What i think to be most interesting, is that the ati drivers initially have that much problems. I mean how can it be that they have so much problems delivering bug free drivers.
JC didn’t mention the number of bugs he found and where, with the drivers, but it seemd there weren’t less.
What about you guys here with radeon cards, have you experienced any problems using the ati-extensions ?
Or is JC using features nobody else from us even thought about. I haven’t read any thread here around describing serious problems with the radeon.
I for my self can’t test this, cause i only own GeForce Cards.
It’s interesting that John Carmack is suffering with z buffer invariance between passes when he switches between normal rendering and vertex programming on NVIDIA. I wonder if this is beyond the scope of glPolygonOffset to fix or if a reliable working glPolygonOffset implementation would solve the problem.
Well Carmack did say that NVIDIA is supposed to make a driver fix or something that will let us use vertex programs and fixed functions in the same pass. I sure hope so, that problem caused me a lot of grief not too long ago. Also from what JC was saying about the ATi pixel shader stuff, it actually made me wish i had a radeon. The ability to read from a texture twice sounds darn cool. Would it be possible to add this kind of support for the geforce 3 and 4Ti cards in the drivers? Or would that have to be a hardware change? Unfortuantly i know the ability to have 6 texture units would have to be a hardware change, too bad.
Also while we are on the topic of carmack discussing the two cards (ati and nvidia) i found that it was kind of wierd that the ati cards support 2 nvidia extensions yet the nvidia cards do not support any ati extensions. What is up with that? I think it would be cool for nvidia to support all ati extensions and ati to support all nvidia extensions. But i dont think that would be possible since both chipsets are very different. That would make a larger die prolly and make the chips cost a hell of a lot more. O well, we still can dream cant we?
This is a complex issue. A reasonable rule of thumb is that both NVIDIA and ATI will do what’s in their own interests. ATI & NVIDIA are not in the same position so their actions are different, but I wouldn’t put it down to altruism. There may also be other issues we never see like I.P. ownership. Personally I think it’s in both their interests to work on common API extensions because it will drive high end sales. The biggest obstacle to high end penetration is advanced feature support in games and the biggest obstacle to advanced feature support is a lack of easy to use, shared vendor API extensions for those features.
[This message has been edited by dorbie (edited 02-11-2002).]
> What about you guys here with radeon cards, have you experienced any problems using the ati-extensions ?
Yeah, tons of problems. At a time i was thinking of simply switching back to my Geforce 2, but after reinstalling the drivers 4 times and reinstalled Win2k, i finally got ride of the (main) bugs. To give you an example, the wireframe mode with texture mapping was randomly crashing my application.
“8:50 pm addendum: Mark Kilgard at Nvidia said that the current drivers already
support the vertex program option to be invarint with the fixed function path,
and that it turned out to be one instruction FASTER, not slower.”
Originally posted by Lars:
[b]What i think to be most interesting, is that the ati drivers initially have that much problems. I mean how can it be that they have so much problems delivering bug free drivers.
JC didn’t mention the number of bugs he found and where, with the drivers, but it seemd there weren’t less.
What about you guys here with radeon cards, have you experienced any problems using the ati-extensions ?
Or is JC using features nobody else from us even thought about. I haven’t read any thread here around describing serious problems with the radeon.
I for my self can’t test this, cause i only own GeForce Cards.
Lars[/b]
I had some problems with my computer freezing with certain vertex shaders on some drivers, but I did away with vertex shaders since they weren’t much use anyway in my project, not sure if it’s been fixed. There were also a problem with glSetFragmentShaderConstantATI() which I was going to report just to find it was solved in the latest drivers before I got to report it. There were a problem with going in and out of fullscreen mode, not a biggie, has been solved. There were a problem with mipmapped cubemaps, which supposedly have been solved but no driver with the fix is available yet, but should be within days.
With the latest driver the only problem that remains for me is the cubemap bug, but it can be worked around temporally by turning mipmapping off.
Does the 8500 support VAR? Or have its own version of VAR? (is that what ‘vertex objects’ are in carmacks article?)
I’d be lost without VAR, it’s really given my project a boost.
I tried an 8500 a few months ago, but the drivers were so bugged that I didn’t have the time to wait for their updated drivers. I was also getting worse frame rates on it than the geforce2 gts, when I finally got it running an opengl app.
Or have its own version of VAR? (is that what ‘vertex objects’ are in carmacks article?)
yes, and it’s much better than VAR, you don’t have to manage and synchronize the AGP memory.
you just call glNewObjectBufferATI() with a byte size and the pointer to your data, and you have an ID for your data in fast memory.
Then you use glArrayObjectATI() instead of gl*Pointer().
I’d be lost without VAR, it’s really given my project a boost.
GL_ATI_vertex_array_object is fast too
I tried an 8500 a few months ago, but the drivers were so bugged that I didn’t have the time to wait for their updated drivers.
it’s true that the drivers are still bugged, but it’s getting better…
I think it’s Carmack saying that the vertex program he writes with matched Z is one instruction less than his earlier vertex program without matched Z. Maybe it was mjk saying it, but the jist is the same.
[This message has been edited by dorbie (edited 02-12-2002).]