problem:using OpenGl to interpolate b-splines in a graphical interface

design:This is a GLUT program that allows the user to left click anywhere in the window and a square, 5 pixels on a side, will be placed at that location. After four points are defined a b-spline will be created in yellow on the screen. If the middle button is pressed over a point, that point is deleted. If the right mouse button is held over the point, the point is dragged until the mouse is un-clicked. There may be any number of points over 4 to draw the spline, and any point may be deleted at any time. The window will resize and keep the aspect ratio of the drawing. (cont.)