[Bf-viewport] Unified Principled BSDF and Eevee PBR

[Clément FOUCAULT]

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)
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>:

> 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
>
> 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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>
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