[Bf-cycles] Realistic Nk-Data Metal BSDF

[Thomas Dinges]

Hi,
yes you can just change the function, that is fine.

Thanks,
Thomas

Am 26.12.2013 20:00, schrieb Lukas Stockner:
> Hi,
> I agree, Vector sockets sounds reasonable. Concerning fresnel_conductor(): I
> have looked into it, but it uses scalars for eta and k, so this would need to
> be changed. This shouldn't be a problem through, since nobody uses it. I'll
> just change it and send the patch to developer.blender.org (I will also change
> the sockets to Vector, but that still remains uncertain).
> Thanks for the feedback,
> Lukas
>
> Am Donnerstag, 26. Dezember 2013, 19:23:48 schrieb Thomas Dinges:
>> Oh and I forgot, we already have a fresnel_conductor() function, which
>> is currently unused in bsdf_util.h, maybe you can re-use that?
>> For OSL you would need to copy the code into node_fresnel.h, and include
>> this in the OSL shader then.
>>
>> Am 26.12.2013 19:17, schrieb 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
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