On Mon, Jul 08, 2002 at 10:52:51AM +0100, Keith Whitwell wrote: > > >>This sounds like Z-buffer fighting. If you draw the same triangle twice > >>with exactly the same vertices you'd expect that the same Z values would > >>be generated for each fragment. But the OpenGL spec doesn't require that > >>to be true, depending on particular state changes between passes. (See > >>the OpenGL spec appendices). > >> > >>If the first triangle is drawn in hardware but the second is drawn with > >>software (or vice versa) you almost never get exactly the same > >>rasterization results. I've also seen cards which will do both passes > >>in hardware but still produce different Z values. > >> > >>glPolygonOffset() is the usual solution to this problem and its up to > >>the application programmer to know when to use it. > >> > >>Strictly speaking, the gloss demo should use glPolygonOffset() for > >>the second rendering pass. But it doesn't because I was lazy when I > >>wrote the demo. > >> > >>So, if my hypothesis is correct, this is an application problem. > >> > > > >Ok, I'll investigate the application to see if it's the problem. > > > >I seem to recall that TuxRacer more or less worked with the 4.2 Radeon > >7500 drivers, but doesn't seem to work with the TCL drivers. This might > >indicate that, eg., one pass is being done with TCL and one with CPU > >transform (and they don't agree)... > > I've seen one case (the red & white parachutes in tuxkart) which are > rendered transparent by the non-tcl driver and opaque by the tcl driver. > If a similar mixup is happening in multipass rendering then it could > account for the artifacts. > > Presumably there are some states where color should be rgba, but we're just > sending the rgb components to hardware. > > How does the problem look if you say 'export RADEON_NO_VTXFMT=t'?
Ok, new screenshots (the no_vtxfmt ones, obviously) are at: http://www.eskimo.com/~elladan/tux/ The extremely bad texture artifacts seem to have gone away - these would be easily explainable as an alpha channel missing. However, the ice problem is still there. It's just not as noticable as before. I could buy that this is an application bug, though. -J ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Oh, it's good to be a geek. http://thinkgeek.com/sf _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
