[Bf-cycles] Realistic Nk-Data Metal BSDF

[Thomas Dinges]

Hi,
looks good already, thank you.

I wouldn't go with color sockets, that is weird, as the resulting color 
is not what the user sets. Probably it would be better to use vector 
sockets for this, but I leave this decision to Brecht. (We already use 
the Vector socket for SSS RGB Radius).

As for presets, not sure. We don't have presets yet for (Shading) Nodes, 
but maybe this could be added.

Also on a side note, maybe you'd like to use this here to upload 
patches: https://developer.blender.org/differential/diff/create/
This way its easier to review the code and we have all infos/patches in 
one place. :)

Best regards,
Thomas

Am 26.12.2013 17:45, schrieb Lukas Stockner:
> Wow, adding a node was really difficult, but I got it working. Attached is a
> patch that adds a "Conductive BSDF" which just calculates reflectance based on
> the Fresnel equation for conductors.
>
> Its inputs are Eta and K, the coefficients of the complex IOR, and Roughness. It
> supports Sharp, Beckmann and GGX microfacets. Performance and sampling look
> just as good as the Glossy BSDF. I haven't tried the OSL version yet since I
> can't get it to build, but the shader itself works in standard 2.69.7 in the
> script node. GPU should work, but not tested since my GPU still is Compute
> Capability 1.3.
>
> Two questions remain: First, how should the ETa and K values be input?
> Currently, since thay are RGB, they just show up as a color. However, their
> compontents can easily reach 5 and higher. 6 Sliders, on the other hand, ane
> probably overkill. Second, should there be a set of preset coefficients to
> choose from (like in the LuxRender plugin), or just a list somewhere in the
> Wiki?
>
> I have rendered a simple demo, the image is on
> http://postimg.org/image/70vyf00yp/ . From left to right, the materials are:
> Silver, Gold, Chrome, Copper and Aluminium. The coefficients are simply from
> multiplication of the PBRT measurements with the CIE XYZ curves and a
> transform to sRGB. If someone is interested, I could post an Octave script for
> it.
>
> Lukas Stockner