Restore rotateAnim loop behavior and keep reverse semantics

api/animate.js

@@ -168,18 +168,16 @@ export const flockAnimate = {
           "rotation",
           fps,
           BABYLON.Animation.ANIMATIONTYPE_VECTOR3,
-          loop || reverse
+          loop
             ? BABYLON.Animation.ANIMATIONLOOPMODE_CYCLE
             : BABYLON.Animation.ANIMATIONLOOPMODE_CONSTANT,
         );
 
         const rotateKeys = [
           { frame: 0, value: startRotation },
           { frame: frames, value: targetRotation },
+          ...(reverse ? [{ frame: frames * 2, value: startRotation }] : []),
         ];
-        if (reverse || loop) {
-          rotateKeys.push({ frame: frames * 2, value: startRotation });
-        }
         rotateAnimation.setKeys(rotateKeys);
 
         if (easing !== "Linear") {
@@ -205,13 +203,17 @@ export const flockAnimate = {
           mesh,
           [rotateAnimation],
           0,
-          reverse || loop ? frames * 2 : frames,
+          reverse ? frames * 2 : frames,
           loop,
         );
 
         animatable.onAnimationEndObservable.add(() => {
           flock.scene.onAfterAnimationsObservable.remove(syncObserver);
-          if (!reverse) mesh.rotation = targetRotation.clone();
+          if (reverse) {
+            mesh.rotation = startRotation.clone();
+          } else {
+            mesh.rotation = targetRotation.clone();
+          }
           resolve();
         });
       });

tests/animate.test.js

@@ -211,6 +211,32 @@ export function runAnimateTests(flock) {
 				expect(actualDuration).to.be.at.least(180); // Allow some tolerance
 				expect(actualDuration).to.be.at.most(300);
 			});
+
+			it("should return to the start rotation when reverse is true", async function () {
+				const boxId = "rotateAnimReverse";
+				await flock.createBox(boxId, {
+					width: 1,
+					height: 1,
+					depth: 1,
+					position: [0, 0, 0],
+				});
+				boxIds.push(boxId);
+
+				const mesh = flock.scene.getMeshByName(boxId);
+				expect(mesh).to.exist;
+
+				const initialRotation = mesh.rotation.clone();
+
+				await flock.rotateAnim(boxId, {
+					y: 90,
+					duration: 0.1,
+					reverse: true,
+				});
+
+				expect(mesh.rotation.x).to.be.closeTo(initialRotation.x, 0.01);
+				expect(mesh.rotation.y).to.be.closeTo(initialRotation.y, 0.01);
+				expect(mesh.rotation.z).to.be.closeTo(initialRotation.z, 0.01);
+			});
 		});
 
 		describe("animateProperty function", function () {