一个简单的中点分割直线裁减算法，实现直线在屏幕中的裁剪算法-A simple linear reduction of the mid-point division algorithm in a straight line on the screen clipping algorithm

用OpenGL实现中点Bresenham算法画直线与圆，改进Bresenham算法画直线-The midpoint of the Bresenham algorithm for drawing a straight line and circle, using OpenGL to improve the Bresenham algorithm draw a straight line

北大版计算机图形学算法实现之中点法画线椭圆圆的VC程序(Peking University version of the computer graphics algorithm implementation of point line drawing ellipsoid, round VC program)