package
  {
          import flash.display.Sprite;
          import flash.display.StageAlign;
          import flash.display.StageScaleMode;
          import flash.events.Event;
          
          public class @ax-animation-ch06-Removal extends Sprite
          {
                  private var count:int = 20;
                  private var balls:Array;
                  
                  
                  public function @ax-animation-ch06-Removal()
                  {
                          init();
                  }
                  
                  private function init():void
                  {
                          stage.scaleMode = StageScaleMode.NO_SCALE;
                          stage.align=StageAlign.TOP_LEFT;
                          balls = new Array();
                          for(var i:int = 0; i < count; i++)
                          {
                                  var ball:animation_ch06_Ball = new animation_ch06_Ball(10);
                                  ball.x = Math.random() * stage.stageWidth;
                                  ball.y = Math.random() * stage.stageHeight;
                                  ball.vx = Math.random() * 2 - 1;
                                  ball.vy = Math.random() * 2 - 1;
                                  addChild(ball);
                                  balls.push(ball);
                          }
                          addEventListener(Event.ENTER_FRAME, onEnterFrame);
                  }
                  
                  private function onEnterFrame(event:Event):void
                  {
                          for(var i:Number = balls.length - 1; i > 0; i--)
                          {
                                  var ball:animation_ch06_Ball = animation_ch06_Ball(balls[i]);
                                  ball.x += ball.vx;
                                  ball.y += ball.vy;
                                  if(ball.x - ball.radius > stage.stageWidth ||
                                     ball.x + ball.radius < 0 ||
                                     ball.y - ball.radius > stage.stageHeight ||
                                     ball.y + ball.radius < 0)
                                  {
                                          removeChild(ball);
                                          balls.splice(i, 1);
                                          if(balls.length <= 0)
                                          {
                                                  removeEventListener(Event.ENTER_FRAME, onEnterFrame);
                                          }
                                  }
  
                          }
                  }
          }
  }