Mine the Harvest

We provide users with a visualization system with IDL, MatLab, and Visit. X-Forwarding can be painfully slow, and we have found that using NXServer, or Googles open source NeatX equivalent, can provide much faster performance.

However, VisIt would launch when X-Forwarded, but not when using NXClient & NeatX. The only messages were:
…
Running: mdserver2.3.2 -host 127.0.0.1 -port 5601
VisIt's viewer exited abnormally! Aborting the Graphical User Interface. VisIt's developers may be reached via the visit-users mailing list.  Please see:
htttp://visit.llnl.gov/FAQ.html#1

I also found that glxinfo would return:

$ glxinfo
name of display: :826.0
Error: couldn't find RGB GLX visual or fbconfig

Solution:

First, I created an xorg.conf to ensure GLX was actually being loaded. (It turned out this was not required as X was autodetecting everything fine without an explicit xorg.conf, but I include it here as it may be helpful in some cases to have an explicit xorg.conf)

Xorg -configure
(renamed xorg.conf and moved to /etc/X11. Ensured Section “Module” included Load “glx”, etc.)

glxinfo still would not work. I then set the following environmental variable:

export  LIBGL_ALWAYS_INDIRECT=yes

Which allowd glxinfo, glxgears, etc. to work. For more information on this environmental, see:

http://unix.stackexchange.com/questions/1437/what-does-libgl-always-indirect-1-actually-do
https://bugs.launchpad.net/xorg-server/+bug/384001

This could then be made into a Gnome Desktop Launcher:

cat VisIt.desktop
[Desktop Entry]
Version=1.0
Type=Application
Terminal=false
Icon[C]=gnome-panel-launcher
Name[C]=VisIt
Exec=env LIBGL_ALWAYS_INDIRECT=yes /usr/local/visit/bin/visit
Name=VisIt
Icon=/usr/share/icons/visit.jpg
Categories=GNOME;Application;Development;

Perhaps the above may be useful to other VisIt users.