Niki Estner wrote:

I did something similiar to hypertextures in the my picture "bear" 
(http://www.grafik.willhalm.de/), so perhaps I should comment
on this. I more or less read the paper of Perlin and Hoffert, but didn't 
like the idea of numerically finding the gradient. That's why I used the
lighting model of Kajiya and Kay from the same proceedings. 

>> Hmm...how is this different from an isosurface? Aside from the more
>> flexible container.
> The difference is: you can design a scene with "basic" objects, render
> them fast until you get the right geometry, and then apply a texture to it
> that deforms the surface.

What prevents you from doing this with isosurfaces? They're not _that_ slow,
if you don't use fancy functions like noise (which would give you 
interesting
hypertextures). That's what I did in my picture: Model the geometry with
simple functions and apply the "fur" later. At the moment, I not sure
whether it's really worth the trouble to implement the hypertextures in
POVRay or whether we can stick with isosurfaces.

>> I think you might be able to warp the height field function in such a
>> way to do this...maybe. But other objects are more of a problem: meshes,
>> CSG, julia fractals, etc.
> Well, I guess the feature I'm thinking of won't work for all kinds of
> objects (nothing new: media doesn't work for meshes, for example)

Well, CSG is possible with Christoph Hormann's isocsg library
(http://www-public.tu-bs.de:8080/~y0013390/pov/ic/index.html), but
meshes and fractals might be indeed, mmh.., "difficult".
 
Thomas

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