VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Tue Mar 30 2004 - 11:28:00 CST

Marc,
  As far as I know such a feature never existed in VMD, though
it would not be too difficult to write one. I assume that what
you're thinking of is a feature that would draw a regularly spaced
grid on the display, so that when you view a structure in an
orthographic projection, you could easily visually estimate distances
by reading the "ruler" while rotating/translating/zooming your
structure, right? For an orthographic projection, it would be simple
since the 'ruler' could be placed at any depth as long as it was
perpendicular to the view direction.

To be usable in a perspective projection it would have to be implemented
as a plane that could be positioned within the scene, which is somewhat
unwieldy, but would work. It could also be auto-oriented to be perpendicular
to the view direction, but the depth would have to be user selectable since
the perspective distortion would make it unusable for measurements otherwise.
I assume that the "ruler" would be obscured by molecular geometry when viewed
in perspective, since you'd only want to compare against geometry at the
same depth. In orthographic you could force the ruler to be drawn on top
of all geometry since its equally accurate at all depths.

Would other people find this useful? Other ideas?

You could implement most of this as a simple Tcl script via the
'draw' commands, but a robust/efficient/usable implementation
would probably require writing C code I suspect.

  John Stone
  vmd_at_ks.uiuc.edu

On Mon, Mar 29, 2004 at 10:44:03PM +0200, Marc Baaden wrote:
>
> Hi,
>
> I think I do remember - from the very early days of VMD - that
> there was an option to display a kind of measuring grid with
> fixed distances (I think 10x10 times 1 A) in order to estimate
> distances "geometrically".
>
> Did this option exist .. and does it still exist ? (I did not
> find anything in the user guide)
>
> Thanks in advance,
> Marc Baaden
>
> --
> Dr. Marc Baaden - Institut de Biologie Physico-Chimique, Paris
> mailto:baaden_at_smplinux.de - http://www.marc-baaden.de
> FAX: +49 697912 39550 - Tel: +33 15841 5176 ou +33 609 843217
> 

-- 
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