[PyMOL] nVidia OpenGL Environment Variable

[Albion B. <ba...@ms...>]

It occured to me that something I use daily with Pymol might not have  
been discussed on this list. If it has, or is documented elsewhere on  
the Pymol webpage, or Wiki, let me know, and disregard this e-mail.

If you have a modern nVidia graphics card (GeForce or newer), and you  
are running it under linux with nVidia's drivers, then this will  
apply to you.

There is an environment variable that can be set to enable realtime  
anti-aliasing. The difference in the rendering quality during active  
use (not in the ray trace mode) is significant. This may degrade  
performance on some cards because there is overhead, but nVidia  
provides different values for the environment variable that use more  
or less GPU time, and therefore can be tuned for the best quality/ 
performance ratio. I have a nVidia 6800GT and I don't see a  
difference in performance with this feature enabled. The key  
environment variable that should be set prior to launching Pymol  
would be as follows

setenv __GL_FSAA_MODE N

where N is a number that corresponds to both your graphics card type,  
and the amount and type of anti-aliasing you want to enable. For  
instance my card supports the following values of N

0 	FSAA disabled
1 	2x Bilinear Multisampling
2 	2x Quincunx Multisampling
3 	FSAA disabled
4 	4x Bilinear Multisampling
5 	4x Gaussian Multisampling
6 	2x Bilinear Multisampling by 4x Supersampling
7 	4x Bilinear Multisampling by 4x Supersampling
8 	4x Bilinear Multisampling by 2x Supersampling

I believe that these features are disabled by default (and effective  
value of 0). I use a value of 7 on my 6800GT (3.2GHz Intel P4 system).

This option is well documented, along with anisotropic texture  
filtering in the driver README on the nVidia website under "OpenGL  
Environment Variable Settings".

Again, you will have to have a properly running nVidia driver under  
Linux, and a nVidia GeForce or better graphics card to enable this  
feature. I have not to date been able to get this to work under Mac  
OS X, and don't believe it is actually supported at this time. If it  
is, and you know how to configure it, please let me know.

Cheers,

Albion