VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Fri Jan 24 2003 - 17:58:35 CST

Michael,

On Fri, Jan 24, 2003 at 02:43:16PM -0600, Michael Redmond wrote:
> John,
> I actually do use that command when running scripts, but I usually hadn't
> included it in the .vmdrc unless I was scripting a specific demo with
> Windows (at least my current Windows version of VMD does not read scripts).

You mentioned that your current Windows version of VMD doesn't read scripts,
can you expand on that? It should read scripts just fine. If you need help
with something there, let me know. On windows, rather than a .vmdrc file
however, VMD looks for a "vmdrc" file (no ".") which is stored in the VMD
installation directory rather than in the user's home directory.

> So I know how to do this and, for now, that is a reasonable solution. I can
> probably even script it to come up with 0.0 eye separation, so to get
> stereo, I would just need to increase that.

Yes, you could do that too as per Warren's suggestion.

Interesting about the glasses losing sync. I don't have any specific
suggestion there, hopefully the NVidia staff can offer more ideas on
that specific issue.

By the way, I heard from some others today that the Quadro speed hit
you're having occurs on several other molecular viz programs:
  VMD, PyMol (unpatched anyway), O, Ensight, and others.

It would be interesting if you know of any other programs, if we sent NVidia
a list of the affected programs, maybe they will take the problem more
seriously, apparently other people have known of this Quadro problem
for a while. So far I haven't heard anything back from NVidia today.

Thanks,
  John Stone
  vmd_at_ks.uiuc.edu

> The NVidia Windows drivers have an option to sync to vertical. I have tried
> to set it but to no effect. It turns out that I use the cheap eDimensional
> "in-line" shutter glasses (about $70), and the image shearing initially
> caused them to lose sync (every 12 seconds, there would be 6 "open shutter"
> glitches 2 seconds apart that corresponded to the shearing). eDimensional
> has a resync utility that I assume finds a good sync period and then forces
> the glasses to ignore signals that are outside that period (not sure, but
> that's how I would do it). This clears up the "open shutter" flashing of
> the glasses, but the image shearing is still there. Again, this is on our
> 550XGL card (real cheap stereo at $250 or less). Out 900XGL also exhibits
> shearing, but it is harder to spot (for us, on one periodic shear in the
> top 10% of the screen - can't test with "in-line" glasses because the DVI
> connector/VGA adapter is not compatible with the eDimensional
> dongle/connection).
>
> So, it appears that the NVidia driver recognizes the need to vertical sync
> and then, for some reason, doesn't actually do it. That's my speculation
> anyway...
>
> This problem does not show up with clone mode (not too surprising). In our
> initial tests, it also does not appear to show up under Linux with the same
> shutter glasses. So someone at NVidia knows how to fix it. Interestingly
> enough, other glitches have show up with Linux stereo, though not yet fully
> verified. If you go to full-screen mode in stereo on one of our Linus apps
> (CEI Enliten), one of the buffers gets corrupted. On the Windows side,
> full-screen openGL stereo (not in a window) also messes up. We can't run
> full-screen stereo Cortona as a result.
>
> Lots of gotchas in the NVidia driver and/or hardware implementation still.
> Too bad...
>
> Thanks
> Mike
> ---
> At 02:18 PM 1/24/2003 -0600, John Stone wrote:
>
> >Michael,
> > You can force VMD to go into stereo mode by default by adding this
> >command to your individual .vmdrc (Unix) or vmdrc (Windows), or for all
> >users that run the program by editing the core VMD startup script and
> >adding it to the end:
> > (install dir)/vmd/scripts/vmd/vmdinit.tcl
> >
> >Here's the command to enable stereo:
> > display stereo CrystalEyes
> >
> >You can enable one of the other stereo modes as well by default, choose
> >whichever fits your use the best.
> >
> >Interesing that you mention their screen tearing problem.
> >Do you have the driver set to force syncing to the monitor's vertical
> >retrace/blank? (does their driver do that by itself?)
> >
> >If you do stereo without forcing sync to vertical retrace you will get
> >all kinds of screen tearing. I assume that their driver would do this
> >by default when its running in a stereo mode however.
> >
> >Regarding the "clone mode" stereo. This can be done with any normal
> >stereo capable system with one of the CyViz stereo splitter boxes.
> >They are expensive, but they'll do it generically for any workstation or
> >PC card with stereo outputs. I know that this sort of thing can also be
> >done on some of the high-end Unix systems. As far as PC's though,
> >yeah, NVidia's cards are probably the only ones that will do that
> >presently, at least as far as I know.
> >
> > John Stone
> > vmd_at_ks.uiuc.edu
> >
> >On Fri, Jan 24, 2003 at 01:54:26PM -0600, Michael Redmond wrote:
> >> My workaround in VMD has always been to immediately go to stereo mode
> >after
> >> starting the program. I don't know if there is a command line option to
> >> start in stereo mode. In VMD this isn't a big deal, but some other apps
> >> (Ensight by CEI in our case), it is a hassle to make have scripts
> >include a
> >> stereo command before doing anything else. All operations are slowed by
> >the
> >> mono performance hit because of slow image update speeds.
> >>
> >> The NVidia cards are also giving me problems in shutter glasses mode
> >(only
> >> under Windows at this point) in that the image "shears" at periodic
> >> intervals (6 shears 2 seconds apart followed by stable image for 12
> >> seconds...this with 120Hz refresh and any type of shutter glasses on
> >> 550XGL). It is a noticeable glitch but one that we are living with for
> >now.
> >> Hopefully NVidia will fix it if they first will acknowledge it is an
> >actual
> >> problem (or undocumented feature I guess).
> >>
> >> Since I work with clone mode stereo for dual projector passive stereo
> >> display, the NVidia cards appear to be the only choice. I haven't seen
> >this
> >> feature in other cards yet.
> >>
> >> Thanks for the input. I sent John's message on the the PNY/NVidia folks
> >and
> >> hopefully something will come of it.
> >>
> >> Mike
> >> ---
> >...
> >NIH Resource for Macromolecular Modeling and Bioinformatics
> >Beckman Institute for Advanced Science and Technology
> >University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
> >Email: johns_at_ks.uiuc.edu Phone: 217-244-3349
> > WWW: http://www.ks.uiuc.edu/~johns/ Fax: 217-244-6078 

-- 
NIH Resource for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
Email: johns_at_ks.uiuc.edu                 Phone: 217-244-3349              
  WWW: http://www.ks.uiuc.edu/~johns/      Fax: 217-244-6078