[offtopic] screen capture using opengl

[Micha Feigin <michf@post.tau.ac.il>]

Sorry for being off topic, I'll be happy if someone can point me at the right
location to ask this.

I'm trying to figure out how to capture the screen using opengl. I tried
glReadPixels but if I understand correctly it is reading from the current
opengl context (the visible part of the current opengl window) and not the full
screen. Is there a way to make the current opengl context the full screen
instead of an opengl window, or is there another way to do this?

Thanks