Fabien Mosen wrote:

> Sorry, but none of the proposals will achieved the desired result.
> Changing IOR only change the way you see trough an object, but
> doesn't (in Pov) affect the path of the light passing trough.
>
> I know an example of "diffractive" raytracing :
> http://math1.uibk.ac.at/%28de%29/~werner/light/spectrum/
>
> But current Pov implementation doesn't allow that.
>
> What I would suggest is : render your scene with 3 or more
> lights, each having a color from the spectrum, and make them
> slightly shifted from each other.
> This would, at least, make interesting shadows...
>
> Cheers,
> Fabien.

There is an old porgram that yeilds some interesting though perhaps
not the desired results your seeking. Here is the entirety of the programs
docs.

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Prisms - Chromatic Dispersion Simulation Program

  (c) Jeff Bowermaster
      Splat! Graphics
      5/23/92

     Adds together three separate Targa images one color from each.
     When refractive objects are given slighty different ior's in each image,
     the effect simulates chromatic dispersion (i.e., prisms 'n rainbows).

        Usage: Prisms [infiles prefix]

     Each file has a prefix name with numeric suffix's 1, 2 and 3.


     Example:

        PICTURE1.TGA, PICTURE2.TGA, PICTURE3.TGA are three images created
        with refractive elements whose ior values differ slightly.  These
        three images would be combined by typing

             Prisms PICTURE

        The summed image will be written to PICTURES.TGA

     This only works with uncompressed type 2 TGA's.  It's easier.

     Some suggested ior values would be 1.4, 1.45 and 1.5 for glass,
     2.4, 2.5 and 2.6 for diamond.  These changes in ior greatly exceed
     reality (a tenth this change is more like it) but when real values
     are used the effects are too subtle to notice.

     Please experiment.

     I experimented with using 6 images instead of three, but the colors
     started washing out.  I did try a variety of range combinations and
     certain refractive objects looked better using certain ranges, but
     the only way to find out is to try 'em.

     No provisions are made for garbage in/garbage out.
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If anyone is interested I have the program and will foreward it those who ask.

K.Tyler

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