From: Nicolas Sapay (
Date: Tue Aug 18 2009 - 10:54:44 CDT

Thanks for the quick answer,

I send you the files off the list. The problem is that I wanted to use
POV-Ray to add an extra effect on the picture, i.e. outlining the shape
of the structure by a thin black line. Is it possible to do that with
Tachyon or TachyonInternal?


John Stone a écrit :
> Nicolas,
> 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.
> Cheers,
> 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