Add type alias support to the reverse bindings (#USDU-3 part 2)

package/com.unity.formats.usd/Dependencies/USD.NET.Unity/UnityTypeBindings.cs

@@ -55,10 +55,12 @@ static public void RegisterTypes()
                 (object obj) => UnityTypeConverter.Vector2ToVec2f((Vector2)obj),
                 (pxr.VtValue value) => UnityTypeConverter.Vec2fToVector2(value),
                 SdfValueTypeNames.Float2));
+            binder.AddTypeAlias(SdfValueTypeNames.TexCoord2f, SdfValueTypeNames.Float2);
             binder.BindType(typeof(Vector3), new UsdTypeBinding(
                 (object obj) => UnityTypeConverter.Vector3ToVec3f((Vector3)obj),
                 (pxr.VtValue value) => UnityTypeConverter.Vec3fToVector3(value),
                 SdfValueTypeNames.Float3));
+            binder.AddTypeAlias(SdfValueTypeNames.TexCoord3f, SdfValueTypeNames.Float3);
             binder.BindType(typeof(Vector4), new UsdTypeBinding(
                 (object obj) => UnityTypeConverter.Vector4ToVec4f((Vector4)obj),
                 (pxr.VtValue value) => UnityTypeConverter.Vec4fToVector4(value),
@@ -77,9 +79,11 @@ static public void RegisterTypes()
             //
             binder.BindArrayType<UnityTypeConverter>(typeof(Vector2[]), typeof(pxr.VtVec2fArray), SdfValueTypeNames.Float2Array);
             binder.BindArrayType<UnityTypeConverter>(typeof(List<Vector2>), typeof(pxr.VtVec2fArray), SdfValueTypeNames.Float2Array, "List");
+            binder.AddTypeAlias(SdfValueTypeNames.TexCoord2fArray, SdfValueTypeNames.Float2Array);
 
             binder.BindArrayType<UnityTypeConverter>(typeof(Vector3[]), typeof(pxr.VtVec3fArray), SdfValueTypeNames.Float3Array);
             binder.BindArrayType<UnityTypeConverter>(typeof(List<Vector3>), typeof(pxr.VtVec3fArray), SdfValueTypeNames.Float3Array, "List");
+            binder.AddTypeAlias(SdfValueTypeNames.TexCoord3fArray, SdfValueTypeNames.Float3Array);
 
             binder.BindArrayType<UnityTypeConverter>(typeof(Vector4[]), typeof(pxr.VtVec4fArray), SdfValueTypeNames.Float4Array);
             binder.BindArrayType<UnityTypeConverter>(typeof(List<Vector4>), typeof(pxr.VtVec4fArray), SdfValueTypeNames.Float4Array, "List");

package/com.unity.formats.usd/Dependencies/USD.NET/USD.NET.api

@@ -14973,12 +14973,14 @@ namespace USD.NET
     {
         public static bool EnableCodeGeneration;
         public TypeBinder() {}
+        public void AddTypeAlias(pxr.SdfValueTypeName alias, pxr.SdfValueTypeName target);
         public void BindArrayType<ConverterT>(System.Type csType, System.Type vtArrayType, pxr.SdfValueTypeName sdfName, string methodNamePrefix = );
         public void BindNativeType(System.Type csType, pxr.SdfValueTypeName sdfName);
         public void BindType(System.Type csType, USD.NET.UsdTypeBinding binding);
         public bool GetBinding(System.Type key, out USD.NET.UsdTypeBinding binding);
         public bool GetReverseBinding(pxr.SdfValueTypeName key, out USD.NET.UsdTypeBinding binding);
         public bool GetReverseBinding(System.Type key, out USD.NET.UsdTypeBinding binding);
+        public bool RemoveTypeAlias(pxr.SdfValueTypeName alias);
     }
 
     public class UsdAssetPathAttribute : System.Attribute

package/com.unity.formats.usd/Dependencies/USD.NET/serialization/TypeBinder.cs

@@ -14,6 +14,8 @@
 
 using System;
 using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using pxr;
 
 namespace USD.NET
 {
@@ -68,6 +70,12 @@ public class TypeBinder
         Dictionary<string, string> typeNameMapping = new Dictionary<string, string>();
         Dictionary<Type, Dictionary<pxr.TfToken, Enum>> enumMaps = new Dictionary<Type, Dictionary<pxr.TfToken, Enum>>();
 
+        /// <summary>
+        /// USD types can be aliased to represent different roles float2/texcoord2, vec3/point/color and drive the interpretation
+        /// Add aliases if your target application need to map multiple USD types to a single type.
+        /// </summary>
+        Dictionary<string, string> typeAliases = new Dictionary<string, string>();
+
         public TypeBinder()
         {
             // TODO: kill this, see above.
@@ -93,12 +101,29 @@ private bool IsCodeGenEnabled()
 #endif
         }
 
+        /// <summary>
+        /// Get a binding from a USD type
+        /// </summary>
+        /// <remarks>
+        /// Used the C# type needs to be derived from the USD type.
+        /// Example: UVs can be of type float2, float3, texcoord2f, texcoord2f
+        /// </remarks>
         public bool GetReverseBinding(pxr.SdfValueTypeName key, out UsdTypeBinding binding)
         {
+            // Check if the given sdf type name is an alias
+            // https://graphics.pixar.com/usd/docs/api/_usd__page__datatypes.html#Usd_Roles
+            string name;
+            bool match = true;
+            if (!typeAliases.TryGetValue(key.GetAsToken(), out name))
+            {
+                name = key.GetAsToken();
+                match = false;
+            }
+
             // TODO: we could keep a reverse mapping, but waiting for deeper performance analysis first.
             foreach (var kvp in bindings)
             {
-                if (kvp.Value.sdfTypeName == key)
+                if (kvp.Value.sdfTypeName.GetAsToken() == name)
                 {
                     binding = kvp.Value;
                     return true;
@@ -414,6 +439,16 @@ object GuidToCs_String(pxr.VtValue vtValue)
             return new Guid(pxr.UsdCs.VtValueTostring(vtValue));
         }
 
+        public void AddTypeAlias(SdfValueTypeName alias, SdfValueTypeName target)
+        {
+            typeAliases.Add(alias.GetAsToken(), target.GetAsToken());
+        }
+
+        public bool RemoveTypeAlias(SdfValueTypeName alias)
+        {
+            return typeAliases.Remove(alias.GetAsToken());
+        }
+
         private void RegisterIntrinsicTypes()
         {
             // --------------------------------------------------------------------------------------- //

package/com.unity.formats.usd/Tests/USD.NET/BasicTests.cs

@@ -659,5 +659,23 @@ public static void ReadNonExistingPrimsTest()
             Assert.True(sample3.number == 0);
             Assert.True(sample3.rel == null);
         }
+
+        [Test]
+        public static void ReverseBindingForAliasedType_NotFoundByDefault()
+        {
+            UsdTypeBinding binding;
+            UsdIo.Bindings.GetReverseBinding(SdfValueTypeNames.Normal3f, out binding);
+            Assert.Null(binding.sdfTypeName);
+        }
+
+        [Test]
+        public static void ReverseBindingForAliasedType_FoundAfterAliasing()
+        {
+            UsdIo.Bindings.AddTypeAlias(SdfValueTypeNames.Normal3f, SdfValueTypeNames.Float3);
+            UsdTypeBinding binding;
+            UsdIo.Bindings.GetReverseBinding(SdfValueTypeNames.Normal3f, out binding);
+            Assert.AreEqual(SdfValueTypeNames.Float3, binding.sdfTypeName);
+            UsdIo.Bindings.RemoveTypeAlias(SdfValueTypeNames.Normal3f);
+        }
     }
 }