图形学实验，用opengl画圆，实现中点Bresenham算法画直线，实现改进Bresenham算法画直线码，实现具有宽度的图形（线刷子或方刷子）-Graphics experiment, using opengl draw a circle to achieve the midpoint of Bresenham algorithm for drawing a straight line, to achieve improved Bresenham algorithm for drawing

长直导线垂直面上磁场仿真，有可视化的图像，简单明了-Magnetic field perpendicular to the surface of a long straight wire simulation, there is a visual image, plain and simple