Some minor rewording improvements/clarifications #218
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This changelist updates the OpenPBR default example, matching its values to the latest default values of the shading model.
From 1.5 to 1.4. As this won't make much difference to the look in implementations that ignore the adjacent IORs of the film. But for those that take it into account, this will make the film visible rather than invisible by default (since `specular_ior` is 1.5 by default, and `coat_ior` 1.6).
This changelist enables Zeltner sheen in the reference implementation of OpenPBR, leveraging the new functionality in MaterialX 1.39. Additionally, the open_pbr_velvet.mtlx example has been updated to account for the visual differences between Conty-Kulla and Zeltner sheen.
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Needs a review. cc @jstone-lucasfilm @virtualzavie @peterkutz |
…n#215) With links to - MaterialX web viewer running OpenPBR default material - OpenPBR-viewer project and web app
Following the discussion of AcademySoftwareFoundation#85.
This changelist updates the types associated with physical color values for subsurface scattering in OpenPBR, aligning with the conclusions of recent threads on ASWF Slack channels. - Change `subsurface_radius_scale` from a `vector3` to a `color3` in the specification, aligning with the MaterialX implementation of OpenPBR. - Change the `radius` input of `subsurface_bsdf` from a `vector3` to a `color3` in the MaterialX implementation, aligning with the current definition of the `subsurface_bsdf` node in MaterialX 1.39.
…into wording_fixes
…, as assumed by Belcour & Barla
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This change looks great to me, though it needs to be proposed as a change to |
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The formula we give for the fuzz layering can be written in a more simplified form (the algebra is trivial). This makes it a bit clearer why the MaterialX form of the layering works, i.e.: <!-- Fuzz Layer -->
<sheen_bsdf name="fuzz_bsdf" type="BSDF">
<input name="weight" type="float" interfacename="fuzz_weight" />
<input name="color" type="color3" interfacename="fuzz_color" />
<input name="roughness" type="float" interfacename="fuzz_roughness" />
<input name="normal" type="vector3" interfacename="geometry_normal" />
<input name="mode" type="string" value="zeltner" />
</sheen_bsdf>
<layer name="fuzz_layer" type="BSDF">
<input name="top" type="BSDF" nodename="fuzz_bsdf" />
<input name="base" type="BSDF" nodename="coat_layer" />
</layer>which does Whereas it's not (immediately) obvious that red formula does that as well. Before 30293bc After 30293bc Though one must assume also that the MaterialX albedo-scaling ignores the fuzz color in the fuzz brdf albedo computation (which it does in the test render implementations), since the fuzz BRDF contains a color factor which is explicitly ignored in the albedo used in the layering formula given. |
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@jstone-lucasfilm can be merged? |
…into wording_fixes
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Added a small clarification to the text to remind that the
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@jstone-lucasfilm Can this be merged? |
Some minor changes are needed to improve the clarity of the wording (around the implementation of the coat details). I discovered these while using the spec myself to implement the Arnold version.