forked from: forked from: flash on 2011-2-24

/**
 * Copyright fakestar0826 ( http://wonderfl.net/user/fakestar0826 )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/x0y2
 */

// forked from fakestar0826's forked from: flash on 2011-2-24
// forked from fakestar0826's flash on 2011-2-24
package {
    import flash.events.Event;
    import flash.display.Sprite;
    public class FlashTest extends Sprite 
    {
        private var particles:Array;
        private var numParticles:uint = 30;
        
        public function FlashTest() 
        {
            // write as3 code here..
            particles = new Array();
            for(var i:int = 0;i < numParticles;i++)
            {
                var p:Ball = new Ball(5, Math.random() * 0xFFFFFF);
                p.x = Math.random() * stage.stageWidth;
                p.y = Math.random() * stage.stageHeight;
                p.mass = 1;
                addChild(p);
                particles.push(p);
            }

            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        }
        
        private function onEnterFrame(e:Event):void
        {
            for(var i:int = 0;i < numParticles;i++)
            {
                var p:Ball = particles[i];
                p.x += p.vx;
                p.y += p.vy;
            }
            for(i = 0;i < numParticles - 1;i++)
            {
                var p1:Ball = particles[i];
                for(var j:int = i + 1;j < numParticles;j++)
                {
                    var p2:Ball = particles[j];
                    gravitate(p1, p2);
                }

            }
        }
        
        private function gravitate(p1:Ball, p2:Ball):void
        {
            var dx:Number = p1.x - p2.x;
            var dy:Number = p1.y - p2.y;
            var distSQ:Number = dx * dx + dy * dy;
            var dist:Number = Math.sqrt(distSQ);
            var force:Number = p1.mass * p2.mass / distSQ;
            var ax:Number = force * dx / dist;
            var ay:Number = force * dy / dist;
            p1.vx += ax / p1.mass;
            p1.vy += ay / p1.mass;
            p2.vx -= ax / p2.mass;
            p2.vy -= ay / p2.mass;
        }

        
    }
}
import flash.display.Sprite;

class Ball extends Sprite
{
    public var vx:Number = 0;
    public var vy:Number = 0;
    public var mass:Number = 1;
    public var radius:Number = 30
    public var color:uint = 0xFF0000;
    
    public function Ball(r:Number = 10, c:uint = 0xFF0000)
    {
        radius = r;
        color = c;
        
        graphics.beginFill(c);
        graphics.drawCircle(0, 0, r);
        graphics.endFill();
    }

}