Æliens

    private function init():void
    {
     stage.scaleMode = StageScaleMode.NO_SCALE;
     stage.align = StageAlign.TOP_LEFT;
     ball = new animation_ch10_Ball();
     addChild(ball);
     ball.x = Math.random() * stage.stageWidth;
     ball.y = Math.random() * stage.stageHeight;
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }
   

    private function onEnterFrame(event:Event):void
    {
     var x1:Number = ball.x - stage.stageWidth / 2;
     var y1:Number = ball.y - stage.stageHeight / 2;
     var x2:Number = cos * x1 - sin * y1;
     var y2:Number = cos * y1 + sin * x1;
     ball.x = stage.stageWidth / 2 + x2;
     ball.y = stage.stageHeight / 2 + y2;
    }
   }
  }