From: John Stone (
Date: Thu Jul 01 2010 - 10:58:26 CDT

  You can add as many lights as you want to a Tachyon scene.
Normally, you would make the radius of a light 0.0 so it is
not visible within the scene as a sphere. The standard lights
are point light sources, and when adding them to the scene you
would need to make sure that you use the correct world coordinates,
which are different from your molecule's coordinate system.

In addition to simple point lights, you can also add point lights
that implement distance attenuation. I have a simple VMD Tcl script
you can use to add "glow lights" to a VMD scene. This script takes
care of the molecule-to-world coordinate transformations so you can
specify the light positions in the molecule's coordinate system.

I've attached the script so you can try it out.


On Sun, Jun 27, 2010 at 08:27:21PM -0400, Andrew wrote:
> Hi,
> I have some questions about VMD and the Tachyon renderer. The first is,
> besides the 4 directional light sources from infinity that VMD offers, are
> there other light options, e.g. adding point light sources? I tried adding
> RAD 0.2
> COLOR 0.5 0.5 0.5
> to the *.dat file created by the File Render Controls, but the resulting
> "lights" at the set (x y z) positions seemed to just be bright discs of
> specified radius without lighting the immediate objects around the
> lights. Is there a way to make "glowing" materials?
> For the color scales, are user created ones possible? Also, any choosable
> scales using the CMYK color space? Finally, is there a way to apply one
> color scale to one object (molecule) and a different color scale to
> another object (molecule)?
> Thank you for your time!
> Cheers,
> Andrew

NIH Resource for Macromolecular Modeling and Bioinformatics
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