Introduction - If you have any usage issues, please Google them yourself
Through the OpenGL primitives, such as triangle, triangle strip, quadrilateral, quadrilateral zone, which can constitute a sphere. Radius control by changing the size of the change by changing the angle can change the size and density of the number of vertices, by calling the callback function, set the mode, you can change the fill state. By calling the function to get the current time can be a function of the amount of time.