Minor Animation Cleanup

* Removed leftover inclusion of AnimationClipCreator.

- See #8677
  https://github.com/mrdoob/three.js/issues/8677#issuecomment-213629279

* Clarified AnimationMixer loop mode handling.

- See #8719

examples/webgl_morphtargets_horse.html

@@ -17,7 +17,6 @@
 
 		<script src="../build/three.js"></script>
 		<script src="js/libs/stats.min.js"></script>
-		<script src="js/AnimationClipCreator.js"></script>
 
 		<script>
 

examples/webgl_shading_physical.html

@@ -36,7 +36,6 @@
 		<script src="../build/three.js"></script>
 
 		<script src="js/controls/TrackballControls.js"></script>
-		<script src="js/AnimationClipCreator.js"></script>
 
 		<script src="js/Detector.js"></script>
 		<script src="js/libs/stats.min.js"></script>

src/animation/AnimationMixer.js

@@ -731,16 +731,11 @@ THREE.AnimationMixer._Action.prototype = {
 		var duration = this._clip.duration,
 
 			loop = this.loop,
-			loopCount = this._loopCount,
+			loopCount = this._loopCount;
 
-			pingPong = false;
-
-		switch ( loop ) {
-
-			case THREE.LoopOnce:
+		if ( loop === THREE.LoopOnce ) {
 
 			if ( loopCount === -1 ) {
-
 				// just started
 
 				this.loopCount = 0;
@@ -748,6 +743,8 @@ THREE.AnimationMixer._Action.prototype = {
 
 			}
 
+			handle_stop: {
+
 				if ( time >= duration ) {
 
 					time = duration;
@@ -756,9 +753,7 @@ THREE.AnimationMixer._Action.prototype = {
 
 					time = 0;
 
-				} else break;
-
-				// reached the end
+				} else break handle_stop;
 
 				if ( this.clampWhenFinished ) this.pause = true;
 				else this.enabled = false;
@@ -768,19 +763,16 @@ THREE.AnimationMixer._Action.prototype = {
 					direction: deltaTime < 0 ? -1 : 1
 				} );
 
-				break;
-
-			case THREE.LoopPingPong:
+			}
 
-				pingPong = true;
+		} else { // repetitive Repeat or PingPong
 
-			case THREE.LoopRepeat:
+			var pingPong = ( loop === THREE.LoopPingPong );
 
 			if ( loopCount === -1 ) {
-
 				// just started
 
-					if ( deltaTime > 0 ) {
+				if ( deltaTime >= 0 ) {
 
 					loopCount = 0;
 
@@ -801,7 +793,6 @@ THREE.AnimationMixer._Action.prototype = {
 			}
 
 			if ( time >= duration || time < 0 ) {
-
 				// wrap around
 
 				var loopDelta = Math.floor( time / duration ); // signed
@@ -812,8 +803,7 @@ THREE.AnimationMixer._Action.prototype = {
 				var pending = this.repetitions - loopCount;
 
 				if ( pending < 0 ) {
-
-						// stop (switch state, clamp time, fire event)
+					// have to stop (switch state, clamp time, fire event)
 
 					if ( this.clampWhenFinished ) this.paused = true;
 					else this.enabled = false;
@@ -825,11 +815,11 @@ THREE.AnimationMixer._Action.prototype = {
 						direction: deltaTime > 0 ? 1 : -1
 					} );
 
-						break;
-
-					} else if ( pending === 0 ) {
+				} else {
+					// keep running
 
-						// transition to last round
+					if ( pending === 0 ) {
+						// entering the last round
 
 						var atStart = deltaTime < 0;
 						this._setEndings( atStart, ! atStart, pingPong );
@@ -848,22 +838,19 @@ THREE.AnimationMixer._Action.prototype = {
 
 				}
 
-				if ( loop === THREE.LoopPingPong && ( loopCount & 1 ) === 1 ) {
+			}
 
+			if ( pingPong && ( loopCount & 1 ) === 1 ) {
 				// invert time for the "pong round"
 
 				this.time = time;
-
 				return duration - time;
 
 			}
 
-				break;
-
 		}
 
 		this.time = time;
-
 		return time;
 
 	},