flash on 2011-2-22

/**
 * Copyright yama3 ( http://wonderfl.net/user/yama3 )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/7CJa
 */

package {
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.geom.Rectangle;
    import flash.geom.Point;
    
    [SWF(width=465, height=465, backgroundColor=0x000000, frameRate=60)]
    
    public class FlashTest extends Sprite {
        private var NUM:int = 20;
        private var _minDist:Number = 130;
        private var _springAmount:Number = 0.001;
        private var _bounce:Number = -0.8;
        private var _ballArr:Array = [];
        private var _flg:Boolean = true;
        
        public function FlashTest() {
            init();            
        }
        
        public function init():void
        {
            for(var i:int=0; i<NUM; i++) {
                var b:Ball = new Ball(10);
                b.x = stage.stageWidth * Math.random();
                b.y = stage.stageHeight * Math.random();
                b._vx = 3 * Math.random() - 1;
                b._vy = 3 * Math.random() - 1;
                b._mass = 3 * Math.random() + 2;
                addChild(b);
                _ballArr.push(b);
            }
            addEventListener(Event.ENTER_FRAME, enterframeHandler);
            stage.addEventListener(MouseEvent.CLICK, clickcheck);
            clickcheck(null);
        }
        private function clickcheck(e:MouseEvent):void
        {
            if(_flg == false) {
                for(var i:int=0; i<NUM; i++) {
                    var b:Ball = _ballArr[i];
                    b.visible = true;
                }
                _flg = true;
            } else {
                for(var n:int=0; n<NUM; n++) {
                    var B:Ball = _ballArr[n];
                    B.visible = false;
                }
                _flg = false;
            }
        }
        
        private function enterframeHandler(e:Event):void
        {
            graphics.clear();
            
            for(var i:int=0; i<NUM; i++) {
                var b:Ball = _ballArr[i];
                b.x += b._vx;
                b.y += b._vy;
                checkWalls(b);
            }
            for(i=0; i<NUM-1; i++) {
                var b0:Ball = _ballArr[i];
                for(var n:int = i + 1; n < NUM; n++) {
                    var b1:Ball = _ballArr[n];
                    spring(b0, b1);
                }
            }
        }
        
        private function spring(b0:Ball, b1:Ball):void
        {
            var dx:Number = b1.x - b0.x;
            var dy:Number = b1.y - b0.y;
            var dist:Number = Math.sqrt(dx * dx + dy * dy);
            if(dist < _minDist && dist > 10)
            {
                var cx:Number = dx / 2 + b0.x;
                var cy:Number = dy / 2 + b0.y;
                
                graphics.beginFill(0xffffff*Math.random());
                graphics.drawCircle(cx, cy, _minDist/dist*2);
                
                if(_flg == true) {
                    graphics.lineStyle(1, 0xff0000, 0.5);
                    graphics.moveTo(b0.x, b0.y);
                    graphics.lineTo(b1.x, b1.y);
                }
                
                var ax:Number = dx * _springAmount;
                var ay:Number = dy * _springAmount;
                b0._vx += ax / b0._mass;
                b0._vy += ay / b0._mass;
                b1._vx -= ax / b1._mass;
                b1._vy -= ay / b1._mass;
            }
        }
        
        private function checkWalls(b:Ball):void
        {
            if(b.x + b.width/2 > stage.stageWidth) {
                b.x = stage.stageWidth - b.width / 2;
                b._vx *= _bounce;
            } else if(b.x-b.width/2<0) {
                b.x = b.width/2;
                b._vx *= _bounce;
            }
            if(b.y + b.height/2 > stage.stageHeight) {
                b.y = stage.stageHeight - b.height / 2;
                b._vy *= _bounce;
            } else if(b.y - b.height / 2 < 0) {
                b.y = b.height/2;
                b._vy *= _bounce;
            }
        }
    }
}

import flash.display.Sprite;

class Ball extends Sprite
{
    public var _radius:Number;
    private var _color:Number;
    public var _vx:Number = 0;
    public var _vy:Number = 0;
    public var _mass:Number = 1;
    
    public function Ball(radius:Number = 40, color:Number = 0xff0000)
    {
        _radius = radius;
        _color = color;
        init();
    }
    
    public  function init():void
    {
        graphics.beginFill(_color);
        graphics.drawCircle(0,0,_radius);
        graphics.endFill();
    }


}