Performance question

OpenGL OpenGL: Advanced Coding
41

Well, I think I know what the problem was, but I can’t go into much detail.

GeForce hardware supports polygon mode directly and completely in hardware. But there are other things that can slow you down that you may have been hitting.

I can’t specify any further than that because to do so would require saying far too much about specific HW and driver details.

I strongly recommend that you do NOT use polygon mode. It’s inefficient even for drawing a wireframe – each line gets drawn twice. If you do use it, different front and back modes is a good way of asking for trouble. In fact, supporting a different mode for front and back was a feature OpenGL should probably have never included.

We do not, in general, try to optimize for stupid applications. So if you tell us to use a different front and back polygon mode, we won’t look at whether CULL_FACE is enabled. You should just be using the same mode for both faces.

  • Matt
42

> I can’t specify any further than that
> because to do so would require saying far
> too much about specific HW and driver
> details.

Aw, c’mon, I live for that kind of dirt!

I can guess, but the details become so
blurry when I do that.

43

Nope, this kind of dirt requires large bribes. In cash, preferably.

No, if you want dirt on our products, you’ll have to ask about something obsolete, like the RIVA 128 (which is before my time at NVIDIA, anyway). I will freely admit how many aspects of that product sucked.

[But it was the right thing for the time.]

  • Matt