POV-Ray : Newsgroups : povray.binaries.images : Triplanar Mapping : Re: Triplanar Mapping Server Time
22 May 2024 00:12:03 EDT (-0400)
  Re: Triplanar Mapping  
From: Samuel B 
Date: 21 Jan 2024 20:25:00
Message: <web.65adc3a893092b9916bed5696e741498@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> Nice work - that's looking really good!  :)
>
> So now here's a question - while trying to hunt down an answer to WFP's default
> importance question, I stumbled upon a thread where clipka discusses
> pleochromism.
>
> https://en.wikipedia.org/wiki/Pleochroism
>
> I know that I've brought up the topic of wet paper in the past in this regard.
>
> It seems that this approach might also make for a good anisotropic effect if we
> roll some layered texturing + filter/transmit into it?
>
> What do you think?
>
> - BW
>
> (You wouldn't believe how hard it is to find an example image of this effect)

For photographic examples, maybe look up tourmaline and axinite/ferroaxinite.

It's an interesting problem. I think rendering pleochromism accurately would
require access to POV-Ray's shader system at a level not exposed to the end user
(i.e., the source code would have to be altered). But maybe you could do as you
seem to suggest, and try using a slope pattern to drive two textures with
differently filtered pigments.

This and other types of special optical effects (such as chatoyancy) are things
most renderers have trouble with. I expect to see such effects supported by
future renderers as time goes on.

Sam


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