On Thursday December 11 2014 12:00:02 xquartz-dev-request@lists.macosforge.org wrote:

However I am concerned about how using GLKit will interact with the X11 GL wrapper libraries. Have those been enhanced to interoperate with GLKit? Thanks in advance for any information. Jack

I think you'll want to use the glu.h found in /opt/X11/include/GL (or /opt/local/include/GL if you installed XQuartz through MacPorts). R.