From 328fde8c5f293c1e6d6b14df0877c533be059855 Mon Sep 17 00:00:00 2001
From: mkuo-lucasfilm <mkuo@lucasfilm.com>
Date: Mon, 24 Jun 2024 07:59:12 -0700
Subject: [PATCH] Adding LamaGeneralizedSchlick and LamaIridescence Nodes
 (#1897)

1. Added a LamaGeneralizedSchlick node to MaterialX (Renderman definition: https://rmanwiki.pixar.com/display/REN26/LamaGeneralizedSchlick)

2. Added a LamaIridescence node to MaterialX (Renderman definition: https://rmanwiki.pixar.com/display/REN26/LamaIridescence)
---
 .../bxdf/lama/lama_generalized_schlick.mtlx   | 198 ++++++++++++++++++
 libraries/bxdf/lama/lama_iridescence.mtlx     |  77 +++++++
 .../lama/lama_generalized_schlick.mtlx        |  28 +++
 .../surfaceshader/lama/lama_iridescence.mtlx  |  20 ++
 4 files changed, 323 insertions(+)
 create mode 100644 libraries/bxdf/lama/lama_generalized_schlick.mtlx
 create mode 100644 libraries/bxdf/lama/lama_iridescence.mtlx
 create mode 100644 resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_generalized_schlick.mtlx
 create mode 100644 resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_iridescence.mtlx

diff --git a/libraries/bxdf/lama/lama_generalized_schlick.mtlx b/libraries/bxdf/lama/lama_generalized_schlick.mtlx
new file mode 100644
index 0000000000..c8c5f40f5b
--- /dev/null
+++ b/libraries/bxdf/lama/lama_generalized_schlick.mtlx
@@ -0,0 +1,198 @@
+<?xml version="1.0"?>
+<materialx version="1.39" colorspace="acescg">
+  <nodedef name="ND_lama_generalized_schlick" node="LamaGeneralizedSchlick" nodegroup="pbr" doc="Lama generalized schlick" version="1.0" isdefaultversion="true">
+    <input name="reflectionTint" type="color3" value="1.0, 1.0, 1.0" uiname="Reflection Tint" uifolder="Main"
+           doc="Color multiplier for external reflection. It should be used with parcimony, as a non-white value breaks physicality." />
+    <input name="transmissionTint" type="color3" value="1.0, 1.0, 1.0" uiname="Transmission Tint" uifolder="Main"
+           doc="Color multiplier for rays going inside the medium (covers external transmission and internal reflection). It should be used with parcimony, as a non-white value breaks physicality. The prefered way to define the color of a dielectric is through the Interior attributes right below." />
+    <input name="fresnelMode" type="integer" uniform="true" enum="Scientific,Artistic" enumvalues="0,1" value="0" uiname="Fresnel Mode" uifolder="Main"
+           doc="Fresnel mode" />
+    <input name="IOR" type="vector3" value="1.5,1.5,1.5" uiname="IOR" uifolder="Main"
+           doc="Index of refraction (often denoted by eta), defining the color reflected by the surface in the normal direction." />
+    <input name="reflectivity" type="color3" value="0.04, 0.04, 0.04" uiname="Reflectivity" uifolder="Main"
+           doc="Color reflected by the surface in the normal direction." />
+    <input name="reflectivity90" type="color3" value="1.0, 1.0, 1.0" uiname="Reflectivity90" uifolder="Main"
+           doc="Color reflected by the surface at the grazing angle. Should be kept at 1,1,1 for most materials." />
+    <input name="reflectivityProfile" type="float" value="0.2" uiname="ReflectivityProfile" uifolder="Main"
+           doc="The inverse of the exponent to use for Schlick." />
+    <input name="roughness" type="float" value="0.1" uimin="0.0" uimax="1.0" uiname="Roughness" uifolder="Main"
+           doc="Micro-facet distribution roughness." />
+    <input name="normal" type="vector3" defaultgeomprop="Nworld" uiname="Normal" uifolder="Main"
+           doc="Shading normal, typically defined by bump or normal mapping. Defaults to the smooth surface normal if not set." />
+    <input name="anisotropy" type="float" value="0.0" uimin="-1.0" uimax="1.0" uiname="Anisotropy" uifolder="Anisotropy"
+           doc="Defines the amount of anisotropy, changing the co-tangent axis roughness from the original value to 1 (or to 0 with a negative value)." />
+    <input name="anisotropyDirection" type="vector3" defaultgeomprop="Tworld" uiname="Direction" uifolder="Anisotropy"
+           doc="Overrides the surface tangent as the anisotropy direction." />
+    <input name="anisotropyRotation" type="float" value="0.0" uiname="Rotation" uifolder="Anisotropy"
+           doc="Rotates the anisotropy direction (possibly overriden by the previous attribute) around the normal, from 0 to 360 degrees." />
+    <input name="absorptionColor" type="color3" value="1.0, 1.0, 1.0" uiname="Absorption Color" uifolder="Interior"
+           doc="Absorption color" />
+    <input name="absorptionRadius" type="float" value="1.0" uiname="Absorption Radius" uifolder="Interior"
+           doc="Absorption radius" />
+    <input name="scatterColor" type="color3" value="0.0, 0.0, 0.0" uiname="Scatter Color" uifolder="Interior"
+           doc="Scatter color" />
+    <input name="scatterAnisotropy" type="float" value="0.0" uimin="-1.0" uimax="1.0" uiname="Scatter Anisotropy" uifolder="Interior"
+           doc="Scatter anisotropy" />
+    <output name="out" type="BSDF" />
+  </nodedef>
+
+  <nodegraph name="IMPL_lama_generalized_schlick" nodedef="ND_lama_generalized_schlick">
+
+    <!-- Dielectric IOR -->
+    <extract name="ior_float" type="float">
+      <input name="in" type="vector3" interfacename="IOR" />
+      <input name="index" type="integer" value="0" />
+    </extract>
+
+    <!-- Color0 -->
+    <convert name="convert_ior" type="color3">
+      <input name="in" type="vector3" interfacename="IOR" />
+    </convert>
+    <add name="ior_plus_one" type="color3">
+      <input name="in1" type="color3" nodename="convert_ior" />
+      <input name="in2" type="float" value="1" />
+    </add>
+    <subtract name="ior_sub_one" type="color3">
+      <input name="in1" type="color3" nodename="convert_ior" />
+      <input name="in2" type="float" value="1" />
+    </subtract>
+    <divide name="ior_divide" type="color3">
+      <input name="in1" type="color3" nodename="ior_sub_one" />
+      <input name="in2" type="color3" nodename="ior_plus_one" />
+    </divide>
+    <multiply name="ior_multiply" type="color3">
+      <input name="in1" type="color3" nodename="ior_divide" />
+      <input name="in2" type="color3" nodename="ior_divide" />
+    </multiply>
+    <multiply name="ior_reflection_tint" type="color3">
+      <input name="in1" type="color3" nodename="ior_multiply" />
+      <input name="in2" type="color3" interfacename="reflectionTint" />
+    </multiply>
+    <multiply name="reflectivity_reflection_tint" type="color3">
+      <input name="in1" type="color3" interfacename="reflectivity" />
+      <input name="in2" type="color3" interfacename="reflectionTint" />
+    </multiply>
+    <switch name="fresnel_mode_switch_reflection" type="color3">
+      <input name="in1" type="color3" nodename="ior_reflection_tint" />
+      <input name="in2" type="color3" nodename="reflectivity_reflection_tint" />
+      <input name="which" type="integer" interfacename="fresnelMode" />
+    </switch>
+
+    <!-- Color90 -->
+    <multiply name="reflectivity90_reflection_tint" type="color3">
+      <input name="in1" type="color3" interfacename="reflectivity90" />
+      <input name="in2" type="color3" interfacename="reflectionTint" />
+    </multiply>
+
+    <!-- Exponent -->
+    <divide name="exponent" type="float">
+      <input name="in1" type="float" value="1" />
+      <input name="in2" type="float" interfacename="reflectivityProfile" />
+    </divide>
+
+    <!-- Roughness -->
+    <subtract name="roughness_inverse" type="float">
+      <input name="in1" type="float" value="1.0" />
+      <input name="in2" type="float" interfacename="roughness" />
+    </subtract>
+    <ifgreatereq name="delta" type="float">
+      <input name="in1" type="float" nodename="roughness_inverse" />
+      <input name="in2" type="float" interfacename="roughness" />
+      <input name="value1" type="float" interfacename="anisotropy" />
+      <input name="value2" type="float" value="0" />
+    </ifgreatereq>
+    <multiply name="roughness_additional" type="float">
+      <input name="in1" type="float" interfacename="anisotropy" />
+      <input name="in2" type="float" nodename="delta" />
+    </multiply>
+    <add name="roughness_bitangent" type="float">
+      <input name="in1" type="float" interfacename="roughness" />
+      <input name="in2" type="float" nodename="roughness_additional" />
+    </add>
+    <clamp name="roughness_bitangent_clamped" type="float">
+      <input name="in" type="float" nodename="roughness_bitangent" />
+    </clamp>
+    <combine2 name="roughness_linear" type="vector2">
+      <input name="in1" type="float" interfacename="roughness" />
+      <input name="in2" type="float" nodename="roughness_bitangent_clamped" />
+    </combine2>
+    <power name="roughness_anisotropic_squared" type="vector2">
+      <input name="in1" type="vector2" nodename="roughness_linear" />
+      <input name="in2" type="float" value="2" />
+    </power>
+    <max name="roughness_anisotropic_squared_clamped" type="vector2">
+      <input name="in1" type="vector2" nodename="roughness_anisotropic_squared" />
+      <input name="in2" type="float" value="0.000001" />
+    </max>
+
+    <!-- Tangent -->
+    <multiply name="tangent_rotate_degree" type="float">
+      <input name="in1" type="float" interfacename="anisotropyRotation" />
+      <input name="in2" type="float" value="-360" />
+    </multiply>
+    <rotate3d name="tangent_rotate" type="vector3">
+      <input name="in" type="vector3" interfacename="anisotropyDirection" />
+      <input name="amount" type="float" nodename="tangent_rotate_degree" />
+      <input name="axis" type="vector3" interfacename="normal" />
+    </rotate3d>
+    <normalize name="tangent_rotate_normalize" type="vector3">
+      <input name="in" type="vector3" nodename="tangent_rotate" />
+    </normalize>
+
+    <!-- Interior -->
+    <divide name="absorption" type="color3">
+      <input name="in1" type="color3" interfacename="absorptionColor" />
+      <input name="in2" type="float" interfacename="absorptionRadius" />
+    </divide>
+    <convert name="absorption_vector" type="vector3">
+      <input name="in" type="color3" nodename="absorption" />
+    </convert>
+    <convert name="scatter_vector" type="vector3">
+      <input name="in" type="color3" interfacename="scatterColor" />
+    </convert>
+    <anisotropic_vdf name="interior_vdf" type="VDF">
+      <input name="absorption" type="vector3" nodename="absorption_vector" />
+      <input name="scattering" type="vector3" nodename="scatter_vector" />
+      <input name="anisotropy" type="float" interfacename="scatterAnisotropy" />
+    </anisotropic_vdf>
+
+    <!-- BTDF -->
+    <dielectric_bsdf name="transmission_bsdf" type="BSDF">
+      <input name="weight" type="float" value="1.0" />
+      <input name="tint" type="color3" interfacename="transmissionTint" />
+      <input name="ior" type="float" nodename="ior_float" />
+      <input name="roughness" type="vector2" nodename="roughness_anisotropic_squared_clamped" />
+      <input name="normal" type="vector3" interfacename="normal" />
+      <input name="tangent" type="vector3" nodename="tangent_rotate_normalize" />
+      <input name="distribution" type="string" value="ggx" />
+      <input name="scatter_mode" type="string" value="T" />
+    </dielectric_bsdf>
+    <layer name="transmission_layer" type="BSDF">
+      <input name="top" type="BSDF" nodename="transmission_bsdf" />
+      <input name="base" type="VDF" nodename="interior_vdf" />
+    </layer>
+
+    <!-- BRDF -->
+    <generalized_schlick_bsdf name="reflection_generalized_schlick_bsdf" type="BSDF">
+      <input name="weight" type="float" value="1.0" />
+      <input name="color0" type="color3" nodename="fresnel_mode_switch_reflection" />
+      <input name="color90" type="color3" nodename="reflectivity90_reflection_tint" />
+      <input name="exponent" type="float" nodename="exponent" />
+      <input name="roughness" type="vector2" nodename="roughness_anisotropic_squared_clamped" />
+      <input name="normal" type="vector3" interfacename="normal" />
+      <input name="tangent" type="vector3" nodename="tangent_rotate_normalize" />
+      <input name="distribution" type="string" value="ggx" />
+      <input name="scatter_mode" type="string" value="R" />
+    </generalized_schlick_bsdf>
+
+    <!-- BSDF -->
+    <layer name="generalized_schlick_bsdf" type="BSDF">
+      <input name="top" type="BSDF" nodename="reflection_generalized_schlick_bsdf" />
+      <input name="base" type="BSDF" nodename="transmission_layer" />
+    </layer>
+
+    <!-- Output -->
+    <output name="out" type="BSDF" nodename="generalized_schlick_bsdf" />
+
+  </nodegraph>
+</materialx>
diff --git a/libraries/bxdf/lama/lama_iridescence.mtlx b/libraries/bxdf/lama/lama_iridescence.mtlx
new file mode 100644
index 0000000000..914f70ae1b
--- /dev/null
+++ b/libraries/bxdf/lama/lama_iridescence.mtlx
@@ -0,0 +1,77 @@
+<?xml version="1.0"?>
+<materialx version="1.39" colorspace="acescg">
+  <nodedef name="ND_lama_iridescence" node="LamaIridescence" nodegroup="pbr" doc="Lama iridescence" version="1.0" isdefaultversion="true">
+    <input name="roughness" type="float" value="0.01" uimin="0.0" uimax="1.0" uiname="Roughness" uifolder="Main"
+           doc="Micro-facet distribution roughness." />
+    <input name="anisotropy" type="float" value="0.0" uimin="-1.0" uimax="1.0" uiname="Anisotropy" uifolder="Anisotropy"
+           doc="Defines the amount of anisotropy, changing the co-tangent axis roughness from the original value to 1 (or to 0 with a negative value)." />
+    <input name="relativeFilmThickness" type="float" value="0.5" uimin="0.0" uimax="1.0" uiname="relativeFilmThickness" uifolder="Main"
+           doc="Relative thin film thickness in the range from 0 to 1 will be scaled to the minimum and maximum thickness, respectively." />
+    <input name="minFilmThickness" type="float" value="400.0" uiname="minFilmThickness" uifolder="Main"
+           doc="Minimum thin film thickness in nanometers, driving the iridescent effect." />
+    <input name="maxFilmThickness" type="float" value="800.0" uiname="maxFilmThickness" uifolder="Main"
+           doc="Maximum thin film thickness in nanometers, driving the iridescent effect." />
+    <input name="filmIOR" type="float" value="1.3" uiname="filmIOR" uifolder="Main"
+           doc="Thin film index of refraction, driving the iridescent effect." />
+    <output name="out" type="BSDF" />
+  </nodedef>
+
+  <nodegraph name="IMPL_lama_iridescence" nodedef="ND_lama_iridescence">
+
+    <!-- Roughness -->
+    <subtract name="roughness_inverse" type="float">
+      <input name="in1" type="float" value="1.0" />
+      <input name="in2" type="float" interfacename="roughness" />
+    </subtract>
+    <ifgreatereq name="delta" type="float">
+      <input name="in1" type="float" nodename="roughness_inverse" />
+      <input name="in2" type="float" interfacename="roughness" />
+      <input name="value1" type="float" interfacename="anisotropy" />
+      <input name="value2" type="float" value="0" />
+    </ifgreatereq>
+    <multiply name="roughness_additional" type="float">
+      <input name="in1" type="float" interfacename="anisotropy" />
+      <input name="in2" type="float" nodename="delta" />
+    </multiply>
+    <add name="roughness_bitangent" type="float">
+      <input name="in1" type="float" interfacename="roughness" />
+      <input name="in2" type="float" nodename="roughness_additional" />
+    </add>
+    <clamp name="roughness_bitangent_clamped" type="float">
+      <input name="in" type="float" nodename="roughness_bitangent" />
+    </clamp>
+    <combine2 name="roughness_linear" type="vector2">
+      <input name="in1" type="float" interfacename="roughness" />
+      <input name="in2" type="float" nodename="roughness_bitangent_clamped" />
+    </combine2>
+    <power name="roughness_anisotropic_squared" type="vector2">
+      <input name="in1" type="vector2" nodename="roughness_linear" />
+      <input name="in2" type="float" value="2" />
+    </power>
+    <max name="roughness_anisotropic_squared_clamped" type="vector2">
+      <input name="in1" type="vector2" nodename="roughness_anisotropic_squared" />
+      <input name="in2" type="float" value="0.000001" />
+    </max>
+
+    <!-- Thinfilm Thickness -->
+    <mix name="thinfilm_thickness" type="float">
+      <input name="fg" type="float" interfacename="maxFilmThickness" />
+      <input name="bg" type="float" interfacename="minFilmThickness" />
+      <input name="mix" type="float" interfacename="relativeFilmThickness" />
+    </mix>
+
+    <!-- BSDF -->
+    <dielectric_bsdf name="iridescence_bsdf" type="BSDF">
+      <input name="roughness" type="vector2" nodename="roughness_anisotropic_squared_clamped" />
+      <input name="ior" type="float" value="1.0" />
+      <input name="thinfilm_thickness" type="float" nodename="thinfilm_thickness" />
+      <input name="thinfilm_ior" type="float" interfacename="filmIOR" />
+      <input name="distribution" type="string" value="ggx" />
+      <input name="scatter_mode" type="string" value="RT" />
+    </dielectric_bsdf>
+
+    <!-- Output -->
+    <output name="out" type="BSDF" nodename="iridescence_bsdf" />
+
+  </nodegraph>
+</materialx>
diff --git a/resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_generalized_schlick.mtlx b/resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_generalized_schlick.mtlx
new file mode 100644
index 0000000000..0a6cff3c53
--- /dev/null
+++ b/resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_generalized_schlick.mtlx
@@ -0,0 +1,28 @@
+<?xml version="1.0"?>
+<materialx version="1.38" colorspace="acescg">
+
+  <!-- LamaGeneralizedSchlick -->
+  <LamaGeneralizedSchlick name="LamaGeneralizedSchlick" type="BSDF">
+    <input name="reflectionTint" type="color3" value="1.0, 1.0, 1.0" />
+    <input name="transmissionTint" type="color3" value="1.0, 1.0, 1.0" />
+    <input name="fresnelMode" type="integer" value="0" />
+    <input name="IOR" type="vector3" value="1.5,1.5,1.5" />
+    <input name="reflectivity" type="color3" value="0.04, 0.04, 0.04" />
+    <input name="reflectivity90" type="color3" value="1.0, 1.0, 1.0" />
+    <input name="reflectivityProfile" type="float" value="0.2" />
+    <input name="roughness" type="float" value="0.1" />
+    <input name="anisotropy" type="float" value="0.0" />
+    <input name="anisotropyRotation" type="float" value="0.0" />
+    <input name="absorptionColor" type="color3" value="1.0, 1.0, 1.0" />
+    <input name="absorptionRadius" type="float" value="1.0" />
+    <input name="scatterColor" type="color3" value="0.0, 0.0, 0.0" />
+    <input name="scatterAnisotropy" type="float" value="0.0" />
+  </LamaGeneralizedSchlick>
+  <surface name="LamaGeneralizedSchlickSurface" type="surfaceshader">
+    <input name="bsdf" type="BSDF" nodename="LamaGeneralizedSchlick" />
+  </surface>
+  <surfacematerial name="LamaGeneralizedSchlickTest" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="LamaGeneralizedSchlickSurface" />
+  </surfacematerial>
+
+</materialx>
diff --git a/resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_iridescence.mtlx b/resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_iridescence.mtlx
new file mode 100644
index 0000000000..a6bc228773
--- /dev/null
+++ b/resources/Materials/TestSuite/pbrlib/surfaceshader/lama/lama_iridescence.mtlx
@@ -0,0 +1,20 @@
+<?xml version="1.0"?>
+<materialx version="1.38" colorspace="acescg">
+
+  <!-- LamaIridescence -->
+  <LamaIridescence name="LamaIridescence" type="BSDF">
+    <input name="roughness" type="float" value="0.01" />
+    <input name="anisotropy" type="float" value="0.0" />
+    <input name="relativeFilmThickness" type="float" value="0.5" />
+    <input name="minFilmThickness" type="float" value="400.0" />
+    <input name="maxFilmThickness" type="float" value="800.0" />
+    <input name="filmIOR" type="float" value="1.3" />
+  </LamaIridescence>
+  <surface name="LamaIridescenceSurface" type="surfaceshader">
+    <input name="bsdf" type="BSDF" nodename="LamaIridescence" />
+  </surface>
+  <surfacematerial name="LamaIridescenceTest" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="LamaIridescenceSurface" />
+  </surfacematerial>
+
+</materialx>