Selecting a visual

OpenGL OpenGL: Advanced Coding
1

Here’s a simple question.
Let’s say my utmost concern is speed.

Is there any point to selecting an OpenGL visual, that is identical to the one I’m already using, except it has 0 stencil buffer bits?

Does this buy me either:

  1. Less Video memory used
  2. Faster FSAA or AF

While I’m at it, if I switched from RGBA of 8880 to 5650, would that make any difference?

Thanks,
TM

2

Well at least those things will free some video memory. Don’t know about the speed, I don’t think stencil buffer affects it.

-Ilkka

3

With and without stencil buffer might not make a difference, because typically the depth buffer is stored interleaved with stencil, so you pay for the bandwidth no matter what (24:8 bit words).

Going from 8880 to 5650 would cut your framebuffer bandwidth in half, and would lead to some speed increase if you’re framebuffer fill bound.

The best way to answer these questions for your own case is to profile your own code, doing it one way or the other.