VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Fri Jan 28 2011 - 10:14:26 CST

Hi,
  In addition to what Axel suggested, my latest versions of Tachyon
add a new flag that lets you limit the number of transparent surfaces
it renders, to get an effect more like what you saw in VMD's OpenGL/GLSL
renderings:
  -trans_max_surfaces XX

Try some number between 1 and 5 for your case, that ought to work
reasonably well.

If you want to try this, I've posted the latest test version of Tachyon
in the VMD alpha test directory, as described here:
  http://www.ks.uiuc.edu/Research/vmd/alpha/

Cheers,
  John Stone
  vmd_at_ks.uiuc.edu

On Fri, Jan 28, 2011 at 10:56:06AM -0500, Axel Kohlmeyer wrote:
> 2011/1/28 Ajasja Ljubeti? <ajasja.ljubetic_at_gmail.com>:
> > Dear All,
> > I'm still having trouble rendering highlytransparent(alpha is set to
> > 0.02)spheres in Tachyon or pov-ray.
> > This is a screen shot, tachyon gives this, pov-ray gives this.
> > I'm happy with the screenshot, but I would need a higher resolution for
> > printing.
>
> ajasja,
>
> transparency is a situation where raytracing will
> give you different results than GLSL due to the
> approximations done in OpenGL rendering.
>
> for that kind of visualization you are better off using
> a Surf representation for the transparent part and
> then use one of the materials with angle dependent
> transparency (BlownGlass or GlassBubble). check out:
> http://picasaweb.google.com/lh/photo/-1WEt4u41zSNcZr5nV-cCQ?feat=directlink
> as an example.
>
> cheers,
> axel.
>
> > Best regards,
> > Ajasja
> >
> > 2010/12/8 Ajasja Ljubeti? <ajasja.ljubetic_at_gmail.com>
> >>
> >> Dear all,
> >> I'm having some trouble rendering a scene with multiple transparent
> >> spheres. In VMD the scene is fine, but using Tachyon the transparency is
> >> different.
> >> Since a picture is worth a thousand words i'm also attaching one:)
> >> I also put the trouble.dat online.
> >> Best regards,
> >> Ajasja Ljubeti?,
> >> Young researcher,
> >> Department of solid state physics,
> >> Institute Jo?ef ?tefan,
> >> Ljubljana Slovenia
> >
> >
>
>
>
> --
> Dr. Axel Kohlmeyer
> akohlmey_at_gmail.com http://goo.gl/1wk0
>
> Institute for Computational Molecular Science
> Temple University, Philadelphia PA, USA. 

-- 
NIH Resource for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
Email: johns_at_ks.uiuc.edu                 Phone: 217-244-3349
  WWW: http://www.ks.uiuc.edu/~johns/      Fax: 217-244-6078