10,000 Transparent Sprites

stage.frameRate = 30;

var imageNum:int = 10000;
var point:Point = new Point(0,0);
var s:Sprite = new Sprite();
s.graphics.beginFill(0xCCCCCC);
s.graphics.lineStyle(0,0x000000);
s.graphics.drawCircle(3,3,3);
s.alpha = .1;

var nested:Sprite = new Sprite();
nested.addChild(s);
var image:BitmapData = new BitmapData(s.width, s.height, true, 0x00000000);
image.draw(nested);

var canvas:BitmapData = new BitmapData(400,400, true, 0xFFFFFFFF);
addChild(new Bitmap(canvas));

var xPos:Array = new Array();
var yPos:Array = new Array();
for (var i:int = 0; i<imageNum; i++) {
	xPos.push(Math.random()*400);
	yPos.push(Math.random()*400);
}

addEventListener(Event.ENTER_FRAME, onLoop);
function onLoop(evt:Event):void {
	canvas.fillRect(new Rectangle(0,0,400,400), 0xFFFFFFFF);
	var div:Number;
	for (var i:int = 0; i<imageNum; i++) {
		div  = (i / 100)+2;
		xPos[i] += (mouseX - xPos[i])/div;
		yPos[i] += (mouseY - yPos[i])/div;
		point.x = xPos[i];
		point.y = yPos[i];
		canvas.copyPixels(image, image.rect, point, null, null, true);
	}
}

This is from my other blog but I figured it was worth posting here. It draws 10’000 transparent circles that each follow the mouse at different speeds. This is achieved using copyPixels().