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.xpos = Math.random() * 200 - 100;
      ball.ypos = Math.random() * 200 - 100;
      ball.zpos = Math.random() * 200 - 100;
      addChild(ball);
     }
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }
  

    private function onEnterFrame(event:Event):void
    {
     var angleX:Number = (mouseY - vpY) * .001;
     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch15_Ball3D = balls[i];
      rotateX(ball, angleX);
     }
     sortZ();
    }
   

    private function rotateX(ball:animation_ch15_Ball3D, angleX:Number):void
    {
     var cosX:Number = Math.cos(angleX);
     var sinX:Number = Math.sin(angleX);
     
     var y1:Number = ball.ypos * cosX - ball.zpos * sinX;
     var z1:Number = ball.zpos * cosX + ball.ypos * sinX;
     
     ball.ypos = y1;
     ball.zpos = z1;
     
     
     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;
     }
    }
   

    private function sortZ():void
    {
     balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch15_Ball3D = balls[i];
      setChildIndex(ball, i);
     }
    }
   }
  }