Determine if an procedure or extension is available.
Given a function name, searches for the function (or "procedure", hence "Proc") in internal tables. If the function is found, a pointer to the function is returned. If the function is not found, Zero is returned.
In addition to an internal freeglut table, this function will also consult glX (on X systems) or wgl (on WIN32 and WINCE), if the freeglut tables do not have the requested function. It should return any OpenGL, glX, or wgl function if those functions are available.
Glut Class | Tao.FreeGlut Namespace