每隔一定的时间间隔就画出赛道与车，而且赛道有不同的标志，就能显示出车在移动了，如果赛道始终是一样的，即使是不断的画出了赛道和车，也不能看出车在移动。 -At a certain time interval to draw the track and vehicle, and the track has different signs, can display vehicle moving, if the track is always the same, even continue to draw the track and car, can not see the car in the mobile