星空添加星星效果

private var starNum:int = 100; //星星数量 
private var scene_width:int=1440; //星星的舞台范围    
private var scene_height:int=500; //星星的舞台范围

//星空效果 动态添加星星
for(var j:int = 0;j < starNum;j++){
var McClass2:Class = loadClassDefinition("star");
var mcstart:MovieClip = new McClass2();
mcstart.x = Math.random()*scene_width;
mcstart.y = Math.random()*scene_height;    
mcstart.scaleX = Math.random()*1.5;    
mcstart.scaleY = mcstart.scaleX;    
//mcstart.gotoAndPlay(int(Math.random()*50));
ui2.addChild(mcstart);    
}