package {
          import flash.display.Sprite;
          import flash.display.StageAlign;
          import flash.display.StageScaleMode;
          import flash.events.Event;
          import flash.events.KeyboardEvent;
          import flash.ui.Keyboard;
  
          public class @ax-animation-ch15-Perspective1 extends Sprite
          {
                  private var ball:animation_ch15_Ball;
                  private var xpos:Number = 0;
                  private var ypos:Number = 0;
                  private var zpos:Number = 0;
                  private var fl:Number = 250;
                  private var vpX:Number = stage.stageWidth / 2;
                  private var vpY:Number = stage.stageHeight / 2;
                  
                  public function @ax-animation-ch15-Perspective1()
                  {
                          trace("hello");
                          init();
                  }
                  
                  private function init():void
                  {
                          stage.align = StageAlign.TOP_LEFT;
                          stage.scaleMode = StageScaleMode.NO_SCALE;
                          
                          ball = new animation_ch15_Ball();
                          addChild(ball);
                          addEventListener(Event.ENTER_FRAME, onEnterFrame);
                          stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);
                  }
                  
                  private function onEnterFrame(event:Event):void
                  {
                          xpos = mouseX - vpX;
                          ypos = mouseY - vpY;
                          var scale:Number = fl / (fl + zpos);
                          ball.scaleX = ball.scaleY = scale;
                          ball.x = vpX + xpos * scale;
                          ball.y = vpY + ypos * scale;
                  }
                  
                  private function onKeyDown(event:KeyboardEvent):void
                  {
                          if(event.keyCode == Keyboard.UP)
                          {
                                  zpos += 5;
                          }
                          else if(event.keyCode == Keyboard.DOWN)
                          {
                                  zpos -= 5;
                          }
                  }
          }
  }