clipka <nomail@nomail> wrote:
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> Warp <war### [at] tagpovrayorg> wrote:
> >   Rendering a (non-rectangular) textured quad is not an unambiguous process.
> > How do you do that? Dividing it into two triangles will get you a texturing
> > artifact.

> Should be not too difficult: Just triangulate the nasty things.

> As long as we're "only" talking about quads and not generic N-gons that should
> not be a big deal. Find the shortest diagonal and cut it in two.

  But if you do that, you will get a texturing artifact, as I said.
Specifically this:

http://warp.povusers.org/images/uvproblem.gif

  (And if someone mentions the term "perspective" as a reply to this post,
I'll smash his face.)

  I suppose that if you subdivide the quad into four triangles (with one
extra vertex at the center of the quad) the artifact will be greatly
lessened, but it would still not be correct. (Basically the triangles
at the top and bottom edges would have their texture completely vertical,
even though it shouldn't be.)

-- 
                                                          - Warp

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