Æliens

    private function init():void
    {
     stage.align = StageAlign.TOP_LEFT;
     stage.scaleMode = StageScaleMode.NO_SCALE;
     
     balls = new Array();
     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch15_Ball3D = new animation_ch15_Ball3D(15);
      balls.push(ball);
      ball.vx = Math.random() * 10 - 5;
      ball.vy = Math.random() * 10 - 5;
      ball.vz = Math.random() * 10 - 5;
      addChild(ball);
     }
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }
  

    
    private function onEnterFrame(event:Event):void
    {
     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch15_Ball3D = balls[i];
      move(ball);
     }
    }
  

    
    private function move(ball:animation_ch15_Ball3D):void
    {
     var radius:Number =  ball.radius;
     
     ball.xpos += ball.vx;
     ball.ypos += ball.vy;
     ball.zpos += ball.vz;
     
     if(ball.xpos + radius > right)
     {
      ball.xpos = right - radius;
      ball.vx *= -1;
     }
     else if(ball.xpos - radius < left)
     {
      ball.xpos = left + radius;
      ball.vx *= -1;
     }
     if(ball.ypos + radius > bottom)
     {
      ball.ypos = bottom - radius;
      ball.vy *= -1;
     }
     else if(ball.ypos - radius < top)
     {
      ball.ypos = top + radius;
      ball.vy *= -1;
     }
     if(ball.zpos + radius > front)
     {
      ball.zpos = front - radius;
      ball.vz *= -1;
     }
     else if(ball.zpos - radius < back)
     {
      ball.zpos = back + radius;
      ball.vz *= -1;
     }
     
  

     if(ball.zpos > -fl)
     {
      var scale:Number = fl / (fl + ball.zpos);
      ball.scaleX = ball.scaleY = scale;
      ball.x = vpX + ball.xpos * scale;
      ball.y = vpY + ball.ypos * scale;
      ball.visible = true;
     }
     else
     {
      ball.visible = false;
     }
    }
   }
  }