[PyMOL] RE: stereo 3d with pymol (NVidia cards)

[DeLano, W. <wa...@su...>]

> From: Peter M. Wolanin [mailto:pwo...@Pr...]

> One other thing with pymol and 3D stereo:  on our system, at least, it
> seems as though the on-screen rendering is much faster and smoother in
> stero mode than in regular mode.  Pymol in its usual mode=20
> seem much slower
> than spdbv.  Is there something that needs to be set in order=20
> to use the
> hardware rendering?

This is a defect in all of the nVidia based solutions I've tested, and =
one of the reasons I don't recommend nVidia cards for stereographics.  =
ATI FireGL or Radeon (+XiG) cards work fine as do various cards from =
3DLabs.  Since this is clearly an nVidia chipset/driver specific issue, =
it is troubling that nVidia doesn't offer an appropriate email address =
or forum where we could report these kinds of low-level problems.

The same behavior is seen with their chipsets under Windows or Linux as =
well and with a few other GLUT-based stereo-capable programs (such as O, =
I believe).  If you have enabled the card's stereo capability, then when =
you create a stereo OpenGL context, you only get good performance when =
the program is actually rendering in stereo mode.  None of the other =
stereo graphics cards in this market seem to suffer this limitation.

The workaround for nVidia cards is to run PyMOL in stereo mode at all =
times but to zero out the stereo parameters when you are not actually =
wearing 3D glasses.  You end up drawing two identical images and =
everything looks peachy.

Here is some Python code which you can run on startup in order to get =
better mono performace with stereo-enabled nVidia cards.  The F1 key =
then becomes the stereo toggle.

Save in a ".py" file, such as $HOME/.pymolrc.py

# nvidia.py : NVidia stereo/mono performance workaround
# (put in your .pymolrc.py file or run this .py program manually)

from pymol import cmd

def nvidia_stereo():
   cmd.stereo("on") # always on
   if float(cmd.get_setting_tuple("stereo_angle")[1][0])!=3D0.0:
      cmd.set("stereo_angle",0)
      cmd.set("stereo_shift",0)
      print "nVidia stereo off"
   else:
      cmd.set("stereo_angle",2.1)
      cmd.set("stereo_shift",2)
      print "nVidia stereo on"
           =20
cmd.set_key("F1",nvidia_stereo)

nvidia_stereo()=20

# end of code

Hope this helps,

Warren

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