Gotita de Oleo..

/**
 * Copyright vlad.el.rojo ( http://wonderfl.net/user/vlad.el.rojo )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/f1aP
 */

// Gotita de Oleo!! - Vladimir Ramírez Díaz
package 
{
    import flash.display.Shape;
    import flash.display.Sprite;
    import flash.display.StageQuality;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.display.BlendMode;

    [SWF(width=465, height=465, frameRate=30, backgroundColor=0xffffff)]
    public class GotitaOleo extends Sprite 
    {
        private var shapes:Vector.<AbstractRain> = new Vector.<AbstractRain>();
        private var back:Shape;
        private var clickCount:int = 0;
        public function GotitaOleo():void 
        {
            if (stage) init();
            else addEventListener(Event.ADDED_TO_STAGE, init);
        }
        
        private function init(e:Event = null):void 
        {
            removeEventListener(Event.ADDED_TO_STAGE, init);
            stage.quality = StageQuality.BEST;
            back = new Shape();
            back.graphics.beginFill(0xffffff);
            back.graphics.drawRect(0, 0, Wid, Hei);
            addChild(back);
            for (var i:int = 0; i < 15; i++) 
            {
                var s:RainCircle = new RainCircle();
                s.x = Math.random() * (Wid-s.width);
                s.y = Math.random() * (Hei-s.height);
                addChild(s);
                shapes.push(s);
            }
            for (var j:int = 0; j < 13; j++) 
            {
                var d:RainDrop = new RainDrop();
                d.x = Math.random() * Wid;
                d.y = Math.random() * Hei;
                shapes.push(d);
                addChild(d);
                
            }
            stage.quality = StageQuality.LOW;
            addEventListener(Event.ENTER_FRAME, onEnter);
            stage.addEventListener(MouseEvent.CLICK, onClick);
        }
        
        private function onClick(e:MouseEvent):void 
        {
            clickCount += 1;
            back.graphics.clear();
            if (clickCount % 2 == 1) {
                back.graphics.beginFill(0x000000);
            }else {
                back.graphics.beginFill(0xffffff);
            }
            back.graphics.drawRect(0, 0, Wid, Hei);
            
            for each(var a:AbstractRain in shapes)
            {
                if(a is RainDrop){
                    if (a.blendMode == BlendMode.DIFFERENCE)
                    {
                                                //a.blendMode = (clickCount % 2 == 1)? BlendMode.SUBTRACT:BlendMode.ADD;
                    }else if(a.blendMode == BlendMode.ADD){
                        a.blendMode = BlendMode.SUBTRACT;
                    }else{
                                                a.blendMode = BlendMode.ADD;
                                        }
                }
            }
        }
        
        private function onEnter(e:Event):void 
        {
            for each(var s:AbstractRain in shapes)
            {
                s.update();
            }
        }
    }    
}

const Wid:int = 465;
const Hei:int = 465;


import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.BlendMode;
import flash.display.Shape;
import flash.geom.Matrix;
import flash.geom.Point;
class AbstractRain extends Bitmap
{
    internal var bd:BitmapData;
    internal var speed:Point;

    public function update():void {
        
    }
    
}
class RainDrop extends AbstractRain
{
    public function RainDrop()
    {
        speed = new Point((Math.random()-0.5), 1.5 + Math.random()*3 );

        var sh:Shape = new Shape();
        
        const Size:int = 5+Math.random()*20;
        
        var color:uint = 0xffffff;
        
        this.blendMode = (Math.random() > 0.5)? BlendMode.DIFFERENCE: BlendMode.ADD;
        

        sh.graphics.beginFill(color);
        
        sh.graphics.moveTo(0, -Size*2.1);
        sh.graphics.curveTo(Size / 1.7, -Size / 3,  Size / 2, 0 );
        sh.graphics.curveTo( 0, Size/1.0,            -Size / 2, 0);
        sh.graphics.curveTo( -Size / 1.7, -Size / 3,    0, -Size * 2.1);
        
        bd = new BitmapData(sh.width, sh.height*2,true, 0x00000000);
        bd.draw(sh, new Matrix(1, 0, 0, 1, sh.width/2, sh.height),null, null, null, true);
        this.bitmapData = bd;
        sh.graphics.clear();
    }
    override public function update():void
    {
        this.x += speed.x;
        this.y += speed.y;
        if (this.y > Hei + this.height) this.y = -this.height;
        if (this.x > Wid + this.width) this.x = -this.width;
        if (this.x < -this.width) this.x = Wid + this.width;
    }
}
class RainCircle extends AbstractRain
{
    public function RainCircle()
    {
        super();
        const Num:int = int(Math.random() * 6) + 3;
        const NormalSize:Number = Num * 1 + Math.random() * 4.5 *Num;
        speed = new Point(1*(Math.random()-0.5), 1.5*(Math.random() - 0.5));
        
        this.blendMode = BlendMode.DIFFERENCE;
        var sh:Shape = new Shape();
        for (var i:int = Num; i > 0; i--) 
        {
            if ( (i % 2) == 1) sh.graphics.beginFill(0xffffff);
            else sh.graphics.beginFill(0x000000);
            sh.graphics.drawCircle(0, 0, (Math.sqrt(i) * (1 + Math.random() * 0.1) * NormalSize*(1+Math.random()*0.0) ));
        }
        
        bd = new BitmapData(sh.width, sh.height, true, 0x00000000);
        bd.draw(sh, new Matrix(1, 0, 0, 1, sh.width/2, sh.height/2),null, null, null, true);
        this.bitmapData = bd;
        sh.graphics.clear();
        
    }

    override public function update():void
    {
        this.x += speed.x;
        this.y += speed.y;
        if (this.y > Hei - this.height) speed.y *= -1; this.y += speed.y
        if (this.y < 0) speed.y *= -1; this.y += speed.y;

        if (this.x > Wid - this.width) speed.x *= -1; this.x += speed.x;
        if (this.x < 0) speed.x *= -1; this.x += speed.x;
        
        
        
    }
}