//@ package -- nodegarden
package {
 import flash.display.Sprite;
 import flash.display.StageScaleMode;
 import flash.display.StageAlign;
 import flash.events.Event;
 import flash.geom.Point;

 [SWF(backgroundColor=0x000000)]
//@ class
 public class animation_ch12_NodeGarden extends Sprite
 {
  private var particles:Array;
  private var numParticles:uint = 30;
  private var minDist:Number = 100;
  private var springAmount:Number = .001;
  
//@ constructor
  public function animation_ch12_NodeGarden()
  {
   init();
  }
//@ init(s)
  
  private function init():void
  {
   stage.scaleMode = StageScaleMode.NO_SCALE;
   stage.align = StageAlign.TOP_LEFT;
   particles = new Array();
//@ particle(s)
   for(var i:uint = 0; i < numParticles; i++)
   {
    var particle:animation_ch12_Ball = new animation_ch12_Ball(5, 0xffffff);
    particle.x = Math.random() * stage.stageWidth;
    particle.y = Math.random() * stage.stageHeight;
    particle.vx = Math.random() * 6 - 3;
    particle.vy = Math.random() * 6 - 3;
    addChild(particle);
    particles.push(particle);
   }
   
//@ event listener
   addEventListener(Event.ENTER_FRAME, onEnterFrame);
  }

//@ animation / frame(s)
  private function onEnterFrame(event:Event):void
  {  
   for(var i:uint = 0; i < numParticles; i++)
   {
    var particle:animation_ch12_Ball = particles[i];
    particle.x += particle.vx;
    particle.y += particle.vy;
//@ chack/ stage
    if(particle.x > stage.stageWidth)
    {
     particle.x = 0;
    }
    else if(particle.x < 0)
    {
     particle.x = stage.stageWidth;
    }
    if(particle.y > stage.stageHeight)
    {
     particle.y = 0;
    }
    else if(particle.y < 0)
    {
     particle.y = stage.stageHeight;
    }
   }
     
//@ process particle(s)
   for(i=0; i < numParticles - 1; i++)
   {
    var partA:animation_ch12_Ball = particles[i];
    for(var j:uint = i + 1; j < numParticles; j++)
    {
     var partB:animation_ch12_Ball = particles[j];
     spring(partA, partB);
    }
   }
  }
  
//@ spring(s0
  private function spring(partA:animation_ch12_Ball, partB:animation_ch12_Ball):void
  {
   var dx:Number = partB.x - partA.x;
   var dy:Number = partB.y - partA.y;
   var dist:Number = Math.sqrt(dx * dx + dy * dy);
   if(dist < minDist)
   {
    var ax:Number = dx * springAmount;
    var ay:Number = dy * springAmount;
    partA.vx += ax;
    partA.vy += ay;
    partB.vx -= ax;
    partB.vy -= ay;
   }
  }
 }
}