[Bf-cycles] Disney BRDF Implementation in Cycles

Stefan Werner swerner at smithmicro.com
Wed May 11 19:06:59 CEST 2016

Eventually, it might be interesting to split it into separate closures, so that one can still use separate ray counts for specular/diffuse/transmission and get them to render into separate passes. This will probably require to put fresnel back into the closures (going back in history, it looks like Cycles initially had that).

Stefan Werner  |  Senior Software Engineer; Productivity & Graphics
Smith Micro Software, Inc.  |  http://www.smithmicro.com <http://www.smithmicro.com/>

On 5/11/16, 4:18 PM, "bf-cycles-bounces at blender.org on behalf of Lukas Stockner" <bf-cycles-bounces at blender.org on behalf of lukas.stockner at freenet.de> wrote:

>The Disney BRDF shader is actually pretty interesting for Cycles!
>I've played around with it for a while as well, but my code isn't fully
>working yet, so it'd be awesome to have your code around.
>Some notes:
>- There's actually a later revision of the paper you linked with a few
>more details, might be handy:
>- There's also a completely revised BSDF that includes actual subsurface
>scattering and transmission, and they note that it solves a few issues
>with energy conservation and path tracing in general that the original
>2012 BRDF has:
>- I'm currently working on energy-conserving microfacet closures, which
>would pretty much solve the issue that caused them to include the sheen
>stuff - at the cost of not being 100% compatible to other implementations.
>But that can all be handled later - in general, it would be awesome to
>have the Disney BRDF/BSDF in Cycles, and your code would certainly be
>welcome! Even if we go with the revised BSDF, it is pretty similar to
>the original BRDF, so it could be upgraded easily.
>Am 11.05.2016 um 15:57 schrieb "Pascal Schön":
>> Hey guys,
>> For a few months now I’m implementing (on a private repository) the
>> Disney BRDF shader
>> (https://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_notes_v2.pdf)
>> as a new node in Cycles. By now there have only been a few external
>> approaches, where a render server (like in Appleseed or Renderman) is
>> accessed by a Blender plugin. But it would be nice to get access to this
>> without any additional software to install.
>> The current state of my implementation is, that the OSL closure is
>> finished and has also been tested against Renderman. Both acted the same
>> in my testcases (except for the rendering approches by the two
>> renderers, which cause some minor differences in indirect lighting).
>> Another step that I’ve taken was to implement the node to easily access
>> the Disney BRDF.
>> Currently OSL has to be activated, because I haven’t done all steps to
>> include the Disney BRDF completely in Cycles. But I think that’s only
>> one small step to take. There I hope to get some help by the community
>> because it's a bit confusing where to add which code fragment.
>> You can see some screenshots here:
>> https://www.dropbox.com/sh/j7w4v0bu9a5jhvz/AADSF3nm3LZCZnHgyPMwhrT6a?dl=0
>> I would be pleased if you tell me if this would be nice to have or if it
>> is too special for Blender.
>> Pascal
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