How to find functions when I need?

Recently,I need a function determining the RGB information on a certain pixel.I searched it in my textbook, but I didn’t find it.Of course,I begin to wonder if openGL has such a function.However, I found that the only thing that I can tell is that my textbook didn’t mention all the fucntion of openGL API. My question is, does a complete API document of openGL exist? If it doesn’t,is there a proper handbook?

thanks for help!

blue book

also look at the extensions registry on this site

you are looking for glReadPixels (search google)

Thanks a lot :slight_smile:

And here is the GLUT API :

:slight_smile: gl