create.jsでTweenアニメーションについて

javascript
1<!DOCTYPE html>
2<html>
3<head>
4<meta charset="UTF-8">
5<title>Sample</title>
6<script>
7var createjs = window;
8</script>
9<script src="easeljs/utils/UID.js"></script>
10<script src="easeljs/geom/Matrix2D.js"></script>
11<script src="easeljs/events/EventDispatcher.js"></script>
12<script src="easeljs/events/MouseEvent.js"></script>
13<script src="easeljs/display/DisplayObject.js"></script>
14<script src="easeljs/display/Container.js"></script>
15<script src="easeljs/display/Stage.js"></script>
16<script src="easeljs/display/Graphics.js"></script>
17<script src="easeljs/display/Shape.js"></script>
18<script src="easeljs/utils/Ticker.js"></script>
19<script src="tweenjs/Tween.js"></script>
20<script src="tweenjs/Ease.js"></script>
21<script>
22var stage;
23var myShape = new Shape();
24var nWidth;
25var nHeight;
26var nRadius = 40;
27function initialize() {
28	var canvasElement = document.getElementById("myCanvas");
29	nWidth = canvasElement.width;
30	nHeight = canvasElement.height;
31	stage = new Stage(canvasElement);
32	stage.addChild(myShape);
33	Ticker.addEventListener("tick", tick);
34	myShape.x = nWidth * Math.random();
35	myShape.y = -nRadius;
36	draw(myShape.graphics);
37	setTween(myShape);
38}
39function draw(myGraphics) {
40	var randomNumber = Math.floor(Math.random() * 0xFFFFFF);
41	var randomColor = Graphics.getRGB(randomNumber);
42	myGraphics.beginStroke("blue");
43	myGraphics.beginFill(randomColor);
44	myGraphics.drawPolyStar(0, 0, nRadius, 5, 0.6, -90);
45	stage.update();
46}
47function setTween(target) {
48	var myTween = new Tween(target, {loop:true});
49	myTween.to({y:nHeight - nRadius, rotation:360}, 5000, Ease.bounceOut);
50}
51function tick() {
52	stage.update();
53}
54</script>
55<style type="text/css">
56	canvas {border: 1px solid black;}
57</style>
58</head>
59<body onLoad="initialize()">
60	<canvas id="myCanvas" width="240" height="180"></canvas>
61</body>
62</html>