips back so the feet
+        // stay under where they were (a rigid thigh + shin approximation of the curved leg).
+        float drop = 12 - 6 * (float) (Math.cos(thighPitch) + Math.cos(thighPitch + knee)) * (float) Math.cos(splay);
+        float back = -6 * (float) (Math.sin(thighPitch) + Math.sin(thighPitch + knee));
+
+        // The body pivots at the neck, so tipping it forward swings the hips back. Move the pivot so
+        // the hips stay on the legs.
+        float cos = (float) Math.cos(tilt);
+        float sin = (float) Math.sin(tilt);
+        float bodyY = drop + 12 - 12 * cos;
+        float bodyZ = back - 12 * sin;
+
+        // The head and arms only turn with the torso's bend, not its rotation, so they get the tilt
+        // themselves (tilt plus the bend's turn is the chest's lean) and sit where the tipped torso puts
+        // them: the neck at the body's pivot, the shoulders 2 pixels down it.
+        float chest = tilt - arch;
+        float shoulderY = bodyY + 2 * cos - 2;
+        float shoulderZ = bodyZ + 2 * sin;
+        // Arms riding on a leaning chest would swing back, so tilt them forward to hang to the knees.
+        float armPitch = tilt - chest * 1.1f;
+        // Follow the chest, then look up by half its lean.
+        float headPitch = tilt - chest * 0.5f;
+
+        return Pose.builder()
+                .set(Bone.BODY, new BoneTransform(0, bodyY, bodyZ, tilt, 0, 0, arch, (float) Math.PI))
+                .set(Bone.HEAD, new BoneTransform(0, bodyY, bodyZ, headPitch, 0, 0, 0, 0))
+                .set(Bone.RIGHT_ARM, new BoneTransform(0, shoulderY, shoulderZ, armPitch, 0, 0.3f, 0.5f, 0))
+                .set(Bone.LEFT_ARM, new BoneTransform(0, shoulderY, shoulderZ, armPitch, 0, -0.3f, 0.5f, 0))
+                // Knees fold back and a little inwards, so the thighs splay out and the feet come in.
+                .set(Bone.RIGHT_LEG, new BoneTransform(0, drop, back, thighPitch, 0, splay, knee,
+                        (float) Math.PI - 0.35f))
+                .set(Bone.LEFT_LEG, new BoneTransform(0, drop, back, thighPitch, 0, -splay, knee,
+                        (float) Math.PI + 0.35f))
+                .build();
+    }
+
     private static Animation of(float length, boolean loops, Function<Float, Pose> sampler) {
         return new Animation() {
             @Override

src/testmod/resources/assets/saturn_emotes_testmod/player_animations/cry.json

@@ -0,0 +1,305 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "cry",
+  "description": "T_T",
+  "author": "dsty",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 60,
+    "stopTick": 61,
+    "isLoop": true,
+    "returnTick": 5,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.34134695
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.22808763
+        }
+      },
+      {
+        "tick": 25,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.21269174
+        }
+      },
+      {
+        "tick": 35,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.32248768
+        }
+      },
+      {
+        "tick": 45,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.0874397
+        }
+      },
+      {
+        "tick": 55,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.17582592
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.21476103
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -6.320644E-4
+        }
+      },
+      {
+        "tick": 25,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.029434478
+        }
+      },
+      {
+        "tick": 35,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.039604172
+        }
+      },
+      {
+        "tick": 45,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.037607383
+        }
+      },
+      {
+        "tick": 55,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.050604735
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.00930274
+        }
+      },
+      {
+        "tick": 25,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0010032838
+        }
+      },
+      {
+        "tick": 35,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.009209918
+        }
+      },
+      {
+        "tick": 45,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.012478679
+        }
+      },
+      {
+        "tick": 55,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.031160546
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.8700758
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.4349194
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.4970688
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.9622451
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.9203311
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": 0.6307226
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -0.2971223
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -0.8864816
+        }
+      }
+    ]
+  }
+}

src/testmod/resources/assets/saturn_emotes_testmod/player_animations/facepalm.json

@@ -0,0 +1,389 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "facepalm",
+  "description": "just facepalm",
+  "author": "dsty",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 60,
+    "stopTick": 61,
+    "isLoop": false,
+    "returnTick": 2,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.067995355
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.14453278
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.11871816
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.19018666
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.20064461
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.060454715
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.086299464
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.087619215
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.083825104
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": 0.036273066
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0041144555
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.12942825
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": -0.050149817
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.08701207
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.08676299
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -3.8523226
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -3.8523226
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.0664942
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.074402
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.074402
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.02932
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -2.02932
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.47555572
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.5093512
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.5093512
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.38563538
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.38563538
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.20147677
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.20521602
+        }
+      },
+      {
+        "tick": 30,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.3274244
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.30787703
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.40478125
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.49199954
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.54730254
+        }
+      },
+      {
+        "tick": 40,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.52019864
+        }
+      },
+      {
+        "tick": 60,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.0
+        }
+      }
+    ]
+  }
+}

src/testmod/resources/assets/saturn_emotes_testmod/player_animations/front_flip.json

@@ -0,0 +1,697 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "front_flip",
+  "description": "Parkour!!!!1",
+  "author": "DKinchik",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 17,
+    "stopTick": 18,
+    "isLoop": false,
+    "returnTick": 1,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "x": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "y": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.7020477
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": 0.7020477
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "head": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "x": -1.9
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "x": -1.9
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "y": 11.169379
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "z": -0.39214998
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "z": 0.1
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "z": 0.1
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -1.9707682
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -1.9707682
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.3665518
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.3665518
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.0793308
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.0793308
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "x": 1.9
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "x": 1.9
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "y": 10.861001
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "y": 12.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "z": -0.5082285
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "z": -0.1
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "z": -0.1
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 3,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 5,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -1.9850811
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -1.9850811
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "x": 0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "x": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "y": -0.061333913
+        }
+      },
+      {
+        "tick": 7,
+        "easing": "OUTQUAD",
+        "body": {
+          "y": 0.48852682
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "CONSTANT",
+        "body": {
+          "y": 0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "y": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 7,
+        "easing": "OUTQUAD",
+        "body": {
+          "pitch": -2.8362873
+        }
+      },
+      {
+        "tick": 15,
+        "easing": "CONSTANT",
+        "body": {
+          "pitch": -6.2831855
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "yaw": 0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "yaw": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INQUAD",
+        "body": {
+          "roll": -0.0
+        }
+      },
+      {
+        "tick": 16,
+        "easing": "INQUAD",
+        "body": {
+          "roll": 0.0
+        }
+      },
+      {
+        "tick": 2,
+        "easing": "INOUTQUAD",
+        "body": {
+          "bend": -0.0
+        }
+      }
+    ]
+  }
+}

src/testmod/resources/assets/saturn_emotes_testmod/player_animations/tpose.json

@@ -0,0 +1,354 @@
+{
+  "version": 1,
+  "valid": true,
+  "name": "tpose",
+  "description": "MENACING",
+  "author": "stephanieisdumb",
+  "emote": {
+    "beginTick": 0,
+    "endTick": 80,
+    "stopTick": 81,
+    "isLoop": true,
+    "returnTick": 20,
+    "nsfw": false,
+    "degrees": false,
+    "moves": [
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -5.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -6.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "x": -6.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -1.0704756
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": 0.059108086
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "pitch": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.61077195
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.008776078
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 0.6060502
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 1.5707964
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 1.5765934
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "roll": 1.5707964
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -1.3806202
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "rightArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 5.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 6.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "x": 6.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 2.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "y": 3.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "z": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": -1.0045553
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.010133168
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": 0.44322997
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": 0.038214765
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "yaw": -0.0
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -0.5571526
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -1.5707964
+        }
+      },
+      {
+        "tick": 50,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -1.5692185
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "roll": -1.5707964
+        }
+      },
+      {
+        "tick": 10,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -1.3810014
+        }
+      },
+      {
+        "tick": 20,
+        "easing": "INOUTQUAD",
+        "leftArm": {
+          "bend": -0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "leftLeg": {
+          "pitch": 0.0
+        }
+      },
+      {
+        "tick": 80,
+        "easing": "INOUTQUAD",
+        "rightLeg": {
+          "pitch": 0.0
+        }
+      }
+    ]
+  }
+}

src/testmod/resources/fabric.mod.json

@@ -7,7 +7,8 @@
   "license": "Apache-2.0",
   "environment": "client",
   "entrypoints": {
-    "client": ["org.saturnclient.emotes.testmod.EmotesTestmod"]
+    "client": ["org.saturnclient.emotes.testmod.EmotesTestmod"],
+    "fabric-client-gametest": ["org.saturnclient.emotes.testmod.EmotesGameTest"]
   },
   "depends": {
     "saturn_emotes": "*",

stonecutter.properties.toml

@@ -2,7 +2,7 @@
 mod.id = "saturn_emotes"
 mod.name = "Saturn Emotes"
 mod.group = "org.saturnclient"
-mod.version = "0.1.0"
+mod.version = "0.1.2"
 
 deps.fabric_loader = "0.19.5"
 loomx.loom_version = "1.17.21"
@@ -38,3 +38,16 @@ deps.fabric_api = "0.138.4+1.21.10"
 ["1.21.11"]
 mod.mc_compat = "1.21.11"
 deps.fabric_api = "0.141.6+1.21.11"
+
+# Built against 26.1 and allowed on its hotfixes (26.1.1, 26.1.2).
+["26.1"]
+mod.mc_compat = "~26.1"
+deps.fabric_api = "0.145.1+26.1"
+
+["26.2"]
+mod.mc_compat = "26.2"
+deps.fabric_api = "0.161.0+26.2"
+
+["26.3"]
+mod.mc_compat = "26.3"
+deps.fabric_api = "0.161.0+26.3"

tools/capture/.gitignore

@@ -0,0 +1,7 @@
+.venv/
+__pycache__/
+# Captures, fetched skins and scratch output: large, and regenerated by the scripts.
+frames/
+skins/
+*.log
+*.png

tools/capture/CheckPort.java

@@ -0,0 +1,19 @@
+import org.saturnclient.emotes.core.bend.LimbBend;
+
+/** Prints LimbBend results for check_port.py to compare with the Python port. */
+public class CheckPort {
+    public static void main(String[] args) {
+        float[][] cases = { {-2, 10, 0.5f, 0, 0}, {-2, 10, 1.75f, 3.5f, 0}, {0, 12, 1.2f, 2.79f, 0},
+                            {0, 12, 0.7f, 3.14159f, 1}, {0, 12, -0.9f, 1.0f, 1} };
+        float[][] points = { {0, 0, 0}, {1.5f, 3, -2.25f}, {-2.25f, 10.25f, 2.25f}, {2, -2.25f, 1}, {0.5f, 12.25f, -1} };
+        float[] out = new float[3];
+        for (float[] c : cases) {
+            LimbBend b = c[4] == 1 ? LimbBend.anchoredAtEnd(c[0], c[1], c[2], c[3], 0.5f, 12)
+                                   : new LimbBend(c[0], c[1], c[2], c[3], 0.5f, 12);
+            for (float[] p : points) {
+                b.bendPoint(p[0], p[1], p[2], out);
+                System.out.printf("%f %f %f %f%n", out[0], out[1], out[2], b.angleAt(p[1]));
+            }
+        }
+    }
+}

tools/capture/README.md

@@ -0,0 +1,63 @@
+# Emote capture
+
+Measures an emote from a store page's 3D preview and writes it as an Emotecraft emote our loader
+reads. It works from pixels only: it renders our own player model in the same pose from the same
+cameras and adjusts the pose until outlines and colours match. It never reads the page's animation
+data.
+
+## Setup
+
+```sh
+python3 -m venv .venv
+.venv/bin/pip install -r requirements.txt
+.venv/bin/playwright install firefox   # Playwright's own Firefox, in its cache folder
+```
+
+## Steps
+
+```sh
+.venv/bin/python capture.py <store url> <name> --skin Steve   # frames/<name>/<view>/<tick>.png + views.json
+.venv/bin/python measure.py <name> --ticks 0:13               # frames/<name>/rig.json (one loop: 13 ticks)
+.venv/bin/python fit.py <name> --symmetric --title "Twerk" --out <path>.json
+```
+
+- **`capture.py`** opens the page in headless Firefox with `viewer.js` injected, switches the
+  preview to 3D and puts a skin on it. `--skin` takes one of the dialog's presets or any Minecraft
+  username. `viewer.js` replaces the page's clock, so frames step one tick (50 ms) at a time however
+  fast the emote moves. It also finds the camera through three.js's devtools hook. Each tick is taken
+  from 10 fixed cameras with a transparent background. It also measures the loop length from the
+  frames.
+- **`skin.py`** fetches that username's skin from Mojang, so our model can wear the same texture.
+- **`measure.py`** fits our rig to every tick. It renders the model with `model.py` (a port of
+  `LimbBend` and `PoseApplier`) and `render.py`, and scores it by outline distance and colour. It
+  searches with CMA-ES on all cores. The first tick is searched in stages: torso and head, then each
+  limb from several starts, then everything, then its back-to-front twins (`flip.py`). It also finds
+  the viewer's scale then. For a whole loop, later rounds refit every tick held near the loop's
+  smoothed curve, so drift can't build up. Leaning further forward while arching further back looks
+  almost the same from every camera, so a small cost on the torso's bend picks the straightest torso.
+- **`fit.py`** smooths each channel over the loop (Fourier harmonics) and stands the emote on the
+  ground. It keys each channel wherever straight-line interpolation misses by more than 1° or 0.1 px.
+  `--symmetric` removes left/right lopsidedness (`symmetry.py`): each tick is averaged with the mirror
+  of the pose half a loop on, which keeps an even sway and drops any lean to one side.
+
+## Checking
+
+- `check_port.py` compares `model.py`'s bend maths with the Java classes (after
+  `./gradlew :core:compileJava`).
+- `synth_test.py` renders our own twerk test animation as a fake capture, so `measure.py` can be
+  scored against a known answer.
+- `symmetry.py <name>` lists the most lopsided channels.
+- `compare.py <name> <tick>` puts the captured frames next to our render of the fit.
+- `overlay.py <name>` draws both outlines on top of each other.
+- `sheet.py` tiles captured frames.
+
+To see it in game, add the JSON to the testmod's `player_animations` and `EMOTECRAFT_EMOTES`, and add
+shots to `EmotesGameTest`.
+
+## Limits
+
+- A loop takes about 45 minutes on 7 cores.
+- The emote comes out with a keyframe on almost every tick for every channel.
+- Other rigs differ from ours (a knee made of two rigid boxes, a torso that doesn't bend), so a fit is
+  our closest match, not an exact copy.
+- Extreme poses can still land in a wrong answer on the first tick. `synth_test.py`'s 80° lean does.

tools/capture/capture.py

@@ -0,0 +1,140 @@
+"""Captures an emote from a store page's 3D viewer, one frame per tick from several fixed cameras.
+
+    .venv/bin/python capture.py <store url> <name> [--seconds 6]
+
+Writes frames/<name>/<view>/<tick>.png (RGBA, transparent background) and frames/<name>/views.json,
+which records each camera exactly so measure.py can render the same views.
+
+The page runs on a clock that viewer.js steps by hand, so every view of a tick shows the same moment
+and nothing is missed however fast the emote moves.
+"""
+import argparse
+import base64
+import io
+import json
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+from playwright.sync_api import sync_playwright
+
+TICK_MS = 50
+# Where the cameras look (viewer world units) and from how far. The model stands about one unit per
+# model pixel, with its middle about 12 units below the viewer's origin.
+TARGET = [0, -12, 0]
+DISTANCE = 50
+FOV = 50
+VIEWS = {f"y{yaw:03d}": (yaw, 0) for yaw in range(0, 360, 45)}
+VIEWS |= {"top000": (0, 50), "top090": (90, 50)}
+
+
+def step(page, ms, grab=False):
+    url = page.evaluate(f"window.__capture.step({ms}, {'true' if grab else 'false'})")
+    if not grab:
+        return None
+    return Image.open(io.BytesIO(base64.b64decode(url.split(",", 1)[1]))).convert("RGBA")
+
+
+def warm_up(page, frames):
+    for _ in range(frames):
+        step(page, 16)
+        page.wait_for_timeout(15)
+
+
+def set_view(page, yaw, pitch):
+    view = {"target": TARGET, "distance": DISTANCE, "yaw": yaw, "pitch": pitch, "fov": FOV}
+    page.evaluate(f"window.__capture.setView({json.dumps(view)})")
+    return view
+
+
+def choose_skin(page, skin):
+    """Puts a skin we have the texture of on the model, so measure.py can match colours too."""
+    page.evaluate("[...document.querySelectorAll('button')].find(b => b.innerText.includes(\"'s skin\")).click()")
+    warm_up(page, 40)
+    page.get_by_text("Change preview skin").last.click(force=True)
+    warm_up(page, 60)
+    preset = page.get_by_role("button", name=skin, exact=True)
+    if preset.count():
+        preset.first.click(force=True)
+    else:
+        page.get_by_placeholder("Enter a Minecraft username").fill(skin)
+        page.keyboard.press("Enter")
+    warm_up(page, 150)
+    page.keyboard.press("Escape")
+
+
+def loop_ticks(masks):
+    """The loop length in ticks: the shift that best maps the front view's masks onto themselves."""
+    best, best_err = None, None
+    for period in range(8, len(masks) // 2):
+        err = np.mean([np.mean(masks[i] != masks[i + period]) for i in range(len(masks) - period)])
+        if best_err is None or err < best_err:
+            best, best_err = period, err
+    return best, best_err
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("url")
+    parser.add_argument("name")
+    parser.add_argument("--seconds", type=float, default=6)
+    parser.add_argument("--skin", default="Steve",
+                        help="a preset from the viewer's skin dialog (Steve, Alex, ...) or a Minecraft username")
+    args = parser.parse_args()
+
+    out = Path("frames") / args.name
+    ticks = round(args.seconds * 1000 / TICK_MS)
+
+    with sync_playwright() as p:
+        browser = p.firefox.launch()
+        page = browser.new_page(viewport={"width": 1280, "height": 900})
+        page.add_init_script(path=str(Path(__file__).with_name("viewer.js")))
+        page.goto(args.url, wait_until="domcontentloaded", timeout=60000)
+        warm_up(page, 200)
+        # The toggle between the video and the 3D viewer sits in the preview's top right corner.
+        page.mouse.click(794, 177)
+        page.wait_for_selector("#skin-viewer", timeout=30000)
+        warm_up(page, 100)
+        choose_skin(page, args.skin)
+        warm_up(page, 200)
+
+        cameras = {}
+        for name, (yaw, pitch) in VIEWS.items():
+            (out / name).mkdir(parents=True, exist_ok=True)
+            cameras[name] = set_view(page, yaw, pitch)
+
+        info = page.evaluate("window.__capture.camera_info()")
+        start = page.evaluate("window.__capture.time()")
+        front_masks = []
+        for tick in range(ticks):
+            for i, (name, (yaw, pitch)) in enumerate(VIEWS.items()):
+                set_view(page, yaw, pitch)
+                # The first view advances the clock by a tick; the rest redraw the same moment.
+                frame = step(page, TICK_MS if i == 0 else 0, grab=True)
+                frame.save(out / name / f"{tick:04d}.png")
+                if name == "y000":
+                    front_masks.append(np.asarray(frame)[:, :, 3] > 127)
+            if tick % 20 == 0:
+                print(f"tick {tick}/{ticks}")
+
+        period, err = loop_ticks(front_masks)
+        meta = {
+            "url": args.url,
+            "skin": args.skin,
+            "tick_ms": TICK_MS,
+            "ticks": ticks,
+            "start_ms": start,
+            "size": list(front_masks[0].shape[::-1]),
+            "aspect": info["aspect"],
+            "near": info["near"],
+            "views": cameras,
+            "loop_ticks": period,
+            "loop_error": err,
+        }
+        (out / "views.json").write_text(json.dumps(meta, indent=2))
+        print(f"loop: {period} ticks ({period * TICK_MS / 1000:.2f} s), mismatch {err:.4f}")
+        browser.close()
+
+
+if __name__ == "__main__":
+    main()

tools/capture/check_port.py

@@ -0,0 +1,27 @@
+"""Compares model.LimbBend with the Java LimbBend, point for point.
+
+    .venv/bin/python check_port.py ../../core/build/classes/java/main   # after ./gradlew :core:compileJava
+
+Runs CheckPort.java against the compiled core classes and fails if any result differs by 1e-3 or more.
+"""
+import subprocess
+import sys
+
+import numpy as np
+
+from model import LimbBend
+
+CASES = [(-2, 10, 0.5, 0, 0), (-2, 10, 1.75, 3.5, 0), (0, 12, 1.2, 2.79, 0), (0, 12, 0.7, 3.14159, 1), (0, 12, -0.9, 1.0, 1)]
+POINTS = np.array([[0, 0, 0], [1.5, 3, -2.25], [-2.25, 10.25, 2.25], [2, -2.25, 1], [0.5, 12.25, -1]])
+
+classes = sys.argv[1]
+java = subprocess.run(["java", "-cp", classes, "CheckPort.java"], capture_output=True, text=True, check=True).stdout
+expected = np.array([[float(v) for v in line.split()] for line in java.strip().splitlines()])
+got = []
+for start, end, angle, axis, anchored in CASES:
+    b = LimbBend(start, end, angle, axis, anchored_at_end=bool(anchored))
+    bent = b.bend_points(POINTS)
+    got += [[*bent[i], b.angle_at(POINTS[i, 1])] for i in range(len(POINTS))]
+err = np.abs(np.array(got) - expected).max()
+print(f"max difference from Java: {err:.2e}")
+sys.exit(0 if err < 1e-3 else 1)

tools/capture/compare.py

@@ -0,0 +1,40 @@
+"""Puts captured frames next to our render of the fitted pose, with the same skin and cameras.
+
+    .venv/bin/python compare.py <name> [tick] [views]
+
+Writes frames/<name>/compare.png: for each view, theirs on the left and ours on the right.
+"""
+import json
+import sys
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+
+from model import Model, rig_to_pose
+from render import Camera, render_colors
+
+name = sys.argv[1]
+tick = int(sys.argv[2]) if len(sys.argv) > 2 else 0
+views = sys.argv[3].split(",") if len(sys.argv) > 3 else ["y000", "y090", "y180", "y270", "y045"]
+base = Path("frames") / name
+meta = json.loads((base / "views.json").read_text())
+data = json.loads((base / "rig.json").read_text())
+rig = np.array(next(t["rig"] for t in data["ticks"] if t["tick"] == tick))
+skin = np.asarray(Image.open(Path("skins") / f"{meta.get('skin', 'Steve')}.png").convert("RGBA"))
+model = Model(spacing=0.12, skin=skin)
+scale = 2
+cams = {v: Camera(meta["views"][v], meta["size"], meta["aspect"], scale) for v in views}
+ours = render_colors(np.concatenate(list(model.pose(rig_to_pose(rig)).values())), model.colors, data["calib"], cams)
+bg = np.array([40, 40, 52], np.uint8)
+tiles = []
+for v in views:
+    theirs = np.asarray(Image.open(base / v / f"{tick:04d}.png").convert("RGBA").reduce(scale))
+    a = np.where(theirs[..., 3:] > 127, theirs[..., :3], bg)
+    image, mask = ours[v]
+    b = np.where(mask[..., None], (image * 255).astype(np.uint8), bg)
+    tiles.append(np.concatenate([a, b], axis=1))
+sheet = np.concatenate(tiles, axis=0)
+ys, xs = np.nonzero((sheet != bg).any(axis=2))
+Image.fromarray(sheet[:, max(xs.min() - 8, 0):xs.max() + 8]).save(base / "compare.png")
+print("wrote", base / "compare.png")

tools/capture/fit.py

@@ -0,0 +1,167 @@
+"""Turns measured rigs (frames/<name>/rig.json) into an Emotecraft emote our loader reads.
+
+    .venv/bin/python fit.py <name> [--out path.json] [--angle-tol 1] [--offset-tol 0.1]
+
+Every channel is keyed independently, keeping only the ticks linear interpolation can't reproduce
+within the tolerances. Values go through the inverse of EmotecraftLoader's conversions.
+"""
+import argparse
+import json
+from pathlib import Path
+
+import numpy as np
+
+from model import INDEX, Model, rest_rig, rig_to_pose
+
+PARTS = {"root": "body", "head": "head", "body": "torso", "right_arm": "rightArm", "left_arm": "leftArm",
+         "right_leg": "rightLeg", "left_leg": "leftLeg"}
+# EmotecraftLoader.REST_PIVOTS: limb positions in the file are absolute pivots.
+REST = {"right_arm": (-5, 2, 0), "left_arm": (5, 2, 0), "right_leg": (-1.9, 12, 0.1), "left_leg": (1.9, 12, 0.1)}
+CHANNELS = ["x", "y", "z", "pitch", "yaw", "roll", "bend", "axis"]
+
+
+def to_file(bone, channel, value):
+    """The inverse of EmotecraftLoader.convert, writing degrees."""
+    if channel in ("x", "y", "z"):
+        if bone == "root":
+            return value / 16 if channel == "z" else -value / 16
+        return value + REST.get(bone, (0, 0, 0))["xyz".index(channel)]
+    degrees = np.degrees(value)
+    if channel == "bend":
+        # Limbs bend the other way in Emotecraft; the torso agrees with ours.
+        return degrees if bone == "body" else -degrees
+    if bone == "root" and channel in ("pitch", "yaw"):
+        return -degrees
+    return degrees
+
+
+def keep(values, tol):
+    """Indices to key so linear interpolation stays within tol of every sample (Douglas-Peucker)."""
+    keys = {0, len(values) - 1}
+
+    def split(a, b):
+        if b - a < 2:
+            return
+        t = np.arange(a, b + 1)
+        line = values[a] + (values[b] - values[a]) * (t - a) / (b - a)
+        err = np.abs(values[a:b + 1] - line)
+        i = int(np.argmax(err))
+        if err[i] > tol:
+            keys.add(a + i)
+            split(a, a + i)
+            split(a + i, b)
+
+    split(0, len(values) - 1)
+    return sorted(keys)
+
+
+def ground(rigs):
+    """Shifts every tick vertically so the lowest foot over the whole emote is where a standing
+    player's feet are. The viewer offset was a guess (measure.py keeps it fixed), so the measured
+    height is only right up to a constant."""
+    model = Model()
+    lowest = lambda rig: max(model.pose(rig_to_pose(rig))[leg][:, 1].max() for leg in ("right_leg", "left_leg"))
+    shift = lowest(rest_rig()) - max(lowest(r) for r in rigs)  # model Y points down
+    for r in rigs:
+        r[INDEX["root_y"]] += shift
+    return shift
+
+
+def periodic_smooth(values, harmonics, angle):
+    """A loop's channel kept to its first few Fourier harmonics: removes the fit's tick-to-tick noise
+    and joins the loop's seam. Returns the smoothed samples plus the loop's next sample (its start
+    again, a whole number of turns on for an angle that spins)."""
+    n = len(values)
+    turns = 0.0
+    if angle:
+        # How far the angle travels in one loop: nothing for a sway, whole turns for a spin.
+        step = (values[0] - values[-1] + np.pi) % (2 * np.pi) - np.pi
+        turns = values[-1] + step - values[0]
+    ramp = turns * np.arange(n + 1) / n
+    spectrum = np.fft.rfft(values - ramp[:n])
+    spectrum[harmonics + 1:] = 0
+    smooth = np.fft.irfft(spectrum, n)
+    return np.append(smooth, smooth[0]) + ramp
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("name")
+    parser.add_argument("--out")
+    parser.add_argument("--angle-tol", type=float, default=1.0, help="degrees")
+    parser.add_argument("--offset-tol", type=float, default=0.1, help="pixels")
+    parser.add_argument("--no-ground", action="store_true", help="keep the measured height")
+    parser.add_argument("--harmonics", type=int, default=4,
+                        help="for a whole loop, how many Fourier harmonics each channel keeps (0 = no smoothing)")
+    parser.add_argument("--rig", help="read this rig file instead of frames/<name>/rig.json")
+    parser.add_argument("--symmetric", action="store_true",
+                        help="for a whole loop that sways once per loop, remove its left/right lopsidedness "
+                             "(see symmetry.py)")
+    parser.add_argument("--title", help="the emote's name (default: from <name>)")
+    parser.add_argument("--description", help="default: where it was measured from")
+    parser.add_argument("--author", default="Saturn capture")
+    args = parser.parse_args()
+
+    base = Path("frames") / args.name
+    data = json.loads(Path(args.rig).read_text() if args.rig else (base / "rig.json").read_text())
+    meta = json.loads((base / "views.json").read_text())
+    ticks = data["ticks"]
+    loop = meta.get("loop_ticks")
+    rigs = [np.array(t["rig"]) for t in ticks]
+    if args.symmetric:
+        if not (loop and len(rigs) == loop):
+            parser.error("--symmetric needs a whole loop")
+        from symmetry import symmetrize
+        rigs = list(symmetrize(rigs, sway=True))
+        print("made symmetric: each tick averaged with the mirror of the pose half a loop on")
+    if not args.no_ground:
+        print(f"grounded: moved {ground(rigs):+.2f} px down")
+    poses = [rig_to_pose(r) for r in rigs]
+    first = ticks[0]["tick"]
+    whole_loop = bool(loop) and len(poses) == loop
+    if whole_loop and args.harmonics:
+        print(f"smoothed each channel to {args.harmonics} harmonics of the {loop}-tick loop")
+
+    moves = {}
+    total = 0
+    for bone, part in PARTS.items():
+        for channel in CHANNELS:
+            raw = np.array([getattr(p[bone], channel) for p in poses], float)
+            angle = channel not in ("x", "y", "z")
+            if angle:
+                raw = np.unwrap(raw)
+            if whole_loop:
+                # A loop's last tick blends back into its first.
+                raw = periodic_smooth(raw, args.harmonics, angle) if args.harmonics else np.append(raw, raw[0])
+            values = np.array([to_file(bone, channel, v) for v in raw])
+            if np.all(np.abs(values - values[0]) < 1e-6) and abs(values[0]) < 1e-6 and channel != "x":
+                continue
+            tol = args.offset_tol if channel in ("x", "y", "z") else args.angle_tol
+            if bone == "root" and channel in ("x", "y", "z"):
+                tol /= 16
+            for i in keep(values, tol):
+                moves.setdefault(i, {}).setdefault(part, {})[channel] = round(float(values[i]), 4)
+                total += 1
+
+    emote = {
+        "version": 3,
+        "name": args.title or args.name.replace("_", " ").title(),
+        "description": args.description or f"Measured from {meta['url']}",
+        "author": args.author,
+        "emote": {
+            "degrees": True,
+            "isLoop": bool(loop),
+            "returnTick": 0,
+            "endTick": len(poses) - 1,
+            "stopTick": len(poses) if whole_loop else len(poses) - 1,
+            "moves": [{"tick": i, "easing": "LINEAR", **parts} for i, parts in sorted(moves.items())],
+        },
+    }
+    out = Path(args.out) if args.out else base / f"{args.name}.json"
+    out.write_text(json.dumps(emote, indent=2))
+    print(f"wrote {out}: {len(emote['emote']['moves'])} ticks keyed, {total} channel keyframes "
+          f"(from {len(poses)} samples, starting at captured tick {first})")
+
+
+if __name__ == "__main__":
+    main()

tools/capture/flip.py

@@ -0,0 +1,55 @@
+"""The back-to-front twin of a rig, which covers the same space with the textures turned round.
+
+The head and torso boxes are centred on their pivots, so spinning either half a turn around its own
+vertical axis leaves it covering the same space; only which face shows changes. The arms hang from
+the torso's sides, so spinning the torso carries each arm to the other side. That twin (torso and
+head facing backwards, arms swapped) is a separate local minimum the search can't walk out of, so
+measure.py jumps to it directly, refines it, and keeps whichever scores lower. Only the colours tell
+them apart.
+
+In rig terms: the torso and head get R Ry(pi); each arm takes the other's rotation times Ry(pi) (a
+half turn around its own length, which moves its off-centre box to the other side of its pivot); and
+bends keep their shape with their direction turned half round, since the frame they're measured in
+turned. The legs hang from the hips and don't change.
+"""
+import numpy as np
+
+from model import INDEX, rotation_zyx
+
+SPIN = np.diag([-1.0, 1.0, -1.0])  # Ry(pi)
+ARMS = {"right_arm": "left_arm", "left_arm": "right_arm"}
+
+
+def euler_zyx(r):
+    """(pitch, yaw, roll) with rotation_zyx(pitch, yaw, roll) == r."""
+    yaw = np.arcsin(np.clip(-r[2, 0], -1, 1))
+    return np.arctan2(r[2, 1], r[2, 2]), yaw, np.arctan2(r[1, 0], r[0, 0])
+
+
+def _spun(rig, source):
+    g = lambda c: rig[INDEX[f"{source}_{c}"]]
+    return euler_zyx(rotation_zyx(g("pitch"), g("yaw"), g("roll")) @ SPIN)
+
+
+def flip_head(rig):
+    """Just the head spun round: a cube on its pivot, so the same space facing the other way."""
+    out = rig.copy()
+    for c, v in zip(("pitch", "yaw", "roll"), _spun(rig, "head")):
+        out[INDEX[f"head_{c}"]] = v
+    return out
+
+
+def twins(rig):
+    """Every back-to-front twin worth trying: the torso with its arms, the head, and both."""
+    return [flip(rig), flip_head(rig), flip_head(flip(rig))]
+
+
+def flip(rig):
+    out = rig.copy()
+    for part, source in [("body", "body"), ("head", "head"), *ARMS.items()]:
+        for c, v in zip(("pitch", "yaw", "roll"), _spun(rig, source)):
+            out[INDEX[f"{part}_{c}"]] = v
+    for part, source in [("body", "body"), *ARMS.items()]:
+        out[INDEX[f"{part}_bend"]] = rig[INDEX[f"{source}_bend"]]
+        out[INDEX[f"{part}_axis"]] = rig[INDEX[f"{source}_axis"]] + np.pi
+    return out

tools/capture/measure.py

@@ -0,0 +1,341 @@
+"""Fits our rig to captured frames, tick by tick, by rendering it and matching outlines and colours.
+
+    .venv/bin/python measure.py <name> [--ticks 0:13] [--workers 7]
+
+Writes frames/<name>/rig.json: the viewer calibration and one rig vector per tick (see model.RIG).
+
+The first tick has nothing to start from, so it's searched in stages: the torso and head, then each
+limb from several starts, then everything together, then its back-to-front twins (see flip.py). It
+also finds the viewer's scale. Later ticks start from the tick before.
+
+For a whole loop, that first pass is only a starting point: warm starts carry any drift from tick to
+tick. Each later round smooths every channel over the loop (a few Fourier harmonics, which have to
+close), and refits every tick held near that curve instead of near its neighbour.
+"""
+import argparse
+import json
+import multiprocessing
+import time
+from pathlib import Path
+
+import cma
+import numpy as np
+from PIL import Image
+
+from flip import twins
+from model import INDEX, RIG, Model, rest_rig, rig_to_pose
+from render import Capture, score
+
+# How far CMA-ES first looks along each parameter: pixels for offsets, radians for angles.
+STEP = np.array([2.0 if name.endswith(("_x", "_y", "_z")) else 0.35 for name in RIG])
+CALIB = ["scale", "view_x", "view_y", "view_z"]
+CALIB_STEP = np.array([0.05, 2, 2, 2])
+# Only the scale is fitted. Moving the viewer, the whole player and the hips all slide the whole model,
+# so no frame can tell them apart: the viewer's offset stays fixed (it centres the player on its
+# origin), and fit.py stands the finished emote on the ground instead.
+CALIB_FREE = [0]
+# Channels a silhouette barely sees (a limb's twist, which way a straight limb would bend) drift
+# unless something holds them near zero.
+QUIET = np.array([1.0 if name.endswith(("_yaw", "_axis")) and not name.startswith(("root", "body")) else 0.0
+                  for name in RIG])
+QUIET_WEIGHT = 0.02
+SMOOTH_WEIGHT = 0.05
+# The search scores colour lightly in a few views: outlines give it a smooth slope to follow, and
+# colour changes abruptly as parts slide across texture edges, which strands it. Choosing between a
+# fit and its back-to-front twins (whose outlines match) is colour's job, so that comparison weighs
+# colour heavily in every view.
+COLOR_VIEWS = {"y000", "y090", "y180", "y270"}
+JUDGE_COLOR_WEIGHT = 2.0
+
+# Anatomy, as soft limits: in a tight pose like a crouch, many limb twists cast nearly the same outline,
+# and these pick the natural one. Nothing is penalised inside the ranges.
+FOLD = {"right_leg": np.pi, "left_leg": np.pi, "right_arm": 0.0, "left_arm": 0.0}  # knees back, elbows forward
+FOLD_RANGE = np.radians(70)
+ROLL_RANGE = np.radians(60)
+PRIOR_WEIGHT = 0.5
+HIP_CENTRE_WEIGHT = 0.002
+# Leaning the torso further forward while arching it further back looks nearly the same from every
+# camera, so a small cost on the torso's bend picks the straightest torso that fits.
+BODY_BEND_WEIGHT = 0.008
+# Where each bend direction is kept (see canonical): half a turn either side of this. Knees fold back
+# and elbows forward; a torso may hunch (0) or arch (pi), so both sit well inside its range.
+AXIS_CENTRE = FOLD | {"body": np.pi / 2}
+
+
+def wrap(a):
+    return (a + np.pi) % (2 * np.pi) - np.pi
+
+
+ANGLES = np.array([not name.endswith(("_x", "_y", "_z")) for name in RIG])
+
+
+def change(rig, previous):
+    """How far each channel moved, the short way round for angles: canonical() keeps them within
+    -pi..pi, so a knee folding back straddles the edge and would look like it swung a whole turn."""
+    d = rig - previous
+    return np.where(ANGLES, wrap(d), d)
+
+
+def anatomy(rig):
+    """How far outside natural joint ranges the rig is (0 inside them)."""
+    total = 0.0
+    for limb, fold in FOLD.items():
+        bend = rig[INDEX[f"{limb}_bend"]]
+        # A negative bend folds the other way.
+        axis = rig[INDEX[f"{limb}_axis"]] + (np.pi if bend < 0 else 0)
+        # Which way a limb folds only matters as much as it bends.
+        total += np.sin(min(abs(bend), np.pi) / 2) * max(0.0, abs(wrap(axis - fold)) - FOLD_RANGE) ** 2
+        total += max(0.0, abs(wrap(rig[INDEX[f"{limb}_roll"]])) - ROLL_RANGE) ** 2
+    return PRIOR_WEIGHT * total + HIP_CENTRE_WEIGHT * rig[INDEX["hip_x"]] ** 2
+
+# The hips carry everything, so the whole player's offset would only duplicate them; it stays at zero.
+# Turning the whole player duplicates turning every part, so it's only fitted with --root, for flips
+# and spins, where it keeps the keyframes simple.
+FITTED = [i for i, n in enumerate(RIG) if not n.startswith("root")]
+ROOT_TURN = [INDEX[n] for n in ("root_pitch", "root_yaw", "root_roll")]
+LIMBS = ("right_leg", "left_leg", "right_arm", "left_arm")
+ALL_PARTS = ("head", "body", "right_arm", "left_arm", "right_leg", "left_leg")
+
+# Per-process state, set by init_worker, so the pool only receives parameter vectors.
+_state = {}
+
+
+def init_worker(directory, skin_path, tick):
+    skin = np.asarray(Image.open(skin_path).convert("RGBA"))
+    cap = Capture(directory)
+    model = Model(skin=skin)
+    # Where each part's points sit in model.colors, to score some of the parts on their own.
+    bounds = np.cumsum([0] + [len(model.local[p]) for p in model.local])
+    spans = {p: (bounds[i], bounds[i + 1]) for i, p in enumerate(model.local)}
+    _state.update(model=model, spans=spans, cameras=cap.cameras, targets=cap.targets(tick))
+
+
+def loss(job):
+    """job = (full vector: rig + calib, previous rig or None, parts to score[, judging]). Scoring only
+    some parts (the torso stage) counts just their points outside the captured outline. Judging weighs
+    colour heavily in every view, to pick between twins."""
+    v, previous, parts, *judging = job
+    judging = bool(judging and judging[0])
+    rig, calib = v[:len(RIG)], v[len(RIG):]
+    m = _state["model"]
+    posed = m.pose(rig_to_pose(rig))
+    parts = parts or ALL_PARTS
+    pts = np.concatenate([posed[p] for p in parts])
+    colors = np.concatenate([m.colors[slice(*_state["spans"][p])] for p in parts])
+    total = score(pts, calib, _state["cameras"], _state["targets"], colors=colors,
+                  color_views=None if judging else COLOR_VIEWS, one_way=len(parts) < len(ALL_PARTS),
+                  color_weight=JUDGE_COLOR_WEIGHT if judging else None)
+    total += QUIET_WEIGHT * np.sum(QUIET * np.sin(rig) ** 2)
+    total += anatomy(rig)
+    total += BODY_BEND_WEIGHT * rig[INDEX["body_bend"]] ** 2
+    if previous is not None:
+        total += SMOOTH_WEIGHT * np.sum((change(rig, previous) / STEP) ** 2) / len(rig)
+    return total
+
+
+def fit(pool, x0, free, sigma, evals, previous=None, parts=None, popsize=24, seed=1):
+    """CMA-ES over the indices in free (of rig + calib); the rest stay at x0."""
+    x0 = np.asarray(x0, float)
+    steps = np.concatenate([STEP, CALIB_STEP])[free]
+
+    def expand(sub):
+        v = x0.copy()
+        v[free] = sub
+        return v
+
+    es = cma.CMAEvolutionStrategy(x0[free], sigma, {
+        "CMA_stds": steps, "popsize": popsize, "maxfevals": evals, "verbose": -9, "seed": seed, "tolfun": 1e-4,
+    })
+    while not es.stop():
+        subs = es.ask()
+        es.tell(subs, pool.map(loss, [(expand(s), previous, parts) for s in subs]))
+    return expand(es.result.xbest), es.result.fbest
+
+
+def canonical(v):
+    """A negative bend is the same shape as a positive one folding the other way. Bend directions are
+    kept within half a turn of AXIS_CENTRE, so a knee folding back doesn't sit on the edge of the range
+    and jump a whole turn between ticks."""
+    v = v.copy()
+    for part, centre in AXIS_CENTRE.items():
+        b, a = INDEX[f"{part}_bend"], INDEX[f"{part}_axis"]
+        if v[b] < 0:
+            v[b], v[a] = -v[b], v[a] + np.pi
+        v[a] = wrap(v[a] - centre) + centre
+    return v
+
+
+def loop_curve(rigs, harmonics):
+    """Each channel of a loop's rigs kept to its first few Fourier harmonics: the loop's own smooth
+    path, which has to come back to where it started."""
+    from fit import periodic_smooth
+    rigs = np.array(rigs)
+    curve = np.empty_like(rigs)
+    for i in range(rigs.shape[1]):
+        values = np.unwrap(rigs[:, i]) if ANGLES[i] else rigs[:, i]
+        curve[:, i] = periodic_smooth(values, harmonics, bool(ANGLES[i]))[:-1]
+    return curve
+
+
+# Starting points for each limb on its own: swung back, hanging, or forward, straight or folded the
+# natural way. One start lands in a different local minimum every run; the best of these doesn't.
+LIMB_STARTS = [(pitch, bend) for pitch in (-1.2, 0.0, 1.2) for bend in (0.0, 1.5)]
+
+
+def fit_limbs(pool, x, fitted, starts, evals):
+    """Fits each limb in turn with the others held, keeping the best of the starts."""
+    fx = None
+    for limb in LIMBS:
+        free = [i for i in fitted if RIG[i].startswith(limb)]
+        best = None
+        for pitch, bend in starts or [(None, None)]:
+            x0 = x.copy()
+            if pitch is not None:
+                x0[free] = 0
+                x0[INDEX[f"{limb}_pitch"]] = pitch
+                x0[INDEX[f"{limb}_bend"]] = bend
+                x0[INDEX[f"{limb}_axis"]] = FOLD[limb]
+            result = fit(pool, x0, free, 1.0 if starts else 0.4, evals)
+            if best is None or result[1] < best[1]:
+                best = result
+        x, fx = best
+    return x, fx
+
+
+def refine_scale(pool, x):
+    """The viewer scale on its own, once the pose explains the whole outline."""
+    from scipy.optimize import minimize_scalar
+
+    def f(scale):
+        v = x.copy()
+        v[len(RIG)] = scale
+        return pool.map(loss, [(v, None, None)])[0]
+
+    result = minimize_scalar(f, bounds=(x[len(RIG)] * 0.85, x[len(RIG)] * 1.15), method="bounded",
+                             options={"xatol": 1e-3})
+    v = x.copy()
+    v[len(RIG)] = result.x
+    return v
+
+
+def settle_facing(pool, x, fx, fitted, previous, log):
+    """Tries each back-to-front twin of a fit, refined, and keeps the best. They cover nearly the same
+    outline, so the search can't get from one to another by itself; only colour decides."""
+    judge = lambda v: pool.map(loss, [(v, previous, None, True)])[0]
+    best, best_judged = (x, fx), judge(x)
+    for twin in twins(x[:len(RIG)]):
+        candidate = fit(pool, np.concatenate([twin, x[len(RIG):]]), fitted, 0.3, 1500, previous)
+        judged = judge(candidate[0])
+        if judged < best_judged:
+            log(f"  a turned-round twin fits better: {judged:.3f} < {best_judged:.3f} (judged on colour)")
+            best, best_judged = candidate, judged
+    return best
+
+
+def first_tick(pool, calib, fitted, log):
+    """Tries the player facing both ways, all the way through, since no single stage can tell them
+    apart reliably: the torso, then each limb from several starts, then each limb again with the
+    others in place, then everything together. The scale is held until the pose explains the whole
+    outline (shrinking always helps a partly wrong pose), then fitted on its own."""
+    torso = [i for i in fitted if RIG[i].startswith(("root", "hip", "body", "head"))]
+    x = np.concatenate([rest_rig(), calib])
+    # The torso and head alone, kept inside the outline and matched by colour.
+    x, fx = fit(pool, x, torso, 1.0, 3000, parts=("head", "body"))
+    log(f"  torso {fx:.3f}")
+    x, fx = fit_limbs(pool, x, fitted, LIMB_STARTS, 500)
+    log(f"  limbs {fx:.3f}")
+    x, fx = fit_limbs(pool, x, fitted, None, 1000)
+    x, fx = fit(pool, x, fitted, 0.3, 3000)
+    log(f"  together {fx:.3f}")
+    # Facing can be wrong at any stage; settle it once the pose explains the whole outline.
+    x, fx = settle_facing(pool, x, fx, fitted, None, log)
+    x, fx = fit(pool, x, fitted, 0.3, 6000)
+    x = refine_scale(pool, x)
+    return fit(pool, x, fitted, 0.2, 3000)
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("name")
+    parser.add_argument("--ticks", default="0:13")
+    parser.add_argument("--calib", default="0.9375,0,-1.5,0",
+                        help="viewer scale (a starting guess) and offset (kept) as scale,x,y,z")
+    parser.add_argument("--workers", type=int, default=max(1, multiprocessing.cpu_count() - 1))
+    parser.add_argument("--rounds", type=int, default=2,
+                        help="for a whole loop, how many times to refit every tick held near the loop's smoothed curve")
+    parser.add_argument("--harmonics", type=int, default=2,
+                        help="Fourier harmonics in that curve: few, since it only decides what the frames can't")
+    parser.add_argument("--root", action="store_true", help="also turn the whole player (flips and spins)")
+    parser.add_argument("--resume", action="store_true",
+                        help="start from the existing rig.json and only run the rounds")
+    args = parser.parse_args()
+
+    directory = Path("frames") / args.name
+    meta = json.loads((directory / "views.json").read_text())
+    skin_path = Path("skins") / f"{meta.get('skin', 'Steve')}.png"
+    if not skin_path.exists():
+        from skin import fetch
+        skin_path.write_bytes(fetch(meta["skin"])[0])
+    calib = [float(c) for c in args.calib.split(",")]
+    fitted = sorted(FITTED + (ROOT_TURN if args.root else []))
+    start, end = map(int, args.ticks.split(":"))
+
+    ticks = list(range(start, end))
+    whole_loop = meta.get("loop_ticks") == len(ticks)
+    out = directory / "rig.json"
+    by_tick = {}
+
+    def save():
+        results = [{k: v for k, v in by_tick[t].items() if k != "rig_array"} for t in ticks if t in by_tick]
+        out.write_text(json.dumps({"rig": RIG, "calib": calib, "scale": 4, "ticks": results}, indent=2))
+
+    def record(tick, x, fx, label, t0):
+        rig = canonical(x[:len(RIG)])
+        init_worker(directory, skin_path, tick)
+        per_view = score(np.concatenate(list(_state["model"].pose(rig_to_pose(rig)).values())), calib,
+                         _state["cameras"], _state["targets"], True, _state["model"].colors, COLOR_VIEWS)
+        print(f"tick {tick}{label}: score {fx:.3f}, worst view {max(per_view, key=per_view.get)} "
+              f"{max(per_view.values()):.2f}, {time.time() - t0:.0f}s", flush=True)
+        by_tick[tick] = {"tick": tick, "rig": rig.tolist(), "rig_array": rig, "score": fx, "views": per_view}
+        save()
+
+    log = lambda m: print(m, flush=True)
+    if args.resume:
+        saved = json.loads(out.read_text())
+        calib = saved["calib"]
+        for t in saved["ticks"]:
+            by_tick[t["tick"]] = t | {"rig_array": canonical(np.array(t["rig"]))}
+    else:
+        # First pass: each tick warm-started from the one before.
+        previous = None
+        for tick in ticks:
+            t0 = time.time()
+            with multiprocessing.Pool(args.workers, init_worker, (directory, skin_path, tick)) as pool:
+                if previous is None:
+                    x, fx = first_tick(pool, calib, fitted, log)
+                    calib = [float(c) for c in x[len(RIG):]]
+                    log("calibration: " + ", ".join(f"{name} {c:.3f}" for name, c in zip(CALIB, calib)))
+                else:
+                    x, fx = fit(pool, np.concatenate([previous, calib]), fitted, 0.3, 4000, previous)
+                    x, fx = settle_facing(pool, x, fx, fitted, previous, log)
+            record(tick, x, fx, "", t0)
+            previous = by_tick[tick]["rig_array"]
+
+    # Later rounds, for a loop: every tick held near the loop's smoothed curve. No tick depends on the
+    # one fitted before it, so drift can't build up, and the curve has to close.
+    for r in range(args.rounds if whole_loop else 0):
+        curve = loop_curve([by_tick[t]["rig_array"] for t in ticks], args.harmonics)
+        for i, tick in enumerate(ticks):
+            t0 = time.time()
+            anchor = canonical(curve[i])
+            with multiprocessing.Pool(args.workers, init_worker, (directory, skin_path, tick)) as pool:
+                # From its own fit and from the curve: the curve can pull a tick off a ridge its own
+                # fit slid along.
+                x, fx = min((fit(pool, np.concatenate([start, calib]), fitted, 0.2, 2000, anchor)
+                             for start in (by_tick[tick]["rig_array"], anchor)), key=lambda c: c[1])
+            record(tick, x, fx, f" (round {r + 1})", t0)
+    print("wrote", directory / "rig.json")
+
+
+if __name__ == "__main__":
+    main()

tools/capture/model.py

@@ -0,0 +1,351 @@
+"""The player model and our pose maths, ported from the library so poses can be rendered in Python.
+
+Mirrors core's LimbBend and Bezier and the fabric mod's PoseApplier: same part boxes and pivots, same
+rotation order (ModelPart's Z, then Y, then X), the same bends, and the same carrying of the head and
+arms by a bent torso. check_port.py compares it against the Java classes.
+
+Model space is Minecraft's: pixels, Y down, the player faces -Z, and its right side is at -X.
+"""
+from dataclasses import dataclass
+
+import numpy as np
+
+BONES = ["root", "head", "body", "right_arm", "left_arm", "right_leg", "left_leg"]
+
+# Default pivots and boxes (from, size) of the vanilla player model with wide arms.
+PIVOTS = {
+    "head": (0, 0, 0),
+    "body": (0, 0, 0),
+    "right_arm": (-5, 2, 0),
+    "left_arm": (5, 2, 0),
+    "right_leg": (-1.9, 12, 0),
+    "left_leg": (1.9, 12, 0),
+}
+BOXES = {
+    "head": ((-4, -8, -4), (8, 8, 8)),
+    "body": ((-4, 0, -2), (8, 12, 4)),
+    "right_arm": ((-3, -2, -2), (4, 12, 4)),
+    "left_arm": ((-1, -2, -2), (4, 12, 4)),
+    "right_leg": ((-2, 0, -2), (4, 12, 4)),
+    "left_leg": ((-2, 0, -2), (4, 12, 4)),
+}
+# The outer skin layer (hat, jacket, sleeves, pants) is this much bigger on every side.
+OVERLAY = {"head": 0.5, "body": 0.25, "right_arm": 0.25, "left_arm": 0.25, "right_leg": 0.25, "left_leg": 0.25}
+# Where each part's base and outer layer start in a 64x64 skin.
+UV = {
+    "head": ((0, 0), (32, 0)),
+    "body": ((16, 16), (16, 32)),
+    "right_arm": ((40, 16), (40, 32)),
+    "left_arm": ((32, 48), (48, 48)),
+    "right_leg": ((0, 16), (0, 32)),
+    "left_leg": ((16, 48), (0, 48)),
+}
+
+SHARPNESS = 0.5
+SEGMENTS = 12
+ARC_SAMPLES = 64
+ROOT_PIVOT_Y = 12.8
+
+
+@dataclass
+class Transform:
+    """BoneTransform: offset in pixels, rotations and bend in radians."""
+    x: float = 0
+    y: float = 0
+    z: float = 0
+    pitch: float = 0
+    yaw: float = 0
+    roll: float = 0
+    bend: float = 0
+    axis: float = 0
+
+
+def rotation_zyx(pitch, yaw, roll):
+    """The matrix ModelPart.translateAndRotate applies: Rz(roll) Ry(yaw) Rx(pitch)."""
+    cx, sx = np.cos(pitch), np.sin(pitch)
+    cy, sy = np.cos(yaw), np.sin(yaw)
+    cz, sz = np.cos(roll), np.sin(roll)
+    rx = np.array([[1, 0, 0], [0, cx, -sx], [0, sx, cx]])
+    ry = np.array([[cy, 0, sy], [0, 1, 0], [-sy, 0, cy]])
+    rz = np.array([[cz, -sz, 0], [sz, cz, 0], [0, 0, 1]])
+    return rz @ ry @ rx
+
+
+def axis_angle(axis, angle):
+    x, y, z = axis
+    c, s = np.cos(angle), np.sin(angle)
+    k = np.array([[0, -z, y], [z, 0, -x], [-y, x, 0]])
+    return np.eye(3) + s * k + (1 - c) * (k @ k)
+
+
+def _bezier(points, t):
+    """Points on a cubic Bézier at each t (an array), like core's Bezier.point."""
+    t = np.asarray(t, float)[:, None]
+    p0, p1, p2, p3 = points
+    u = 1 - t
+    return u ** 3 * p0 + 3 * u * u * t * p1 + 3 * u * t * t * p2 + t ** 3 * p3
+
+
+def _bezier_derivative(points, t):
+    t = np.asarray(t, float)[:, None]
+    p0, p1, p2, p3 = points
+    u = 1 - t
+    return 3 * u * u * (p1 - p0) + 6 * u * t * (p2 - p1) + 3 * t * t * (p3 - p2)
+
+
+class LimbBend:
+    """Port of core's LimbBend. Vectorised over points."""
+
+    def __init__(self, start, end, angle, axis, sharpness=SHARPNESS, segments=SEGMENTS, anchored_at_end=False):
+        self.start = start
+        self.length = end - start
+        self.anchored_at_end = anchored_at_end
+        self.segments = segments
+        self.angle = angle
+        self.dir = np.array([np.sin(axis), 0, -np.cos(axis)])
+        self.n = np.array([self.dir[2], 0, -self.dir[0]])
+        self.ring = np.zeros((segments + 1, 3))
+        self.ring_angle = np.zeros(segments + 1)
+        if self.straight:
+            self.ring[:, 1] = start + self.length * np.arange(segments + 1) / segments
+            return
+        self._build(self._spine(min(1, max(0, sharpness))))
+
+    @property
+    def straight(self):
+        return abs(self.angle) < 1e-4
+
+    def _spine(self, sharpness):
+        half = self.length / 2
+        top = np.array([0, self.start, 0.0])
+        joint = np.array([0, self.start + half, 0.0])
+        lower = np.array([self.dir[0] * np.sin(self.angle), np.cos(self.angle), self.dir[2] * np.sin(self.angle)])
+        bottom = joint + lower * half
+        pull = 2 / 3 + sharpness / 3
+        return [top, top + (joint - top) * pull, bottom + (joint - bottom) * pull, bottom]
+
+    def _build(self, curve):
+        ts = np.arange(ARC_SAMPLES + 1) / ARC_SAMPLES
+        pts = _bezier(curve, ts)
+        lengths = np.concatenate([[0], np.cumsum(np.linalg.norm(np.diff(pts, axis=0), axis=1))])
+        total = lengths[-1]
+        scale = self.length / total
+        top = pts[0]
+        # For each ring, the arc-length sample it falls in (LimbBend's while loop), then t within it.
+        target = total * np.arange(self.segments + 1) / self.segments
+        sample = np.clip(np.searchsorted(lengths, target, side="left") - 1, 0, ARC_SAMPLES - 1)
+        span = lengths[sample + 1] - lengths[sample]
+        f = np.where(span > 0, (target - lengths[sample]) / np.where(span > 0, span, 1), 0)
+        t = ts[sample] + (ts[sample + 1] - ts[sample]) * f
+        self.ring = top + (_bezier(curve, t) - top) * scale
+        tangent = _bezier_derivative(curve, t)
+        self.ring_angle = np.arctan2(tangent @ self.dir, tangent[:, 1])
+
+    def _mirror(self, y):
+        return 2 * self.start + self.length - y
+
+    def _rotate(self, v, a):
+        """Rodrigues' rotation of rows of v around n by per-row angles a."""
+        n = self.n
+        cos, sin = np.cos(a)[:, None], np.sin(a)[:, None]
+        cross = np.cross(np.broadcast_to(n, v.shape), v)
+        dot = (v @ n)[:, None]
+        return v * cos + cross * sin + n * dot * (1 - cos)
+
+    def _from_start(self, p):
+        along = (p[:, 1] - self.start) / self.length * self.segments
+        ring = np.clip(np.floor(along).astype(int), 0, self.segments - 1)
+        f = np.clip(along - ring, 0, 1)
+        extra = np.where(along <= 0, p[:, 1] - self.start,
+                         np.where(along >= self.segments, p[:, 1] - (self.start + self.length), 0))
+        f = np.where(along <= 0, 0, np.where(along >= self.segments, 1, f))
+        center = self.ring[ring] + (self.ring[ring + 1] - self.ring[ring]) * f[:, None]
+        a = self.ring_angle[ring] + (self.ring_angle[ring + 1] - self.ring_angle[ring]) * f
+        local = np.stack([p[:, 0], extra, p[:, 2]], axis=1)
+        return self._rotate(local, a) + center
+
+    def bend_points(self, p):
+        if self.anchored_at_end:
+            q = p.copy()
+            q[:, 1] = self._mirror(q[:, 1])
+            out = self._from_start(q)
+            out[:, 1] = self._mirror(out[:, 1])
+            return out
+        return self._from_start(p)
+
+    def _angle_from_start(self, y):
+        along = np.clip((y - self.start) / self.length * self.segments, 0, self.segments)
+        ring = min(int(along), self.segments - 1)
+        return self.ring_angle[ring] + (self.ring_angle[ring + 1] - self.ring_angle[ring]) * (along - ring)
+
+    def angle_at(self, y):
+        return -self._angle_from_start(self._mirror(y)) if self.anchored_at_end else self._angle_from_start(y)
+
+
+def limb_bend(bone, t):
+    if t is None or t.bend == 0:
+        return None
+    if bone in ("right_arm", "left_arm"):
+        return LimbBend(-2, 10, t.bend, t.axis)
+    if bone in ("right_leg", "left_leg"):
+        return LimbBend(0, 12, t.bend, t.axis)
+    if bone == "body":
+        return LimbBend(0, 12, t.bend, t.axis, anchored_at_end=True)
+    return None
+
+
+def textured_points(bone, skin, spacing=0.5):
+    """Points on a part's base and outer layer with their skin colours, in the part's own space.
+
+    Follows ModelPart.Cube: each face's corners and UV rectangle, and Polygon's corner-to-UV order.
+    Outer layer points are only kept where the skin has pixels there.
+    """
+    (fx, fy, fz), (dx, dy, dz) = BOXES[bone]
+    pts, cols = [], []
+    for layer, (u, v) in enumerate(UV[bone]):
+        g = OVERLAY[bone] if layer else 0
+        f, gg, h = fx - g, fy - g, fz - g
+        i, j, k = fx + dx + g, fy + dy + g, fz + dz + g
+        c = [(f, gg, h), (i, gg, h), (i, j, h), (f, j, h), (f, gg, k), (i, gg, k), (i, j, k), (f, j, k)]
+        l, m, n, o = u, u + dz, u + dz + dx, u + dz + dx + dx
+        pp, q = u + dz + dx + dz, u + dz + dx + dz + dx
+        r, ss, t = v, v + dz, v + dz + dy
+        faces = [  # corners, (u1, v1, u2, v2)
+            ((5, 4, 0, 1), (m, r, n, ss)),   # DOWN: minY, the top in model space
+            ((2, 3, 7, 6), (n, ss, o, r)),   # UP: maxY, the bottom
+            ((0, 4, 7, 3), (l, ss, m, t)),   # WEST: -X, the player's right
+            ((1, 0, 3, 2), (m, ss, n, t)),   # NORTH: -Z, the front
+            ((5, 1, 2, 6), (n, ss, pp, t)),  # EAST: +X, the player's left
+            ((4, 5, 6, 7), (pp, ss, q, t)),  # SOUTH: +Z, the back
+        ]
+        for corners, (u1, v1, u2, v2) in faces:
+            a, b, _, d = (np.array(c[x], float) for x in corners)
+            ns = max(2, int(np.ceil(np.linalg.norm(b - a) / spacing)) + 1)
+            nt = max(2, int(np.ceil(np.linalg.norm(d - a) / spacing)) + 1)
+            # Sample cell centres so every point falls inside one texture pixel.
+            sv, tv = np.meshgrid((np.arange(ns) + 0.5) / ns, (np.arange(nt) + 0.5) / nt, indexing="ij")
+            sv, tv = sv.ravel(), tv.ravel()
+            face = a + sv[:, None] * (b - a) + tv[:, None] * (d - a)
+            tu = np.clip(np.floor(u2 + sv * (u1 - u2)).astype(int), min(u1, u2), max(u1, u2) - 1)
+            tvv = np.clip(np.floor(v1 + tv * (v2 - v1)).astype(int), min(v1, v2), max(v1, v2) - 1)
+            rgba = skin[tvv, tu]
+            keep = rgba[:, 3] > 0 if layer else np.ones(len(face), bool)
+            pts.append(face[keep])
+            cols.append(rgba[keep, :3])
+    return np.concatenate(pts), np.concatenate(cols).astype(float) / 255
+
+
+def surface_points(bone, spacing=0.5, overlay=True):
+    """Points on the surface of a part's box (outer layer included), in the part's own space."""
+    (fx, fy, fz), (sx, sy, sz) = BOXES[bone]
+    g = OVERLAY[bone] if overlay else 0
+    lo = np.array([fx - g, fy - g, fz - g])
+    hi = np.array([fx + sx + g, fy + sy + g, fz + sz + g])
+    axes = [np.linspace(lo[i], hi[i], max(2, int(np.ceil((hi[i] - lo[i]) / spacing)) + 1)) for i in range(3)]
+    pts = []
+    for fixed in range(3):
+        a, b = [i for i in range(3) if i != fixed]
+        u, v = np.meshgrid(axes[a], axes[b], indexing="ij")
+        for side in (lo[fixed], hi[fixed]):
+            face = np.empty((u.size, 3))
+            face[:, a], face[:, b], face[:, fixed] = u.ravel(), v.ravel(), side
+            pts.append(face)
+    return np.unique(np.round(np.concatenate(pts), 4), axis=0)
+
+
+class Model:
+    """Poses the player's parts. pose() returns model-space points for each part.
+
+    With a skin (an RGBA array), the points carry the skin's colours in self.colors, and the outer layer
+    only exists where the skin has pixels. Without one, parts are plain boxes including the outer layer.
+    """
+
+    def __init__(self, spacing=0.5, skin=None):
+        if skin is None:
+            self.local = {bone: surface_points(bone, spacing) for bone in PIVOTS}
+            self.colors = None
+        else:
+            textured = {bone: textured_points(bone, skin, spacing) for bone in PIVOTS}
+            self.local = {bone: pts for bone, (pts, _) in textured.items()}
+            self.colors = np.concatenate([cols for _, cols in textured.values()])
+
+    def part_frames(self, pose):
+        """Each part's pivot, rotation and bend after PoseApplier.apply, in root space."""
+        frames = {}
+        for bone in PIVOTS:
+            t = pose.get(bone)
+            pivot = np.array(PIVOTS[bone], float)
+            rot = np.eye(3)
+            if t is not None:
+                pivot = pivot + [t.x, t.y, t.z]
+                rot = rotation_zyx(t.pitch, t.yaw, t.roll)
+            frames[bone] = [pivot, rot, limb_bend(bone, t)]
+
+        body_pivot, body_rot, body_bend = frames["body"]
+        if body_bend is not None and not body_bend.straight:
+            for bone in ("head", "right_arm", "left_arm"):
+                pivot, rot, bend = frames[bone]
+                local = body_rot.T @ (pivot - body_pivot)
+                moved = body_bend.bend_points(local[None, :])[0]
+                turn = axis_angle(body_bend.n, body_bend.angle_at(local[1]))
+                frames[bone] = [body_pivot + body_rot @ moved, body_rot @ turn @ body_rot.T @ rot, bend]
+        return frames
+
+    def pose(self, pose):
+        frames = self.part_frames(pose)
+        root = pose.get("root")
+        if root is not None:
+            r_rot = rotation_zyx(root.pitch, root.yaw, root.roll)
+            pivot = np.array([0, ROOT_PIVOT_Y, 0])
+            r_pos = np.array([root.x, root.y, root.z]) + pivot - r_rot @ pivot
+        else:
+            r_rot, r_pos = np.eye(3), np.zeros(3)
+        out = {}
+        for bone, (pivot, rot, bend) in frames.items():
+            p = self.local[bone]
+            if bend is not None and not bend.straight:
+                p = bend.bend_points(p)
+            out[bone] = (p @ rot.T + pivot) @ r_rot.T + r_pos
+        return out
+
+
+# --- The rig the fitter works in -------------------------------------------------------------------
+#
+# Moving every pivot freely lets parts drift apart, so the fitter uses a jointed rig instead and
+# converts it to BoneTransforms: the legs hang from the hips, the torso's hip end sits on the hips,
+# and the head and arms hang from the torso (PoseApplier then carries them along its bend).
+
+RIG = (
+    ["root_x", "root_y", "root_z", "root_pitch", "root_yaw", "root_roll", "hip_x", "hip_y", "hip_z"]
+    + [f"body_{c}" for c in ("pitch", "yaw", "roll", "bend", "axis")]
+    + [f"head_{c}" for c in ("pitch", "yaw", "roll")]
+    + [f"{limb}_{c}" for limb in ("right_arm", "left_arm", "right_leg", "left_leg")
+       for c in ("pitch", "yaw", "roll", "bend", "axis")]
+)
+INDEX = {name: i for i, name in enumerate(RIG)}
+
+
+def rig_to_pose(v):
+    g = lambda name: float(v[INDEX[name]])
+    hip = np.array([g("hip_x"), g("hip_y"), g("hip_z")])
+    body_rot = rotation_zyx(g("body_pitch"), g("body_yaw"), g("body_roll"))
+    # The torso's bottom middle (0, 12, 0) in its own space stays on the hips; a bend keeps it fixed.
+    hips_rest = np.array([0, 12, 0.0])
+    body_pivot = hips_rest + hip - body_rot @ hips_rest
+    pose = {
+        "root": Transform(g("root_x"), g("root_y"), g("root_z"), g("root_pitch"), g("root_yaw"), g("root_roll")),
+        "body": Transform(*body_pivot, g("body_pitch"), g("body_yaw"), g("body_roll"), g("body_bend"), g("body_axis")),
+        "head": Transform(*body_pivot, g("head_pitch"), g("head_yaw"), g("head_roll")),
+    }
+    for arm in ("right_arm", "left_arm"):
+        rest = np.array(PIVOTS[arm], float)
+        # Where the shoulder sits on the (unbent) tipped torso; PoseApplier adds the bend's carry.
+        offset = body_pivot + body_rot @ rest - rest
+        pose[arm] = Transform(*offset, *(g(f"{arm}_{c}") for c in ("pitch", "yaw", "roll", "bend", "axis")))
+    for leg in ("right_leg", "left_leg"):
+        pose[leg] = Transform(*hip, *(g(f"{leg}_{c}") for c in ("pitch", "yaw", "roll", "bend", "axis")))
+    return pose
+
+
+def rest_rig():
+    return np.zeros(len(RIG))

tools/capture/overlay.py

@@ -0,0 +1,63 @@
+"""Draws the fitted pose's outline over the captured frames, to see where the fit is off.
+
+    .venv/bin/python overlay.py <name> [--ticks 0:13:3] [--views y000,y090,y045,top000]
+
+Writes frames/<name>/overlay.png: rows are views, columns ticks. Red is where only our model is, blue
+where only theirs is, and grey where both are.
+"""
+import argparse
+import json
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+
+from model import Model, rig_to_pose
+from render import Camera, render_masks
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("name")
+    parser.add_argument("--ticks", default="0:13:3")
+    parser.add_argument("--views", default="y000,y090,y045,top000")
+    args = parser.parse_args()
+
+    base = Path("frames") / args.name
+    meta = json.loads((base / "views.json").read_text())
+    data = json.loads((base / "rig.json").read_text())
+    by_tick = {t["tick"]: np.array(t["rig"]) for t in data["ticks"]}
+    ticks = [t for t in range(*map(int, args.ticks.split(":"))) if t in by_tick]
+    views = args.views.split(",")
+    scale = 2
+    cams = {v: Camera(meta["views"][v], meta["size"], meta["aspect"], scale) for v in views}
+    model = Model(spacing=0.25)
+
+    tiles = []
+    for v in views:
+        row = []
+        for t in ticks:
+            pts = np.concatenate(list(model.pose(rig_to_pose(by_tick[t])).values()))
+            ours = render_masks(pts, data["calib"], {v: cams[v]})[v]
+            frame = Image.open(base / v / f"{t:04d}.png").reduce(scale)
+            theirs = np.asarray(frame)[:, :, 3] > 127
+            img = np.full(ours.shape + (3,), 30, np.uint8)
+            img[theirs & ours] = (150, 150, 150)
+            img[ours & ~theirs] = (230, 60, 60)
+            img[theirs & ~ours] = (60, 110, 240)
+            row.append(img)
+        tiles.append(row)
+
+    both = np.zeros(tiles[0][0].shape[:2], bool)
+    for row in tiles:
+        for img in row:
+            both |= img.sum(axis=2) > 90
+    ys, xs = np.nonzero(both)
+    y0, y1, x0, x1 = max(ys.min() - 4, 0), ys.max() + 4, max(xs.min() - 4, 0), xs.max() + 4
+    sheet = np.concatenate([np.concatenate([img[y0:y1, x0:x1] for img in row], axis=1) for row in tiles], axis=0)
+    Image.fromarray(sheet).save(base / "overlay.png")
+    print("wrote", base / "overlay.png", "ticks", ticks)
+
+
+if __name__ == "__main__":
+    main()

tools/capture/render.py

@@ -0,0 +1,174 @@
+"""Renders model points through the cameras capture.py used, and scores them against captured masks."""
+import json
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+from scipy.ndimage import distance_transform_edt
+
+# Model space (Y down, facing -Z) to the viewer's world (Y up, facing +Z): Minecraft's scale(-1, -1, 1)
+# after turning the player 180 degrees to face south.
+FLIP = np.diag([1.0, -1.0, -1.0])
+
+
+class Camera:
+    """A three.js PerspectiveCamera placed with lookAt, as viewer.js places it."""
+
+    def __init__(self, view, size, aspect, scale):
+        yaw, pitch = np.radians(view["yaw"]), np.radians(view["pitch"])
+        target = np.array(view["target"], float)
+        d = view["distance"]
+        self.position = target + d * np.array([np.cos(pitch) * np.sin(yaw), np.sin(pitch), np.cos(pitch) * np.cos(yaw)])
+        z = self.position - target
+        z /= np.linalg.norm(z)
+        x = np.cross([0, 1, 0], z)
+        x /= np.linalg.norm(x)
+        y = np.cross(z, x)
+        self.rotation = np.stack([x, y, z])  # world to camera
+        self.f = 1 / np.tan(np.radians(view["fov"]) / 2)
+        self.aspect = aspect
+        self.width, self.height = size[0] // scale, size[1] // scale
+
+    def project(self, world):
+        c = (world - self.position) @ self.rotation.T
+        depth = -c[:, 2]
+        nx = self.f / self.aspect * c[:, 0] / depth
+        ny = self.f * c[:, 1] / depth
+        return np.stack([(nx + 1) / 2 * self.width, (1 - ny) / 2 * self.height], axis=1)
+
+
+def to_world(points, calib):
+    """calib = (scale, tx, ty, tz): where the viewer puts the model."""
+    return calib[0] * points @ FLIP.T + np.asarray(calib[1:4])
+
+
+def splat(px, width, height):
+    """A mask covering every projected point, 2x2 pixels each so the surface has no holes."""
+    mask = np.zeros((height, width), bool)
+    x = np.floor(px[:, 0] - 0.5).astype(int)
+    y = np.floor(px[:, 1] - 0.5).astype(int)
+    for dx in (0, 1):
+        for dy in (0, 1):
+            xs, ys = x + dx, y + dy
+            ok = (xs >= 0) & (xs < width) & (ys >= 0) & (ys < height)
+            mask[ys[ok], xs[ok]] = True
+    return mask
+
+
+def color_features(rgb):
+    """Lighting-tolerant colour: hue and saturation as opponent channels divided by brightness, plus
+    log brightness. Shading scales all three channels, which leaves the first two alone."""
+    lum = rgb.mean(axis=-1)
+    o1 = rgb[..., 0] - rgb[..., 1]
+    o2 = (rgb[..., 0] + rgb[..., 1]) / 2 - rgb[..., 2]
+    return np.stack([o1 / (lum + 0.05), o2 / (lum + 0.05), np.log(lum + 0.05)], axis=-1)
+
+
+class Target:
+    """One captured view of one tick, downscaled, with the distance maps the score needs."""
+
+    def __init__(self, mask, rgb=None):
+        self.mask = mask
+        self.outside = distance_transform_edt(~mask)
+        self.ys, self.xs = np.nonzero(mask)
+        self.features = None if rgb is None else color_features(rgb)
+
+
+def downscale(alpha, scale):
+    h, w = alpha.shape
+    blocks = alpha[: h // scale * scale, : w // scale * scale].reshape(h // scale, scale, w // scale, scale)
+    return blocks.mean(axis=(1, 3)) > 127
+
+
+def downscale_rgb(rgba, scale):
+    """Mean colour of the covered pixels in each block (0-1)."""
+    h, w = rgba.shape[:2]
+    blocks = rgba[: h // scale * scale, : w // scale * scale].astype(float)
+    blocks = blocks.reshape(h // scale, scale, w // scale, scale, 4)
+    alpha = blocks[..., 3:] / 255
+    return (blocks[..., :3] / 255 * alpha).sum(axis=(1, 3)) / np.maximum(alpha.sum(axis=(1, 3)), 1e-6)
+
+
+class Capture:
+    """The frames and cameras of one capture."""
+
+    def __init__(self, directory, scale=4, views=None):
+        self.dir = Path(directory)
+        self.meta = json.loads((self.dir / "views.json").read_text())
+        self.scale = scale
+        self.names = views or list(self.meta["views"])
+        self.cameras = {n: Camera(self.meta["views"][n], self.meta["size"], self.meta["aspect"], scale) for n in self.names}
+
+    def targets(self, tick):
+        out = {}
+        for n in self.names:
+            rgba = np.asarray(Image.open(self.dir / n / f"{tick:04d}.png"))
+            out[n] = Target(downscale(rgba[:, :, 3], self.scale), downscale_rgb(rgba, self.scale))
+        return out
+
+
+# How much a unit of colour difference counts against a pixel of outline distance, and how much
+# brightness counts next to hue and saturation.
+COLOR_WEIGHT = 0.5
+BRIGHTNESS_WEIGHT = 0.3
+
+
+def score(points, calib, cameras, targets, per_view=False, colors=None, color_views=None, one_way=False,
+          color_weight=None):
+    """Mean outline distance in pixels, both ways (our points outside theirs and theirs outside ours),
+    plus, with colours, how different the colours are where both outlines cover a pixel.
+
+    one_way only counts our points outside theirs, for fitting some of the parts: the rest of their
+    outline is still unexplained, and shouldn't pull the parts being fitted towards it."""
+    world = to_world(points, calib)
+    total = {}
+    for name, cam in cameras.items():
+        t = targets[name]
+        px = cam.project(world)
+        xi = np.clip(px[:, 0].astype(int), 0, cam.width - 1)
+        yi = np.clip(px[:, 1].astype(int), 0, cam.height - 1)
+        ours_out = t.outside[yi, xi].mean()
+        if colors is not None and t.features is not None and (color_views is None or name in color_views):
+            depth = -((world - cam.position) @ cam.rotation.T)[:, 2]
+            image, mask = splat_color(px, depth, colors, cam.width, cam.height)
+            both = mask & t.mask
+            diff = np.abs(color_features(image[both]) - t.features[both])
+            color = (diff[:, 0] + diff[:, 1] + BRIGHTNESS_WEIGHT * diff[:, 2]).mean() if both.any() else 0
+        else:
+            mask = splat(px, cam.width, cam.height)
+            color = 0
+        theirs_out = 0 if one_way or not len(t.ys) else distance_transform_edt(~mask)[t.ys, t.xs].mean()
+        total[name] = ours_out + theirs_out + (COLOR_WEIGHT if color_weight is None else color_weight) * color
+    return total if per_view else sum(total.values()) / len(total)
+
+
+def render_masks(points, calib, cameras):
+    world = to_world(points, calib)
+    return {n: splat(c.project(world), c.width, c.height) for n, c in cameras.items()}
+
+
+def splat_color(px, depth, colors, width, height):
+    """Colour image of the nearest point in each pixel (2x2 pixels per point), and its coverage mask."""
+    order = np.argsort(-depth)  # far to near, so nearer points are written last and win
+    x = np.floor(px[order, 0] - 0.5).astype(int)
+    y = np.floor(px[order, 1] - 0.5).astype(int)
+    # All four pixels of every point in one write; a write per offset would let far points overwrite
+    # pixels near points filled at another offset.
+    xs = np.stack([x, x + 1, x, x + 1], axis=1).ravel()
+    ys = np.stack([y, y, y + 1, y + 1], axis=1).ravel()
+    cs = np.repeat(colors[order], 4, axis=0)
+    ok = (xs >= 0) & (xs < width) & (ys >= 0) & (ys < height)
+    image = np.zeros((height, width, 3))
+    mask = np.zeros((height, width), bool)
+    image[ys[ok], xs[ok]] = cs[ok]
+    mask[ys[ok], xs[ok]] = True
+    return image, mask
+
+
+def render_colors(points, colors, calib, cameras):
+    world = to_world(points, calib)
+    out = {}
+    for n, c in cameras.items():
+        depth = -((world - c.position) @ c.rotation.T)[:, 2]
+        out[n] = splat_color(c.project(world), depth, colors, c.width, c.height)
+    return out

tools/capture/requirements.txt

@@ -0,0 +1,5 @@
+cma==4.5.0
+numpy==2.5.3
+pillow==12.3.0
+playwright==1.63.0
+scipy==1.18.1

tools/capture/sheet.py

@@ -0,0 +1,20 @@
+"""Tiles frames into a contact sheet: rows are views, columns are ticks, cropped to the player."""
+import sys
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+
+name, views, ticks = sys.argv[1], sys.argv[2].split(","), range(*map(int, sys.argv[3].split(":")))
+out = sys.argv[4] if len(sys.argv) > 4 else "sheet.png"
+frames = [[Image.open(Path("frames") / name / v / f"{t:04d}.png") for t in ticks] for v in views]
+alpha = np.maximum.reduce([np.asarray(f)[:, :, 3] for row in frames for f in row])
+ys, xs = np.nonzero(alpha)
+box = (xs.min() - 4, ys.min() - 4, xs.max() + 4, ys.max() + 4)
+w, h = box[2] - box[0], box[3] - box[1]
+sheet = Image.new("RGBA", (w * len(ticks), h * len(views)), (40, 40, 52, 255))
+for r, row in enumerate(frames):
+    for c, f in enumerate(row):
+        sheet.alpha_composite(f.crop(box), (c * w, r * h))
+sheet.save(out)
+print(sheet.size)

tools/capture/skin.py

@@ -0,0 +1,29 @@
+"""Fetches a player's skin texture from Mojang, the same one the store viewer shows for that username.
+
+    .venv/bin/python skin.py <username> [out.png]
+"""
+import base64
+import json
+import subprocess
+import sys
+
+
+def get(url):
+    # curl uses the system's certificate store, which python.org's Python doesn't.
+    return subprocess.run(["curl", "-sSf", url], capture_output=True, check=True).stdout
+
+
+def fetch(username):
+    """Returns (png bytes, slim arms)."""
+    uuid = json.loads(get(f"https://api.mojang.com/users/profiles/minecraft/{username}"))["id"]
+    profile = json.loads(get(f"https://sessionserver.mojang.com/session/minecraft/profile/{uuid}"))
+    prop = next(p for p in profile["properties"] if p["name"] == "textures")
+    skin = json.loads(base64.b64decode(prop["value"]))["textures"]["SKIN"]
+    return get(skin["url"]), skin.get("metadata", {}).get("model") == "slim"
+
+
+if __name__ == "__main__":
+    png, slim = fetch(sys.argv[1])
+    out = sys.argv[2] if len(sys.argv) > 2 else f"skins/{sys.argv[1]}.png"
+    open(out, "wb").write(png)
+    print(out, "slim" if slim else "wide")

tools/capture/symmetry.py

@@ -0,0 +1,110 @@
+"""Left/right symmetry of a measured loop: how lopsided it is, and a symmetric version of it.
+
+    .venv/bin/python symmetry.py <name> [--rig path.json]
+
+A mirror swaps the left and right limbs and flips every sideways channel (the hips' x, yaws, rolls and
+bend directions). A pose that sways once per loop should be the mirror of itself half a loop later;
+one with no sideways motion, the mirror of itself at the same moment. Whatever breaks that is
+lopsidedness the fit picked up (one leg bent more, one side swinging further), not the dance.
+
+symmetrize() averages each tick with the mirror of its partner, which keeps the sway and removes the
+rest. fit.py --symmetric uses it.
+"""
+import argparse
+import json
+from pathlib import Path
+
+import numpy as np
+
+from model import INDEX, RIG
+
+SIDES = {"right_arm": "left_arm", "left_arm": "right_arm", "right_leg": "left_leg", "left_leg": "right_leg"}
+ANGLES = np.array([not name.endswith(("_x", "_y", "_z")) for name in RIG])
+
+
+def wrap(a):
+    return (a + np.pi) % (2 * np.pi) - np.pi
+
+
+def mirror(rig):
+    """The pose reflected through the player's middle (x -> -x). Rotations about x keep their angle and
+    those about y and z flip (S Rz Ry Rx S with S = diag(-1, 1, 1)); a bend direction, measured around
+    the limb from its front, flips too."""
+    out = np.empty_like(rig)
+    for i, name in enumerate(RIG):
+        part, _, channel = name.rpartition("_")
+        source = next((f"{SIDES[p]}{name[len(p):]}" for p in SIDES if name.startswith(p)), name)
+        value = rig[INDEX[source]]
+        out[i] = -value if channel in ("x", "yaw", "roll", "axis") else value
+    return out
+
+
+def shifted(rigs, fraction):
+    """Each channel of a loop evaluated `fraction` of a loop later, between samples too, through its
+    Fourier series. Angles that go round whole turns in a loop keep doing so."""
+    rigs = np.asarray(rigs, float)
+    n = len(rigs)
+    out = np.empty_like(rigs)
+    k = np.arange(n // 2 + 1)
+    for i in range(rigs.shape[1]):
+        values = np.unwrap(rigs[:, i]) if ANGLES[i] else rigs[:, i]
+        turns = 0.0
+        if ANGLES[i]:
+            turns = values[-1] + wrap(values[0] - values[-1]) - values[0]
+        ramp = turns * np.arange(n) / n
+        spectrum = np.fft.rfft(values - ramp) * np.exp(2j * np.pi * k * fraction)
+        out[:, i] = np.fft.irfft(spectrum, n) + ramp + turns * fraction
+    return out
+
+
+def partners(rigs, sway):
+    """The mirrored partner of every tick: half a loop on for a pose that sways once per loop."""
+    rigs = np.asarray(rigs, float)
+    source = shifted(rigs, 0.5) if sway else rigs
+    return np.array([mirror(r) for r in source])
+
+
+def difference(a, b):
+    d = a - b
+    return np.where(ANGLES, wrap(d), d)
+
+
+def symmetrize(rigs, sway):
+    """Each tick averaged with its mirrored partner (the short way round for angles)."""
+    rigs = np.asarray(rigs, float)
+    return rigs - difference(rigs, partners(rigs, sway)) / 2
+
+
+def lopsidedness(rigs, sway):
+    """Per channel: how far each tick is from its mirrored partner, as (mean, rms) over the loop. The
+    mean is a steady lean to one side; the rms includes one side swinging further than the other."""
+    d = difference(np.asarray(rigs, float), partners(rigs, sway))
+    return d.mean(axis=0), np.sqrt((d ** 2).mean(axis=0))
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("name")
+    parser.add_argument("--rig")
+    args = parser.parse_args()
+    path = Path(args.rig) if args.rig else Path("frames") / args.name / "rig.json"
+    rigs = np.array([t["rig"] for t in json.loads(path.read_text())["ticks"]])
+
+    # Which pairing fits: a sway once per loop, or none.
+    for sway in (True, False):
+        _, rms = lopsidedness(rigs, sway)
+        angle_rms = np.degrees(np.sqrt((rms[ANGLES] ** 2).mean()))
+        offset_rms = np.sqrt((rms[~ANGLES] ** 2).mean())
+        print(f"{'sway once per loop' if sway else 'no sway':18s}: rms {angle_rms:.1f} deg, {offset_rms:.2f} px")
+
+    sway = True
+    mean, rms = lopsidedness(rigs, sway)
+    print("\nMost lopsided channels (tick vs its mirrored partner half a loop on):")
+    order = np.argsort(-np.where(ANGLES, np.degrees(rms), rms * 5))
+    for i in order[:14]:
+        unit, f = ("deg", np.degrees) if ANGLES[i] else ("px", lambda v: v)
+        print(f"  {RIG[i]:18s} steady {f(mean[i]):+6.1f} {unit}, rms {f(rms[i]):5.1f} {unit}")
+
+
+if __name__ == "__main__":
+    main()

tools/capture/synth_test.py

@@ -0,0 +1,85 @@
+"""End-to-end check of measure.py on frames with a known answer: our own twerk test animation, rendered
+by model.py as if it were a capture, then measured like one.
+
+    .venv/bin/python synth_test.py make <capture to copy cameras from> [ticks]   # writes frames/synth
+    .venv/bin/python measure.py synth --ticks 0:4
+    .venv/bin/python synth_test.py check
+"""
+import json
+import sys
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+from scipy.spatial import cKDTree
+
+from model import INDEX, Model, rest_rig, rig_to_pose
+from render import Camera, render_colors
+
+# Where the fake viewer puts the model: Minecraft's player scale, feet 25 units below the origin.
+CALIB = (0.9375, 0, -1.5, 0)
+SKIN = "Steve"
+OUT = Path("frames/synth")
+
+
+def twerk(t):
+    """TestAnimations.twerk, written in rig terms."""
+    up = 0.5 * (1 - np.cos(t / 8 * 2 * np.pi))
+    thigh, knee, splay, tilt, arch = -1.1 + 0.15 * up, 1.75 - 0.3 * up, 0.55, 1.4, 0.4 + 0.3 * up
+    drop = 12 - 6 * (np.cos(thigh) + np.cos(thigh + knee)) * np.cos(splay)
+    back = -6 * (np.sin(thigh) + np.sin(thigh + knee))
+    chest = tilt - arch
+    v = rest_rig()
+    s = lambda name, value: v.__setitem__(INDEX[name], value)
+    s("hip_y", drop), s("hip_z", back)
+    s("body_pitch", tilt), s("body_bend", arch), s("body_axis", np.pi)
+    s("head_pitch", tilt - chest * 0.5)
+    for arm, roll in (("right_arm", 0.3), ("left_arm", -0.3)):
+        s(f"{arm}_pitch", tilt - chest * 1.1), s(f"{arm}_roll", roll), s(f"{arm}_bend", 0.5)
+    for leg, sign in (("right_leg", 1), ("left_leg", -1)):
+        s(f"{leg}_pitch", thigh), s(f"{leg}_roll", sign * splay), s(f"{leg}_bend", knee)
+        s(f"{leg}_axis", np.pi - sign * 0.35)
+    return v
+
+
+def skin():
+    return np.asarray(Image.open(f"skins/{SKIN}.png").convert("RGBA"))
+
+
+def make(source, ticks):
+    meta = json.loads((Path("frames") / source / "views.json").read_text())
+    model = Model(spacing=0.08, skin=skin())
+    cams = {n: Camera(v, meta["size"], meta["aspect"], 1) for n, v in meta["views"].items()}
+    for tick in range(ticks):
+        pts = np.concatenate(list(model.pose(rig_to_pose(twerk(tick))).values()))
+        for name, (image, mask) in render_colors(pts, model.colors, CALIB, cams).items():
+            (OUT / name).mkdir(parents=True, exist_ok=True)
+            rgba = np.concatenate([image * 255, mask[..., None] * 255], axis=-1).astype(np.uint8)
+            Image.fromarray(rgba).save(OUT / name / f"{tick:04d}.png")
+    meta |= {"url": "synthetic twerk", "skin": SKIN, "ticks": ticks, "loop_ticks": None}
+    (OUT / "views.json").write_text(json.dumps(meta, indent=2))
+    print(f"wrote {ticks} ticks to {OUT}")
+
+
+def check():
+    data = json.loads((OUT / "rig.json").read_text())
+    print("calibration:", np.round(data["calib"], 3), "true:", CALIB)
+    model = Model(skin=skin())
+    for entry in data["ticks"]:
+        truth, got = model.pose(rig_to_pose(twerk(entry["tick"]))), model.pose(rig_to_pose(np.array(entry["rig"])))
+        # The fitted pose sits in the fitted calibration's frame; compare where the viewer shows them.
+        to = lambda p, c: c[0] * p + np.asarray(c[1:]) * [1, -1, -1]
+        parts = []
+        for part in truth:
+            a, b = to(truth[part], CALIB), to(got[part], data["calib"])
+            parts.append((part, np.linalg.norm(a - b, axis=1).mean(), cKDTree(b).query(a)[0].mean()))
+        print(f"tick {entry['tick']}: score {entry['score']:.3f}  "
+              + "  ".join(f"{p} {d:.2f}/{s:.2f}" for p, d, s in parts))
+    print("(per part: mean point-for-point / shape-only distance, in model pixels)")
+
+
+if __name__ == "__main__":
+    if sys.argv[1] == "make":
+        make(sys.argv[2], int(sys.argv[3]) if len(sys.argv) > 3 else 4)
+    else:
+        check()

tools/capture/viewer.js

@@ -0,0 +1,88 @@
+// Injected before the page loads. It puts the page on a clock we step by hand, and uses three.js's
+// devtools hook to find the renderer and the camera it draws with. Only the clock and the camera are
+// touched: the frames are measured from pixels, never from the scene's animation data.
+(() => {
+    let now = 0;
+    let callbacks = [];
+    let nextId = 1;
+
+    const realDateNow = Date.now.bind(Date);
+    const epoch = realDateNow();
+    performance.now = () => now;
+    Date.now = () => epoch + now;
+    window.requestAnimationFrame = (cb) => {
+        const id = nextId++;
+        callbacks.push({ id, cb });
+        return id;
+    };
+    window.cancelAnimationFrame = (id) => {
+        callbacks = callbacks.filter((c) => c.id !== id);
+    };
+
+    // The camera placement to force on every render: a point the camera orbits, its distance, and the
+    // yaw/pitch it looks from (degrees; yaw 0 looks at the model's front).
+    let view = null;
+    let lastFrame = null;
+
+    const capture = {
+        renderers: [],
+        camera: null,
+        /** Advances the clock by ms and runs one animation frame. Returns the frame as a PNG data URL. */
+        step(ms, grab) {
+            now += ms;
+            lastFrame = null;
+            const due = callbacks;
+            callbacks = [];
+            for (const { cb } of due) {
+                try { cb(now); } catch (e) { console.error(e); }
+            }
+            return grab ? lastFrame : null;
+        },
+        time() { return now; },
+        setView(v) { view = v; },
+        camera_info() {
+            const cam = capture.camera;
+            return cam && { fov: cam.fov, aspect: cam.aspect, near: cam.near, far: cam.far,
+                            position: cam.position.toArray(), quaternion: cam.quaternion.toArray() };
+        },
+    };
+    window.__capture = capture;
+
+    function place(camera) {
+        const toRad = Math.PI / 180;
+        const yaw = view.yaw * toRad;
+        const pitch = view.pitch * toRad;
+        const [tx, ty, tz] = view.target;
+        camera.position.set(
+            tx + view.distance * Math.cos(pitch) * Math.sin(yaw),
+            ty + view.distance * Math.sin(pitch),
+            tz + view.distance * Math.cos(pitch) * Math.cos(yaw));
+        camera.up.set(0, 1, 0);
+        camera.lookAt(tx, ty, tz);
+        if (view.fov) {
+            camera.fov = view.fov;
+        }
+        camera.updateProjectionMatrix();
+        camera.updateMatrixWorld(true);
+    }
+
+    const hook = new EventTarget();
+    hook.addEventListener('observe', (event) => {
+        const obj = event.detail;
+        if (obj && obj.isWebGLRenderer && !capture.renderers.includes(obj)) {
+            capture.renderers.push(obj);
+            const render = obj.render.bind(obj);
+            obj.render = (scene, camera) => {
+                capture.camera = camera;
+                if (view) {
+                    place(camera);
+                }
+                const result = render(scene, camera);
+                // Read the drawing buffer in the same task as the draw, before the browser clears it.
+                lastFrame = obj.domElement.toDataURL('image/png');
+                return result;
+            };
+        }
+    });
+    window.__THREE_DEVTOOLS__ = hook;
+})();

tools/emotecraft/convert.py

@@ -0,0 +1,211 @@
+"""Converts Emotecraft's binary .emotecraft files to the Emotecraft JSON our EmotecraftLoader reads.
+
+    python3 convert.py <file.emotecraft>... [--out-dir DIR]
+
+Writes <id>.json next to each file (or into DIR), with the id made from the file's name, and prints
+what each file holds. Standard library only.
+
+The binary is Emotecraft's network packet (EmotePacket): an int version, a purpose byte and a count of
+sub-packets, each an id byte, a version byte, an int size and its data. Sub-packet 0 is the animation
+in player-animator's legacy format (PlayerAnimationLibrary's LegacyAnimationBinary), whose values are
+the same raw values Emotecraft JSON holds (radians, absolute pivots, the whole player in blocks), so
+they're written out as they are with "degrees": false. Sub-packet 17 is the name, description and
+author (header version 1 and up). Anything else (the icon, the scale channels, easing arguments) is left out, since our loader
+doesn't read it.
+
+One thing moves: in the legacy format the whole-player part "body" also carries the torso's bend.
+In JSON, "body" is only the whole player, so its bend goes to "torso", as PlayerAnimationLibrary does.
+"""
+import argparse
+import json
+import re
+import struct
+import sys
+from pathlib import Path
+
+ANIMATION, HEADER = 0, 17
+AXES = ["x", "y", "z", "pitch", "yaw", "roll"]
+BEND_AXES = ["axis", "bend"]
+SCALE_AXES = ["scaleX", "scaleY", "scaleZ"]
+# The fixed part order before version 2 named its parts.
+V1_PARTS = ["head", "body", "rightArm", "leftArm", "rightLeg", "leftLeg"]
+# PlayerAnimationLibrary's EasingType ids. Our Easing.fromName reads the same names.
+EASINGS = {
+    0: "LINEAR", 1: "CONSTANT", 6: "EASEINSINE", 7: "EASEOUTSINE", 8: "EASEINOUTSINE",
+    9: "EASEINCUBIC", 10: "EASEOUTCUBIC", 11: "EASEINOUTCUBIC", 12: "EASEINQUAD", 13: "EASEOUTQUAD",
+    14: "EASEINOUTQUAD", 15: "EASEINQUART", 16: "EASEOUTQUART", 17: "EASEINOUTQUART",
+    18: "EASEINQUINT", 19: "EASEOUTQUINT", 20: "EASEINOUTQUINT", 21: "EASEINEXPO", 22: "EASEOUTEXPO",
+    23: "EASEINOUTEXPO", 24: "EASEINCIRC", 25: "EASEOUTCIRC", 26: "EASEINOUTCIRC", 27: "EASEINBACK",
+    28: "EASEOUTBACK", 29: "EASEINOUTBACK", 30: "EASEINELASTIC", 31: "EASEOUTELASTIC",
+    32: "EASEINOUTELASTIC", 33: "EASEINBOUNCE", 34: "EASEOUTBOUNCE", 35: "EASEINOUTBOUNCE",
+}
+
+
+class Reader:
+    def __init__(self, data):
+        self.data, self.pos = data, 0
+
+    def take(self, fmt):
+        values = struct.unpack_from(">" + fmt, self.data, self.pos)
+        self.pos += struct.calcsize(">" + fmt)
+        return values[0] if len(values) == 1 else values
+
+    def bool(self):
+        return self.take("b") != 0
+
+    def string(self):
+        size = self.take("i")
+        text = self.data[self.pos:self.pos + size].decode("utf-8")
+        self.pos += size
+        return text
+
+
+def read_channel(r, version, keyframe_size):
+    """[(tick, value, easing id)], or None when the channel is off."""
+    if version >= 2:
+        enabled, count = r.bool(), r.take("i")
+    else:
+        count = r.take("i")
+        enabled = count >= 0
+    if not enabled:
+        r.pos += max(count, 0) * keyframe_size
+        return None
+    keys = []
+    for _ in range(count):
+        start = r.pos
+        tick, value, easing = r.take("ifb")
+        keys.append((tick, value, easing))
+        r.pos = start + keyframe_size
+    return keys
+
+
+def read_part(r, name, version, keyframe_size):
+    channels = {axis: read_channel(r, version, keyframe_size) for axis in AXES}
+    # Every part but the head (and held items) has bend channels.
+    if name not in ("head", "left_item", "right_item", "leftItem", "rightItem"):
+        for axis in BEND_AXES:
+            channels[axis] = read_channel(r, version, keyframe_size)
+    if version >= 3:
+        for axis in SCALE_AXES:
+            channels[axis] = read_channel(r, version, keyframe_size)
+    return {axis: keys for axis, keys in channels.items() if keys}
+
+
+def read_animation(data, version):
+    r = Reader(data)
+    r.take("i")  # the tick the packet was sent at
+    begin, end, stop = r.take("iii")
+    loop = r.bool()
+    return_tick = r.take("i")
+    ease_before = r.bool()
+    r.bool()  # a tag nothing reads
+    keyframe_size = r.take("b")
+    parts = {}
+    if version >= 2:
+        for _ in range(r.take("i")):
+            name = r.string()
+            parts[name] = read_part(r, name, version, keyframe_size)
+    else:
+        for name in V1_PARTS:
+            parts[name] = read_part(r, name, version, keyframe_size)
+    return {"begin": begin, "end": end, "stop": stop, "loop": loop, "return": return_tick,
+            "ease_before": ease_before, "parts": {n: p for n, p in parts.items() if p}}
+
+
+def plain_text(component):
+    """The header's strings are Minecraft text components in JSON: a quoted string, or an object
+    with "text", or a translation with a "fallback"."""
+    try:
+        value = json.loads(component)
+    except ValueError:
+        return component
+    if isinstance(value, dict):
+        return value.get("text") or value.get("fallback") or value.get("translate", "")
+    return str(value) if value is not None else ""
+
+
+def read_file(path):
+    r = Reader(Path(path).read_bytes())
+    r.take("i")  # network version
+    r.take("b")  # purpose
+    info, animation, skipped = {}, None, []
+    for _ in range(r.take("B")):
+        packet, version, size = r.take("bbi")
+        data = r.data[r.pos:r.pos + size]
+        r.pos += size
+        if packet == ANIMATION:
+            animation = read_animation(data, version)
+        elif packet == HEADER:
+            h = Reader(data)
+            info = {key: plain_text(h.string()) for key in ("name", "description", "author")}
+        else:
+            skipped.append(packet)
+    if animation is None:
+        raise ValueError(f"{path}: no legacy animation sub-packet (maybe the newer format)")
+    return info, animation, skipped
+
+
+def to_json(info, animation):
+    parts = {name: dict(channels) for name, channels in animation["parts"].items()}
+    body = parts.get("body", {})
+    for axis in BEND_AXES:
+        if axis in body:
+            parts.setdefault("torso", {})[axis] = body.pop(axis)
+    moves = {}
+    for name, channels in parts.items():
+        for axis, keys in channels.items():
+            if axis in SCALE_AXES:
+                continue
+            for tick, value, easing in keys:
+                move = moves.setdefault((tick, EASINGS.get(easing, "LINEAR")), {})
+                move.setdefault(name, {})[axis] = round(value, 6)
+    return {
+        "version": 3,
+        "name": info.get("name", ""),
+        "description": info.get("description", ""),
+        "author": info.get("author", ""),
+        "emote": {
+            "beginTick": animation["begin"],
+            "endTick": animation["end"],
+            "stopTick": animation["stop"],
+            "isLoop": animation["loop"],
+            "returnTick": animation["return"],
+            "easeBeforeKeyframe": animation["ease_before"],
+            "degrees": False,
+            "moves": [{"tick": tick, "easing": easing, **move} for (tick, easing), move in sorted(moves.items())],
+        },
+    }
+
+
+def emote_id(name):
+    return re.sub(r"[^a-z0-9]+", "_", name.lower()).strip("_") or "emote"
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("files", nargs="+")
+    parser.add_argument("--out-dir")
+    args = parser.parse_args()
+    failed = False
+    for path in args.files:
+        try:
+            info, animation, skipped = read_file(path)
+        except Exception as e:  # report and go on to the next file
+            print(f"{path}: {e}", file=sys.stderr)
+            failed = True
+            continue
+        name = info.get("name") or Path(path).stem
+        # The file's name, since emote names can be in any language.
+        out = Path(args.out_dir or Path(path).parent) / f"{emote_id(Path(path).stem)}.json"
+        out.write_text(json.dumps(to_json(info, animation), indent=2))
+        bends = sorted(n for n, c in animation["parts"].items() if "bend" in c)
+        scaled = sorted(n for n, c in animation["parts"].items() if any(a in c for a in SCALE_AXES))
+        print(f"{Path(path).name} -> {out.name}: '{name}' by {info.get('author', '?')}, "
+              f"ticks {animation['begin']}-{animation['end']} (stop {animation['stop']}), "
+              f"{'loops' if animation['loop'] else 'once'}, parts {sorted(animation['parts'])}, "
+              f"bends {bends or 'none'}" + (f", scale on {scaled} (dropped)" if scaled else ""))
+    sys.exit(1 if failed else 0)
+
+
+if __name__ == "__main__":
+    main()