"SharkD" <nomail@nomail> wrote:
> > CSG only works (properly) with solids. As your mesh isn't closed, it's not a
> > solid, and therefore *cannot* give any sensible results (unless you want to
> > exploit exactly what PoV-ray happens to make of it).
>
> If it's not a solid, then Constructive *Solid* Geometry should not work with it
> at all.

So you're saying that it should give an error instead of rendering at all?

The problem here is that PoV-ray would have to actually test whether a mesh is
solid or not, which could become a quite intensive thing with large meshes.
There would also be numercial precision issues; simply put, some meshes may
turn out to be "almost-but-not-quite solid" not because they have real
significant "holes", but just minor impurities because of the way they were
generated, which wouldn't interfere with CSG in practice; so it would be hard
to draw a clear line between "solid" and "non-solid".

So for the sake of parsing speed, software complexity and robustness, it's
easier to leave it up to the user to ensure that his mesh is "solid enough" to
be used in CSG.

> You yourself even said earlier that, "There's nothing really strange about solid
> meshes which do not form a closed surface, as long as the inside_vector is
> defined properly." Have you changed your mind since then or something?

No, that was someone else who stated that...

> Further, you said that a non-closed solid mesh should behave just like a plane
> or heightfield. This is *not* happening in this case, therefore--if one should
> consider your earlier statements to be true--it must be considered a bug.

.... and this as well. *My* only mistake might have been to not vehemently
protest against these statements back then.

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