实验内容

：(1)理解glut程序框架(2)理解窗口到视区的变换(3)理解OpenGL实现动画的原理(4)添加代码实现中点Bresenham算法画直线(5)添加代码实现改进Bresenham算法画直线(6)添加代码实现圆的绘制（可以适当对框架坐标系进行修改）

-Experimental content

: (1) understand the glut application framework (2) understand the window to viewport transformation (3) understand the OpenGL implementation, the principles of animation (4) add the code to achieve the midpoint of the Bresenham algorithm draw a straight line (5) add the code to achieve improved Bresenham algorithm draw a straight line (6) add code round draw (which can be an appropriate framework coordinate system be modified