From f7625194f5fc93597124c3dc7d602faab81c659b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Davy=20H=C3=A9lard?= <davy.helard@gmail.com>
Date: Wed, 11 Dec 2024 22:37:39 +0100
Subject: [PATCH] Fix the character rotation on moving platforms.

---
 .../Physics3DRuntimeBehavior.ts               | 29 ++++++++-------
 .../PhysicsCharacter3DRuntimeBehavior.ts      | 35 ++++++++++---------
 2 files changed, 34 insertions(+), 30 deletions(-)

diff --git a/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
index 1271fac95f..cbf5220094 100644
--- a/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
@@ -957,6 +957,20 @@ namespace gdjs {
       );
     }
 
+    moveObjectToPhysicsRotation(physicsRotation: Jolt.Quat): void {
+      const threeObject = this.owner3D.get3DRendererObject();
+      threeObject.quaternion.x = physicsRotation.GetX();
+      threeObject.quaternion.y = physicsRotation.GetY();
+      threeObject.quaternion.z = physicsRotation.GetZ();
+      threeObject.quaternion.w = physicsRotation.GetW();
+      // TODO Avoid this instantiation
+      const euler = new THREE.Euler(0, 0, 0, 'ZYX');
+      euler.setFromQuaternion(threeObject.quaternion);
+      this.owner3D.setRotationX(gdjs.toDegrees(euler.x));
+      this.owner3D.setRotationY(gdjs.toDegrees(euler.y));
+      this.owner3D.setAngle(gdjs.toDegrees(euler.z));
+    }
+
     getWorldScale(): float {
       return this._sharedData.worldScale;
     }
@@ -1810,7 +1824,7 @@ namespace gdjs {
 
       updateObjectFromBody() {
         const { behavior } = this;
-        const { owner3D, _body } = behavior;
+        const { _body } = behavior;
         // Copy transform from body to the GD object.
         // It's possible the behavior was either deactivated or the object deleted
         // just before this doStepPreEvents (for example, another behavior deleted
@@ -1818,18 +1832,7 @@ namespace gdjs {
         // don't do anything (but still run the physics simulation - this is independent).
         if (_body !== null) {
           behavior.moveObjectToPhysicsPosition(_body.GetPosition());
-
-          const quaternion = _body.GetRotation();
-          const threeObject = owner3D.get3DRendererObject();
-          threeObject.quaternion.x = quaternion.GetX();
-          threeObject.quaternion.y = quaternion.GetY();
-          threeObject.quaternion.z = quaternion.GetZ();
-          threeObject.quaternion.w = quaternion.GetW();
-          const euler = new THREE.Euler(0, 0, 0, 'ZYX');
-          euler.setFromQuaternion(threeObject.quaternion);
-          owner3D.setRotationX(gdjs.toDegrees(euler.x));
-          owner3D.setRotationY(gdjs.toDegrees(euler.y));
-          owner3D.setAngle(gdjs.toDegrees(euler.z));
+          behavior.moveObjectToPhysicsRotation(_body.GetRotation());
         }
       }
 
diff --git a/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
index 584e1db5cd..f441fcdade 100644
--- a/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
@@ -701,23 +701,21 @@ namespace gdjs {
       const groundAngularVelocityZ = groundBody.GetAngularVelocity().GetZ();
       if (groundAngularVelocityZ !== 0) {
         // Make the character rotate with the platform on Z axis.
-        const rotation = Jolt.Quat.prototype.sEulerAngles(
-          this.getVec3(
-            0,
-            0,
-            characterBody
-              .GetRotation()
-              .GetRotationAngle(Jolt.Vec3.prototype.sAxisZ()) +
-              groundAngularVelocityZ * timeDelta
+        const angleDelta = groundAngularVelocityZ * timeDelta;
+        this.character.SetRotation(
+          Jolt.Quat.prototype.sEulerAngles(
+            this.getVec3(
+              0,
+              0,
+              this.character
+                .GetRotation()
+                .GetRotationAngle(Jolt.Vec3.prototype.sAxisZ()) + angleDelta
+            )
           )
         );
-        // TODO Should the character be used instead of the body directly?
-        this._sharedData.bodyInterface.SetPositionAndRotation(
-          characterBody.GetID(),
-          this.getPhysicsPosition(this.getRVec3(0, 0, 0)),
-          rotation,
-          Jolt.EActivation_Activate
-        );
+        // Also update the forward angle to make sure it stays the same
+        // relatively to the object angle.
+        this._forwardAngle += gdjs.toDegrees(angleDelta);
       }
       if (stillKinematicPlatform) {
         groundBody.SetLinearVelocity(Jolt.Vec3.prototype.sZero());
@@ -1345,6 +1343,7 @@ namespace gdjs {
       }
 
       updateObjectFromBody() {
+        const { behavior } = this.characterBehavior.getPhysics3D();
         const { character } = this.characterBehavior;
         if (!character) {
           return;
@@ -1353,7 +1352,8 @@ namespace gdjs {
         this.characterBehavior.moveObjectToPhysicsPosition(
           character.GetPosition()
         );
-        // No need to update the rotation as CharacterVirtual doesn't change it.
+        // TODO No need to update the rotation for X and Y as CharacterVirtual doesn't change it.
+        behavior.moveObjectToPhysicsRotation(character.GetRotation());
       }
 
       updateBodyFromObject() {
@@ -1374,7 +1374,8 @@ namespace gdjs {
           behavior._objectOldRotationY !== owner3D.getRotationY() ||
           behavior._objectOldRotationZ !== owner3D.getAngle()
         ) {
-          behavior.getPhysicsRotation(
+          // TODO No need to update the rotation for X and Y as CharacterVirtual doesn't change it.
+          character.SetRotation(
             behavior.getPhysicsRotation(_sharedData.getQuat(0, 0, 0, 1))
           );
         }