Support custom kind value.

src/pprinter.cc

@@ -453,7 +453,7 @@ std::string print_prim_metas(const PrimMeta &meta, const uint32_t indent) {
   }
 
   if (meta.kind) {
-    ss << pprint::Indent(indent) << "kind = " << quote(to_string(meta.kind.value())) << "\n";
+    ss << pprint::Indent(indent) << "kind = " << quote(meta.get_kind()) << "\n";
   }
 
   // TODO: UTF-8 ready pprint
@@ -1804,6 +1804,9 @@ std::string to_string(tinyusdz::Kind v) {
     return "subcomponent";
   } else if (v == tinyusdz::Kind::SceneLibrary) {
     return "sceneLibrary";
+  } else if (v == tinyusdz::Kind::UserDef) {
+    // Should use PrimMeta::get_kind() to get actual Kind string value.
+    return "[[InternalError. UserDefKind]]";
   } else {
     return "[[InvalidKind]]";
   }

src/prim-types.cc

@@ -622,8 +622,11 @@ nonstd::optional<Kind> KindFromString(const std::string &str) {
   } else if (str == "sceneLibrary") {
     // https://developer.apple.com/documentation/arkit/usdz_schemas_for_ar/scenelibrary
     return Kind::SceneLibrary;
+  } else if (str.empty()) {
+    return nonstd::nullopt;
+  } else {
+    return Kind::UserDef;
   }
-  return nonstd::nullopt;
 }
 
 bool ValidatePrimElementName(const std::string &name) {
@@ -1313,6 +1316,7 @@ const PrimMeta &Prim::metas() const {
   return EmptyStaticMeta::GetEmptyStaticMeta();
 }
 
+
 bool SetCustomDataByKey(const std::string &key, const MetaVariable &var,
                         CustomDataType &custom) {
   // split by namespace
@@ -1581,6 +1585,19 @@ AssetInfo PrimMeta::get_assetInfo(bool *is_authored) const {
   return ainfo;
 }
 
+const std::string PrimMeta::get_kind() const {
+
+  if (kind.has_value()) {
+    if (kind.value() == Kind::UserDef) {
+      return _kind_str;
+    } else {
+      return to_string(kind.value());
+    }
+  }
+
+  return "";
+}
+
 bool IsXformablePrim(const Prim &prim) {
   uint32_t tyid = prim.type_id();
 

src/prim-types.hh

@@ -90,6 +90,7 @@ enum class Purpose {
 // USDZ extension: sceneLibrary
 // https://developer.apple.com/documentation/arkit/usdz_schemas_for_ar/scenelibrary
 //
+
 enum class Kind {
   Model,
   Group,
@@ -97,6 +98,7 @@ enum class Kind {
   Component,
   Subcomponent,
   SceneLibrary,  // USDZ extension
+  UserDef, // Unknown or user defined Kind
   Invalid
 };
 
@@ -791,7 +793,9 @@ struct Payload {
 struct PrimMetas {
   nonstd::optional<bool> active;  // 'active'
   nonstd::optional<bool> hidden;  // 'hidden'
-  nonstd::optional<Kind> kind;    // 'kind'
+  nonstd::optional<Kind> kind;    // 'kind'. user-defined kind value is stored in _kind_str;
+  std::string _kind_str;
+
   nonstd::optional<Dictionary>
       assetInfo;  // 'assetInfo' // TODO: Use AssetInfo?
   nonstd::optional<Dictionary> customData;  // `customData`
@@ -804,6 +808,10 @@ struct PrimMetas {
 
   nonstd::optional<bool> instanceable; // 'instanceable'
 
+  // String representation of Kind.
+  // For user-defined Kind, it returns `_kind_str`
+  const std::string get_kind() const;
+
   //
   // AssetInfo utility function
   //

src/usda-reader.cc

@@ -942,7 +942,10 @@ class USDAReader::Impl {
               // USDZ specific: https://developer.apple.com/documentation/arkit/usdz_schemas_for_ar/scenelibrary
               out->kind = Kind::SceneLibrary;
             } else {
-              PUSH_ERROR_AND_RETURN("Invalid token for `kind` metadataum.");
+              // NOTE: empty token allowed.
+
+              out->kind = Kind::UserDef;
+              out->_kind_str = tok.str();
             }
             DCOUT("Added kind: " << to_string(out->kind.value()));
           } else {

src/usdc-reader.cc

@@ -1825,13 +1825,26 @@ bool USDCReader::Impl::ParsePrimSpec(const crate::FieldValuePairVector &fvs,
       }
     } else if (fv.first == "kind") {
       if (auto pv = fv.second.as<value::token>()) {
-        if (auto kv = KindFromString(pv->str())) {
-          primMeta.kind = kv.value();
-        } else {
-          PUSH_ERROR_AND_RETURN_TAG(
-              kTag, fmt::format("Invalid token for `kind` Prim metadata: `{}`",
-                                pv->str()));
-        }
+
+          const value::token tok = (*pv);
+          if (tok.str() == "subcomponent") {
+            primMeta.kind = Kind::Subcomponent;
+          } else if (tok.str() == "component") {
+            primMeta.kind = Kind::Component;
+          } else if (tok.str() == "model") {
+            primMeta.kind = Kind::Model;
+          } else if (tok.str() == "group") {
+            primMeta.kind = Kind::Group;
+          } else if (tok.str() == "assembly") {
+            primMeta.kind = Kind::Assembly;
+          } else if (tok.str() == "sceneLibrary") {
+            // USDZ specific: https://developer.apple.com/documentation/arkit/usdz_schemas_for_ar/scenelibrary
+            primMeta.kind = Kind::SceneLibrary;
+          } else {
+
+            primMeta.kind = Kind::UserDef;
+            primMeta._kind_str = tok.str();
+          }
       } else {
         PUSH_ERROR_AND_RETURN_TAG(kTag,
                                   "`kind` must be type `token`, but got type `"

tests/usda/user-def-kind-001.usda

@@ -0,0 +1,6 @@
+#usda 1.0
+
+def "bora" (
+  kind = "muda"
+) {
+}