VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Tue Dec 15 2009 - 15:20:01 CST

Rich,
  Can you send me the VMD startup messages that get printed on the
text console when you're remote displaying on one of the machines
that flickers? Whether you render with Mesa or some other OpenGL
shouldn't have much effect since the rendering should be done on
the local Mac display and not on the remote machine, and in particular
since the glXSwapBuffers() call will be handled entirely on the Mac
side and not by the remote machine. So the results you got with your
Mesa test don't surprise me at present. The bugs in the ATI drivers
have historically affected only the Linux platform, and not MacOS X
or Windows, so I don't expect this has much to do with the graphics
chipset if you only see this behavior when using a remote X11
connection. If you saw the same flickering behavior on a locally
displayed VMD session, then I would be more apt to question the
ATI driver on the Mac. Send me those VMD startup messages on
the afflicted machines, and I'll ponder what might be causing this
other than some sort of bug on the MacOS X X11/GLX server side.

Cheers,
  John Stone
  vmd_at_ks.uiuc.edu

On Tue, Dec 15, 2009 at 01:03:07PM -0800, Rich Cook wrote:
> I'm wondering if folks here can help me troubleshoot this issue.
>
> We have VMD installed on our large computer clusters and users like to
> visualize their data and display back to their desktops. This is more
> convenient than moving the data.
>
> A few of my users are having flickering issues with VMD on their Mac
> laptops. The symptoms: VMD runs normally, but the screen flickers
> between a garbage image, mostly white, and the correct display. This
> makes VMD unusable for them in the way they'd like to be using it.
>
> They are running Mac OS X 10.5.8, using Apple's X11 (X.org) version
> 2.1.6 or the newer XQuartz 2.4.0 from
> http://xquartz.macosforge.org/trac/wiki and using ATI graphics cards
> (models 2600 and 4780). I have read "out there" that there are ATI issues
> with VMD. True?
>
> This problem exists on three different Mac laptops we've tested here.
> I don't have any problems displaying to my mac in my office, using
> 10.5.8 and XQuarts 2.4.0 on an intel mac with nVidia GeForce 7300
> card. They do not have any problem when running VMD on their desktop,
> only when displaying back. I suspected GLX at first, it looked like
> something was up with glSwapBuffers. To test this, I tried setting
> LD_LIBRARY_PATH on the remote machine so that VMD loads OS Mesa and
> thus does software rendering, but this surprisingly does not eliminate
> the flicker.
>
> How to proceed to get more information? I can run in debug mode, but
> don't know what to look for. I tried changing graphics settings in
> the menu, but none made any difference.
>
> thanks!
> /* A function that takes a single integer argument and returns
> a pointer to a function that takes two integer arguments and
> returns a floating-point number. */
> float (*func2(int a))(int, int);
> Rich Cook
> rcook_at_llnl.gov
>
>
> 

-- 
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