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AIRmichael

Multiple render passes causes artefacts on ATI

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Hey, I have a problem with multiple render passes. I use glDepthFunc(GL_LEQUAL);. It seems that it works fine on NVidia cards, but on ATI cards artefacts can be seen. That means lines/dots nearby the camera that vanishes/popups while looking around. How can that be fixed? Greetings, Michael L. [edited by - AIRmichael on October 24, 2003 1:08:56 PM]

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Woooo dude, I think you have the syntax of the function wrong. glBlendFunc takes 2 paramateres for instance: glBlendFunc(GL_SRC_COLOR, GL_ONE). I''m not sure why yours even compiled. Try looking up the syntax in the MSDN library on microsoft''s site or whichever you use, but hey if one parameter works I''d be suprised.

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Known for their poor precision? I think you are very much mistaken. Both ATi and nVidia run at the same precisions (16/32 bit colour, 16/24 bit depth buffer), ATi has 24bit floating point math in fragment programs whilst nVidia has 16bit and 32bit (and is far slower).

I can do multipass rendering just fine on ATi cards, with better results than my previous nVidia card gave. What are your near and far clipping planes set to?

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Just try to use the texture matrix and scroll x or y position by a large number.
Any value above 128 or below -128 should do, but try 10000 to be sure

You''ll get weird lines on an ATI, and magnification seems to fail - but no problem on my gf3.

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Oops sry. My mistake. Looks like i used a vertex prog.

Plz try writing a value > 128 or value < -128 to the output texcoord of a vertex program... That should expose the precision probs.

The ATI card responsible was a Radeon 9000 DDR x86/SSE2 (taken from glGetString(GL_RENDERER)).

[edited by - baskuenen on November 3, 2003 10:29:01 PM]

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Perhaps older cards might have that issue, though Im running a 9800 pro, which is probably why Im not getting the same problems you were getting.

Personally I agree that the pre-r300 cards werent overly great, however you really should try a r300+ card... they are really pretty good. Ive only come across very few issues with my 9800pro, and ATi dev relations have been very helpful and are eager to work with people to isolate bugs.

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quote:
Original post by Maximus
Perhaps older cards might have that issue, though Im running a 9800 pro, which is probably why Im not getting the same problems you were getting.

Personally I agree that the pre-r300 cards werent overly great, however you really should try a r300+ card... they are really pretty good. Ive only come across very few issues with my 9800pro, and ATi dev relations have been very helpful and are eager to work with people to isolate bugs.


Respect for testing Maximus!

I''ve never had a response on mail to GeForce for bugreports. They probably take the bugs (or me) not very serious.
So thats a + for ATI.

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