Add support for MDL 1.10 (#2214)

Update the MDL code generator to make use of MDL 1.10 features that. This includes: - taking the color82 of the generalized Schlick BSDF into account - implement the Zeltner mode for the Sheen BSDF - add energy conservation to the Oren-Nayar diffuse BSDF
AcademySoftwareFoundation · Feb 13, 2025 · 7fc041d · 7fc041d
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diff --git a/libraries/pbrlib/genmdl/pbrlib_genmdl_impl.mtlx b/libraries/pbrlib/genmdl/pbrlib_genmdl_impl.mtlx
@@ -23,7 +23,7 @@
   <implementation name="IM_subsurface_bsdf_genmdl" nodedef="ND_subsurface_bsdf" sourcecode="materialx::pbrlib_{{MDL_VERSION_SUFFIX}}::mx_subsurface_bsdf(mxp_weight:{{weight}}, mxp_color:{{color}}, mxp_radius:{{radius}}, mxp_anisotropy:{{anisotropy}}, mxp_normal:{{normal}})" target="genmdl" />
 
   <!-- <sheen_bsdf> -->
-  <implementation name="IM_sheen_bsdf_genmdl" nodedef="ND_sheen_bsdf" sourcecode="materialx::pbrlib_{{MDL_VERSION_SUFFIX}}::mx_sheen_bsdf(mxp_weight:{{weight}}, mxp_color:{{color}}, mxp_roughness:{{roughness}}, mxp_normal:{{normal}}, mxp_base:{{base}})" target="genmdl" />
+  <implementation name="IM_sheen_bsdf_genmdl" nodedef="ND_sheen_bsdf" sourcecode="materialx::pbrlib_{{MDL_VERSION_SUFFIX}}::mx_sheen_bsdf(mxp_weight:{{weight}}, mxp_color:{{color}}, mxp_roughness:{{roughness}}, mxp_normal:{{normal}}, mxp_mode:{{mode}}, mxp_base:{{base}})" target="genmdl" />
 
   <!-- <chiang_hair_bsdf> -->
   <implementation name="IM_chiang_hair_bsdf_genmdl" nodedef="ND_chiang_hair_bsdf" sourcecode="materialx::pbrlib_{{MDL_VERSION_SUFFIX}}::mx_chiang_hair_bsdf(mxp_tint_R:{{tint_R}}, mxp_tint_TT:{{tint_TT}}, mxp_tint_TRT:{{tint_TRT}}, mxp_ior:{{ior}}, mxp_roughness_R:{{roughness_R}}, mxp_roughness_TT:{{roughness_TT}}, mxp_roughness_TRT:{{roughness_TRT}}, mxp_cuticle_angle:{{cuticle_angle}}, mxp_absorption_coefficient:{{absorption_coefficient}}, mxp_curve_direction:{{curve_direction}})" target="genmdl" />

diff --git a/resources/Materials/TestSuite/pbrlib/bsdf/sheen_bsdf.mtlx b/resources/Materials/TestSuite/pbrlib/bsdf/sheen_bsdf.mtlx
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+<materialx version="1.39">
+  <nodegraph name="conty_kulla_sheen">
+    <sheen_bsdf name="conty_kulla_sheen_bsdf1" type="BSDF">
+      <input name="weight" type="float" value="1.0" />
+      <input name="color" type="color3" value="0.516, 0.524, 0.778" />
+      <input name="roughness" type="float" value="0.3" />
+      <input name="mode" type="string" value="conty_kulla" />
+    </sheen_bsdf>
+    <surface name="surface1" type="surfaceshader">
+      <input name="bsdf" type="BSDF" nodename="conty_kulla_sheen_bsdf1" />
+      <input name="opacity" type="float" value="1.0" />
+    </surface>
+    <output name="out" type="surfaceshader" nodename="surface1" />
+  </nodegraph>
+
+  <nodegraph name="zeltner_sheen">
+    <sheen_bsdf name="zeltner_sheen_bsdf2" type="BSDF">
+      <input name="weight" type="float" value="1.0" />
+      <input name="color" type="color3" value="0.516, 0.524, 0.778" />
+      <input name="roughness" type="float" value="0.3" />
+      <input name="mode" type="string" value="zeltner" />
+    </sheen_bsdf>
+    <surface name="surface2" type="surfaceshader">
+      <input name="bsdf" type="BSDF" nodename="zeltner_sheen_bsdf2" />
+      <input name="opacity" type="float" value="1.0" />
+    </surface>
+    <output name="out" type="surfaceshader" nodename="surface2" />
+  </nodegraph>
+</materialx>
diff --git a/source/MaterialXGenMdl/MdlShaderGenerator.cpp b/source/MaterialXGenMdl/MdlShaderGenerator.cpp
@@ -52,10 +52,12 @@ const string MDL_VERSION_1_6 = "1.6";
 const string MDL_VERSION_1_7 = "1.7";
 const string MDL_VERSION_1_8 = "1.8";
 const string MDL_VERSION_1_9 = "1.9";
+const string MDL_VERSION_1_10 = "1.10";
 const string MDL_VERSION_SUFFIX_1_6 = "1_6";
 const string MDL_VERSION_SUFFIX_1_7 = "1_7";
 const string MDL_VERSION_SUFFIX_1_8 = "1_8";
 const string MDL_VERSION_SUFFIX_1_9 = "1_9";
+const string MDL_VERSION_SUFFIX_1_10 = "1_10";
 
 } // anonymous namespace
 
@@ -281,6 +283,8 @@ ShaderPtr MdlShaderGenerator::generate(const string& name, ElementPtr element, G
                 finalOutput = "mk_color3(" + result + ".x, " + result + ".y, 0.0)";
             else if (outputType == Type::VECTOR3)
                 finalOutput = "mk_color3(" + result + ")";
+            else if (outputType == Type::VECTOR4)
+                finalOutput = "mk_color3(" + result + ".x, " + result + ".y, " + result + ".z)";
             else if (outputType == Type::COLOR3)
                 finalOutput = result;
             else if (outputType == Type::COLOR4)
@@ -765,10 +769,13 @@ void MdlShaderGenerator::emitMdlVersionNumber(GenContext& context, ShaderStage&
         case GenMdlOptions::MdlVersion::MDL_1_8:
             emitString(MDL_VERSION_1_8, stage);
             break;
+        case GenMdlOptions::MdlVersion::MDL_1_9:
+            emitString(MDL_VERSION_1_9, stage);
+            break;
         default:
-            // GenMdlOptions::MdlVersion::MDL_1_9
+            // GenMdlOptions::MdlVersion::MDL_1_10
             // GenMdlOptions::MdlVersion::MDL_LATEST
-            emitString(MDL_VERSION_1_9, stage);
+            emitString(MDL_VERSION_1_10, stage);
             break;
     }
     emitLineEnd(stage, true);
@@ -787,10 +794,12 @@ const string& MdlShaderGenerator::getMdlVersionFilenameSuffix(GenContext& contex
             return MDL_VERSION_SUFFIX_1_7;
         case GenMdlOptions::MdlVersion::MDL_1_8:
             return MDL_VERSION_SUFFIX_1_8;
+        case GenMdlOptions::MdlVersion::MDL_1_9:
+            return MDL_VERSION_SUFFIX_1_9;
         default:
-            // GenMdlOptions::MdlVersion::MDL_1_9
+            // GenMdlOptions::MdlVersion::MDL_1_10
             // GenMdlOptions::MdlVersion::MDL_LATEST
-            return MDL_VERSION_SUFFIX_1_9;
+            return MDL_VERSION_SUFFIX_1_10;
     }
 }
 

diff --git a/source/MaterialXGenMdl/MdlShaderGenerator.h b/source/MaterialXGenMdl/MdlShaderGenerator.h
@@ -26,7 +26,8 @@ class MX_GENMDL_API GenMdlOptions : public GenUserData
         MDL_1_7,
         MDL_1_8,
         MDL_1_9,
-        MDL_LATEST = MDL_1_9
+        MDL_1_10,
+        MDL_LATEST = MDL_1_10
     };
 
     /// Create MDL code generator options with default values.

diff --git a/source/MaterialXGenMdl/MdlSyntax.cpp b/source/MaterialXGenMdl/MdlSyntax.cpp
@@ -23,6 +23,7 @@ TYPEDESC_REGISTER_TYPE(MDL_FILTERLOOKUPMODE, "filterlookup")
 TYPEDESC_REGISTER_TYPE(MDL_FILTERTYPE, "filtertype")
 TYPEDESC_REGISTER_TYPE(MDL_DISTRIBUTIONTYPE, "distributiontype")
 TYPEDESC_REGISTER_TYPE(MDL_SCATTER_MODE, "scatter_mode")
+TYPEDESC_REGISTER_TYPE(MDL_SHEEN_MODE, "mode")
 
 } // namespace Type
 
@@ -196,6 +197,7 @@ const StringVec MdlSyntax::FILTERLOOKUPMODE_MEMBERS = { "closest", "linear", "cu
 const StringVec MdlSyntax::FILTERTYPE_MEMBERS = { "box", "gaussian" };
 const StringVec MdlSyntax::DISTRIBUTIONTYPE_MEMBERS = { "ggx" };
 const StringVec MdlSyntax::SCATTER_MODE_MEMBERS = { "R", "T", "RT" };
+const StringVec MdlSyntax::SHEEN_MODE_MEMBERS = { "conty_kulla", "zeltner" };
 
 const string MdlSyntax::PORT_NAME_PREFIX = "mxp_";
 
@@ -453,6 +455,14 @@ MdlSyntax::MdlSyntax()
             "mx_scatter_mode_R",
             "mx_scatter_mode_R",
             SCATTER_MODE_MEMBERS));
+
+    registerTypeSyntax(
+        Type::MDL_SHEEN_MODE,
+        std::make_shared<MdlEnumSyntax>(
+            "mx_sheen_mode",
+            "mx_sheen_mode_conty_kulla",
+            "mx_sheen_mode_conty_kulla",
+            SHEEN_MODE_MEMBERS));
 }
 
 TypeDesc MdlSyntax::getEnumeratedType(const string& value) const

diff --git a/source/MaterialXGenMdl/MdlSyntax.h b/source/MaterialXGenMdl/MdlSyntax.h
@@ -53,6 +53,7 @@ class MX_GENMDL_API MdlSyntax : public Syntax
     static const StringVec FILTERTYPE_MEMBERS;
     static const StringVec DISTRIBUTIONTYPE_MEMBERS;
     static const StringVec SCATTER_MODE_MEMBERS;
+    static const StringVec SHEEN_MODE_MEMBERS;
     static const string PORT_NAME_PREFIX; // Applied to input and output names to avoid collisions with reserved words in MDL
 
     /// Get an type description for an enumeration based on member value
@@ -85,6 +86,7 @@ TYPEDESC_DEFINE_TYPE(MDL_FILTERLOOKUPMODE, "filterlookup", TypeDesc::BASETYPE_NO
 TYPEDESC_DEFINE_TYPE(MDL_FILTERTYPE, "filtertype", TypeDesc::BASETYPE_NONE, TypeDesc::SEMANTIC_ENUM, 0)
 TYPEDESC_DEFINE_TYPE(MDL_DISTRIBUTIONTYPE, "distributiontype", TypeDesc::BASETYPE_NONE, TypeDesc::SEMANTIC_ENUM, 0)
 TYPEDESC_DEFINE_TYPE(MDL_SCATTER_MODE, "scatter_mode", TypeDesc::BASETYPE_NONE, TypeDesc::SEMANTIC_ENUM, 0)
+TYPEDESC_DEFINE_TYPE(MDL_SHEEN_MODE, "mode", TypeDesc::BASETYPE_NONE, TypeDesc::SEMANTIC_ENUM, 0)
 
 } // namespace Type
 

diff --git a/source/MaterialXGenMdl/mdl/materialx/pbrlib.mdl b/source/MaterialXGenMdl/mdl/materialx/pbrlib.mdl
@@ -19,12 +19,12 @@
 //     Document version 1.39, June 29, 2024
 //     see www.materialx.org 
 // in
-//     NVIDIA Material Definition Language 1.9
+//     NVIDIA Material Definition Language 1.10
 //     Language Specification
-//     Document version 1.9.2, September 16, 2024
+//     Document version 1.10.1, November 04, 2024
 //     www.nvidia.com/mdl
 
-mdl 1.9;
+mdl 1.10;
 
 // forward the latest version
-export using .::pbrlib_1_9 import *;
+export using .::pbrlib_1_10 import *;