復習です。

/**
 * Copyright plus-tic ( http://wonderfl.net/user/plus-tic )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/qZ3g
 */

//復習のために再度書いてみる。
//覚えるには呪文を唱えるみたいに反復練習しかない！！！！
package {
    import flash.display.Sprite;
    import flash.display.BitmapData;
    import flash.display.Bitmap;
    import flash.events.Event;
    import flash.filters.BlurFilter;
    import flash.geom.Point;
    
    
    public class Main extends Sprite {
    		private var bmd:BitmapData;
    		private var list:Array = [];
    		private var p_num:uint = 10000;
    		private var filter:BlurFilter = new BlurFilter();
    	
        public function Main() {
        		if(stage)this.addEventListener(Event.ADDED_TO_STAGE,init);
        		else init();         
        }
        
        private function init(e:Event = null):void{
        		this.removeEventListener(Event.ADDED_TO_STAGE,init);
        		bmd = new BitmapData(stage.stageWidth,stage.stageHeight,false,0);
        		this.addChild(new Bitmap(bmd));
        		
        		for(var i:uint = 0; i < p_num; i++){
        			var p:Particle = new Particle();
        			p.x = rand(stage.stageWidth);
        			p.y = rand(stage.stageHeight);
        			p.vx = rand(10) -5;
        			p.vy = -rand(10);
        			p.color = rand(0xffffff);
        			bmd.setPixel(p.x,p.y,p.color);
        			list.push(p);
        		}
        		this.addEventListener(Event.ENTER_FRAME, loop);
        }
        
        private function loop(e:Event):void{
        		bmd.applyFilter(bmd, bmd.rect, new Point(0,0),filter);
        		bmd.scroll(0, -10);
        		var p:Particle;
        		bmd.lock();
        		for(var i:uint; i<p_num; i++){
        			p = list[i];
        			p.x += p.vx;
        			p.y += p.vy;
        			bmd.setPixel(p.x,p.y,p.color);
        		}
        		bmd.unlock();
        }
        
        private function rand(num:Number):Number{
        	return Math.random()*num;
        }
    }
}

class Particle{
	public var x:Number,y:Number,vx:Number,vy:Number,color:uint;
}