if(particle.x > stage.stageWidth)
      {
       particle.x = 0;
      }
      else if(particle.x < 0)
      {
       particle.x = stage.stageWidth;
      }
      if(particle.y > stage.stageHeight)
      {
       particle.y = 0;
      }
      else if(particle.y < 0)
      {
       particle.y = stage.stageHeight;
      }
     }