Merge branch 'dev_1.1' into resources_section

portsmouth · web-flow · commit 7870058b35b1 · 2024-06-24T17:59:10.000+01:00
diff --git a/examples/open_pbr_default.mtlx b/examples/open_pbr_default.mtlx
@@ -20,7 +20,7 @@
     <input name="transmission_scatter" type="color3" value="0, 0, 0" />
     <input name="transmission_scatter_anisotropy" type="float" value="0.0" />
     <input name="transmission_dispersion_scale" type="float" value="0.0" />
-    <input name="transmission_dispersion_abbe_number" type="float" value="0.0" />
+    <input name="transmission_dispersion_abbe_number" type="float" value="20.0" />
     <input name="subsurface_weight" type="float" value="0" />
     <input name="subsurface_color" type="color3" value="0.8, 0.8, 0.8" />
     <input name="subsurface_radius" type="float" value="1.0" />
@@ -35,9 +35,9 @@
     <input name="coat_roughness_anisotropy" type="float" value="0.0" />
     <input name="coat_ior" type="float" value="1.6" />
     <input name="coat_darkening" type="float" value="1.0" />
-    <input name="thin_film_weight" type="float" value="0.0" />
-    <input name="thin_film_thickness" type="float" value="0" />
-    <input name="thin_film_ior" type="float" value="1.5" />
+    <input name="thin_film_weight" type="float" value="0" />
+    <input name="thin_film_thickness" type="float" value="0.5" />
+    <input name="thin_film_ior" type="float" value="1.4" />
     <input name="emission_luminance" type="float" value="0.0" />
     <input name="emission_color" type="color3" value="1, 1, 1" />
     <input name="geometry_opacity" type="float" value="1" />
diff --git a/examples/open_pbr_velvet.mtlx b/examples/open_pbr_velvet.mtlx
@@ -8,6 +8,6 @@
     <input name="specular_roughness" type="float" value="0.8" />
     <input name="fuzz_weight" type="float" value="1" />
     <input name="fuzz_color" type="color3" value="0.4, 0.4, 0.4" />
-    <input name="fuzz_roughness" type="float" value="0.2" />
+    <input name="fuzz_roughness" type="float" value="0.5" />
   </open_pbr_surface>
 </materialx>
diff --git a/index.html b/index.html
@@ -868,7 +868,7 @@
 --------------------------|-----------|----------|:---------------:|:-------------:|:--------:|----------------------------------------------
 **`thin_film_weight`**    | Weight    | `float`  | $ [0, 1]      $ |               | $ 0    $ | Coverage weight of the thin film
 **`thin_film_thickness`** | Thickness | `float`  | $ [0, \infty) $ | $ [0, 1]    $ | $ 0.5  $ | Thickness of the film in micrometers ($\mathrm{\mu m}$)
-**`thin_film_ior`**       | IOR       | `float`  | $ (0, \infty) $ | $ [1, 3]    $ | $ 1.5  $ | Refractive index of the film
+**`thin_film_ior`**       | IOR       | `float`  | $ (0, \infty) $ | $ [1, 3]    $ | $ 1.4  $ | Refractive index of the film
 
 ![](images/thin_film_0nm.png width=99%) ![](images/thin_film_300nm.png width=99%) ![](images/thin_film_600nm.png width=99%)
 <div class="shifted-caption">
@@ -1074,7 +1074,7 @@
 
 The fuzz BRDF $f_\mathrm{fuzz}$ and VDF $V_\mathrm{fuzz}$ are assumed to be derived from an anisotropic microflake volume model with a fiber-like distribution. We recommend the specific model of [#Zeltner2022] (based on the earlier work of [#Heitz2015]), which has the following characteristics:
 
-- The fuzz represents a homogeneous volumetric layer with a fiber-like SGGX microflake [#Heitz2015] phase function. This is approximated using a Linearly Transformed Cosines (LTC) model [#Heitz2016b] fitted to volumetric simulations. The microflake fibers are assumed to have a single-scattering albedo that effectively produces a reflection tinted with the **`fuzz_color`** after multiple scattering.
+- The fuzz represents a homogeneous volumetric layer with a fiber-like SGGX microflake [#Heitz2015] phase function. This is approximated using a Linearly Transformed Cosines (LTC) model [#Heitz2016b] fitted to volumetric simulations. The microflake fibers are assumed to have a single-scattering albedo that effectively produces a reflection tinted with the **`fuzz_color`** after multiple scattering, allowing the fuzz to darken as well as lighten.
 - The volumetric fuzz layer is assumed to have a fixed unit optical thickness in all channels, and is purely scattering so no energy is absorbed. Thus any light not reflected after multiple scattering is assumed to transmit to the lower layers, and the transmittance is gray so the base is not tinted by the fuzz. The amount of this fixed thickness fuzz is controlled via the layer coverage weight **`fuzz_weight`**. The fuzz layer is also assumed to be index-matched with the adjacent slab above it, i.e. the fibers are embedded in the surrounding dielectric medium, thus there is no Fresnel reflection from the slab.
 - The **`fuzz_roughness`** parameter controls how fibre-like the microflake distribution of the layer is. At low roughness the microflakes are highly fibre-like (i.e. thin fibres oriented along the normal) producing a high-sheen fabric appearance, while at high roughness the microflakes are spherical producing a dusty appearance.
 
diff --git a/parametrization.md.html b/parametrization.md.html
@@ -63,7 +63,7 @@
 | **Thin-film**                                                                                                                                         |
 | `thin_film_weight`                    | Weight              | `float`   | $ [0, 1]        $ |               | $ 0                $ |                  |
 | `thin_film_thickness`                 | Thickness           | `float`   | $ [0, \infty)   $ | $ [0, 1] $    | $ 0.5              $ | $\mathrm{\mu m}$ |
-| `thin_film_ior`                       | IOR                 | `float`   | $ (0, \infty)   $ | $ [1, 3]    $ | $ 1.5              $ |                  |
+| `thin_film_ior`                       | IOR                 | `float`   | $ (0, \infty)   $ | $ [1, 3]    $ | $ 1.4              $ |                  |
 | **Geometry**                                                                                                                                          |
 | `geometry_opacity`                    | Opacity             | `float`   | $ [0, 1]        $ |               | $ 1                $ |                  |
 | `geometry_thin_walled`                | Thin walled         | `boolean` | {false, true}     |               | false                |                  |
diff --git a/reference/open_pbr_surface.mtlx b/reference/open_pbr_surface.mtlx
@@ -69,7 +69,7 @@
            doc="Coverage weight of the thin-film. Use for materials such as multi-tone car paint or soap bubbles." />
     <input name="thin_film_thickness" type="float" value="0.5" uimin="0.0" uisoftmax="1.0" uiname="Thin Film Thickness" uifolder="Thin Film" uiadvanced="true"
            doc="The thickness of the thin-film layer on the base (in micrometers)." />
-    <input name="thin_film_ior" type="float" value="1.5" uimin="0.0" uisoftmin="1.0" uisoftmax="3.0" uiname="Thin Film Index of Refraction" uifolder="Thin Film" uiadvanced="true"
+    <input name="thin_film_ior" type="float" value="1.4" uimin="0.0" uisoftmin="1.0" uisoftmax="3.0" uiname="Thin Film Index of Refraction" uifolder="Thin Film" uiadvanced="true"
            doc="The index of refraction of the thin-film." />
     <input name="emission_luminance" type="float" value="0.0" uimin="0.0" uisoftmax="1000.0" uiname="Emission Luminance" uifolder="Emission"
            doc="The amount of emitted light, as a luminance in nits." />
@@ -558,12 +558,12 @@
     </layer>
 
     <!-- Fuzz Layer -->
-    <!-- TODO: Add a new BSDF node for the selected fuzz model in OpenPBR -->
     <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" />
