[Bf-viewport] Unified Principled BSDF and Eevee PBR

[metalliandy]

Yea, sounds good to me. No need to over complicate the GUI.

Cheers, Brecht.

-Andy


On 27/06/2017 22:15, Brecht Van Lommel wrote:
> If we need multiple models then I think it would be good to have them 
> as an enum in a single node. For tutorials, addons and our 
> implementation it's a lot simpler I think. We can hide/show sockets as 
> needed, and convert parameters between the different models automatically.
>
> On Tue, Jun 27, 2017 at 9:52 PM, Clément FOUCAULT 
> <foucault.clem at gmail.com <mailto:foucault.clem at gmail.com>> wrote:
>
>     I also don't quite like the fact of removing the specular
>     workflow. But supporting it would add some usability issue
>     (discussed previously but maybe reopened for debate). Adding a
>     Specular Node is just a matter of usability / UI point of
>     view. For now just supporting the Principled BSDF should cover
>     most of the use cases.
>
>     About your statements on the Metallic workflow:
>
>     >There are often texture interpolation issues where a dielectric and metallic materials meet
>     (https://s3.amazonaws.com/docs.knaldtech.com/docuwiki/light_fringe_values_close.jpg
>     <https://s3.amazonaws.com/docs.knaldtech.com/docuwiki/light_fringe_values_close.jpg>)
>     This will happen with both workflow. I understand that
>     interpolation of metallic values produces colored specular. In
>     specular workflow it won't.
>     The real workaround on this is to use layered material that are
>     rendered separately, but this is too heavy for realtime games.
>
>     >The metallic workflow is most often locked to 4% reflectivity for dielectrics which gives less control to
>     experienced artists.
>     False, the metallic workflow (as per Unreal Implementation) is
>     using disney approach to give a specular input to tweak
>     dielectrics specular values. So you can go up to 8% with default
>     range and beyond if you want. Unfortunately it seems that Unity
>     does not handle that. Still Metallic material inputs can be
>     exported as Specular inputs. The other way in not easily doable.
>
>     >Semi-conductors (Rust, Magnetite etc.) and crystalline objects (gem stones etc.) cannot be rendered
>     accurately as they require a reflectivity of between 4-18%.
>     Read previous point.
>
>     > It's much easier to use incorrect values within the metalness mask when less experienced artists author
>     content, which can break the workflow.
>     It's equally easy to put incorrect Specular values with specular
>     workflow ;) that's why they came up with the metallic one in the
>     first place.
>
>     Regards.
>
>     Clément
>
>     2017-06-27 19:42 GMT+02:00 metalliandy
>     <metalliandy666 at googlemail.com
>     <mailto:metalliandy666 at googlemail.com>>:
>
>         Hey all,
>
>         I wanted to pop in and mention that the Specular workflow is
>         absolutely not a legacy option within PBR game dev. It's a
>         higher quality alternative to the metalness workflow that is
>         often used when users are not constrained by memory
>         limitations. This is why it is supported in Unity & Toolbag etc.
>
>         https://docs.unity3d.com/Manual/StandardShaderMetallicVsSpecular.html
>         <https://docs.unity3d.com/Manual/StandardShaderMetallicVsSpecular.html>
>
>         The metalness workflow has some great positives ofc, but it
>         also has some serious limitations when it comes to accurately
>         rendering materials.
>
>         For example:
>
>           * There are often texture interpolation issues where a
>             dielectric and metallic materials meet
>             (https://s3.amazonaws.com/docs.knaldtech.com/docuwiki/light_fringe_values_close.jpg
>             <https://s3.amazonaws.com/docs.knaldtech.com/docuwiki/light_fringe_values_close.jpg>)
>           * The metallic workflow is most often locked to 4%
>             reflectivity for dielectrics which gives less control to
>             experienced artists.
>           * Semi-conductors (Rust, Magnetite etc.) and crystalline
>             objects (gem stones etc.) cannot be rendered accurately as
>             they require a reflectivity of between 4-18%.
>           * It's much easier to use incorrect values within the
>             metalness mask when less experienced artists author
>             content, which can break the workflow.
>
>         As such I wouldn't recommend removing the specular workflow
>         from Blender as it would be severely limiting the usefulness
>         of the viewport for artists that do not use the metallic
>         workflow.
>
>         Cheers,
>
>         -Andy
>
>
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