"jr" <cre### [at] gmailcom> wrote:

> the GTS library provides 'gts_surface_is_closed' to check for holes, and there
> is a "repair" utility (part of download) for that case (though I have not used
> that yet).  there are 'stl2gts' utilities out there, complemented by 'gts2pov'
> (link below).

Interesting.  I would love to know how _that_ all works.  Undoubtedly some
vector black magic and maybe crossing tests.

> re order of vertices, I think you're right, I seem to remember it matters when
> the normal(s) need calculating.

re ordering of vertices, so if they're wrong then they'd need . . . reordering.
:D

I found this just now - I have yet to understand anything about it.

https://math.stackexchange.com/questions/689418/how-to-compute-surface-normal-pointing-out-of-the-object


> regards, jr.

re guards, it always seems like the sanity checks for thing like this
(degenerate, normal direction, dupes, missing) wind up overwhelming the actual
code for the object.

regards,

BW

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