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Hi Randall,<br><br>
I will handle the patch. Yes - this was a known problem that was
(admittedly quite low down) on my "to do" list - thank you for
taking the time to make the fix. <br><br>
You say that "none of the new unstructured volume renderers properly
support Mesa" - have you encountered problems with more than just
the PT mapper? I believe the ray caster works (uses the same code -
structured and unstructured - to display the results), and the ZSweep
mapper uses this code as well. Please let me know if you are having
problems with those classes.<br><br>
Lisa<br><br>
<br><br>
At 09:26 AM 4/4/2006, Randall Hand wrote:<br>
<blockquote type=cite class=cite cite="">(For those of you who've dug
through this already on the vtk-users, I am sorry. Just want to
make sure the right people get their eyeballs on this).<br><br>
I've been trying to do some volume rendering on an in-house dataset and
it's been giving me nothing but trouble. I finally broke down and
wrote a simple driver app to do nothing but volume rendering & save
the result to a PNG on disk, and came to a few surprising
conclusions. Basically, vtkProjectedTetrahedraMapper doesn't work
with mangled mesa. I can remove the "UseMesaClasses" from
the beginning of the code and everything works just fine but it does
throw a window on the screen. Add them back, and all I get is empty
space for outputs. <br><br>
Ok, after alot of digging I found the problem. It seems that none of the
new unstructured volume renderers properly support Mesa. My best guess is
that it was setting up the scene with mangled-mesa contexts, and then the
Volume Rendering was using true OpenGL. Every command probably
returned an error (no GL context), but nothing checks it, so it rendering
blindly & ignorant of what was going on. <br><br>
After alot of work, I managed to apply the same structure as the other
objects to the vtkProjectedTetrahedraMapper successfully. There is now a
vtkProjectedTetrahedraMapper that, with the help of the
vtkVolumeRenderingFactory, can properly instantiate either a
vtkOpenGLProjectedTetrahedraMap<br>
per or a vtkMesaProjectedTetrahedraMapper. >From the testing
I've done here (with the hello-world code shown originally), I've been
able to switch between the two pretty easily and get almost identical
results. There are a few discrepancies, but since this is a
hardware accelerated version it's very susceptible to the fine variations
between how Mesa emulates the hardware and various hardware platforms
actually work. <br><br>
So, who @Kitware do I need to talk to to get this patch back to
mainstream? I plan to file a bug on it, with code attached,
tomorrow morning when I return to the office. This is a little
larger patch that I usually deal with (4 new files, extensive changes to
a few others), so what's the preferred format for a patch this
size? I know there's a command with 'cvs diff' to get
"patch"-style diffs, which seems the best option, but I always
forget it...<br><br>
<br>
-- <br>
Randall Hand<br>
Visualization Scientist, <br>
ERDC-MSRC Vicksburg, MS<br>
Homepage: <a href="http://www.yeraze.com">http://www.yeraze.com</a> <br>
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