这种简单方法利用cleardevice()和delay()函数相互配合，先画一幅图形，让它延迟一个时间，然后清屏，再画另一幅，如此反复，形成动态效果。-This simple method uses cleardevice () and delay () function with each other, first draw a graph, let a time delay, then the screen is cleared, and then draw another one, and so forth, the formation of dynamic effects.