We have also included a small OpenGL/GLUT integration sample (Tutorial\OpenGL) based on Nvidia tessellation example (http://developer.download.nvidia.com/SDK/10/opengl/samples.html#tessellation). This is a very minimal sample and it uses a slightly different approach than the D3D9 tutorial. As you can see by comparing tessellation.cpp with tessellation_original.cpp there are only a few lines of code added to the original NVIDIA sample. The main program communicates to GFx through high level call calls such as Init(), ShutDown, AdvanceAndDisplay(), etc. and all the GFx specific implementation code is encapsulated into GFxPlayerImpl class (GFxPlayerGL.cpp).