Add opacityMode attrib support(introduced from UsdPreviewSurface v2.6)

src/pprinter.cc

@@ -2451,6 +2451,23 @@ std::string to_string(tinyusdz::CollectionInstance::ExpansionRule rule) {
   return s;
 }
 
+std::string to_string(const tinyusdz::UsdPreviewSurface::OpacityMode v) {
+  std::string s;
+
+  switch (v) {
+    case tinyusdz::UsdPreviewSurface::OpacityMode::Transparent: {
+      s = "transparent";
+      break;
+    }
+    case tinyusdz::UsdPreviewSurface::OpacityMode::Presence: {
+      s = "presence";
+      break;
+    }
+  }
+
+  return s;
+}
+
 std::string to_string(const tinyusdz::UsdUVTexture::SourceColorSpace v) {
   std::string s;
 
@@ -3947,6 +3964,8 @@ static std::string print_shader_params(const UsdPreviewSurface &shader,
                          indent);
   ss << print_typed_attr(shader.roughness, "inputs:roughness", indent);
   ss << print_typed_attr(shader.opacity, "inputs:opacity", indent);
+  ss << print_typed_token_attr(shader.opacityMode, "inputs:opacityMode",
+                         indent);
   ss << print_typed_attr(shader.opacityThreshold, "inputs:opacityThreshold",
                          indent);
   ss << print_typed_attr(shader.normal, "inputs:normal", indent);

src/pprinter.hh

@@ -209,6 +209,8 @@ std::string to_string(const UsdPrimvarReader_float4 &shader,
 std::string to_string(const UsdPrimvarReader_int &shader,
                       const uint32_t indent = 0, bool closing_brace = true);
 
+std::string to_string(const UsdPreviewSurface::OpacityMode v);
+
 std::string to_string(const UsdUVTexture::SourceColorSpace v);
 std::string to_string(const UsdUVTexture::Wrap v);
 

src/prim-reconstruct.cc

@@ -3985,6 +3985,18 @@ bool ReconstructShader<UsdPreviewSurface>(
   (void)references;
   (void)options;
 
+  auto OpacityModeHandler = [](const std::string &tok)
+      -> nonstd::expected<UsdPreviewSurface::OpacityMode, std::string> {
+    using EnumTy = std::pair<UsdPreviewSurface::OpacityMode, const char *>;
+    const std::vector<EnumTy> enums = {
+        std::make_pair(UsdPreviewSurface::OpacityMode::Transparent, "transparent"),
+        std::make_pair(UsdPreviewSurface::OpacityMode::Presence, "presence"),
+    };
+
+    return EnumHandler<UsdPreviewSurface::OpacityMode>(
+        "inputs:opacityMode", tok, enums);
+  };
+
   std::set<std::string> table;
   table.insert("info:id"); // `info:id` is already parsed in ReconstructPrim<Shader>
   for (auto &prop : properties) {
@@ -4004,6 +4016,11 @@ bool ReconstructShader<UsdPreviewSurface>(
                          UsdPreviewSurface, surface->clearcoatRoughness)
     PARSE_TYPED_ATTRIBUTE(table, prop, "inputs:opacity", UsdPreviewSurface,
                          surface->opacity)
+    // From 2.6
+    PARSE_TIMESAMPLED_ENUM_PROPERTY(table, prop, "inputs:opacityMode",
+                       UsdPreviewSurface::OpacityMode, OpacityModeHandler, UsdPreviewSurface,
+                       surface->opacityMode, options.strict_allowedToken_check)
+
     PARSE_TYPED_ATTRIBUTE(table, prop, "inputs:opacityThreshold",
                          UsdPreviewSurface, surface->opacityThreshold)
     PARSE_TYPED_ATTRIBUTE(table, prop, "inputs:ior", UsdPreviewSurface,

src/usdShade.hh

@@ -198,6 +198,13 @@ struct UsdUVTexture : ShaderNode {
 // $USD/pxr/usdImaging/plugin/usdShaders/shaders/shaderDefs.usda
 
 struct UsdPreviewSurface : ShaderNode {
+  
+  // From 2.6
+  // NOTE: When opacityThreshold is non-zero, opacityMode is ignored. 
+  enum class OpacityMode {
+    Transparent, // "transparent" : the material will still receive a lighting response
+    Presence, // "presence" : no lighting response
+  };
 
   TypedAttributeWithFallback<Animatable<value::color3f>> diffuseColor{value::color3f{0.18f, 0.18f, 0.18f}};  // "inputs:diffuseColor"
   TypedAttributeWithFallback<Animatable<value::color3f>> emissiveColor{value::color3f{0.0f, 0.0f, 0.0f}};  // "inputs:emissiveColor"
@@ -216,6 +223,9 @@ struct UsdPreviewSurface : ShaderNode {
   TypedAttributeWithFallback<Animatable<float>> clearcoatRoughness{0.01f};  // "inputs:clearcoatRouighness"
   TypedAttributeWithFallback<Animatable<float>> roughness{0.5f};  // "inputs:roughness"
   TypedAttributeWithFallback<Animatable<float>> opacity{1.0f};  // "inputs:opacity"
+
+  TypedAttributeWithFallback<Animatable<OpacityMode>> opacityMode{OpacityMode::Transparent};  // "inputs:opacityMode"
+
   TypedAttributeWithFallback<Animatable<float>> opacityThreshold{0.0f};  // "inputs:opacityThreshold"
   TypedAttributeWithFallback<Animatable<float>> ior{1.5f};  // "inputs:ior"
 

tests/usda/shader-opacityMode-000.usda

@@ -0,0 +1,10 @@
+#usda 1.0
+
+def Shader "OpacityMode"
+{
+    uniform token info:id = "UsdPreviewSurface"
+    token inputs:opacityMode = "transparent"
+
+    token outputs:displacement
+    token outputs:surface
+}

tests/usda/shader-opacityMode-001.usda

@@ -0,0 +1,10 @@
+#usda 1.0
+
+def Shader "OpacityMode"
+{
+    uniform token info:id = "UsdPreviewSurface"
+    token inputs:opacityMode = "presence"
+
+    token outputs:displacement
+    token outputs:surface
+}