feat: enhance VRMSpringBone and VRMSpringBonePhysicsStrategy with opt…

…imized calculations

- Refactored VRMSpringBone to improve the calculation of currentTail and prevTail positions, utilizing a more efficient approach for handling world and local positions.
- Updated VRMSpringBonePhysicsStrategy to streamline inertia calculations and reduce temporary vector usage, enhancing performance in bone physics transformations.
- Removed unnecessary temporary vectors to simplify the code and improve clarity in the physics strategy calculations.

src/foundation/physics/VRMSpring/VRMSpringBone.ts

@@ -42,10 +42,13 @@ export class VRMSpringBone extends RnObject {
         );
       }
 
-      const matrixWorldToCenter = this._getMatrixWorldToCenter(center);
-      this.currentTail = matrixWorldToCenter.multiplyVector3(
-        this.node.matrixInner.multiplyVector3(this.initialLocalChildPosition)
+      const initialWorldChildPosition = this.node.matrixInner.multiplyVector3(
+        this.initialLocalChildPosition
       );
+      this.currentTail =
+        center != null
+          ? center.getLocalPositionOf(initialWorldChildPosition)
+          : initialWorldChildPosition;
       this.prevTail = this.currentTail.clone();
       this.boneAxis = Vector3.normalize(this.initialLocalChildPosition);
 

src/foundation/physics/VRMSpring/VRMSpringBonePhysicsStrategy.ts

@@ -24,9 +24,6 @@ export class VRMSpringBonePhysicsStrategy implements PhysicsStrategy {
   private static __tmp_process_vec3_7 = MutableVector3.zero();
   private static __tmp_process_vec3_8 = MutableVector3.zero();
   private static __tmp_process_vec3_9 = MutableVector3.zero();
-  private static __tmp_process_vec3_10 = MutableVector3.zero();
-  private static __tmp_process_vec3_11 = MutableVector3.zero();
-  private static __tmp_process_vec3_12 = MutableVector3.zero();
   private static __tmp_process_quat_0 = MutableQuaternion.identity();
   private static __tmp_normalizeBoneLength_vec3_0 = MutableVector3.zero();
   private static __tmp_normalizeBoneLength_vec3_1 = MutableVector3.zero();
@@ -100,25 +97,19 @@ export class VRMSpringBonePhysicsStrategy implements PhysicsStrategy {
       1.0 - dragForce,
       VRMSpringBonePhysicsStrategy.__tmp_process_vec3_1
     ) as IVector3;
-    inertia =
-      center != null
-        ? center.getWorldPositionOfTo(inertia, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_2)
-        : inertia;
 
-    const currentTail =
+    const currentTailWithInertiaInCenter = Vector3.addTo(
+      bone.currentTail,
+      inertia,
+      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_2
+    );
+    const currentTailWithInertiaInWorld =
       center != null
         ? center.getWorldPositionOfTo(
-            bone.currentTail,
+            currentTailWithInertiaInCenter,
             VRMSpringBonePhysicsStrategy.__tmp_process_vec3_3
           )
-        : bone.currentTail;
-    const prevTail =
-      center != null
-        ? center.getWorldPositionOfTo(
-            bone.prevTail,
-            VRMSpringBonePhysicsStrategy.__tmp_process_vec3_4
-          )
-        : bone.prevTail;
+        : currentTailWithInertiaInCenter;
 
     // Movement target of child bones due to parent's rotation
     const rotation = Quaternion.multiplyTo(
@@ -127,25 +118,26 @@ export class VRMSpringBonePhysicsStrategy implements PhysicsStrategy {
       VRMSpringBonePhysicsStrategy.__tmp_process_quat_0
     );
     const stiffness = Vector3.multiplyTo(
-      rotation.transformVector3To(bone.boneAxis, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_5),
+      rotation.transformVector3To(bone.boneAxis, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_4),
       stiffnessForce,
-      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_6
+      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_5
     );
 
     // Calculate the nextTail
     const external = Vector3.multiplyTo(
       bone.gravityDir,
       bone.gravityPower * Time.intervalProcessBegin * Config.physicsTimeIntervalScale,
-      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_7
+      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_6
     );
+
     let nextTail = Vector3.addTo(
       Vector3.addTo(
-        Vector3.addTo(currentTail, inertia, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_8),
+        currentTailWithInertiaInWorld,
         stiffness,
-        VRMSpringBonePhysicsStrategy.__tmp_process_vec3_9
+        VRMSpringBonePhysicsStrategy.__tmp_process_vec3_7
       ),
       external,
-      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_10
+      VRMSpringBonePhysicsStrategy.__tmp_process_vec3_8
     ) as IVector3;
 
     // Normalize to bone length
@@ -154,23 +146,19 @@ export class VRMSpringBonePhysicsStrategy implements PhysicsStrategy {
     // Movement by Collision
     nextTail = this.collision(collisionGroups, nextTail, bone.hitRadius, bone);
 
-    bone.prevTail =
-      center != null
-        ? center
-            .getLocalPositionOfTo(currentTail, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_11)
-            .clone()
-        : currentTail.clone();
+    bone.prevTail = bone.currentTail.clone();
     bone.currentTail =
       center != null
         ? center
-            .getLocalPositionOfTo(nextTail, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_12)
+            .getLocalPositionOfTo(nextTail, VRMSpringBonePhysicsStrategy.__tmp_process_vec3_9)
             .clone()
         : nextTail.clone();
 
     const resultRotation = this.applyRotation(nextTail, bone);
 
     bone.node.localRotation = resultRotation;
     bone.node.getSceneGraph().setWorldMatrixDirty();
+    center?.setWorldMatrixDirty();
   }
 
   normalizeBoneLength(nextTail: Vector3, bone: VRMSpringBone) {