From: John Stone (
Date: Tue Aug 18 2009 - 10:23:05 CDT

  Hmm, I hadn't encountered that before, I'll have to look at the
POV-Ray export code. The "nan" looks to me like we've got a degenerate
triangle getting exported, which is definitely undesirable. I would suggest
that you try rendering the same scene using TachyonInternal, which will avoid
the file generation step, and thus avoid the problem with the NaN numeric value
being emitted and then later failing to parse. Try that and let me know if
it works for you. Ultimately, I'll probably have to add a bit of code that
catches this situation. Can you send me a tar.gz file containing the structure
and VMD saved state that results in the scene that triggers the problem?
If you can send it to me, I should be able to reproduce it here and change the
code to prevent this from occuring.

  John Stone

On Tue, Aug 18, 2009 at 04:53:10PM +0200, Nicolas SAPAY wrote:
> Hello,
> I'm trying to render a picture with POV-Ray using a pov file generated by
> VMD. Unfortunately, POV-Ray crashes at the following line:
> // MoleculeID: 0 ReprID: 4 Beginning polyhedra
> VMD_triangle(<-0.28497034,0.30557495,2.2290211>,<-0.28497034,0.30557495,2.229021
> 1>,<-0.28497034,0.30557495,2.2290211>,<nan
> Parse Error: Expected 'numeric expression', undeclared identifier 'nan' found
> instead
> The problem comes from the polyhedra representation used on some part of
> my system. From what I understand about the VMD_triangle macro, it looks
> like a corner of the polyhedra is missing in the pov file. Does someone
> have ever faced this problem?
> Cheers,
> Nicolas
> --
> [ Nicolas Sapay - Post-Doctoral Fellow ]
> BP53, 38041 Grenoble cedex 9, France
> Phone: +33 (0)4 76 03 76 44/53

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