Dave Martin wrote:

On Monday 24 Jan 2005 17:50, Jim Wilson wrote:

Erik Hofman said:

Dave Martin wrote:

On Monday 24 Jan 2005 14:01, Oliver C. wrote:

I assume that this feature is not supported by the hardware on the
consumer video cards.
So OpenGL falls back to software mode.
That's why we get 1-3 fps here.

Well, thats interesting; would that also explain why the normal 'point'
lighting has such a crippling effect on the frame-rate?

To be honest, I don't exactly know why it has this effect on framerate
(or why it isn't supported very well).

An alternative might be to use pentagonal vertex-fans and alpha blending
which supposedly should perform quite well on all modern hardware.

That might work quite well. I've kind of wondered myself what the deal is.
It does not seem logical that adding that property should cause the driver
to drop into software rendering. It ought to just ignore it.

The opengl interface itself (for a variety of good reasons) doesn't provide you a way to directly tell if something is implimented in hardware or software. Note that this isn't dropping your whole card into software rendering mode, it's just the specific things that aren't supported in hardware need to be done in software. There are two sides to the issue of having the api tell you whats done in hardware vs. software. Believe me, it's been debated by a lot smarter people than we have here. :-) OpenGL has chosen a certain way to do it (for valid reasons) so we need to make the best of it.



Curtis Olson        http://www.flightgear.org/~curt
HumanFIRST Program  http://www.humanfirst.umn.edu/
FlightGear Project  http://www.flightgear.org
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