Ken <tyl### [at] pacbellnet> wrote:
>  In the sample below we have an example of degenerate triangles. The
> indented triangles are those that Pov reports as being degenerate.
> When rendered as a union the degenerate warnings appear. When commented
> out those warnings disappear. When rendered as a mesh however Pov fails
> to report them as being degenerate. This has been true since the mesh
> wrapper was added in Pov v3.0x. Why are they not being reported as
> degenerate triangles when used in a mesh ?
>
> I have asked this before and have never received a response. Hopefully
> someone has an idea now that I have provided an example to evaluate the
> discrepancy with.

It would seem to be the simple fact that when parsing meshes POV-Ray ignores
degenerate triangles completely, whereas in the union each triangle is
parsed as an individual object and so degenerate cases do get reported (a
possibly dubious theory arrived at by the fact that creating a mesh composed
entirely of degenerate triangles simply reports "no triangles in mesh").

I can only imagine the rationale is that meshes are generally outputted by a
program (conversion or otherwise), and might very well contain many
triangles that POV-Ray can't use (in which case warnings would simply be
annoying, rather than useful).  Non-mesh triangles, on the other hand, would
usually be entered by hand, and as such a degenerate triangle is more likely
to be a genuine user mistake....perhaps?!

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