Le 21/07/2019 à 22:53, Robert Munyer a écrit :
> I wanted an icosahedron module for OpenSCAD, and didn't find anything
> on-line that I liked, so I wrote this:
> 
>   intersection_for
>       (a_z = [-180 : 72 : 179],
>        a_y = [atan2 (4, 3 + sqrt (5)),
>               atan2 (sqrt (10 + sqrt (20)), sqrt (5 - sqrt (20)))])
>     rotate ([0, a_y, a_z])
>       cube ([2, 2, sqrt (3/4) + sqrt (5/12)], true);
> 
> I thought that I could double-check my math by verifying that my
> angles matched POV-Ray's angles.  They didn't quite match.  A close
> view of a POV-Ray icosahedron vertex reveals that it is malformed
> (see PNG in message with same subject, in povray.binaries.images).
> 
> calculated: 52.6226318593503043571428615050624824299049526181
> pov-ray:    52.6625
> 
> calculated: 10.8123169635717062912849447744842228988908330822
> pov-ray:    10.8125
> 
> One of POV-Ray's angles is wrong only in the last digit, but the
> other angle has _three_ wrong digits.
> 

You might want to open an issue at https://github.com/POV-Ray/povray/issues

I made a fix on bugfix/angles-of-platonic-polyhedrons in
https://github.com/LeForgeron/povray.git , to be integrated in hgpovray
in the meantime.

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