OpenGL support should be available on OS X

[darkaegisagain]

I was able to build the OpenSubdiv source with OpenGL transform feedback support under OS X, although OS X does not have a complete implementation of OpenGL 4.2 which is required by the current build it has enough features to make this work correctly.

This provides hardware acceleration of OpenGL on OS X and was a simple change in the cmake build system.

You can add me as a contributor and I can make the required changes.

[jtran56]

Filed as internal issue #142046.

[darkaegisagain]

FYI.. I currently work for nVidia and I worked on the OpenGL / OpenCL Framework at Apple for 10 years. Feel free to ask for help, I may know a few things.. 👍

[significant-bit]

+1 interest in maintaining Mac support

[davidgyu]

Yes, indeed! The OpenSubdiv XFB implementation should work on Mac, and it does when OpenSubdiv is using GLEW but GLEW should not be required. We'd welcome a PR to fix to the CMake build. Thanks!