From: John Stone (
Date: Fri Mar 09 2007 - 10:10:11 CST

  Ah, I see the issue. Well, you have a choice of either force-enabling
full rendering functionality (and risking crashes due to a number of
known ATI driver bugs that are to my knowledge still not fixed based
on recent reports from others), or using a different machine or a different
video card. If you wish to take your chances with the ATI video driver
and tell VMD to enable all rendering features, you can do this by
setting the environment variable VMDDISABLEATILINUXWORKAROUND, like this:

After setting that environment variable, you should be able to start
VMD again, but without the functionality limitations imposed by default
when an ATI Linux driver is detected. Do not be surprised if you manage
to crash VMD, the X server, or even lockup your machine, as I've seen all
of these situations occur with both the open source and ATI provided
drivers for Linux. Oddly, the same hardware works fine with the ATI
provided Windows driver, so I think this is mainly an issue with their
Linux driver series.

If you're able to use VMD reliably with full features with your ATI
Linux driver I would be very interested to hear about it, as many other
ATI users have encountered stability problems when using the advanced OpenGL
rendering features. Any tips that help others with their ATI drivers
are appreciated.

If you have stability problems when full functionality is enabled I would
report this to ATI on their support forums. If you don't get a response
from them, then it may be time to consider getting a different video card
if working with volumetric data is important to you.

  John Stone

On Fri, Mar 09, 2007 at 04:54:26PM +0100, Pawel Wielgus wrote:
> Thanks for your reply.
> When my VMD starts, one can read:
> Info) ATI Linux driver detected, limiting features to avoid driver bugs.
> Info) OpenGL renderer: MOBILITY RADEON X300 Generic
> Info) GLSL rendering mode is NOT available.
> Info) Textures: 2-D (2048x2048), 3-D (2048x2048x2048), Multitexture (8)
> I really don't know what 'limiting features' mean. What I know for sure
> is that I really had lots of troubles when compiling ATI fglrx drivers.
> And I did it finally only against 2.6.10 kernel. But that's a long story...
> What do you think? Any special features in fglrx configuration needed ?
> Pawel
> John Stone wrote:
> > Pawel,
> > Yes, the VolumeSlice representation has been available for some time
> > and should work fine so long as you have a video card that supports
> > 3-D (volumetric) texturing. You can check this by reading the VMD OpenGL
> > related startup messages. You should see a texturing info line like
> > the one I've pasted below:
> > Info) OpenGL renderer: ZFB, VIS
> > Info) Features: STENCIL MSAA(16) MDE MTX GAS
> > Info) Textures: 2-D (4096x4096), 3-D (512x512x512), Multitexture (4)
> >
> > The important part of that status line is: "3-D (512x512x512)"
> >
> > What video chipset are you using? Have you checked to make sure
> > that you're using the latest video driver available for your hardware?
> >
> > John Stone
> >
> >
> > On Fri, Mar 09, 2007 at 04:27:17PM +0100, Pawel Wielgus wrote:
> >
> >>Dear VMD Users,
> >>
> >>may I ask you a question concerning the visualization of volumetric data?
> >>I have a simple example of density for CH4 (just for graphical testing)
> >>in a Gaussian03 cube format. The volumetric data is read properly, and
> >>using 'Drawing method = Isosurface' I can easily get the density.
> >>
> >>But as only I switch to 'Drawing method = VolumeSlice' everything
> >>disapears. As far as I know the volume slices (along cartesian axis) are
> >>possible with VMD-1.8.5.
> >>
> >>What wrong am I doing ? Should I switch any options on ? Could you give
> >>me any hint?
> >>
> >>
> >>Regards
> >>
> >>
> >>Pawel Wielgus
> >>
> >>
> >
> >

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