Does anyone know if the current drivers for the parhelia support this feature?

[CaineTanathos]

I few days ago I read a rumor about the NV40 that their pipelines could be variable . I know its just a rumor. But then I remembered something about the features about the parhelia.
on this link: parhelia - 36stage_shader

As you can see you can combine 2 pixelshader stages, so you get 10 stages.

For more complex pixelshaders based games this would improve de performance of the parhelia (I think ).

So if anyone knows if this is implemented at the moment, let me/us know.

[TdB]

I always assumed that they used that feature in the reef-demo, because a gf4ti had problems with the shaders while parhelia and r300 based cards didn´t have any trouble. My theory was that the shaders in the demo used more stages than a standard dx8 card could handle.

but thats just a guess....

[CaineTanathos]

yeah but maybe its being hardcoded, like the displacement mapping, so its only for the demo.

[TdB]

if it was hardcoded then it wouldn´t work on r300 cards.
I think they used standard directx 8.1 calls in that demo, since it works so well on the newer radeons.

of course there could be plenty of other reasons why it wouldn´t work on a gf4ti.

[Jon P. Inghram]

Doesn't work 100% on my Radeon 8500 either, it's missing the fog effect on the fish and the caustic lighting effect from the light shining though the water.

[DGhost]

Last I checked the switching between 4x 5 stage pipelines and 2x 10 stage pipelines was handled automatically by the drivers when you execute the shader. It all depended on what ops you were executing and how many instructions the shader had. That being said, it was about a year ago when I was looking at it and I do not have any of the documents here (the computers I used are currently packed up back home awaiting my return).

Caine - yes, it would improve performance. It was one of the things that Matrox banked on - its shader execution was faster than anything out at the time. It didn't need raw fillrate as the next generation of games are gonna be held up by the cards ability to handle pixel shaders. NVidia realized this as well, hence all the major arch changes made for GeForceFX.

However, the biggest problem right now is that it is limited to PS 1.x level shaders. There were so many impovements made to PS2.0 shaders that make them easier to work with (not to mention just plain better) that many developers are targeting PS2.0

RE: reef demo - It used 4 textures in the pixel shaders, something which other cards were iffy on handling correctly. Especially for the way Matrox used them in the reef demo. Newer cards (R300 series, for example) have a much more flexible architecture to allow the sort of things that Matrox did with the Parhelia. Perhaps. In theory you could do that sort of thing with the 8500, but in practice i doubt that it would have worked.

Spppeaking of which. I just noticed that on Matrox's Parhelia Tech sheet (here), Hardware Displacement Mapping is not listed... odd...

[bsdgeek]

Originally posted by DGhost
Spppeaking of which. I just noticed that on Matrox's Parhelia Tech sheet (here), Hardware Displacement Mapping is not listed... odd...

How uncharacteristic of Matrox to omit such a feature!