How to retrieve points information on a rendered window?

[purecash]

Say, a window has been created and there have been some points rendered. Which openGL function can I use to get x,y,z,r,g,b values of all the points rendered on that screen? Thank you very much!

[Hlz]

Look at glReadPixels to get colors and depth values. Look at gluUnProject to get back to world-space.

PS. Please don't cross post.