用c++编写的池塘夜雨，用Winmain函数编写界面，显示效果为一滴滴雨滴（短的线段）从上而下降落，降落水面后变成涟漪（椭圆）-Written by c++ pond night rain, the preparation of the interface with Winmain function, display a bit rain (short line segments) from the top down, down, do