private function init():void
    {
     stage.align = StageAlign.TOP_LEFT;
     stage.scaleMode = StageScaleMode.NO_SCALE;
     ball = new animation_ch14_Ball(20);
     ball.vx = 10;
     addChild(ball);
     segments = new Array();
     for(var i:uint = 0; i < numSegments; i++)
     {
      var segment:animation_ch14_Segment = new animation_ch14_Segment(50, 10);
      addChild(segment);
      segments.push(segment);
     }
     segment.x = stage.stageWidth / 2;
     segment.y = stage.stageHeight;
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }