VMD-L Mailing List

From: Eric Smoll (ericsmoll_at_gmail.com)
Date: Thu Oct 16 2014 - 13:01:57 CDT

Hello John,

Unfortunately, large black filled cylinders also refuse to show up with
povray. My issue goes beyond infinitesimal width of a line.
Interesting, when I visualize the bounds of my system with thick blue
"lines" (perhaps they are cylinders) drawn with "pbc box", povray has no
problem rendering this.

Notes on the commands I am using:

I set the color with "graphics top color 16". This shows up as black in my
opengl window.

I draw each cylinder with "graphics top cylinder {# # #} {# # #} radius 0.5
filled yes resolution 100"

I render the image with "render POV3 name.pov povray +W# +H# -Itest.pov
-Otest.png +D +X +A +FN"

Also note that I set the color and draw the cylinders by calling a tcl
function.

Best,
Eric

On Wed, Oct 15, 2014 at 9:25 PM, Eric Smoll <ericsmoll_at_gmail.com> wrote:

> Hello John,
>
> That makes sense. Thank you for the explanation.
>
> Best,
> Eric
>
> On Wed, Oct 15, 2014 at 9:03 PM, John Stone <johns_at_ks.uiuc.edu> wrote:
>
>> Hi,
>> Ray tracers don't like lines or points, because they are
>> infinitesimal objects that don't have a width, and such an
>> object can't ever be hit by a ray... VMD tries to emulate
>> lines and points by drawing very thin cylinders and spheres,
>> but there's a limit to the efficacy of this approach, and in
>> general it is best to draw cylinders and spheres rather than
>> lines and points when working with ray tracers... Lines and
>> points are really only useful in the context of rasterization
>> where they bear some relationship to the pixel grid of the
>> screen...
>>
>> Cheers,
>> John Stone
>> vmd_at_ks.uiuc.edu
>>
>> On Wed, Oct 15, 2014 at 08:46:05PM -0600, Eric Smoll wrote:
>> > Hello VMD users,
>> >
>> > Lines generated with "graphics top line {# # #} {# # #} width 2"
>> show up
>> > in theA OpenGL display but are not rendered with a command like
>> "render
>> > POV3 name.pov povray +W# +H# -Iname.pov -Oname.png +D +X +A +FN" Is
>> there
>> > some reason why this would fail?
>> > Best,
>> > Eric
>>
>> --
>> NIH Center for Macromolecular Modeling and Bioinformatics
>> Beckman Institute for Advanced Science and Technology
>> University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
>> http://www.ks.uiuc.edu/~johns/ Phone: 217-244-3349
>> http://www.ks.uiuc.edu/Research/vmd/
>>
>
>