I'v read <<OpenGL Programming Guide, Sixth Edition>>, especially, Chapter 12: Evaluators and NURBS. Everything is well until I try the examples of the GLU NURBS Interface, when the program doesn't passed for the gl/glu.h doesn't include the macro GLU_NURBS_MODE. So I wonder the version of my OpenGL system is low, because my OS is Windows XP, the version is only 1.1 that Windows OS only supported. I want to get 2.1 version of OpenGL on Windows OS or other way that NURBS can be rendered and tessellated, Could You Help me, please? Waiting for your reply.