From 005822fe7938a8e29c899d955b3f2f6132ea8284 Mon Sep 17 00:00:00 2001
From: Niklas Harrysson <niklas.harrysson@gmail.com>
Date: Sun, 31 Jul 2022 12:34:35 +0200
Subject: [PATCH 1/5] Initial changes to support new OSL closures in
 MaterialXGenOsl

---
 CMakeLists.txt                                |  4 ++
 .../genosl/legacy/mx_anisotropic_vdf.osl      |  5 ++
 .../{ => legacy}/mx_burley_diffuse_bsdf.osl   |  0
 .../genosl/{ => legacy}/mx_conductor_bsdf.osl |  0
 .../genosl/legacy/mx_dielectric_bsdf.osl      | 36 +++++++++++++
 .../legacy/mx_generalized_schlick_bsdf.osl    | 38 +++++++++++++
 .../mx_oren_nayar_diffuse_bsdf.osl            |  0
 .../genosl/{ => legacy}/mx_sheen_bsdf.osl     |  0
 .../genosl/legacy/mx_subsurface_bsdf.osl      |  5 ++
 libraries/pbrlib/genosl/legacy/mx_surface.osl |  5 ++
 .../{ => legacy}/mx_translucent_bsdf.osl      |  0
 .../pbrlib/genosl/mx_anisotropic_vdf.osl      |  5 +-
 .../pbrlib/genosl/mx_dielectric_bsdf.osl      | 31 ++---------
 .../genosl/mx_generalized_schlick_bsdf.osl    | 39 +++-----------
 .../pbrlib/genosl/mx_subsurface_bsdf.osl      |  3 +-
 libraries/pbrlib/genosl/mx_surface.osl        |  2 +-
 libraries/pbrlib/genosl/mx_uniform_edf.inline |  1 -
 .../pbrlib/genosl/pbrlib_genosl_impl.mtlx     | 54 +++++++++++++++++--
 .../Nodes/ClosureLayerNodeOsl.cpp             | 41 +++++++++++++-
 source/MaterialXGenOsl/OslShaderGenerator.cpp |  3 ++
 source/MaterialXGenOsl/OslSyntax.cpp          | 16 ++++++
 21 files changed, 219 insertions(+), 69 deletions(-)
 create mode 100644 libraries/pbrlib/genosl/legacy/mx_anisotropic_vdf.osl
 rename libraries/pbrlib/genosl/{ => legacy}/mx_burley_diffuse_bsdf.osl (100%)
 rename libraries/pbrlib/genosl/{ => legacy}/mx_conductor_bsdf.osl (100%)
 create mode 100644 libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl
 create mode 100644 libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl
 rename libraries/pbrlib/genosl/{ => legacy}/mx_oren_nayar_diffuse_bsdf.osl (100%)
 rename libraries/pbrlib/genosl/{ => legacy}/mx_sheen_bsdf.osl (100%)
 create mode 100644 libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
 create mode 100644 libraries/pbrlib/genosl/legacy/mx_surface.osl
 rename libraries/pbrlib/genosl/{ => legacy}/mx_translucent_bsdf.osl (100%)
 delete mode 100644 libraries/pbrlib/genosl/mx_uniform_edf.inline

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 07a4a782b4..3176993844 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -51,6 +51,8 @@ option(MATERIALX_TEST_RENDER "Run rendering tests for MaterialX Render module. G
 option(MATERIALX_WARNINGS_AS_ERRORS "Interpret all compiler warnings as errors." OFF)
 option(MATERIALX_DYNAMIC_ANALYSIS "Build MaterialX libraries with dynamic analysis on supporting platforms." OFF)
 
+option(MATERIALX_OSL_LEGACY_CLOSURES "Code generation support for the old legacy OSL closures." OFF)
+
 set(MATERIALX_PYTHON_VERSION "" CACHE STRING
     "Python version to be used in building the MaterialX Python package (e.g. '2.7').")
 set(MATERIALX_PYTHON_EXECUTABLE "" CACHE FILEPATH
@@ -119,6 +121,7 @@ mark_as_advanced(MATERIALX_PYTHON_EXECUTABLE)
 mark_as_advanced(MATERIALX_PYTHON_OCIO_DIR)
 mark_as_advanced(MATERIALX_PYTHON_PYBIND11_DIR)
 mark_as_advanced(MATERIALX_OIIO_DIR)
+mark_as_advanced(MATERIALX_OSL_LEGACY_CLOSURES)
 mark_as_advanced(MATERIALX_OSL_BINARY_OSLC)
 mark_as_advanced(MATERIALX_OSL_BINARY_TESTRENDER)
 mark_as_advanced(MATERIALX_OSL_INCLUDE_PATH)
@@ -136,6 +139,7 @@ if (MATERIALX_BUILD_GEN_MDL)
 endif()
 
 # Add global definitions
+add_definitions(-DMATERIALX_OSL_LEGACY_CLOSURES=${MATERIALX_OSL_LEGACY_CLOSURES})
 add_definitions(-DMATERIALX_OSL_BINARY_OSLC=\"${MATERIALX_OSL_BINARY_OSLC}\")
 add_definitions(-DMATERIALX_OSL_BINARY_TESTRENDER=\"${MATERIALX_OSL_BINARY_TESTRENDER}\")
 add_definitions(-DMATERIALX_OSL_INCLUDE_PATH=\"${MATERIALX_OSL_INCLUDE_PATH}\")
diff --git a/libraries/pbrlib/genosl/legacy/mx_anisotropic_vdf.osl b/libraries/pbrlib/genosl/legacy/mx_anisotropic_vdf.osl
new file mode 100644
index 0000000000..6d52e08509
--- /dev/null
+++ b/libraries/pbrlib/genosl/legacy/mx_anisotropic_vdf.osl
@@ -0,0 +1,5 @@
+void mx_anisotropic_vdf(vector absorption, vector scattering, float anisotropy, output VDF vdf)
+{
+    // Not implemented in vanilla OSL
+    vdf = 0; // volume_henyey_greenstein(color(absorption), color(scattering), color(0.0), anisotropy);
+}
diff --git a/libraries/pbrlib/genosl/mx_burley_diffuse_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_burley_diffuse_bsdf.osl
similarity index 100%
rename from libraries/pbrlib/genosl/mx_burley_diffuse_bsdf.osl
rename to libraries/pbrlib/genosl/legacy/mx_burley_diffuse_bsdf.osl
diff --git a/libraries/pbrlib/genosl/mx_conductor_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_conductor_bsdf.osl
similarity index 100%
rename from libraries/pbrlib/genosl/mx_conductor_bsdf.osl
rename to libraries/pbrlib/genosl/legacy/mx_conductor_bsdf.osl
diff --git a/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl
new file mode 100644
index 0000000000..15b4291546
--- /dev/null
+++ b/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl
@@ -0,0 +1,36 @@
+#include "lib/mx_microfacet_specular.osl"
+
+void mx_dielectric_bsdf(float weight, color tint, float ior, vector2 roughness, normal N, vector U, string distribution, string scatter_mode, output BSDF bsdf)
+{
+    if (scatter_mode == "T")
+    {
+        bsdf.response = tint * weight * microfacet(distribution, N, U, roughness.x, roughness.y, ior, 1);
+        bsdf.throughput = tint * weight;
+        return;
+    }
+
+    float NdotV = clamp(dot(N,-I), M_FLOAT_EPS, 1.0);
+    float F0 = mx_ior_to_f0(ior);
+    float F = mx_fresnel_schlick(NdotV, F0);
+
+    // Calculate compensation for multiple scattering.
+    // This should normally be done inside the closure
+    // but since vanilla OSL doesen't support this we
+    // add it here in shader code instead.
+    vector2 safeAlpha = clamp(roughness, M_FLOAT_EPS, 1.0);
+    float avgAlpha = mx_average_alpha(safeAlpha);
+    float comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
+
+    // Calculate throughput from directional albedo.
+    float dirAlbedo = mx_ggx_dir_albedo(NdotV, avgAlpha, ior) * comp;
+    bsdf.throughput = 1.0 - dirAlbedo * weight;
+
+    if (scatter_mode == "R")
+    {
+        bsdf.response = tint * weight * comp * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, ior, 0);
+    }
+    else
+    {
+        bsdf.response = tint * weight * comp * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, ior, 2);
+    }
+}
diff --git a/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl
new file mode 100644
index 0000000000..0fac609523
--- /dev/null
+++ b/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl
@@ -0,0 +1,38 @@
+#include "lib/mx_microfacet_specular.osl"
+
+void mx_generalized_schlick_bsdf(float weight, color color0, color color90, float exponent, vector2 roughness, normal N, vector U, string distribution, string scatter_mode, output BSDF bsdf)
+{
+    float avgF0 = dot(color0, color(1.0 / 3.0));
+    float ior = mx_f0_to_ior(avgF0);
+
+    if (scatter_mode == "T")
+    {
+        bsdf.response = weight * microfacet(distribution, N, U, roughness.x, roughness.y, ior, 1);
+        bsdf.throughput = weight;
+        return;
+    }
+
+    float NdotV = fabs(dot(N,-I));
+    color F = mx_fresnel_schlick(NdotV, color0, color90, exponent);
+
+    // Calculate compensation for multiple scattering.
+    // This should normally be done inside the closure
+    // but since vanilla OSL doesen't support this we
+    // add it here in shader code instead.
+    vector2 safeAlpha = clamp(roughness, M_FLOAT_EPS, 1.0);
+    float avgAlpha = mx_average_alpha(safeAlpha);
+    color comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
+
+    // Calculate throughput from directional albedo.
+    color dirAlbedo = mx_ggx_dir_albedo(NdotV, avgAlpha, color0, color90) * comp;
+    float avgDirAlbedo = dot(dirAlbedo, color(1.0 / 3.0));
+    bsdf.throughput = 1.0 - avgDirAlbedo * weight;
+
+    // Calculate the reflection response, setting IOR to zero to disable internal Fresnel.
+    bsdf.response = F * comp * weight * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, 0.0, 0);
+
+    if (scatter_mode == "RT")
+    {
+        bsdf.response += bsdf.throughput * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, ior, 1);
+    }
+}
diff --git a/libraries/pbrlib/genosl/mx_oren_nayar_diffuse_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_oren_nayar_diffuse_bsdf.osl
similarity index 100%
rename from libraries/pbrlib/genosl/mx_oren_nayar_diffuse_bsdf.osl
rename to libraries/pbrlib/genosl/legacy/mx_oren_nayar_diffuse_bsdf.osl
diff --git a/libraries/pbrlib/genosl/mx_sheen_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_sheen_bsdf.osl
similarity index 100%
rename from libraries/pbrlib/genosl/mx_sheen_bsdf.osl
rename to libraries/pbrlib/genosl/legacy/mx_sheen_bsdf.osl
diff --git a/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
new file mode 100644
index 0000000000..826eee2bd6
--- /dev/null
+++ b/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
@@ -0,0 +1,5 @@
+void mx_subsurface_bsdf(float weight, color _color, vector radius, float anisotropy, normal N, output BSDF bsdf)
+{
+    // TODO: Subsurface closure is not supported by vanilla OSL.
+    bsdf = _color * weight * diffuse(N);
+}
diff --git a/libraries/pbrlib/genosl/legacy/mx_surface.osl b/libraries/pbrlib/genosl/legacy/mx_surface.osl
new file mode 100644
index 0000000000..b9a3c443d8
--- /dev/null
+++ b/libraries/pbrlib/genosl/legacy/mx_surface.osl
@@ -0,0 +1,5 @@
+void mx_surface(BSDF bsdf, EDF edf, float opacity, output surfaceshader result)
+{
+    float opacity_weight = clamp(opacity, 0.0, 1.0);
+    result = (bsdf.response + edf) * opacity_weight + transparent() * (1.0 - opacity_weight);
+}
diff --git a/libraries/pbrlib/genosl/mx_translucent_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_translucent_bsdf.osl
similarity index 100%
rename from libraries/pbrlib/genosl/mx_translucent_bsdf.osl
rename to libraries/pbrlib/genosl/legacy/mx_translucent_bsdf.osl
diff --git a/libraries/pbrlib/genosl/mx_anisotropic_vdf.osl b/libraries/pbrlib/genosl/mx_anisotropic_vdf.osl
index 6d52e08509..6b2a7d5298 100644
--- a/libraries/pbrlib/genosl/mx_anisotropic_vdf.osl
+++ b/libraries/pbrlib/genosl/mx_anisotropic_vdf.osl
@@ -1,5 +1,6 @@
 void mx_anisotropic_vdf(vector absorption, vector scattering, float anisotropy, output VDF vdf)
 {
-    // Not implemented in vanilla OSL
-    vdf = 0; // volume_henyey_greenstein(color(absorption), color(scattering), color(0.0), anisotropy);
+    // TODO: Need to remap parameters to match the new closure, 
+    // or change the MaterialX spec to OSL parameterization.
+    vdf = 0;
 }
diff --git a/libraries/pbrlib/genosl/mx_dielectric_bsdf.osl b/libraries/pbrlib/genosl/mx_dielectric_bsdf.osl
index 15b4291546..69773b3ced 100644
--- a/libraries/pbrlib/genosl/mx_dielectric_bsdf.osl
+++ b/libraries/pbrlib/genosl/mx_dielectric_bsdf.osl
@@ -1,36 +1,15 @@
-#include "lib/mx_microfacet_specular.osl"
-
 void mx_dielectric_bsdf(float weight, color tint, float ior, vector2 roughness, normal N, vector U, string distribution, string scatter_mode, output BSDF bsdf)
 {
-    if (scatter_mode == "T")
+    if (scatter_mode == "R")
     {
-        bsdf.response = tint * weight * microfacet(distribution, N, U, roughness.x, roughness.y, ior, 1);
-        bsdf.throughput = tint * weight;
-        return;
+        bsdf = weight * dielectric_bsdf(N, U, tint, color(0.0), roughness.x, roughness.y, ior, distribution);
     }
-
-    float NdotV = clamp(dot(N,-I), M_FLOAT_EPS, 1.0);
-    float F0 = mx_ior_to_f0(ior);
-    float F = mx_fresnel_schlick(NdotV, F0);
-
-    // Calculate compensation for multiple scattering.
-    // This should normally be done inside the closure
-    // but since vanilla OSL doesen't support this we
-    // add it here in shader code instead.
-    vector2 safeAlpha = clamp(roughness, M_FLOAT_EPS, 1.0);
-    float avgAlpha = mx_average_alpha(safeAlpha);
-    float comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
-
-    // Calculate throughput from directional albedo.
-    float dirAlbedo = mx_ggx_dir_albedo(NdotV, avgAlpha, ior) * comp;
-    bsdf.throughput = 1.0 - dirAlbedo * weight;
-
-    if (scatter_mode == "R")
+    else if (scatter_mode == "T")
     {
-        bsdf.response = tint * weight * comp * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, ior, 0);
+        bsdf = weight * dielectric_bsdf(N, U, color(0.0), tint, roughness.x, roughness.y, ior, distribution);
     }
     else
     {
-        bsdf.response = tint * weight * comp * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, ior, 2);
+        bsdf = weight * dielectric_bsdf(N, U, tint, tint, roughness.x, roughness.y, ior, distribution);
     }
 }
diff --git a/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl b/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl
index 0fac609523..a8f74de0a3 100644
--- a/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl
+++ b/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl
@@ -1,38 +1,15 @@
-#include "lib/mx_microfacet_specular.osl"
-
 void mx_generalized_schlick_bsdf(float weight, color color0, color color90, float exponent, vector2 roughness, normal N, vector U, string distribution, string scatter_mode, output BSDF bsdf)
 {
-    float avgF0 = dot(color0, color(1.0 / 3.0));
-    float ior = mx_f0_to_ior(avgF0);
-
-    if (scatter_mode == "T")
+    if (scatter_mode == "R")
     {
-        bsdf.response = weight * microfacet(distribution, N, U, roughness.x, roughness.y, ior, 1);
-        bsdf.throughput = weight;
-        return;
+        bsdf = weight * generalized_schlick_bsdf(N, U, tint, color(0.0), roughness.x, roughness.y, color0, color90, exponent, distribution);
     }
-
-    float NdotV = fabs(dot(N,-I));
-    color F = mx_fresnel_schlick(NdotV, color0, color90, exponent);
-
-    // Calculate compensation for multiple scattering.
-    // This should normally be done inside the closure
-    // but since vanilla OSL doesen't support this we
-    // add it here in shader code instead.
-    vector2 safeAlpha = clamp(roughness, M_FLOAT_EPS, 1.0);
-    float avgAlpha = mx_average_alpha(safeAlpha);
-    color comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);
-
-    // Calculate throughput from directional albedo.
-    color dirAlbedo = mx_ggx_dir_albedo(NdotV, avgAlpha, color0, color90) * comp;
-    float avgDirAlbedo = dot(dirAlbedo, color(1.0 / 3.0));
-    bsdf.throughput = 1.0 - avgDirAlbedo * weight;
-
-    // Calculate the reflection response, setting IOR to zero to disable internal Fresnel.
-    bsdf.response = F * comp * weight * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, 0.0, 0);
-
-    if (scatter_mode == "RT")
+    else if (scatter_mode == "T")
     {
-        bsdf.response += bsdf.throughput * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, ior, 1);
+        bsdf = weight * generalized_schlick_bsdf(N, U, color(0.0), tint, roughness.x, roughness.y, color0, color90, exponent, distribution);
+    }
+    else
+    {
+        bsdf = weight * generalized_schlick_bsdf(N, U, tint, tint, roughness.x, roughness.y, color0, color90, exponent, distribution);
     }
 }
diff --git a/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl b/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl
index 17a4aff2cb..826eee2bd6 100644
--- a/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl
+++ b/libraries/pbrlib/genosl/mx_subsurface_bsdf.osl
@@ -1,6 +1,5 @@
 void mx_subsurface_bsdf(float weight, color _color, vector radius, float anisotropy, normal N, output BSDF bsdf)
 {
     // TODO: Subsurface closure is not supported by vanilla OSL.
-    bsdf.response = _color * weight * diffuse(N);
-    bsdf.throughput = color(0.0);
+    bsdf = _color * weight * diffuse(N);
 }
diff --git a/libraries/pbrlib/genosl/mx_surface.osl b/libraries/pbrlib/genosl/mx_surface.osl
index b9a3c443d8..a997b47fe4 100644
--- a/libraries/pbrlib/genosl/mx_surface.osl
+++ b/libraries/pbrlib/genosl/mx_surface.osl
@@ -1,5 +1,5 @@
 void mx_surface(BSDF bsdf, EDF edf, float opacity, output surfaceshader result)
 {
     float opacity_weight = clamp(opacity, 0.0, 1.0);
-    result = (bsdf.response + edf) * opacity_weight + transparent() * (1.0 - opacity_weight);
+    result = (bsdf + edf) * opacity_weight + transparent() * (1.0 - opacity_weight);
 }
diff --git a/libraries/pbrlib/genosl/mx_uniform_edf.inline b/libraries/pbrlib/genosl/mx_uniform_edf.inline
deleted file mode 100644
index aabebe91ab..0000000000
--- a/libraries/pbrlib/genosl/mx_uniform_edf.inline
+++ /dev/null
@@ -1 +0,0 @@
-{{color}} * emission()
diff --git a/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx b/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
index f2748f7cba..5c995b4caf 100644
--- a/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
+++ b/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
@@ -2,57 +2,101 @@
 <materialx version="1.38">
 
   <!-- <oren_nayar_diffuse_bsdf> -->
-  <implementation name="IM_oren_nayar_diffuse_bsdf_genosl" nodedef="ND_oren_nayar_diffuse_bsdf" file="mx_oren_nayar_diffuse_bsdf.osl" function="mx_oren_nayar_diffuse_bsdf" target="genosl" />
+  <!--
+  <implementation name="IM_oren_nayar_diffuse_bsdf_genosl" nodedef="ND_oren_nayar_diffuse_bsdf" file="legacy/mx_oren_nayar_diffuse_bsdf.osl" function="mx_oren_nayar_diffuse_bsdf" target="genosl" />
+  -->
+  <implementation name="IM_oren_nayar_diffuse_bsdf_genosl" nodedef="ND_oren_nayar_diffuse_bsdf" sourcecode="{{weight}} * oren_nayar_diffuse_bsdf({{normal}}, {{color}}, {{roughness}})" target="genosl" />
 
   <!-- <burley_diffuse_bsdf> -->
-  <implementation name="IM_burley_diffuse_bsdf_genosl" nodedef="ND_burley_diffuse_bsdf" file="mx_burley_diffuse_bsdf.osl" function="mx_burley_diffuse_bsdf" target="genosl" />
+  <!--
+  <implementation name="IM_burley_diffuse_bsdf_genosl" nodedef="ND_burley_diffuse_bsdf" file="legacy/mx_burley_diffuse_bsdf.osl" function="mx_burley_diffuse_bsdf" target="genosl" />
+  -->
+  <implementation name="IM_burley_diffuse_bsdf_genosl" nodedef="ND_burley_diffuse_bsdf" sourcecode="{{weight}} * burley_diffuse_bsdf({{normal}}, {{color}}, {{roughness}})" target="genosl" />
 
   <!-- <translucent_bsdf> -->
-  <implementation name="IM_translucent_bsdf_genosl" nodedef="ND_translucent_bsdf" file="mx_translucent_bsdf.osl" function="mx_translucent_bsdf" target="genosl" />
+  <!--
+  <implementation name="IM_translucent_bsdf_genosl" nodedef="ND_translucent_bsdf" file="legacy/mx_translucent_bsdf.osl" function="mx_translucent_bsdf" target="genosl" />
+  -->
+  <implementation name="IM_translucent_bsdf_genosl" nodedef="ND_translucent_bsdf" sourcecode="{{weight}} * translucent_bsdf({{normal}}, {{color}})" target="genosl" />
 
   <!-- <dielectric_bsdf> -->
+  <!--
+  <implementation name="IM_dielectric_bsdf_genosl" nodedef="ND_dielectric_bsdf" file="legacy/mx_dielectric_bsdf.osl" function="mx_dielectric_bsdf" target="genosl" />
+  -->
   <implementation name="IM_dielectric_bsdf_genosl" nodedef="ND_dielectric_bsdf" file="mx_dielectric_bsdf.osl" function="mx_dielectric_bsdf" target="genosl" />
 
   <!-- <conductor_bsdf> -->
-  <implementation name="IM_conductor_bsdf_genosl" nodedef="ND_conductor_bsdf" file="mx_conductor_bsdf.osl" function="mx_conductor_bsdf" target="genosl" />
+  <!--
+  <implementation name="IM_conductor_bsdf_genosl" nodedef="ND_conductor_bsdf" file="legacy/mx_conductor_bsdf.osl" function="mx_conductor_bsdf" target="genosl" />
+  -->
+  <implementation name="IM_conductor_bsdf_genosl" nodedef="ND_conductor_bsdf" sourcecode="{{weight}} * conductor_bsdf({{normal}}, {{tangent}}, {{roughness}}.x, {{roughness}}.y, {{ior}}, {{extinction}}, {{distribution}})" target="genosl" />
 
   <!-- <generalized_schlick_bsdf> -->
+  <!--
+  <implementation name="IM_generalized_schlick_bsdf_genosl" nodedef="ND_generalized_schlick_bsdf" file="legacy/mx_generalized_schlick_bsdf.osl" function="mx_generalized_schlick_bsdf" target="genosl" />
+  -->
   <implementation name="IM_generalized_schlick_bsdf_genosl" nodedef="ND_generalized_schlick_bsdf" file="mx_generalized_schlick_bsdf.osl" function="mx_generalized_schlick_bsdf" target="genosl" />
 
   <!-- <subsurface_bsdf> -->
   <implementation name="IM_subsurface_bsdf_genosl" nodedef="ND_subsurface_bsdf" file="mx_subsurface_bsdf.osl" function="mx_subsurface_bsdf" target="genosl" />
 
   <!-- <sheen_bsdf> -->
+  <!--
   <implementation name="IM_sheen_bsdf_genosl" nodedef="ND_sheen_bsdf" file="mx_sheen_bsdf.osl" function="mx_sheen_bsdf" target="genosl" />
+  -->
+  <implementation name="IM_sheen_bsdf_genosl" nodedef="ND_sheen_bsdf" sourcecode="{{weight}} * sheen_bsdf({{normal}}, {{color}}, {{roughness}})" target="genosl" />
 
   <!-- <anisotropic_vdf> -->
+  <!--
+  <implementation name="IM_anisotropic_vdf_genosl" nodedef="ND_anisotropic_vdf" file="mx_anisotropic_vdf.osl" function="mx_anisotropic_vdf" target="genosl" />
+  -->
   <implementation name="IM_anisotropic_vdf_genosl" nodedef="ND_anisotropic_vdf" file="mx_anisotropic_vdf.osl" function="mx_anisotropic_vdf" target="genosl" />
 
   <!-- <thin_film_bsdf> -->
   <implementation name="IM_thin_film_bsdf_genosl" nodedef="ND_thin_film_bsdf" target="genosl" />
 
   <!-- <uniform_edf> -->
-  <implementation name="IM_uniform_edf_genosl" nodedef="ND_uniform_edf" file="mx_uniform_edf.inline" target="genosl" />
+  <!--
+  <implementation name="IM_uniform_edf_genosl" nodedef="ND_uniform_edf" sourcecode="{{color}} * emission()" target="genosl" />
+  -->
+  <implementation name="IM_uniform_edf_genosl" nodedef="ND_uniform_edf" sourcecode="uniform_edf({{color}})" target="genosl" />
 
   <!-- <layer> -->
   <implementation name="IM_layer_bsdf_genosl" nodedef="ND_layer_bsdf" target="genosl" />
   <implementation name="IM_layer_vdf_genosl" nodedef="ND_layer_vdf" target="genosl" />
 
   <!-- <mix> -->
+  <!--
   <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" target="genosl" />
   <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" target="genosl" />
+  -->
+  <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" sourcecode="mix({{fg}}, {{bg}}, {{mix}})" target="genosl" />
+  <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" sourcecode="mix({{fg}}, {{bg}}, {{mix}})" target="genosl" />
 
   <!-- <add> -->
+  <!--
   <implementation name="IM_add_bsdf_genosl" nodedef="ND_add_bsdf" target="genosl" />
   <implementation name="IM_add_edf_genosl" nodedef="ND_add_edf" target="genosl" />
+  -->
+  <implementation name="IM_add_bsdf_genosl" nodedef="ND_add_bsdf" sourcecode="({{in1}} + {{in2}})" target="genosl" />
+  <implementation name="IM_add_edf_genosl" nodedef="ND_add_edf" sourcecode="({{in1}} + {{in2}})" target="genosl" />
 
   <!-- <multiply> -->
+  <!--
   <implementation name="IM_multiply_bsdfC_genosl" nodedef="ND_multiply_bsdfC" target="genosl" />
   <implementation name="IM_multiply_bsdfF_genosl" nodedef="ND_multiply_bsdfF" target="genosl" />
   <implementation name="IM_multiply_edfC_genosl" nodedef="ND_multiply_edfC" target="genosl" />
   <implementation name="IM_multiply_edfF_genosl" nodedef="ND_multiply_edfF" target="genosl" />
+  -->
+  <implementation name="IM_multiply_bsdfC_genosl" nodedef="ND_multiply_bsdfC" sourcecode="({{in2}} * {{in1}})" target="genosl" />
+  <implementation name="IM_multiply_bsdfF_genosl" nodedef="ND_multiply_bsdfF" sourcecode="({{in2}} * {{in1}})" target="genosl" />
+  <implementation name="IM_multiply_edfC_genosl" nodedef="ND_multiply_edfC" sourcecode="({{in2}} * {{in1}})" target="genosl" />
+  <implementation name="IM_multiply_edfF_genosl" nodedef="ND_multiply_edfF" sourcecode="({{in2}} * {{in1}})" target="genosl" />
 
   <!-- <surface> -->
+  <!--
+  <implementation name="IM_surface_genosl" nodedef="ND_surface" file="legacy/mx_surface.osl" function="mx_surface" target="genosl" />
+  -->
   <implementation name="IM_surface_genosl" nodedef="ND_surface" file="mx_surface.osl" function="mx_surface" target="genosl" />
 
   <!-- <displacement> -->
diff --git a/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp b/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp
index 051360eeb8..79f1be8ffc 100644
--- a/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp
+++ b/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp
@@ -19,7 +19,6 @@ ShaderNodeImplPtr ClosureLayerNodeOsl::create()
 void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext& context, ShaderStage& stage) const
 {
     const ShaderGenerator& shadergen = context.getShaderGenerator();
-    ClosureContext* cct = context.getClosureContext();
 
     ShaderNode& node = const_cast<ShaderNode&>(_node);
 
@@ -38,6 +37,8 @@ void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext&
     ShaderNode* top = topInput->getConnection()->getNode();
     ShaderNode* base = baseInput->getConnection()->getNode();
 
+#if MATERIALX_OSL_LEGACY_CLOSURES
+
     if (top->hasClassification(ShaderNode::Classification::THINFILM))
     {
         // This is a layer node with thin-film as top layer.
@@ -49,6 +50,8 @@ void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext&
             throw ExceptionShaderGenError("Thin-film can only be applied to a sibling node, not through a graph interface");
         }
 
+        ClosureContext* cct = context.getClosureContext();
+
         // Set the extra parameters for thin-film.
         ClosureContext::ClosureParams params;
         params[THICKNESS] = top->getInput(THICKNESS);
@@ -102,6 +105,42 @@ void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext&
             shadergen.emitLine(output->getVariable() + ".throughput = " + topResult + ".throughput * " + baseResult + ".throughput", stage);
         }
     }
+
+#else
+
+    if (top->hasClassification(ShaderNode::Classification::THINFILM))
+    {
+        // Make sure the connection to base is a sibling node and not the graph interface.
+        if (base->getParent() != node.getParent())
+        {
+            throw ExceptionShaderGenError("Thin-film can only be applied to a sibling node, not through a graph interface");
+        }
+
+        // TODO: Thin-film is not supported yet.
+        // Emit the function call for base layer but
+        // store the base result in the layer result variable.
+        ScopedSetVariableName setVariable(output->getVariable(), base->getOutput());
+        shadergen.emitFunctionCall(*base, context, stage);
+    }
+    else
+    {
+        // Emit the function call for top and base layer.
+        shadergen.emitFunctionCall(*top, context, stage);
+        shadergen.emitFunctionCall(*base, context, stage);
+
+        // Get the result variables.
+        const string& topResult = topInput->getConnection()->getVariable();
+        const string& baseResult = baseInput->getConnection()->getVariable();
+
+        // Emit the layer closure call.
+        shadergen.emitLineBegin(stage);
+        shadergen.emitOutput(output, true, false, context, stage);
+        shadergen.emitString(" = layer(" + topResult + ", " + baseResult + ")", stage);
+        shadergen.emitLineEnd(stage);
+    }
+
+#endif // MATERIALX_OSL_LEGACY_CLOSURES
+
 }
 
 MATERIALX_NAMESPACE_END
diff --git a/source/MaterialXGenOsl/OslShaderGenerator.cpp b/source/MaterialXGenOsl/OslShaderGenerator.cpp
index 1d4c6834aa..170e430ad7 100644
--- a/source/MaterialXGenOsl/OslShaderGenerator.cpp
+++ b/source/MaterialXGenOsl/OslShaderGenerator.cpp
@@ -165,6 +165,8 @@ OslShaderGenerator::OslShaderGenerator() :
     // <!-- <layer> -->
     registerImplementation("IM_layer_bsdf_" + OslShaderGenerator::TARGET, ClosureLayerNodeOsl::create);
     registerImplementation("IM_layer_vdf_" + OslShaderGenerator::TARGET, ClosureLayerNodeOsl::create);
+
+#if MATERIALX_OSL_LEGACY_CLOSURES
     // <!-- <mix> -->
     registerImplementation("IM_mix_bsdf_" + OslShaderGenerator::TARGET, ClosureMixNode::create);
     registerImplementation("IM_mix_edf_" + OslShaderGenerator::TARGET, ClosureMixNode::create);
@@ -176,6 +178,7 @@ OslShaderGenerator::OslShaderGenerator() :
     registerImplementation("IM_multiply_bsdfF_" + OslShaderGenerator::TARGET, ClosureMultiplyNode::create);
     registerImplementation("IM_multiply_edfC_" + OslShaderGenerator::TARGET, ClosureMultiplyNode::create);
     registerImplementation("IM_multiply_edfF_" + OslShaderGenerator::TARGET, ClosureMultiplyNode::create);
+#endif // MATERIALX_OSL_LEGACY_CLOSURES
 
     // <!-- <thin_film> -->
     registerImplementation("IM_thin_film_bsdf_" + OslShaderGenerator::TARGET, NopNode::create);
diff --git a/source/MaterialXGenOsl/OslSyntax.cpp b/source/MaterialXGenOsl/OslSyntax.cpp
index 8a68b06561..c0d3848a35 100644
--- a/source/MaterialXGenOsl/OslSyntax.cpp
+++ b/source/MaterialXGenOsl/OslSyntax.cpp
@@ -457,6 +457,8 @@ OslSyntax::OslSyntax()
             "struct textureresource { string filename; string colorspace; };")
     );
 
+#if MATERIALX_OSL_LEGACY_CLOSURES
+
     registerTypeSyntax
     (
         Type::BSDF,
@@ -468,6 +470,20 @@ OslSyntax::OslSyntax()
             "struct BSDF { closure color response; color throughput; float thickness; float ior; };")
     );
 
+#else
+
+    registerTypeSyntax
+    (
+        Type::BSDF,
+        std::make_shared<ScalarTypeSyntax>(
+            "BSDF",
+            "null_closure",
+            "0",
+            "closure color")
+    );
+
+#endif // MATERIALX_OSL_LEGACY_CLOSURES
+
     registerTypeSyntax
     (
         Type::EDF,

From 207dea82ca252dc1cac7a7c82c9cc6fa84edee4d Mon Sep 17 00:00:00 2001
From: Niklas Harrysson <niklas.harrysson@gmail.com>
Date: Sun, 31 Jul 2022 22:19:19 +0200
Subject: [PATCH 2/5] Fix closure mix node

---
 libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx b/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
index 5c995b4caf..694e6da74b 100644
--- a/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
+++ b/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
@@ -70,8 +70,8 @@
   <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" target="genosl" />
   <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" target="genosl" />
   -->
-  <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" sourcecode="mix({{fg}}, {{bg}}, {{mix}})" target="genosl" />
-  <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" sourcecode="mix({{fg}}, {{bg}}, {{mix}})" target="genosl" />
+  <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" sourcecode="mix({{bg}}, {{fg}}, {{mix}})" target="genosl" />
+  <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" sourcecode="mix({{bg}}, {{fg}}, {{mix}})" target="genosl" />
 
   <!-- <add> -->
   <!--

From 7f84e3806fc81a7351be4b0d95f942dda6e49998 Mon Sep 17 00:00:00 2001
From: Niklas Harrysson <niklas.harrysson@gmail.com>
Date: Mon, 1 Aug 2022 22:28:10 +0200
Subject: [PATCH 3/5] Additional fixes for codegen with new OSL closures.

---
 CMakeLists.txt                                |  7 +-
 libraries/CMakeLists.txt                      |  8 ++-
 .../genosl/legacy/mx_conductor_bsdf.osl       |  2 +-
 .../genosl/legacy/mx_dielectric_bsdf.osl      |  2 +-
 .../legacy/mx_generalized_schlick_bsdf.osl    |  2 +-
 .../pbrlib/genosl/legacy/mx_sheen_bsdf.osl    |  2 +-
 .../genosl/mx_generalized_schlick_bsdf.osl    |  6 +-
 .../pbrlib/genosl/pbrlib_genosl_impl.legacy   | 71 +++++++++++++++++++
 .../pbrlib/genosl/pbrlib_genosl_impl.mtlx     | 44 ------------
 .../Nodes/ClosureLayerNodeOsl.cpp             | 17 +++--
 source/MaterialXGenOsl/OslShaderGenerator.cpp |  4 +-
 source/MaterialXGenOsl/OslSyntax.cpp          |  2 +-
 12 files changed, 105 insertions(+), 62 deletions(-)
 create mode 100644 libraries/pbrlib/genosl/pbrlib_genosl_impl.legacy

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3176993844..a5759e92dc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -50,8 +50,7 @@ option(MATERIALX_INSTALL_PYTHON "Install the MaterialX Python package as a third
 option(MATERIALX_TEST_RENDER "Run rendering tests for MaterialX Render module. GPU required for graphics validation." ON)
 option(MATERIALX_WARNINGS_AS_ERRORS "Interpret all compiler warnings as errors." OFF)
 option(MATERIALX_DYNAMIC_ANALYSIS "Build MaterialX libraries with dynamic analysis on supporting platforms." OFF)
-
-option(MATERIALX_OSL_LEGACY_CLOSURES "Code generation support for the old legacy OSL closures." OFF)
+option(MATERIALX_OSL_LEGACY_CLOSURES "Code generation support for the old legacy OSL closures." ON)
 
 set(MATERIALX_PYTHON_VERSION "" CACHE STRING
     "Python version to be used in building the MaterialX Python package (e.g. '2.7').")
@@ -139,10 +138,12 @@ if (MATERIALX_BUILD_GEN_MDL)
 endif()
 
 # Add global definitions
-add_definitions(-DMATERIALX_OSL_LEGACY_CLOSURES=${MATERIALX_OSL_LEGACY_CLOSURES})
 add_definitions(-DMATERIALX_OSL_BINARY_OSLC=\"${MATERIALX_OSL_BINARY_OSLC}\")
 add_definitions(-DMATERIALX_OSL_BINARY_TESTRENDER=\"${MATERIALX_OSL_BINARY_TESTRENDER}\")
 add_definitions(-DMATERIALX_OSL_INCLUDE_PATH=\"${MATERIALX_OSL_INCLUDE_PATH}\")
+if (MATERIALX_OSL_LEGACY_CLOSURES)
+    add_definitions(-DMATERIALX_OSL_LEGACY_CLOSURES)
+endif()
 if(MATERIALX_BUILD_OIIO)
     add_definitions(-DMATERIALX_BUILD_OIIO)
 endif()
diff --git a/libraries/CMakeLists.txt b/libraries/CMakeLists.txt
index 01919ca3a5..661b684f6b 100644
--- a/libraries/CMakeLists.txt
+++ b/libraries/CMakeLists.txt
@@ -1,3 +1,9 @@
 install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/
         DESTINATION "${MATERIALX_INSTALL_STDLIB_PATH}" MESSAGE_NEVER
-        PATTERN "CMakeLists.txt" EXCLUDE)
+        PATTERN "CMakeLists.txt" EXCLUDE
+        PATTERN "pbrlib_genosl_impl.legacy" EXCLUDE)
+
+if (MATERIALX_OSL_LEGACY_CLOSURES)
+    install(FILES "${CMAKE_CURRENT_SOURCE_DIR}/pbrlib/genosl/pbrlib_genosl_impl.legacy"
+        DESTINATION "${MATERIALX_INSTALL_STDLIB_PATH}/pbrlib/genosl/" RENAME pbrlib_genosl_impl.mtlx)
+endif()
diff --git a/libraries/pbrlib/genosl/legacy/mx_conductor_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_conductor_bsdf.osl
index e13b38fd7e..850ff58f62 100644
--- a/libraries/pbrlib/genosl/legacy/mx_conductor_bsdf.osl
+++ b/libraries/pbrlib/genosl/legacy/mx_conductor_bsdf.osl
@@ -1,4 +1,4 @@
-#include "lib/mx_microfacet_specular.osl"
+#include "../lib/mx_microfacet_specular.osl"
 
 void mx_conductor_bsdf(float weight, color ior_n, color ior_k, vector2 roughness, normal N, vector U, string distribution, output BSDF bsdf)
 {
diff --git a/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl
index 15b4291546..a17fdd40cf 100644
--- a/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl
+++ b/libraries/pbrlib/genosl/legacy/mx_dielectric_bsdf.osl
@@ -1,4 +1,4 @@
-#include "lib/mx_microfacet_specular.osl"
+#include "../lib/mx_microfacet_specular.osl"
 
 void mx_dielectric_bsdf(float weight, color tint, float ior, vector2 roughness, normal N, vector U, string distribution, string scatter_mode, output BSDF bsdf)
 {
diff --git a/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl
index 0fac609523..ee34727ec1 100644
--- a/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl
+++ b/libraries/pbrlib/genosl/legacy/mx_generalized_schlick_bsdf.osl
@@ -1,4 +1,4 @@
-#include "lib/mx_microfacet_specular.osl"
+#include "../lib/mx_microfacet_specular.osl"
 
 void mx_generalized_schlick_bsdf(float weight, color color0, color color90, float exponent, vector2 roughness, normal N, vector U, string distribution, string scatter_mode, output BSDF bsdf)
 {
diff --git a/libraries/pbrlib/genosl/legacy/mx_sheen_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_sheen_bsdf.osl
index bf4efe90c4..e94325fe99 100644
--- a/libraries/pbrlib/genosl/legacy/mx_sheen_bsdf.osl
+++ b/libraries/pbrlib/genosl/legacy/mx_sheen_bsdf.osl
@@ -1,4 +1,4 @@
-#include "lib/mx_microfacet_sheen.osl"
+#include "../lib/mx_microfacet_sheen.osl"
 
 // TODO: Vanilla OSL doesn't have a proper sheen closure,
 // so use 'diffuse' scaled by sheen directional albedo for now.
diff --git a/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl b/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl
index a8f74de0a3..955de3c1fa 100644
--- a/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl
+++ b/libraries/pbrlib/genosl/mx_generalized_schlick_bsdf.osl
@@ -2,14 +2,14 @@ void mx_generalized_schlick_bsdf(float weight, color color0, color color90, floa
 {
     if (scatter_mode == "R")
     {
-        bsdf = weight * generalized_schlick_bsdf(N, U, tint, color(0.0), roughness.x, roughness.y, color0, color90, exponent, distribution);
+        bsdf = weight * generalized_schlick_bsdf(N, U, color(1.0), color(0.0), roughness.x, roughness.y, color0, color90, exponent, distribution);
     }
     else if (scatter_mode == "T")
     {
-        bsdf = weight * generalized_schlick_bsdf(N, U, color(0.0), tint, roughness.x, roughness.y, color0, color90, exponent, distribution);
+        bsdf = weight * generalized_schlick_bsdf(N, U, color(0.0), color(1.0), roughness.x, roughness.y, color0, color90, exponent, distribution);
     }
     else
     {
-        bsdf = weight * generalized_schlick_bsdf(N, U, tint, tint, roughness.x, roughness.y, color0, color90, exponent, distribution);
+        bsdf = weight * generalized_schlick_bsdf(N, U, color(1.0), color(1.0), roughness.x, roughness.y, color0, color90, exponent, distribution);
     }
 }
diff --git a/libraries/pbrlib/genosl/pbrlib_genosl_impl.legacy b/libraries/pbrlib/genosl/pbrlib_genosl_impl.legacy
new file mode 100644
index 0000000000..82cb424b33
--- /dev/null
+++ b/libraries/pbrlib/genosl/pbrlib_genosl_impl.legacy
@@ -0,0 +1,71 @@
+<?xml version="1.0"?>
+<materialx version="1.38">
+
+  <!-- <oren_nayar_diffuse_bsdf> -->
+  <implementation name="IM_oren_nayar_diffuse_bsdf_genosl" nodedef="ND_oren_nayar_diffuse_bsdf" file="legacy/mx_oren_nayar_diffuse_bsdf.osl" function="mx_oren_nayar_diffuse_bsdf" target="genosl" />
+
+  <!-- <burley_diffuse_bsdf> -->
+  <implementation name="IM_burley_diffuse_bsdf_genosl" nodedef="ND_burley_diffuse_bsdf" file="legacy/mx_burley_diffuse_bsdf.osl" function="mx_burley_diffuse_bsdf" target="genosl" />
+
+  <!-- <translucent_bsdf> -->
+  <implementation name="IM_translucent_bsdf_genosl" nodedef="ND_translucent_bsdf" file="legacy/mx_translucent_bsdf.osl" function="mx_translucent_bsdf" target="genosl" />
+
+  <!-- <dielectric_bsdf> -->
+  <implementation name="IM_dielectric_bsdf_genosl" nodedef="ND_dielectric_bsdf" file="legacy/mx_dielectric_bsdf.osl" function="mx_dielectric_bsdf" target="genosl" />
+
+  <!-- <conductor_bsdf> -->
+  <implementation name="IM_conductor_bsdf_genosl" nodedef="ND_conductor_bsdf" file="legacy/mx_conductor_bsdf.osl" function="mx_conductor_bsdf" target="genosl" />
+
+  <!-- <generalized_schlick_bsdf> -->
+  <implementation name="IM_generalized_schlick_bsdf_genosl" nodedef="ND_generalized_schlick_bsdf" file="legacy/mx_generalized_schlick_bsdf.osl" function="mx_generalized_schlick_bsdf" target="genosl" />
+
+  <!-- <subsurface_bsdf> -->
+  <implementation name="IM_subsurface_bsdf_genosl" nodedef="ND_subsurface_bsdf" file="legacy/mx_subsurface_bsdf.osl" function="mx_subsurface_bsdf" target="genosl" />
+
+  <!-- <sheen_bsdf> -->
+  <implementation name="IM_sheen_bsdf_genosl" nodedef="ND_sheen_bsdf" file="legacy/mx_sheen_bsdf.osl" function="mx_sheen_bsdf" target="genosl" />
+
+  <!-- <anisotropic_vdf> -->
+  <implementation name="IM_anisotropic_vdf_genosl" nodedef="ND_anisotropic_vdf" file="legacy/mx_anisotropic_vdf.osl" function="mx_anisotropic_vdf" target="genosl" />
+
+  <!-- <thin_film_bsdf> -->
+  <implementation name="IM_thin_film_bsdf_genosl" nodedef="ND_thin_film_bsdf" target="genosl" />
+
+  <!-- <uniform_edf> -->
+  <implementation name="IM_uniform_edf_genosl" nodedef="ND_uniform_edf" sourcecode="{{color}} * emission()" target="genosl" />
+
+  <!-- <layer> -->
+  <implementation name="IM_layer_bsdf_genosl" nodedef="ND_layer_bsdf" target="genosl" />
+  <implementation name="IM_layer_vdf_genosl" nodedef="ND_layer_vdf" target="genosl" />
+
+  <!-- <mix> -->
+  <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" target="genosl" />
+  <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" target="genosl" />
+
+  <!-- <add> -->
+  <implementation name="IM_add_bsdf_genosl" nodedef="ND_add_bsdf" target="genosl" />
+  <implementation name="IM_add_edf_genosl" nodedef="ND_add_edf" target="genosl" />
+
+  <!-- <multiply> -->
+  <implementation name="IM_multiply_bsdfC_genosl" nodedef="ND_multiply_bsdfC" target="genosl" />
+  <implementation name="IM_multiply_bsdfF_genosl" nodedef="ND_multiply_bsdfF" target="genosl" />
+  <implementation name="IM_multiply_edfC_genosl" nodedef="ND_multiply_edfC" target="genosl" />
+  <implementation name="IM_multiply_edfF_genosl" nodedef="ND_multiply_edfF" target="genosl" />
+
+  <!-- <surface> -->
+  <implementation name="IM_surface_genosl" nodedef="ND_surface" file="legacy/mx_surface.osl" function="mx_surface" target="genosl" />
+
+  <!-- <displacement> -->
+  <implementation name="IM_displacement_float_genosl" nodedef="ND_displacement_float" file="mx_displacement_float.osl" function="mx_displacement_float" target="genosl" />
+  <implementation name="IM_displacement_vector3_genosl" nodedef="ND_displacement_vector3" file="mx_displacement_vector3.osl" function="mx_displacement_vector3" target="genosl" />
+
+  <!-- <roughness_anisotropy> -->
+  <implementation name="IM_roughness_anisotropy_genosl" nodedef="ND_roughness_anisotropy" file="mx_roughness_anisotropy.osl" function="mx_roughness_anisotropy" target="genosl" />
+
+  <!-- <roughness_dual> -->
+  <implementation name="IM_roughness_dual_genosl" nodedef="ND_roughness_dual" file="mx_roughness_dual.osl" function="mx_roughness_dual" target="genosl" />
+
+  <!-- <artistic_ior> -->
+  <implementation name="IM_artistic_ior_genosl" nodedef="ND_artistic_ior" file="mx_artistic_ior.osl" function="mx_artistic_ior" target="genosl" />
+
+</materialx>
diff --git a/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx b/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
index 694e6da74b..d0ef04c048 100644
--- a/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
+++ b/libraries/pbrlib/genosl/pbrlib_genosl_impl.mtlx
@@ -2,63 +2,36 @@
 <materialx version="1.38">
 
   <!-- <oren_nayar_diffuse_bsdf> -->
-  <!--
-  <implementation name="IM_oren_nayar_diffuse_bsdf_genosl" nodedef="ND_oren_nayar_diffuse_bsdf" file="legacy/mx_oren_nayar_diffuse_bsdf.osl" function="mx_oren_nayar_diffuse_bsdf" target="genosl" />
-  -->
   <implementation name="IM_oren_nayar_diffuse_bsdf_genosl" nodedef="ND_oren_nayar_diffuse_bsdf" sourcecode="{{weight}} * oren_nayar_diffuse_bsdf({{normal}}, {{color}}, {{roughness}})" target="genosl" />
 
   <!-- <burley_diffuse_bsdf> -->
-  <!--
-  <implementation name="IM_burley_diffuse_bsdf_genosl" nodedef="ND_burley_diffuse_bsdf" file="legacy/mx_burley_diffuse_bsdf.osl" function="mx_burley_diffuse_bsdf" target="genosl" />
-  -->
   <implementation name="IM_burley_diffuse_bsdf_genosl" nodedef="ND_burley_diffuse_bsdf" sourcecode="{{weight}} * burley_diffuse_bsdf({{normal}}, {{color}}, {{roughness}})" target="genosl" />
 
   <!-- <translucent_bsdf> -->
-  <!--
-  <implementation name="IM_translucent_bsdf_genosl" nodedef="ND_translucent_bsdf" file="legacy/mx_translucent_bsdf.osl" function="mx_translucent_bsdf" target="genosl" />
-  -->
   <implementation name="IM_translucent_bsdf_genosl" nodedef="ND_translucent_bsdf" sourcecode="{{weight}} * translucent_bsdf({{normal}}, {{color}})" target="genosl" />
 
   <!-- <dielectric_bsdf> -->
-  <!--
-  <implementation name="IM_dielectric_bsdf_genosl" nodedef="ND_dielectric_bsdf" file="legacy/mx_dielectric_bsdf.osl" function="mx_dielectric_bsdf" target="genosl" />
-  -->
   <implementation name="IM_dielectric_bsdf_genosl" nodedef="ND_dielectric_bsdf" file="mx_dielectric_bsdf.osl" function="mx_dielectric_bsdf" target="genosl" />
 
   <!-- <conductor_bsdf> -->
-  <!--
-  <implementation name="IM_conductor_bsdf_genosl" nodedef="ND_conductor_bsdf" file="legacy/mx_conductor_bsdf.osl" function="mx_conductor_bsdf" target="genosl" />
-  -->
   <implementation name="IM_conductor_bsdf_genosl" nodedef="ND_conductor_bsdf" sourcecode="{{weight}} * conductor_bsdf({{normal}}, {{tangent}}, {{roughness}}.x, {{roughness}}.y, {{ior}}, {{extinction}}, {{distribution}})" target="genosl" />
 
   <!-- <generalized_schlick_bsdf> -->
-  <!--
-  <implementation name="IM_generalized_schlick_bsdf_genosl" nodedef="ND_generalized_schlick_bsdf" file="legacy/mx_generalized_schlick_bsdf.osl" function="mx_generalized_schlick_bsdf" target="genosl" />
-  -->
   <implementation name="IM_generalized_schlick_bsdf_genosl" nodedef="ND_generalized_schlick_bsdf" file="mx_generalized_schlick_bsdf.osl" function="mx_generalized_schlick_bsdf" target="genosl" />
 
   <!-- <subsurface_bsdf> -->
   <implementation name="IM_subsurface_bsdf_genosl" nodedef="ND_subsurface_bsdf" file="mx_subsurface_bsdf.osl" function="mx_subsurface_bsdf" target="genosl" />
 
   <!-- <sheen_bsdf> -->
-  <!--
-  <implementation name="IM_sheen_bsdf_genosl" nodedef="ND_sheen_bsdf" file="mx_sheen_bsdf.osl" function="mx_sheen_bsdf" target="genosl" />
-  -->
   <implementation name="IM_sheen_bsdf_genosl" nodedef="ND_sheen_bsdf" sourcecode="{{weight}} * sheen_bsdf({{normal}}, {{color}}, {{roughness}})" target="genosl" />
 
   <!-- <anisotropic_vdf> -->
-  <!--
-  <implementation name="IM_anisotropic_vdf_genosl" nodedef="ND_anisotropic_vdf" file="mx_anisotropic_vdf.osl" function="mx_anisotropic_vdf" target="genosl" />
-  -->
   <implementation name="IM_anisotropic_vdf_genosl" nodedef="ND_anisotropic_vdf" file="mx_anisotropic_vdf.osl" function="mx_anisotropic_vdf" target="genosl" />
 
   <!-- <thin_film_bsdf> -->
   <implementation name="IM_thin_film_bsdf_genosl" nodedef="ND_thin_film_bsdf" target="genosl" />
 
   <!-- <uniform_edf> -->
-  <!--
-  <implementation name="IM_uniform_edf_genosl" nodedef="ND_uniform_edf" sourcecode="{{color}} * emission()" target="genosl" />
-  -->
   <implementation name="IM_uniform_edf_genosl" nodedef="ND_uniform_edf" sourcecode="uniform_edf({{color}})" target="genosl" />
 
   <!-- <layer> -->
@@ -66,37 +39,20 @@
   <implementation name="IM_layer_vdf_genosl" nodedef="ND_layer_vdf" target="genosl" />
 
   <!-- <mix> -->
-  <!--
-  <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" target="genosl" />
-  <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" target="genosl" />
-  -->
   <implementation name="IM_mix_bsdf_genosl" nodedef="ND_mix_bsdf" sourcecode="mix({{bg}}, {{fg}}, {{mix}})" target="genosl" />
   <implementation name="IM_mix_edf_genosl" nodedef="ND_mix_edf" sourcecode="mix({{bg}}, {{fg}}, {{mix}})" target="genosl" />
 
   <!-- <add> -->
-  <!--
-  <implementation name="IM_add_bsdf_genosl" nodedef="ND_add_bsdf" target="genosl" />
-  <implementation name="IM_add_edf_genosl" nodedef="ND_add_edf" target="genosl" />
-  -->
   <implementation name="IM_add_bsdf_genosl" nodedef="ND_add_bsdf" sourcecode="({{in1}} + {{in2}})" target="genosl" />
   <implementation name="IM_add_edf_genosl" nodedef="ND_add_edf" sourcecode="({{in1}} + {{in2}})" target="genosl" />
 
   <!-- <multiply> -->
-  <!--
-  <implementation name="IM_multiply_bsdfC_genosl" nodedef="ND_multiply_bsdfC" target="genosl" />
-  <implementation name="IM_multiply_bsdfF_genosl" nodedef="ND_multiply_bsdfF" target="genosl" />
-  <implementation name="IM_multiply_edfC_genosl" nodedef="ND_multiply_edfC" target="genosl" />
-  <implementation name="IM_multiply_edfF_genosl" nodedef="ND_multiply_edfF" target="genosl" />
-  -->
   <implementation name="IM_multiply_bsdfC_genosl" nodedef="ND_multiply_bsdfC" sourcecode="({{in2}} * {{in1}})" target="genosl" />
   <implementation name="IM_multiply_bsdfF_genosl" nodedef="ND_multiply_bsdfF" sourcecode="({{in2}} * {{in1}})" target="genosl" />
   <implementation name="IM_multiply_edfC_genosl" nodedef="ND_multiply_edfC" sourcecode="({{in2}} * {{in1}})" target="genosl" />
   <implementation name="IM_multiply_edfF_genosl" nodedef="ND_multiply_edfF" sourcecode="({{in2}} * {{in1}})" target="genosl" />
 
   <!-- <surface> -->
-  <!--
-  <implementation name="IM_surface_genosl" nodedef="ND_surface" file="legacy/mx_surface.osl" function="mx_surface" target="genosl" />
-  -->
   <implementation name="IM_surface_genosl" nodedef="ND_surface" file="mx_surface.osl" function="mx_surface" target="genosl" />
 
   <!-- <displacement> -->
diff --git a/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp b/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp
index 79f1be8ffc..f11ad6a54f 100644
--- a/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp
+++ b/source/MaterialXGenOsl/Nodes/ClosureLayerNodeOsl.cpp
@@ -37,7 +37,9 @@ void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext&
     ShaderNode* top = topInput->getConnection()->getNode();
     ShaderNode* base = baseInput->getConnection()->getNode();
 
-#if MATERIALX_OSL_LEGACY_CLOSURES
+#ifdef MATERIALX_OSL_LEGACY_CLOSURES
+
+    ClosureContext* cct = context.getClosureContext();
 
     if (top->hasClassification(ShaderNode::Classification::THINFILM))
     {
@@ -50,8 +52,6 @@ void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext&
             throw ExceptionShaderGenError("Thin-film can only be applied to a sibling node, not through a graph interface");
         }
 
-        ClosureContext* cct = context.getClosureContext();
-
         // Set the extra parameters for thin-film.
         ClosureContext::ClosureParams params;
         params[THICKNESS] = top->getInput(THICKNESS);
@@ -125,8 +125,15 @@ void ClosureLayerNodeOsl::emitFunctionCall(const ShaderNode& _node, GenContext&
     else
     {
         // Emit the function call for top and base layer.
-        shadergen.emitFunctionCall(*top, context, stage);
-        shadergen.emitFunctionCall(*base, context, stage);
+        // Make sure the connections are sibling nodes and not the graph interface.
+        if (top->getParent() == node.getParent())
+        {
+            shadergen.emitFunctionCall(*top, context, stage);
+        }
+        if (base->getParent() == node.getParent())
+        {
+            shadergen.emitFunctionCall(*base, context, stage);
+        }
 
         // Get the result variables.
         const string& topResult = topInput->getConnection()->getVariable();
diff --git a/source/MaterialXGenOsl/OslShaderGenerator.cpp b/source/MaterialXGenOsl/OslShaderGenerator.cpp
index 170e430ad7..b7eddaba34 100644
--- a/source/MaterialXGenOsl/OslShaderGenerator.cpp
+++ b/source/MaterialXGenOsl/OslShaderGenerator.cpp
@@ -166,7 +166,8 @@ OslShaderGenerator::OslShaderGenerator() :
     registerImplementation("IM_layer_bsdf_" + OslShaderGenerator::TARGET, ClosureLayerNodeOsl::create);
     registerImplementation("IM_layer_vdf_" + OslShaderGenerator::TARGET, ClosureLayerNodeOsl::create);
 
-#if MATERIALX_OSL_LEGACY_CLOSURES
+#ifdef MATERIALX_OSL_LEGACY_CLOSURES
+
     // <!-- <mix> -->
     registerImplementation("IM_mix_bsdf_" + OslShaderGenerator::TARGET, ClosureMixNode::create);
     registerImplementation("IM_mix_edf_" + OslShaderGenerator::TARGET, ClosureMixNode::create);
@@ -178,6 +179,7 @@ OslShaderGenerator::OslShaderGenerator() :
     registerImplementation("IM_multiply_bsdfF_" + OslShaderGenerator::TARGET, ClosureMultiplyNode::create);
     registerImplementation("IM_multiply_edfC_" + OslShaderGenerator::TARGET, ClosureMultiplyNode::create);
     registerImplementation("IM_multiply_edfF_" + OslShaderGenerator::TARGET, ClosureMultiplyNode::create);
+
 #endif // MATERIALX_OSL_LEGACY_CLOSURES
 
     // <!-- <thin_film> -->
diff --git a/source/MaterialXGenOsl/OslSyntax.cpp b/source/MaterialXGenOsl/OslSyntax.cpp
index c0d3848a35..abc92e756e 100644
--- a/source/MaterialXGenOsl/OslSyntax.cpp
+++ b/source/MaterialXGenOsl/OslSyntax.cpp
@@ -457,7 +457,7 @@ OslSyntax::OslSyntax()
             "struct textureresource { string filename; string colorspace; };")
     );
 
-#if MATERIALX_OSL_LEGACY_CLOSURES
+#ifdef MATERIALX_OSL_LEGACY_CLOSURES
 
     registerTypeSyntax
     (

From 7df75902ce89b6807f16bc842cf03969ddb5b423 Mon Sep 17 00:00:00 2001
From: Niklas Harrysson <niklas.harrysson@gmail.com>
Date: Mon, 1 Aug 2022 22:38:53 +0200
Subject: [PATCH 4/5] Fix bug in OSL shader code snippet

---
 libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl b/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
index 826eee2bd6..17a4aff2cb 100644
--- a/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
+++ b/libraries/pbrlib/genosl/legacy/mx_subsurface_bsdf.osl
@@ -1,5 +1,6 @@
 void mx_subsurface_bsdf(float weight, color _color, vector radius, float anisotropy, normal N, output BSDF bsdf)
 {
     // TODO: Subsurface closure is not supported by vanilla OSL.
-    bsdf = _color * weight * diffuse(N);
+    bsdf.response = _color * weight * diffuse(N);
+    bsdf.throughput = color(0.0);
 }

From aad506a50f30b37a67e28ad9a55889174a097d0b Mon Sep 17 00:00:00 2001
From: Niklas Harrysson <niklas.harrysson@gmail.com>
Date: Mon, 1 Aug 2022 23:29:54 +0200
Subject: [PATCH 5/5] Update a doc string

---
 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a5759e92dc..651c1b4eb6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -50,7 +50,7 @@ option(MATERIALX_INSTALL_PYTHON "Install the MaterialX Python package as a third
 option(MATERIALX_TEST_RENDER "Run rendering tests for MaterialX Render module. GPU required for graphics validation." ON)
 option(MATERIALX_WARNINGS_AS_ERRORS "Interpret all compiler warnings as errors." OFF)
 option(MATERIALX_DYNAMIC_ANALYSIS "Build MaterialX libraries with dynamic analysis on supporting platforms." OFF)
-option(MATERIALX_OSL_LEGACY_CLOSURES "Code generation support for the old legacy OSL closures." ON)
+option(MATERIALX_OSL_LEGACY_CLOSURES "Build OSL shader generation supporting the legacy OSL closures." ON)
 
 set(MATERIALX_PYTHON_VERSION "" CACHE STRING
     "Python version to be used in building the MaterialX Python package (e.g. '2.7').")