[Mesa3d-users] Rendering Errors in Software Rasterizer (Normals Swapping?)

[John W. <bit...@gm...>]

Hello Mesa3d-users,

I am encountering different rendering behavior between two seemingly
compatible Linux environments. After about a week of troubleshooting
this, researching Google, mailing list archives, and bug trackers, I
would be most grateful for any assistance from this list. Below are
links to screen-shots and troubleshooting information:

Screenshots of the issue:
http://lh6.ggpht.com/_mTZwuLfG_iE/SvTnUfC0eWI/AAAAAAAAAB0/SUeL9K7CPcU/s800/screenshots.jpeg

Server environment information:
http://docs.google.com/View?id=ddkkm9rx_2fvwmsdpt

Desktop environment information:
http://docs.google.com/View?id=ddkkm9rx_3dgj28nf4

We have a legacy windows application (without source) that we are
adapting to run under wine on a headless Cent OS server to perform
work in batches. We have a custom windows wrapper around this legacy
application to make it scriptable and capture a couple of screen shots
using GDI+ during the batch jobs. This works fine on my Ubuntu
desktop, but on the server it appears that some of the GL polygons
have their normals swapped (I'm not an expert graphics programmer so I
hope I have these terms correct).

On my desktop I have a NVidia 8800GTS. To try and isolate the problem,
I wanted to force my desktop to use the software renderer. For some
unknown reason setting LIBGL_ALWAYS_SOFTWARE=1 has no effect. Instead
I compiled Mesa using the xlib software driver. When using this libGL
version the application continues to work just fine on my desktop.

The server on the other hand, is a managed environment without root
access. The default version of libGL caused the application to crash,
which initially, I thought was due to an older version of Xvfb. After
learning much more about xorg, I came to realize that it was not the
version of Xvfb that made things marginally work, but rather the libGL
version that was built as a result of building Xvfb/Mesa. Now I am
only building Mesa and libXmu on the server and using the older Xvfb.

On the server experiencing the problem, I have set MESA_DEBUG=FP to
try and get some debug information. I also tried to set
LIBGL_DEBUG=verbose but that seems to have no effect on either
machine. Two messages were encountered at various times -only- on the
server:

"Mesa warning: couldn't open libtxc_dxtn.so, software DXTn
compression/decompression unavailable"
and
"Mesa warning: XGetGeometry failed!"


I downloaded the libtxc_dxtn from
http://www.t2-project.org/packages/libtxc-dxtn.html but that did not
seem to fix the problem. However the debug message changed to:

"Mesa warning: software DXTn compression/decompression available"


Overall these two machines are
* Using the same version of Mesa
* Both using software rendering
* Both using the same version of wine

Which leads me to believe this must be a subtle dependency problem,
either at runtime or build time. At this point though, I would have no
idea what could affect the rendering in such a way.

Any suggestions would be greatly appreciated.

Thank you,
John