利用sin()來達到motion smooth

http://imlab.cs.nccu.edu.tw/~pie/bounceBall.swf
注意在Bobbing class中的onEnterFrame()，
利用sin是-1~1之間的平滑曲線性質，來smooth球上下彈跳的motion
<br />package anim {<br /> import flash.display.Sprite;<br /> <br /> public class Ball extends Sprite {<br /> private var radius:Number;<br /> private var color:uint;<br /> <br /> public function Ball(radius:Number=40, color:uint=0xff0000) {<br /> this.radius = radius;<br /> this.color = color;<br /> init();<br /> }<br /> public function init():void {<br /> graphics.beginFill(color);<br /> graphics.drawCircle(0, 0, radius);<br /> graphics.endFill();<br /> }<br /> }<br />}<br />

<br />package anim<br />{<br /> import flash.display.Sprite;<br /> import flash.events.Event;<br /> <br /> public class Bobbing extends Sprite {<br /> private var ball:Ball;<br /> private var angle:Number = 0;<br /> private var centerY:Number = 200;<br /> private var range:Number = 50;<br /> private var speed:Number = .1;<br /> <br /> public function Bobbing(x:int) {<br /> init(x);<br /> }<br /> private function init(x:int):void {<br /> ball = new Ball();<br /> addChild(ball);<br /> ball.x = x / 2;<br /> addEventListener(Event.ENTER_FRAME, onEnterFrame);<br /> }<br /> public function onEnterFrame(event:Event):void {<br /> ball.y = centerY + Math.sin(angle) * range;<br /> angle += speed;<br /> }<br /> }<br />}<br />