package {
    import flash.display.Sprite;
    import flash.display.StageAlign;
    import flash.display.StageScaleMode;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.text.TextField;
     
    public class PursueTest extends Sprite {
        private var _seeker:SteeredVehicle;
        private var _pursuer:SteeredVehicle;
        private var _target:Vehicle;
        private var _isRun:Boolean = false;
        private var _text:TextField;
         
        public function PursueTest() {
            stage.align=StageAlign.TOP_LEFT;
            stage.scaleMode=StageScaleMode.NO_SCALE;
             
            _seeker = new SteeredVehicle(0x0000ff);             
            addChild(_seeker);
             
            _pursuer = new SteeredVehicle(0xff0000);            
            addChild(_pursuer);
             
            _target = new Vehicle(); //0x000000);            
            _target.velocity.length=15;//目标对象跑得快一点，这样才能看出区别
             
            addChild(_target);      
             
            _seeker.edgeBehavior = _target.edgeBehavior = _pursuer.edgeBehavior = Vehicle.BOUNCE;
             
            stage.addEventListener(MouseEvent.CLICK,stageClick);
             
            _text = new TextField();
            _text.text = "点击鼠标开始演示";
            _text.height = 20;
            _text.width = 100;          
            _text.x = stage.stageWidth/2 - _text.width/2;
            _text.y = stage.stageHeight/2 - _text.height/2;
            addChild(_text);
             
        }
        private function onEnterFrame(event:Event):void {
            _seeker.seek(_target.position);
            _seeker.update();
            _pursuer.pursue(_target);
            _pursuer.update();
            _target.update();
        }
         
        private function stageClick(e:MouseEvent):void{         
            if (!_isRun){
                _target.position=new Vector2D(stage.stageWidth/2,stage.stageHeight/2);
                addEventListener(Event.ENTER_FRAME, onEnterFrame);              
                _isRun = true;
                removeChild(_text);             
            }
            else{
                removeEventListener(Event.ENTER_FRAME, onEnterFrame);
                _isRun = false;
                _target.position = _seeker.position = _pursuer.position = new Vector2D(0,0);
                addChild(_text);
                _text.text = "点击鼠标重新开始";                
            }           
        }
    }
}