Mike Raiford wrote:
> stbenge wrote:
> 
>> It's a mesh stone shape, with many mesh inclusions. Each inclusion is 
>> a disc-shaped chip, colored randomly, and given a specular highlight 
>> with a metallic value of one to really bring out the color. They were 
>> placed randomly. The ones residing inside the stone were rendered, the 
>> rest were not.
> 
> I was wondering how you could simulate the fire effect that opals have. 
> Very tough thing to simulate in CG, if you ask me. I've not attempted 
> this, but I have given it some thought.

To model it accurately would require more time than we have, I think. We 
might be able to place hollow inclusions within the stone which have a 
regular surface normal (like "quilted" or "leopard"), and add dispersion 
on top of that.

> BTW, I built a nice list of dispersion and IOR values for many types of 
> gemstones/minerals. Does anyone think this could be of utility at all?

There is already such a utility called NewIOR.INC by Sven-Erik Andersen. 
I use it a reference, since I like to build my materials myself. But if 
you can improve on it (and maybe implement a birefringence model), then 
I'll take a look at it. I still haven't rendered calcite :)

Sam

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