Re: [Mesa3d-users] rendering artifacts mesa vs hardware

[tom f. <tf...@al...>]

burlen <bur...@gm...> writes:
> Hi Tom, many thanks for responding,
>
> I played with the environment vars you mentioned and I'm seeing a
> whole bunch of the following coming from where VTK puts the camera
> matrix in to the matrix stack. I don't know weather or not to be
> worried.
>
> Mesa: User error: GL_INVALID_OPERATION in glReadBuffer(buffer=0x405)
>
> Breakpoint 2, _mesa_ReadBuffer (buffer=1028) at main/buffers.c:519
> 519        _mesa_readbuffer(ctx, buffer, srcBuffer);

Yeah, I get this error all the time in my current GPU VR pipeline.
That seems to work, so the error is non-critical at least.  Though I do
go behind VTK's back a bit and pull out the rug..  Anyway, if the read
buffer was wrong you're most likely to see *nothing* instead of the
artifacts you're encountering, so I don't think this is the root issue.

I'm still curious if fiddling IceT on/off has an effect, though...

Another option would be to make something in the scene have just
a smidgen of transparency.  That should force ParaView to sort
everything, instead of relying on a painter's alg, and thus it might
workaround the issue.

-tom

> tom fogal wrote:
> > Hi Burlen!  Hope you're doing well.
> >
> > burlen <bur...@gm...> writes:
> >   
> >> Thanks for your help,
> >> It didn't make a difference, but I agree it looks like depth buffer
> >> issue.
> >>     
> >
> > I think you should file a bug, not all the Mesa devs follow this list.
> >
> >   https://bugs.freedesktop.org/
> >
> > A (very unlikely to be enlightening) thing to try is to export:
> >
> >   LIBGL_ALWAYS_SOFTWARE=1
> >   LIBGL_ALWAYS_INDIRECT=1
> >   MESA_DEBUG=1
> >
> > and re-run.  Other than the libtxc warning, any errors you see on your
> > terminal may be relevant.
> >
> >   
> >> Another issue I am seeing in the mesa rendering has to do with
> >> inconsistent choice of which tubes are on top. This occurs in
> >> parallel rendering only so I didn't mention it before. You can see
> >> the inconsistency by comparing the hardware/nvidia and mesa in these
> >> images:
> >>
> >> http://nashi-submaster.ucsd.edu/movies/PV/tube-filter-artifact/mesa-artifa
> cts
> >> -decomp.png
> >> http://nashi-submaster.ucsd.edu/movies/PV/tube-filter-artifact/nvidia-no-a
> rti
> >> facts-decomp.png
> >>     
> >
> > It looks like these are changing per-tile -- you can see the obvious
> > banding along the rightmost streamlines.  Does enabing/disabling IceT
> > in ParaView solve the problem?  I'm guessing that will change how PV
> > does load decomposition as well, but if not you might want to play with
> > those settings.
> >
> > Best,
> >
> > -tom
> >
> >   
> >> Jeff Lee wrote:
> >>     
> >>> looks like a depth buffering issue - what happens when you setenv 
> >>> MESA_GLX_DEPTH_BITS 24?
> >>>
> >>> On Fri, Jan 15, 2010 at 12:22 PM, burlen <bur...@gm... 
> >>> <mailto:bur...@gm...>> wrote:
> >>>
> >>>     I would like to report an issues I see when I replace hardware
> >>>     rendering
> >>>     in my app with mesa. I am new to mesa so I am not sure where the bug
> >>>     lies, in the app or mesa. So I suspect it may be in mesa because
> >>>     hardware rendering works fine , I have doubts because I don't know if
> >>>     the app does anything special when it uses mesa. I hope some one here
> >>>     can say for sure weather or not it's a mesa issue.
> >>>
> >>>     The issue is strong artifacts appear on the surface of rendering
> >>>     tubes.
> >>>     zooming in makes the artifacts recede to the edges of the tubes but
> >>>     never completely go away. Here is an illustration of the artifacts
> >>>     and a
> >>>     hardware rendering that doesn't have the artifacts.
> >>>
> >>>     http://nashi-submaster.ucsd.edu/movies/PV/tube-filter-artifact/mesa-a
> rt
> >>>       
> >> ifacts.png
> >>     
> >>>     http://nashi-submaster.ucsd.edu/movies/PV/tube-filter-artifact/nvidia
> -n
> >>>       
> >> o-artifacts.png
> >>     
> >>>     By the way, I reproduced on two machines with intel and gcc
> >>>     compiler and
> >>>     two mesa version 7.5.1 and 7.7.
> >>>
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