For the application that I’m working w/, I need fast readback capability from both the color and depth buffers of a given context. So far, I’ve been sticking w/ glReadPixels. I was poking around and discovered wglCreate/Save/Restore/DeleteBufferRegionARB.It looks like a good was to take a snapshot of the buffers. What I’m wondering is this: is it possible to directly access the buffers that you’ve stored using this technique? If not, is there another way (faster than glReadPixels)?
No, it is just a nice clean way to save/restore. Faster than glReadPixels would be to keep the in video memory. pbuffers would be better way since you can render to it.
My biggest problem is this: I MUST be able to capture the buffer contents w/o altering the rendering method(s) used, AND the access needs to be post-processed and exported to non-OpenGL processes. If I use video memory, that’s out right?
AFAIK, yes, that is out.
I’m sure some vendors (SGI) have made special functions available for sending the generated GL image to another hardware or API, but I have a lack of knowledge in that area.