Feat: Add UsdTransform2d export support

package/com.unity.formats.usd/Dependencies/USD.NET.Unity/Shading/UsdPreviewSurface/UsdTransform2dSample.cs

@@ -0,0 +1,56 @@
+// Copyright 2021 Unity Technologies. All rights reserved.
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using UnityEngine;
+
+namespace USD.NET.Unity
+{
+    /// <summary>
+    /// The following is based on the Pixar specification found here:
+    /// https://graphics.pixar.com/usd/release/spec_usdpreviewsurface.html#transform2d
+    /// </summary>
+    [System.Serializable]
+    [UsdSchema("Shader")]
+    public class UsdTransform2dSample : ShaderSample
+    {
+        public UsdTransform2dSample()
+        {
+            id = new pxr.TfToken("UsdTransform2d");
+        }
+
+        /// <summary>
+        /// Name of the primvar to be read from the primitive.
+        /// </summary>
+        [InputParameter("in")]
+        public Connectable<pxr.TfToken> @in = new Connectable<pxr.TfToken>();
+
+        [InputParameter("_Scale")]
+        public Connectable<Vector2> scale = new Connectable<Vector2>(new Vector2(1.0f, 1.0f));
+
+        [InputParameter("_Translation")]
+        public Connectable<Vector2> translation = new Connectable<Vector2>(new Vector2(0.0f, 0.0f));
+
+        [InputParameter("_Rotation")]
+        public Connectable<float> rotation = new Connectable<float>(0.0f);
+
+        public class Outputs : SampleBase
+        {
+            public Vector2? result;
+        }
+
+        [UsdNamespace("outputs")]
+        public Outputs outputs = new Outputs();
+    }
+}

package/com.unity.formats.usd/Runtime/Scripts/IO/Materials/ShaderExporterBase.cs

@@ -83,8 +83,11 @@ protected static string SetupTexture(Scene scene,
                         // normal needs to be converted if the one on disk isn't really a normal map
                         // (e.g. created from greyscale)
                         UnityEditor.TextureImporter importer =
-                            (UnityEditor.TextureImporter)UnityEditor.AssetImporter.GetAtPath(
-                                UnityEditor.AssetDatabase.GetAssetPath(srcTexture2d));
+                            UnityEditor.AssetImporter.GetAtPath(
+                                UnityEditor.AssetDatabase.GetAssetPath(srcTexture2d)) as UnityEditor.TextureImporter;
+
+                        if (!importer) break;
+
                         if (importer.textureType != UnityEditor.TextureImporterType.NormalMap)
                         {
                             Debug.LogWarning("Texture " + textureName + " is set as NormalMap but isn't marked as such",
@@ -298,10 +301,44 @@ protected static string SetupTexture(Scene scene,
                 filePath = ImporterBase.MakeRelativePath(scene.FilePath, filePath);
                 filePath = filePath.Replace("\\", "/");
 
+                // uvReader - gets UV data from mesh
                 var uvReader = new PrimvarReaderSample<Vector2>();
                 uvReader.varname.defaultValue = new TfToken("st");
                 scene.Write(usdShaderPath + "/uvReader", uvReader);
-                var usdTexReader = new TextureReaderSample(filePath, usdShaderPath + "/uvReader.outputs:result");
+                var connectionPath = "/uvReader.outputs:result";
+
+                var textureOffset = material.GetTextureOffset(textureName);
+                var textureScale = material.GetTextureScale(textureName);
+                var textureRotation = material.HasProperty(textureName + "Rotation") ? Mathf.Rad2Deg * material.GetFloat(textureName + "Rotation") : 0f;
+
+                if (textureOffset == Vector2.zero && textureScale == Vector2.one)
+                {
+                    textureOffset = material.mainTextureOffset;
+                    textureScale = material.mainTextureScale;
+                }
+
+                // Workaround: texture rotation in USDZ rotates around top left corner while glTF rotates around bottom left corner.
+                // Since shaders are built for the latter we need to compensate here.
+                var v = new Vector2(0 * textureScale.x, 1 * textureScale.y);
+                v = Matrix4x4.Rotate(Quaternion.Euler(0, 0, textureRotation)) * new Vector4(v.x, v.y, 0, 1);
+                v.y -= 1 * textureScale.y;
+                textureOffset -= v;
+
+                // export UsdTransform2d, only if non-default offset/scale
+                if(textureOffset != Vector2.zero || textureScale != Vector2.one || textureRotation != 0)
+                {
+                    var usdTransform = new UsdTransform2dSample();
+                    usdTransform.scale = new Connectable<Vector2>(textureScale);
+                    usdTransform.translation = new Connectable<Vector2>(textureOffset);
+                    if(textureRotation != 0)
+                        usdTransform.rotation = new Connectable<float>(textureRotation);
+                    usdTransform.@in.SetConnectedPath(usdShaderPath + "/uvReader.outputs:result");
+                    scene.Write(usdShaderPath + "/usdTransform", usdTransform);
+                    connectionPath = "/usdTransform.outputs:result";
+                }
+
+                // texture reader - actual texture data based on transformed UV coordinates
+                var usdTexReader = new TextureReaderSample(filePath, usdShaderPath + connectionPath);
                 usdTexReader.wrapS =
                     new Connectable<TextureReaderSample.WrapMode>(
                         TextureReaderSample.GetWrapMode(srcTexture2d.wrapModeU));
@@ -312,9 +349,9 @@ protected static string SetupTexture(Scene scene,
                 {
                     usdTexReader.scale = new Connectable<Vector4>(scale);
                 }
-
                 // usdTexReader.isSRGB = new Connectable<TextureReaderSample.SRGBMode>(TextureReaderSample.SRGBMode.Auto);
                 scene.Write(usdShaderPath + "/" + textureName, usdTexReader);
+
                 return usdShaderPath + "/" + textureName + ".outputs:" + textureOutput;
             }
             else

package/com.unity.formats.usd/Runtime/Scripts/IO/Materials/StandardShaderExporter.cs

@@ -301,6 +301,7 @@ private static void ExportStandardCommon(Scene scene,
         {
             Color c;
 
+#if EXPORT_UNITY_SPECIFIC_DATA
             // Export all generic parameter.
             // These are not useful to UsdPreviewSurface, but enable perfect round-tripping.
             surface.unity.shaderName = mat.shader.name;
@@ -333,6 +334,7 @@ private static void ExportStandardCommon(Scene scene,
                         break;
                 }
             }
+#endif
 #endif
 
             if (mat.HasProperty("_MainTex") && mat.GetTexture("_MainTex") != null)