Just want to pose if this is something that would be possible to implement
without difficulty and how popular the idea would be.

Quite often I use fresnel reflection for my materials, which requires the
use of 'ior'.  However, this poses a problem if I want to create a single
material with different sub-materials. (e.g. checker pattern with chrome
and plastic tiles).  Each of the sub-materials needs it's own ior value,
however this is part of the material block so it can't be mapped.  Having
the ability to map materials would allow this to be done much easier.

I suppose this can be acheived somewhat by changing the  maximum reflection
values, but I don't necessarily like altering it from 1, and I don't know
what it's effect is on fresnel calculations, (maybe I'll have to test this
out).

I know it could also have odd effects on transparent materials, but this is
something that may be a usuable off-shoot as well.

Personally, I think the presence of fresnel reflection makes this a
worthwhile addition, depending on whether it can be implemented easily or
not.

Other ways to implement this flexibilty would be with interior mapping (not
likely the best alternative) or either being able to move the ior to the
finish block or adding a separate ior strictly for fresnel in the finish
block.

As a side note, does anyone (particularly the more veteran POVers or
developers) know the reason for not allowing patterned textures in layered
textures?  I've always just accepted it, but over the years, I've never had
an explanation why this is the case.

-tgq

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Just for information ..
i was beleiving that they allow Patterned layered texture ..
its just that the layered texture must have transparent pigment rgbt like
.instead of rgb ...
is that right ?




news:web.452e76d1e4e2d417c150d4c10@news.povray.org...
> Just want to pose if this is something that would be possible to implement
> without difficulty and how popular the idea would be.
>
> Quite often I use fresnel reflection for my materials, which requires the
> use of 'ior'.  However, this poses a problem if I want to create a single
> material with different sub-materials. (e.g. checker pattern with chrome
> and plastic tiles).  Each of the sub-materials needs it's own ior value,
> however this is part of the material block so it can't be mapped.  Having
> the ability to map materials would allow this to be done much easier.
>
> I suppose this can be acheived somewhat by changing the  maximum
reflection
> values, but I don't necessarily like altering it from 1, and I don't know
> what it's effect is on fresnel calculations, (maybe I'll have to test this
> out).
>
> I know it could also have odd effects on transparent materials, but this
is
> something that may be a usuable off-shoot as well.
>
> Personally, I think the presence of fresnel reflection makes this a
> worthwhile addition, depending on whether it can be implemented easily or
> not.
>
> Other ways to implement this flexibilty would be with interior mapping
(not
> likely the best alternative) or either being able to move the ior to the
> finish block or adding a separate ior strictly for fresnel in the finish
> block.
>
> As a side note, does anyone (particularly the more veteran POVers or
> developers) know the reason for not allowing patterned textures in layered
> textures?  I've always just accepted it, but over the years, I've never
had
> an explanation why this is the case.
>
> -tgq
>
>
>

Post a reply to this message

"Penelope20k" <pen### [at] caramailfr> wrote:
> Just for information ..
> i was beleiving that they allow Patterned layered texture ..
> its just that the layered texture must have transparent pigment rgbt like
> .instead of rgb ...
> is that right ?
>

What I'm talking about is layering textures over patterned textures.

The following is not valid:
//START
#declare TLaq=//lacquer texture
texture{
  pigment{rgbt 1}
  finish{ambient 0 diffuse 0.4 conserve_energy reflection {0 1 metallic 0
fresnel on}}
}

#declare T1=texture{pigment{granite} finish{ambient 0 diffuse 0.5}}//checker
texture 1
#declare T2=texture{pigment{agate}   finish{ambient 0 diffuse 0.5}}//checker
texture 2

#declare TBase=texture{checker texture{T1} texture{T2}}//checker texture

#declare Mat=
material{
  texture{TBase}//checker texture
  texture{TTop} //overlay lacquer
  interior{ior 1.4}
}
//END

the texure TBase is a patterned texture and it is not allowed to be layered
over.  The solution here is to layer TTop over each of T1 and T2 before
putting them in the TBase texture, ie turn the problem inside out.  However
this is just a simple demonstration, it is not always as easy as that to
work around it with more complex textures.

I'm just wondering what the reason for this is.


-tgq

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