VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Fri Jan 24 2003 - 14:18:32 CST

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
> ---
> At 11:44 AM 1/24/2003 -0800, DeLano, Warren wrote:
> >PyMOL is similarly tweaked by nVidia's stereo support. The only trivial
> >solution I've found is to leave PyMOL in stereo mode and render both the
> >left and right buffers, even when you want a mono image. You just set the
> >stereo angle and stereo separation to zero -- I bet the same trivial
> >workaround could be applied to VMD.
> >
> >The performance hit is still 50%, but that's a whole lot better than the
> >99% percent hit you get from the software renderer. I don't have access
> >to this hardware myself, so I haven't figured out a more efficient
> >workaround.
> >
> >Cheers,
> >Warren
> >
> >
> >
> >--
> >mailto:warren_at_sunesis.com
> >Warren L. DeLano, Ph.D.
> >Informatics Manager
> >Sunesis Pharmaceuticals, Inc.
> >341 Oyster Point Blvd.
> >S. San Francisco, CA 94080
> >(650)-266-3606 FAX:(650)-266-3501
> >
> >
> >
> >> -----Original Message-----
> >> From: John Stone [mailto:johns_at_ks.uiuc.edu]
> >> Sent: Friday, January 24, 2003 8:20 AM
> >> To: Michael Redmond
> >> Cc: vmd-l_at_ks.uiuc.edu
> >> Subject: Re: Stereo mode on NVidia/Win2000
> >>
> >>
> >>
> >> Dear Michael,
> >> The response you got is accurate. However, this is normal
> >> practice, and
> >> there are no such performance issues on the many many other
> >> cards and drivers
> >> out there. I could produce a list of around 30 other video
> >> boards that
> >> don't have this problem. I can only assume that the NVidia
> >> drivers you're
> >> using "punt" in this particular case and fall back to a
> >> software rendering
> >> operation of some kind?
> >>
> >> Since they (NVidia) don't currently mention this deficiency in their
> >> latest 4191 driver README, I think that they should begin by
> >> documenting
> >> this problem, along with suggested workarounds. I know of
> >> various other
> >> NVidia driver bugs which are also not documented, though I
> >> have reported
> >> them previously.
> >>
> >> If they have a suggestion that doesn't involve creating and destroying
> >> windows on the fly, I'm willing to consider it. I still feel
> >> that this
> >> is a deficiency in their OpenGL implementation since no other platform
> >> I'm aware of has this problem. Page 436 of the OpenGL 1.2
> >> programming guide
> >> specifically covers the expected behavior when the
> >> drawbuffers are set to
> >> GL_FRONT and GL_BACK when running in a stereoscopic visual. Clearly
> >> the intent is that using GL_FRONT and GL_BACK allows one to draw
> >> monoscopic images regardless of the use of a
> >> stereoscopic-capable OpenGL
> >> context. If they disagree, I'd like to know what their rationale is.
> >>
> >> Anyway, if they have any suggestions, let me know. I'm
> >> willing to build
> >> you a special version of VMD to see if it cures the problems
> >> you're having.
> >> I'd still like to see NVidia get serious about documenting
> >> the limitations
> >> of their drivers, both on Windows and on Linux. Right now
> >> its a bit like
> >> walking into a mine field blindfolded. The situation would be greatly
> >> improved if they provided the sort of documentation with their drivers
> >> that vendors like Sun, SGI, and HP have historically given out.
> >> Here's a good example of what they should be shipping with their
> >> driver software:
> >>
> >> http://wwws.sun.com/software/graphics/OpenGL/1.2.3/SolImpPerfG
> >> uide1.2.3.pdf
> >>
> >> If you read Sun's docs, you'll see that they specifically address the
> >> OpenGL operations which can cause software rasterization to occur on
> >> the various graphics boards they sell. Since NVidia doesn't
> >> provide any
> >> docs of this sort with their drivers, we're left wondering why their
> >> cards behave badly in various circumstances, not knowing if its a bug
> >> in their driver, or simply a limitation of the hardware. Many people
> >> would love to see NVidia step up and produce a document of
> >> this quality
> >> to ship with their Windows and Linux drivers. Presently,
> >> they have lots
> >> of example apps on their web site, but they don't address many of the
> >> issues like the stereo performance you're having, nor similar
> >> issues with
> >> enabling multisample antialiasing on high-res windows, etc.
> >>
> >> Anyway, if you want to pass this along to them, that would be helpful.
> >> If they have any suggestions regarding workarounds for the
> >> stereo performance
> >> problem you're having, I'm willing to see if we can implement
> >> them for you.
> >>
> >> John
> >>
> >> On Fri, Jan 24, 2003 at 09:29:55AM -0600, Michael Redmond wrote:
> >> > We have been running VMD with Quadro cards (550XGL and
> >> 900XGL) under
> >> > Windows 2000. We use quad-buffered OpenGL stereo support of
> >> the Detonator
> >> > drivers with shutter glasses (all kinds) or in Clone mode
> >> (with a Geowall
> >> > stereo projection system). It basically works, but we have
> >> a performance
> >> > problem when we start up VMD in default, mono mode. Image
> >> manipulation is
> >> > horrendously slow! However, as soon as we switch to
> >> Crystaleyes stereo,
> >> > performance is great (maybe 30X speedup). Other
> >> applications have similar
> >> > problems in both Windows and Linux.
> >> >
> >> > I have been working with PNY and NVidia folks to address
> >> this and other
> >> > Quadro issues. I got a note back with the following query:
> >> >
> >> > ---
> >> > The performance problem I would guarantee is because they
> >> are using a
> >> > stereo pixel format in mono-mode (i.e. selecting a stereo
> >> pixel format
> >> > and then setting the buffer to back/front not back_left, back_right,
> >> > front_left, front_right). This will cause the driver to drop to a
> >> > software path.
> >> >
> >> > This may in turn be causing the issues with the switching etc.
> >> >
> >> > Do they have control over the application source code?
> >> >
> >> > Could they confirm if they are using mono-mode or not?
> >> >
> >> > ___
> >> >
> >> > At this point, I haven't looked at the source. I am hoping
> >> I can get a
> >> > quick answer here without having to try deciphering source.
> >> >
> >> > If this is the problem, is there a way to address it in
> >> future versions of
> >> > VMD?
> >> >
> >> > Thanks
> >> > Mike Redmond
> >> > Associate Director, eMedia Center
> >> > UW-Madison
> >>
> >> --
> >> 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