Accessing the color buffer

OpenGL OpenGL: Advanced Coding
1

Hello everyone!

Does anybody know if it is possible to access directly OpenGL’s color buffer (for example to do a full scene embossing or some other effect like that)?

With kind regards
pgup

2

The functions you’re looking for are glReadPixels and glWritePixels, check out the definitions in the spec.

3

Sorry, I forgot to say that I like the whole thing in a real time animation. If i remeber right glRead and glWrite are just too slow to do this. Any ideas?

Thanks a lot
pgup

4

yuo mean, you want the animation to have interactive (or, at least, high) frame- rates rather than “real-time”, which means subtly different things. FEH.

cheers,
John

5

yes, ‘high frame-rate’ is the keyword. thanks for the correction.
greets
pgup

6

well i get high framerates using my tnt2 with draw/write pixels. check the nvidia performance faq (valid for most cards )

7

These two functions is generally slow, I mean less fast, because you choose the wrong pixelformat. Go for zed’s advice and read the FAQ.