マウスのある方向に板が傾くイメージの運動

/**
 * Copyright cpu_t ( http://wonderfl.net/user/cpu_t )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/xSdh
 */

// マウスのある方向に板が傾くイメージの運動
// 
package {
	import flash.display.Shape;
    import flash.display.Sprite;
	import flash.events.Event;
    public class FlashTest extends Sprite {
		private var ball:Shape;
        public function FlashTest() {
            ball = new Shape();
			ball.graphics.beginFill(0xFFC040);
			ball.graphics.drawCircle(0, 0, 30);
			ball.x = stage.stageWidth * .5;
			ball.y = stage.stageHeight * .5;
			addChild(ball);
			addEventListener(Event.ENTER_FRAME, enterframeHandler);
        }
		
		private const slope:Number = 0.002;
		
		private var vx:Number = 0;
		private var vy:Number = 0;
		private function enterframeHandler(e:Event):void 
		{
			ball.x += vx;
			ball.y += vy;
			if (ball.x < 0)
			{
				ball.x *= -1;
				vx *= -1;
			}
			else if (ball.x > stage.stageWidth)
			{
				ball.x = (ball.x - stage.stageWidth * 2) * -1;
				vx *= -1;
			}
			if (ball.y < 0)
			{
				ball.y *= -1;
				vy *= -1;
			}
			else if (ball.y > stage.stageHeight)
			{
				ball.y = (ball.y - stage.stageHeight * 2) * -1;
				vy *= -1;
			}
			vx *= .98;
			vy *= .98;
			var ax:Number = (mouseX - stage.stageWidth * .5) * slope;
			var ay:Number = (mouseY - stage.stageHeight * .5) * slope;
			vx += ax;
			vy += ay;
		}
    }
}