If you're using cl-opengl and want to use advanced opengl functionality, at time of writing it helps to know to do:
; N.B. don't use any ext. functions which go through GetProcAddress
; until AFTER an opengl sdl surface exists, presumably there's late binding going on...
(setf cl-opengl-bindings:*gl-get-proc-address* #'sdl-cffi::sdl-gl-get-proc-address)