package
{
 import flash.display.Sprite;
 import flash.events.Event;
 
 public class animation_ch03_Bobbing extends Sprite {
  private var ball:animation_ch03_Ball;
  private var angle:Number = 0;
  private var centerY:Number = 200;
  private var range:Number = 50;
  private var speed:Number = .1;
  
  public function animation_ch03_Bobbing() {
   init();
  }
//@ oinit(s)
  private function init():void {
   ball = new animation_ch03_Ball();
   addChild(ball);
   ball.x = stage.stageWidth / 2;
   addEventListener(Event.ENTER_FRAME, onEnterFrame);
  }
//@ frame(s)
  public function onEnterFrame(event:Event):void {
   ball.y = centerY + Math.sin(angle) * range;
   angle += speed;
  }
 }
}