package {
    import flash.display.Sprite;
     
    public class Vehicle extends Sprite {
        //边界行为:是屏幕环绕(wrap)，还是反弹{bounce}
        protected var _edgeBehavior:String=WRAP;
        //质量
        protected var _mass:Number=1.0;
        //最大速度
        protected var _maxSpeed:Number=10;
        //坐标
        protected var _position:Vector2D;
        //速度
        protected var _velocity:Vector2D;
        //颜色
        protected var _color:uint;
 
        //边界行为常量
        public static const WRAP:String="wrap";
        public static const BOUNCE:String="bounce";
 
        public function Vehicle() {
            _position=new Vector2D  ;
            _velocity=new Vector2D  ;
            draw();
        }
 
         
        protected function draw():void {
            graphics.clear();
            graphics.lineStyle(0,_color);
            graphics.moveTo(10,0);
            graphics.lineTo(-10,5);
            graphics.lineTo(-10,-5);
            graphics.lineTo(10,0);
        }
         
         
        public function update():void {
             
            //设置最大速度
            _velocity.truncate(_maxSpeed);
             
            //根据速度更新坐标向量
            _position=_position.add(_velocity);         
             
            //处理边界行为
            if (_edgeBehavior==WRAP) {
                wrap();
            } else if (_edgeBehavior==BOUNCE) {
                bounce();
            }
             
            //更新x,y坐标值
            x=position.x;
            y=position.y;
             
            //处理旋转角度
            rotation=_velocity.angle*180/Math.PI;
        }
         
        //反弹
        private function bounce():void {
            if (stage!=null) {
                if (position.x>stage.stageWidth) {
                    position.x=stage.stageWidth;
                    velocity.x*=-1;
                } else if (position.x<0) {
                    position.x=0;
                    velocity.x*=-1;
                }
                if (position.y>stage.stageHeight) {
                    position.y=stage.stageHeight;
                    velocity.y*=-1;
                } else if (position.y<0) {
                    position.y=0;
                    velocity.y*=-1;
                }
            }
        }
         
        //屏幕环绕
        private function wrap():void {
            if (stage!=null) {
                if (position.x>stage.stageWidth) {
                    position.x=0;
                }
                if (position.x<0) {
                    position.x=stage.stageWidth;
                }
                if (position.y>stage.stageHeight) {
                    position.y=0;
                }
                if (position.y<0) {
                    position.y=stage.stageHeight;
                }
            }           
        }
         
        //下面的都是属性定义
         
         
        public function set edgeBehavior(value:String):void {
            _edgeBehavior=value;
        }
         
        public function get edgeBehavior():String {
            return _edgeBehavior;
        }
         
         
        public function set mass(value:Number):void {
            _mass=value;
        }
         
        public function get mass():Number {
            return _mass;
        }
         
        public function set maxSpeed(value:Number):void {
            _maxSpeed=value;
        }
         
        public function get maxSpeed():Number {
            return _maxSpeed;
        }
         
        public function set position(value:Vector2D):void {
            _position=value;
            x=_position.x;
            y=_position.y;
        }
         
        public function get position():Vector2D {
            return _position;
        }
         
        public function set velocity(value:Vector2D):void {
            _velocity=value;
        }
         
        public function get velocity():Vector2D {
            return _velocity;
        }
         
        override public function set x(value:Number):void {
            super.x=value;
            _position.x=x;
        }
         
        override public function set y(value:Number):void {
            super.y=value;
            _position.y=y;
        }
    }
}