On Fri, 06 Feb 1998 21:11:40 GMT, ron### [at] farmworkscom (Ronald L. Parker)
wrote:

>The problem you're seeing is probably what would happen when different
>surfaces of the mesh have different textures applied.  If POV leaves
>through a different texture than it enters through,
>Texture_In_Ray_Container fails when it should succeed, and POV seems
>to believe it's entering the object again, causing the refraction to
>be messed up in a predictable but nontrivial way.  If the IOR of the
>exit texture is the same as that of the entry texture (and it should
>be, for real-world objects) it passes straight through the surface.
>Otherwise, strange things happen.  If the entire mesh has the same
>texture, however, you shouldn't be seeing a problem.  I haven't
>verified any of this experimentally, of course, but that's what it
>looks like from reading the code.
>
>On the other hand, if you just have a bunch of independent triangles
>that aren't part of a mesh but happen to be adjacent, they will all
>have independent copies of the texture, and Texture_In_Ray_Container
>will always return strange results.

After playing with Rhino a bit, I see that it exports meshes of smooth
triangles, so this last point is not the case, and that it tends to
allow only one texture for the entire object, so the first point
probably isn't either.  In that case, another thing you might
consider, and something you can't really fix, is that those smooth
triangles don't _really_ bulge in the center, they just have their
normals distorted so that they appear to.  That's really not quite
enough for proper refraction and reflection, as the difference between
the apparent and the actual surface can contribute to significant and
noticeable artifacts.  One way to help minimize this is to increase
the number of triangles in your mesh.

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[ron### [at] farmworkscom (Ronald L. Parker)]

Thanks for all the information! Actually, this is quite embarrassing
as I never actually tested to give ior to a mesh object. I assumed it
wouldn't work since a mesh is merely a collection of triangles, and a
totally flat object with refraction is pointless. 

if Inside is _only_ used by CSG, that would mean that things like
halos and attenuation would work aswell. 

-- 
Every action has an equal and opposite satisfaction.

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