VMD-L Mailing List

From: Paul Grayson (pgrayson_at_ks.uiuc.edu)
Date: Fri Aug 30 2002 - 09:59:54 CDT

> OK, I have checked it, and see that right now there is a uniform color
> definition via 'graphics $graphicsmol color yellow'. So where would I
> be able to attribute a color to a given point/triangle ? I guess somewhere
> in the procedure hull_surface, but I don't really know what to change.

Okay, first, next to the line in lipid_surface

    set coords [ $heads get {x y z} ]

you should also set up an array of the color values you want, like
this -

    set colors [ $heads get beta ]

Then, next to

    lappend triangles "\"$coords0\" \"$coords1\" \"$coords2\""

you should also build up a list of color values that corresponds to
the list of triangles - probably the average of the values at the
three vertices is fine.

The last line of code in the script draws the triangles using the
lists generated above. Add a line right before that that uses your
corresponding color list to set the color each time. Does that make
sense?

> OK, that is one kind of work-around. I guess my real problem is that for
> the surface I am looking at, I need several normals depending on where I
> am on the surface.

Oh, now I'm wondering if you really want to be using the lipid_surface
script. lipid_surface is really only applicable to lipid membranes -
did you try out the more general 3d_delaunay_surface?

Both of these scripts should use correct normals - that's why I use
the "trinorm" graphics function instead of "triangle". You should be
able to extract the normal information from the script right there.

-Paul