分别采用DDA法、中点画线法和Bresenham画线算法编制直线扫描转换程序。从键盘输入两端点坐标，就能在显示器屏幕上画出对应的线段。-Using the DDA method, in line and stipple painting line algorithm Bresenham line scan conversion process. Keyboard input from the two end points of the coordinates, we can draw in th