VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Tue Sep 30 2003 - 10:04:21 CDT

Hi,
  VMD's Display->Antialiasing checkbox enables or disables OpenGL
multisample antialiasing on-the-fly from within the program, but this
feature depends on the video driver configuration etc. If you have the
NVidia __GL_FSAA_MODE variable set, this overrides VMD's ability to turn
antialiasing on and off. There's no vendor-independent way to specify
what antialiasing mode is used, which is why NVidia chose to do it with
their own set of environment variables. In summary, you need to be
sure that you've setup your OpenGL drivers and any related variables
appropriately since they can have tremendous impact on the performance
and reliability of VMD.

Thanks,
  John Stone
  vmd_at_ks.uiuc.edu

On Tue, Sep 30, 2003 at 11:30:48AM -0300, Alan Wilter Sousa da Silva wrote:
> Hi List!
>
> Hi John Stone!
>
> About my problem in getting messing images with snapshot I have to say
> that I found out a solution. It's basically what you point out.
>
> Changing the antialising nvidia driver parameter does the job.
> For my Gforce2 I have to do:
>
> export __GL_FSAA_MODE=3
>
> then
> vmd
>
> Surely I can insert that line in vmd startup script, right?
> BTW, VMD has a proper option for changing antialising?
>
> Thank you very much.
>
> PS: Follows text grabbed from nvidia docs.
>
> (app-e) APPENDIX E: OPENGL ENVIRONMENT VARIABLE SETTINGS
> __________________________________________________________________________
>
> FULL SCENE ANTI-ALIASING
>
> Anti-aliasing is a technique used to smooth the edges of objects in a
> scene to reduce the jagged "stairstep" effect that sometimes appears.
> Full scene anti-aliasing is supported on GeForce or newer hardware.
> By setting the appropriate environment variable, you can enable full
> scene anti-aliasing in any OpenGL application on these GPUs.
>
> Several anti-aliasing methods are available and you can select between
> them by setting the __GL_FSAA_MODE environment variable appropriately.
> Note that increasing the number of samples taken during FSAA rendering
> may decrease performance.
>
> The following tables describe the possible values for __GL_FSAA_MODE
> and their effect on various NVIDIA GPUs.
>
> __GL_FSAA_MODE GeForce, GeForce2, Quadro, and Quadro2 Pro
> -----------------------------------------------------------------------
> 0 FSAA disabled
> 1 FSAA disabled
> 2 FSAA disabled
> 3 1.5 x 1.5 Supersampling
> 4 2 x 2 Supersampling
> 5 FSAA disabled
>
>
> __GL_FSAA_MODE GeForce4 MX, GeForce4 4xx Go, Quadro4 380,550,580 XGL,
> and Quadro4 NVS
> -----------------------------------------------------------------------
> 0 FSAA disabled
> 1 2x Bilinear Multisampling
> 2 2x Quincunx Multisampling
> 3 FSAA disabled
> 4 2 x 2 Supersampling
> 5 FSAA disabled
>
>
> __GL_FSAA_MODE GeForce3, Quadro DCC, GeForce4 Ti, GeForce4 4200 Go,
> and Quadro4 700,750,780,900,980 XGL
> -----------------------------------------------------------------------
> 0 FSAA disabled
> 1 2x Bilinear Multisampling
> 2 2x Quincunx Multisampling
> 3 FSAA disabled
> 4 4x Bilinear Multisampling
> 5 4x Gaussian Multisampling
>
> __GL_FSAA_MODE GeForce FX, Quadro FX
> -----------------------------------------------------------------------
> 0 FSAA disabled
> 1 2x Bilinear Multisampling
> 2 2x Quincunx Multisampling
> 3 FSAA disabled
> 4 4x Bilinear Multisampling
> 5 4x Gaussian Multisampling
>
> NOTE: 2x Bilinear Multisampling by 4x Supersampling and 4x Bilinear
> Multisampling by 4x Supersampling are not available when using UBB.
>
> --------------------------
> Alan Wilter Sousa da Silva
> --------------------------
> B.Sc. - Dep. Física - UFPA
> M.Sc. - Dep. Física - PUC/RJ
> D.Sc. - IBCCF/UFRJ
> Bolsista Pesquisador LAC-INPE
> São José dos Campos (SP), Brasil
> www.lac.inpe.br/~alan 

-- 
NIH Resource for Macromolecular Modeling and Bioinformatics
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