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[Req] Specular / IOR mapping of texture

Posted: Tue Mar 13, 2007 12:09 am
by mrCarnivore
Another very important aspect for a photorealistic renderer is imho the ability to pply a texture as a specular map. Meaning, that the specularity of a glossy surface can vary according to a (bw-)texture.
This is extremely important if you want to render realistic skin or dirty glossy materials.

Posted: Tue Mar 13, 2007 12:12 am
by OnoSendai
Well.. you can blend with a diffuse material, or with another specular material with lower fresnel_fraction if you want :)

Posted: Tue Mar 13, 2007 12:27 am
by SmartDen
Can you give an example, Ono? Or anybody else?

Posted: Tue Mar 13, 2007 12:52 am
by mrCarnivore
@OnoSendai: Mmh. Haven't thought about that. Guess I have to admit it is possible. :D
But as with alpha-mapping this technique is hardly user-friendly. And as far as I understand it, you can only use it as a blend between TWO material settings and not a gradual change in paramtesrs according to the grey-level of the texture pixel...

@SmartDen: OnoSendai is referring to the technique described here:
http://www2.indigorenderer.com/joomla/f ... php?t=1225
Although in this case it is decribed for alpha-mapping, it can also be used for specular-mapping or any other change of material-paramters according to a texture...

Posted: Tue Mar 13, 2007 1:01 am
by suvakas
You can blend as many blend-materials as you want :wink:
What do you mean its not working with gradual greys? The blend mask can have whatever gradient in it :roll:

Suvakas

Posted: Tue Mar 13, 2007 1:30 am
by mrCarnivore
suvakas wrote:You can blend as many blend-materials as you want :wink:
Ok, I will put that remark in the theoretically-possible-but-really-not-usable corner... :wink:
But hey, if you write a nice exporter that handles all the awkwardness and delivers a nive user-interface and this blend-blending does not slow down indigo even more, be my guest. :P
suvakas wrote:What do you mean its not working with gradual greys? The blend mask can have whatever gradient in it :roll:

Suvakas
Is that so? What you are telling me is that if I have a material with exponent 50 and a material with exponent 1000 I can gradually blend those two materials using a texture that consists of shades of grey?

Posted: Tue Mar 13, 2007 1:33 am
by OnoSendai
mrCarnivore wrote:
Is that so? What you are telling me is that if I have a material with exponent 50 and a material with exponent 1000 I can gradually blend those two materials using a texture that consists of shades of grey?
Yes.. that should work fine. :)

Posted: Tue Mar 13, 2007 1:48 am
by suvakas
Hey Ono, I just did a test with blend materials and I can't blend between 2 separate blend materials that are using null material (confusing? :) )

Suvakas

Here is an example:

Posted: Tue Mar 13, 2007 1:57 am
by OnoSendai
Yeah, that doesn't work Suvakas.
I don't know if you will ever be able to blend multiple transparent materials together. (have to think about it some more :) )

Posted: Tue Mar 13, 2007 2:01 am
by suvakas
Gotcha ! Ok. Actually it would be no problem for me cause i never use a combo like this. Just fooled around for testing purposes :)

Suvakas

Posted: Tue Mar 13, 2007 2:30 am
by Kram1032
lol funny result!

Posted: Tue Mar 13, 2007 3:11 am
by mrCarnivore
Which brings me back to my original request... :D

So you just want to leave this current realisation or are you thinking about implementing a more user-friendly approach?

Posted: Tue Mar 13, 2007 4:14 am
by CTZn
The exponent of phong can be mapped already isnt'it ?