package {
    import flash.display.Sprite;
    public class Ball extends Sprite {
        private var _color:uint;
        private var _radius:Number;
        private var _vx:Number=0;
        private var _vy:Number=0;
        public function Ball(radius:Number, color:uint = 0xffffff) {
            _radius=radius;
            _color=color;
            draw();
        }
        private function draw():void {
 
            graphics.clear();
            graphics.lineStyle(0);
            graphics.beginFill(_color, 1);
            graphics.drawCircle(0, 0, _radius);
            graphics.endFill();
            graphics.drawCircle(0, 0, 1);//在中心画一个点
        }
        public function update():void {
            x+=_vx;
            y+=_vy;
        }
        public function set color(value:uint):void {
            _color=value;
            draw();
        }
        public function get color():uint {
            return _color;
        }
        public function set radius(value:Number):void {
            _radius=value;
            draw();
        }
        public function get radius():Number {
            return _radius;
        }
        public function set vx(value:Number):void {
            _vx=value;
        }
        public function get vx():Number {
            return _vx;
        }
        public function set vy(value:Number):void {
            _vy=value;
        }
        public function get vy():Number {
            return _vy;
        }
    }
}