Rune wrote in message <3a6f30de@news.povray.org>...
> "Wlodzimierz ABX Skiba" wrote:
> > what about deformations where deformation not exist along
> > four directions but beetween them ?
>
> What do you mean, "between them"? The tangent vectors are very very small,
> so they're always deformed almost exactly the same.

Four tangents describe four directions. What about deformation which operate on
space between this directions and leave space along this directions ? For
example imagine that your tangents are on axis x,z,-x,-z and normal point
somewhere up. Than imagine such deformation:
deform(P)=<P.x*(2^P.z),P.y,P.z*(2^P.x)>
along axes x and z this not change values therefore
deform(<x,y,0>)=<x,y,0>
deform(<0,y,z>)=<0,y,z>

> > if I understand in your method accuracy of this plane
> > depends of length of your vectors/tangents
>
> Yes, the smaller the vectors, the more precise. Therefore I always use very
> small lengths.
>
> > and I think this length should be also customizable
>
> No, I simply always use a very small length. There's no need to make it
> customisable.

there is need - accuracy of floating point operations !!!


> If you have a more accurate method (in POV-script) I'd be happy
> to test it and see if the results are better.

I don't want say that this method is wrong at all, I want say that this method
could be wrong for some situations if you not allow customizable accuracy
(number of points, value of Small). And I want to say that you can use
personalized deform_of_normal to achive exact (!) method value of deformed
normal instead of aproximated (3a34cd8f@news.povray.org)

ABX

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