@Ribarm
however your observation is appropriate
. . . in the code I wrote,
I ignore the pair (13 xxx yyy zzz)
assuming that it coincides with (10 xxx yyy zzz) . . .
I did this because the 3dface I'm using,
they are always triangular
and with codes 10 and 13 coinciding. . .
so the code i attached doesn't work in case that
3dfaces have 4 sides
or if they have 3 sides
but for example the code 13 coincides
with code 11 or 12 . . .
