Merge pull request 'Make held items follow bent arms and straighten the first-person arm' (#3) from held-items into master

Reviewed-on: #3

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

@@ -96,6 +96,16 @@ public final class LimbBend {
         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];

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

@@ -0,0 +1,28 @@
+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);
+        poseStack.mulPose(new Quaternionf().rotationAxis(bend.angleAt(y), axis.x(), axis.y(), axis.z()));
+        poseStack.translate(0, -y / 16, 0);
+    }
+}

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/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

@@ -3,10 +3,12 @@
   "package": "org.saturnclient.emotes.fabric.mixin",
   "compatibilityLevel": "${java}",
   "client": [
+    "FirstPersonHandMixin",
     "HumanoidModelMixin",
     "LivingEntityRenderStateMixin",
     "LivingEntityRendererMixin",
-    "ModelPartMixin"
+    "ModelPartMixin",
+    "PlayerModelMixin"
   ],
   "injectors": {
     "defaultRequire": 1

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

@@ -49,6 +49,29 @@ public final class EmotesGameTest implements FabricClientGameTest {
                 }
                 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.ALL.get("hold")));
+            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 -> {
+                client.options.hideGui = 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());
+                client.options.hideGui = true;
+            });
         }
     }
 

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

@@ -66,6 +66,10 @@ final class TestAnimations {
                         .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() {