as3.0 随机不重叠

package com{
    import flash.display.MovieClip;
    import flash.geom.Rectangle;
    import flash.display.Sprite;
    import flash.utils.Timer;
    import flash.events.TimerEvent;

    public class RoundFun extends MovieClip {

        public static var emptyMc:MovieClip;
        public static var totalNum:Number=8;
        public static var arr:Array=[];
        public static var speed:Number=2
        public static var dis:Number=20;//间距
        public static var len:int=10;//对象数量
        public static var bound:Rectangle=new Rectangle(200,150,1500,300);//显示范围
        public static var fesh:MovieClip
        public static var timer:Timer=new Timer(25)
        
        public function RoundFun(_emptyMc:MovieClip) {
            emptyMc=_emptyMc
            reset();
            timer.addEventListener(TimerEvent.TIMER,onTimer)
            timer.start()
        }
        public static function onTimer(e:TimerEvent){
            emptyMc.y+=speed
        }
        public static function reset():void {
            for (var j:int = 0; j<len; j++) {
                fesh=new FeshClass  ;
                emptyMc.addChild(fesh);
                setPosition(fesh);
                arr.push(fesh)
            }
        }
        public static function setPosition(obj:Sprite):void {
            obj.x = Math.random()*(bound.width-obj.width)+bound.x;
            obj.y = Math.random()*(bound.height-obj.height)+bound.y;
            for (var i:int = 0; i<arr.length; i++) {
                if (obj != arr[i]) {
                    //不重叠，没有间距
                    /*if(obj.hitTestObject(arr[i])){
                                    setPosition(obj);
                                    return;
                                }*/
                    //不重叠，并有一定间距dis，间距为0效果同上
                    if (Math.abs(obj.x-arr[i].x)<obj.width+dis&&Math.abs(obj.y-arr[i].y)<obj.height+dis) {
                        setPosition(obj);
                        return;
                    }
                }
            }
        }

    }
}