How to draw bounded b-spline surface in OpenGL?

OpenGL OpenGL: Basic Coding
1

I want to draw a bounded b-spline surface with 26 b-spline boundary curves.

[ATTACH=CONFIG]1272[/ATTACH]

I can draw b-spline surface (without any boundary) in OpenGL，but it is too difficult for me to draw surface and fit the boundary curves.

Any suggestions or ideas are appreciated.

PS: The Files is a sample in .stp format