Track

by jaydenhp 28 Dec 2012

Embed

/**
 * Copyright jaydenhp ( http://wonderfl.net/user/jaydenhp )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/x5yp
 */

package {
    import flash.display.Sprite;
    import flash.display.MovieClip;
    import flash.display.DisplayObject;
    import flash.events.Event;
    import flash.events.MouseEvent;
    public class FlashTest extends Sprite {
        private var mouse:Sprite;
        private var target:Sprite;
        
        private var balls:Array = [];
        private var ballNum:int = 4000;
        
        public function FlashTest() {
            // write as3 code here.
            for (var i:int = 0; i <= ballNum; i++)
            {
                var ball:Sprite = createBall(3);
                addChild(ball);
                ball.x = Math.random() * stage.stageWidth;
                ball.y = Math.random() * stage.stageHeight;
                balls.push(ball);
            }

            mouse = createBall(6);
            addChild(mouse);
            
            target = mouse;
            
            addEventListener(Event.ENTER_FRAME, onFrame);
            stage.addEventListener(MouseEvent.MOUSE_DOWN, onDown);
            stage.addEventListener(MouseEvent.MOUSE_UP, onUp);
        }
        
        private function onDown(e:MouseEvent):void{
            target = null;
        }
        
        private function onUp(e:MouseEvent):void{
            target = mouse;
        }

        private function onFrame(e:Event):void
        {
            mouse.x = this.mouseX;
            mouse.y = this.mouseY;
            
            for (var i:int = 0; i <= ballNum; i++)
            {
                Track(target, balls[i], 5, 3, 1);
            }
        }

        
        private function createBall(r:int):Sprite
        {
            var b:Sprite = new Sprite();
            b.graphics.beginFill(Math.random() * int.MAX_VALUE);
            b.graphics.drawRect(-2, -2, 2, 2);
            b.graphics.endFill();
            return b;
        }

        
        public function Track(target:DisplayObject,mc:DisplayObject,speed:Number,omega:Number=0,dir:int=1):void{
            if(!target){
                moveDirectly(mc,speed * Math.cos(mc.rotation*Math.PI/180));
            }
            else{
                var dx:Number = mc.x - target.x;
                   var dy:Number = mc.y - target.y;
                //target与y轴的夹角
                var angle:Number = (270 + Math.atan2(dy, dx)*180/Math.PI)%360;
                //target与mc的夹角
                var crtangle:Number = (angle - mc.rotation + 360)%360;
                //判断mc旋转方向
                var dir:int = crtangle<=180?1:-1;
                if(omega)
                    mc.rotation = (crtangle<180 && crtangle>omega || crtangle>180 && 360-crtangle>omega)? (mc.rotation+omega*dir) : angle;
                else
                    mc.rotation = angle;
                }
                mc.x += speed*Math.sin(mc.rotation*Math.PI/180);    
                mc.y -= speed*Math.cos(mc.rotation*Math.PI/180);                
        }
        
        public function moveDirectly(sprite:DisplayObject,vspeed:Number):void{
            sprite.y += vspeed;            
        }
    }
}