Hello,
I have this problem and I’m trying to solve it using various methods:
- Draw Big/Slow scene
- Save the backbuffer
- Swap
- LOOP at interactive rate :
Restore the back buffer
Draw something fast
Swap
I’ve tryed various methods, but none is successfully working, specially with 2-3 years old hardware. ON my NV GT 220 any method works fast.
- Using AUX buffers and glCopyPixels : it is the fastest method, but it is almost unsupported
- Using PBOs : really really slow on previous generation hardware
- Using glCopyTexImage2D : fast but not fast enought for interactive rates on older hardware.
- FBOs? Probably will end having the same performance of PBOs?
- Any extension to do this?
I’d like to target at least opengl 2.1 .
What should I do to correctly save / restore the backbuffer ? I want to save just RGB, and I don’t want to access the data from the CPU, so the saved image should be resident in VRAM.
Thank you for any advice