package {
 import flash.display.Sprite;
 import flash.display.StageAlign;
 import flash.display.StageScaleMode;
 import flash.events.Event;

 public class animation_ch15_RotateY extends Sprite
 {
  private var balls:Array;
  private var numBalls:uint = 50;
  private var fl:Number = 250;
  private var vpX:Number = stage.stageWidth / 2;
  private var vpY:Number = stage.stageHeight / 2;
  
  public function animation_ch15_RotateY()
  {
   init();
  }
//@ init(s)  
  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);
  }
 //@ frame(s) 
  private function onEnterFrame(event:Event):void
  {
   var angleY:Number = (mouseX - vpX) * .001;
   for(var i:uint = 0; i < numBalls; i++)
   {
    var ball:animation_ch15_Ball3D = balls[i];
    rotateY(ball, angleY);
   }
   sortZ();
  }
//@ rotate Y
  
  private function rotateY(ball:animation_ch15_Ball3D, angleY:Number):void
  {
   var cosY:Number = Math.cos(angleY);
   var sinY:Number = Math.sin(angleY);
   
   var x1:Number = ball.xpos * cosY - ball.zpos * sinY;
   var z1:Number = ball.zpos * cosY + ball.xpos * sinY;
   
   ball.xpos = x1;
   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;
   }
  }
 //@ sort Z 
  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);
   }
  }
 }
}