I'm learning OpenGL and I want to get a surface with a slight hump in the middle. I'm currently using this code and im not sure how to adjust the ctrl points to make it the way i want. Its currentl...

EDIT: This is a library bug. I reported it to the HOpenGL mail list. I use 9-point rectangular method to represent a circle/ellipse as a NURBS. The points are p1, p2, ..., p9, p9 = p1. They lay a...