X Programming Ref

Xlib programming Reference:

PDF:     http://www.x.org/archive/X11R7.0/doc/PDF/xlib.pdf

HTML: http://tronche.com/gui/x/xlib/function-index.html

For indirect rendering through X which the softpipe uses, calls to Xlib are in drisw_glx.c module in  src/glx, with the indirection table created when __GLXInitialize is called to initialized GL over X.

Also, an architectural diagram of how VitualGL uses GLX to bind OpenGL rendering context to X windows.

http://en.wikipedia.org/wiki/VirtualGL