Fix Export Transform Overrides (#USDU-216) (#279)

* Fix the XForm override export and add the option to the recorder

* Remove sublayers, remove ref from root, ass tests

* Rename exportXformOverride to exportTransformOverride

* Update changelog

* Fix UI Labels to workaround layout issues

* Fixes from PR review.

- Fix for null ref exception when the source GO is not a UsdAsset
- Fix for unclear UI

* XFormable schema type should not override the actual schema type.

* Removes the reference to the original file from exported override files written out by Recorder.

* Switch transform export back to Xform from Xformable, because using base UsdGeomXformable prim types is unusual

---------

Co-authored-by: Vicky Clark <[email protected]>
Co-authored-by: Andrew Lee <[email protected]>
Co-authored-by: Vicky Clark <[email protected]>

Author: 3 people

.gitignore

@@ -72,4 +72,5 @@ TestProject/**/Logs
 TestProject/**/*.csproj
 TestProject/**/*.sln
 TestProject/Usd-Development/Library
+TestProject/Usd-Development/.vs
 build_usdcs

README.md

@@ -124,6 +124,34 @@ When compatibility with runtime is required (i.e for a standalone build), the re
 
 >  **Note:** This feature has no dependency to and is not based on the Recorder package.
 
+### Exporting Transform Overrides
+
+Modifications to transforms in USD files can be exported as overrides to the original files. 
+
+Overrides can be exported from the USD menu with the GameObject containing the UsdAsset component selected, which will export transform overrides for the entire hierarchy. Alternatively, you can also export just the overrides when exporting from the Recorder window by changing the 'Override Setting' to 'Export Transform Overrides Only'.
+
+For full asset pipeline flexibility these override files do not include a reference to the original file, but this can be added by manually adding a sublayer in the header of the resulting USDA file:
+
+```
+#usda 1.0
+(
+    defaultPrim = "myCube"
+    endTimeCode = 0
+    startTimeCode = 0
+    upAxis = "Y"
+    subLayers = [
+        @c:/path/to/original/myCube.usda@
+    ]
+)
+
+over "myCube"
+{
+    ...
+}
+```
+
+Note: Modifications to the transform of the Root GameObject is not currently reflected in the override, as Unity assumes the root in all USD files is at the origin.
+
 # License
 
 The USD Unity SDK is licensed under the terms of the Apache

package/com.unity.formats.usd/CHANGELOG.md

@@ -1,7 +1,11 @@
-# Changes in usd-unitysdk for Unity
+# Changes in usd-unity-sdk for Unity
 
 ## Unreleased
+### Features
+- The USD Recorder now has an option to export transform overrides.
+
 ### Bug Fixes
+- "Export Transform Override" now properly exports modified transforms only.
 - Fixed a bug where importing materials exported from USD version >= 21.11 would fail.
 - Fixed loading of meshes with arbitrary primvars.
 - Fixed regression in animated mesh properties.
@@ -17,7 +21,7 @@
 - Fixed an import bug causing instanced primitives not to be sanitized to fit Unity formats, including converting basis, triangulating and unwinding meshes, and unrolling primvars.
 
 ### Changed
-- GC allocs reduced by half for Scene.GetAttributeAtPath and Scene.GetRelationshipAtPath
+- GC allocs reduced by half for Scene.GetAttributeAtPath and Scene.GetRelationshipAtPath.
 - Disabled plugins on unsupported platforms.
 - Optimized triangulation to reduce the chance of a "Timed out while waiting for thread" error on importing a complex mesh.
 - Optimized PointInstance importing.

package/com.unity.formats.usd/Editor/Recorder/Editors/UsdRecorderSettingsEditor.cs

@@ -1,5 +1,6 @@
 #if RECORDER_AVAILABLE
 using UnityEditor.Recorder;
+using UnityEngine;
 
 namespace UnityEditor.Formats.USD.Recorder
 {
@@ -12,7 +13,8 @@ protected override void FileTypeAndFormatGUI()
             EditorGUILayout.PropertyField(serializedObject.FindProperty("interpolationType"));
             EditorGUILayout.PropertyField(serializedObject.FindProperty("coordinateConversion"));
             EditorGUILayout.PropertyField(serializedObject.FindProperty("activePolicy"));
-            EditorGUILayout.PropertyField(serializedObject.FindProperty("exportMaterials"));
+            EditorGUILayout.PropertyField(serializedObject.FindProperty("exportTransformOverrides"), new GUIContent("Override Setting"));
+            EditorGUILayout.PropertyField(serializedObject.FindProperty("exportMaterials"), new GUIContent("Materials"));
             EditorGUILayout.PropertyField(serializedObject.FindProperty("scale"));
         }
     }

package/com.unity.formats.usd/Editor/Recorder/UsdRecorder.cs

@@ -70,6 +70,7 @@ protected override void SessionCreated(RecordingSession session)
             context.basisTransform = Settings.BasisTransformation;
             context.activePolicy = Settings.ActivePolicy;
             context.exportMaterials = Settings.ExportMaterials;
+            context.exportTransformOverrides = Settings.ExportTransformOverrides;
 
             context.scale = Settings.Scale;
 

package/com.unity.formats.usd/Editor/Recorder/UsdRecorderInput.cs

@@ -1,6 +1,7 @@
 #if RECORDER_AVAILABLE
 using Unity.Formats.USD;
 using UnityEditor.Recorder;
+using USD.NET;
 
 namespace UnityEditor.Formats.USD.Recorder
 {
@@ -11,10 +12,28 @@ public class UsdRecorderInput : RecorderInput
 
         protected override void BeginRecording(RecordingSession session)
         {
+            if (Context.exportTransformOverrides)
+            {
+                // Settings.
+                UsdAsset usdAsset = Settings.GameObject.GetComponentInParent<UsdAsset>(); // Get the UsdAsset component in this GameObject or its nearest parent
+                if (usdAsset != null)
+                {
+                    Context.scene.AddSubLayer(usdAsset.GetScene());
+                    Context.scene.WriteMode = Scene.WriteModes.Over;
+                }
+                else
+                    UnityEngine.Debug.LogError($"Unable to perform a 'transform overrides only' recording as <{Settings.GameObject.name}> is not a UsdAsset.");
+            }
             SceneExporter.SyncExportContext(Settings.GameObject, Context);
             SceneExporter.Export(Settings.GameObject,
                 Context,
                 zeroRootTransform: false);
+
+            if (Context.exportTransformOverrides)
+            {
+                // this is very brittle- if we have the chance of other sublayers in future we should store the index it was added at and only erase that one.
+                Context.scene.Stage.GetRootLayer().GetSubLayerPaths().Erase(0);
+            }
         }
 
         protected override void NewFrameReady(RecordingSession session)

package/com.unity.formats.usd/Editor/Recorder/UsdRecorderSettings.cs

@@ -18,6 +18,7 @@ public class UsdRecorderSettings : RecorderSettings
         [SerializeField] ActiveExportPolicy activePolicy = ActiveExportPolicy.ExportAsVisibility;
         [SerializeField] bool exportMaterials = true;
         [SerializeField] float scale = 1;
+        [SerializeField] ExportOverridesSetting exportTransformOverrides;
 
         public UsdRecorderSettings()
         {
@@ -31,6 +32,12 @@ public enum Format
             USDZ,
         }
 
+        public enum ExportOverridesSetting
+        {
+            ExportInFull,
+            ExportTransformOverridesOnly
+        }
+
         public UsdInterpolationType InterpolationType
         {
             get => interpolationType;
@@ -49,6 +56,12 @@ public bool ExportMaterials
             set => exportMaterials = value;
         }
 
+        public bool ExportTransformOverrides
+        {
+            get => exportTransformOverrides == ExportOverridesSetting.ExportTransformOverridesOnly ? true : false;
+            set => exportTransformOverrides = value ? ExportOverridesSetting.ExportTransformOverridesOnly : ExportOverridesSetting.ExportInFull;
+        }
+
         public ActiveExportPolicy ActivePolicy
         {
             get => activePolicy;

package/com.unity.formats.usd/Editor/Unity.Formats.USD.Editor.api

@@ -82,6 +82,7 @@ namespace UnityEditor.Formats.USD.Recorder
         public Unity.Formats.USD.BasisTransformation BasisTransformation { get; set; }
         public UnityEditor.Formats.USD.Recorder.UsdRecorderSettings.Format ExportFormat { get; }
         public bool ExportMaterials { get; set; }
+        public bool ExportTransformOverrides { get; set; }
         protected virtual string Extension { get; }
         public virtual System.Collections.Generic.IEnumerable<UnityEditor.Recorder.RecorderInputSettings> InputsSettings { get; }
         public pxr.UsdInterpolationType InterpolationType { get; set; }

package/com.unity.formats.usd/Runtime/Scripts/Behaviors/UsdAsset.cs

@@ -600,6 +600,7 @@ public void ExportOverrides(Scene sceneInWhichToStoreTransforms)
             {
                 throw new Exception("Could not open base layer: " + sceneToReference.usdFullPath);
             }
+            overs.AddSubLayer(baseLayer);
 
             overs.Time = baseLayer.Time;
             overs.StartTime = baseLayer.StartTime;
@@ -614,20 +615,20 @@ public void ExportOverrides(Scene sceneInWhichToStoreTransforms)
                     overs,
                     BasisTransformation.SlowAndSafe,
                     exportUnvarying: false,
-                    zeroRootTransform: true);
-
-                var rel = ImporterBase.MakeRelativePath(overs.FilePath, sceneToReference.usdFullPath);
-                GetFirstPrim(overs).GetReferences().AddReference(rel, GetFirstPrim(baseLayer).GetPath());
+                    zeroRootTransform: true,
+                    exportOverrides: true);
             }
-            catch (System.Exception ex)
+            catch (Exception ex)
             {
                 Debug.LogException(ex);
-                return;
             }
             finally
             {
                 if (overs != null)
                 {
+                    // Remove the reference to the original USD from the override file for flexibility in an asset pipeline
+                    // TODO: Make this an optional setting
+                    overs.Stage.GetRootLayer().GetSubLayerPaths().Erase(0);
                     overs.Save();
                     overs.Close();
                 }

package/com.unity.formats.usd/Runtime/Scripts/IO/Geometry/XformExporter.cs

@@ -25,8 +25,6 @@ public static void ExportXform(ObjectContext objContext, ExportContext exportCon
             UnityEngine.Profiling.Profiler.BeginSample("USD: Xform Conversion");
 
             XformSample sample = (XformSample)objContext.sample;
-            var localRot = objContext.gameObject.transform.localRotation;
-            var localScale = objContext.gameObject.transform.localScale;
             var path = new pxr.SdfPath(objContext.path);
 
             // If exporting for Z-Up, rotate the world.
@@ -37,9 +35,32 @@ public static void ExportXform(ObjectContext objContext, ExportContext exportCon
                 correctZUp,
                 path.IsRootPrimPath(),
                 exportContext.basisTransform);
-
             UnityEngine.Profiling.Profiler.EndSample();
 
+            // If exporting overrides, only export what changed
+            if (exportContext.exportTransformOverrides)
+            {
+                UnityEngine.Profiling.Profiler.BeginSample("USD: Xform override check");
+                var sourceSample = new XformSample();
+                float tolerance = 0.0001f;
+                exportContext.scene.Read(path, sourceSample);
+                bool areClose = true;
+                for (int i = 0; i < 16; i++)
+                {
+                    if (Mathf.Abs(sample.transform[i] - sourceSample.transform[i]) > tolerance)
+                    {
+                        areClose = false;
+                        break;
+                    }
+                }
+                UnityEngine.Profiling.Profiler.EndSample();
+                if (areClose)
+                {
+                    return;
+                }
+            }
+
+
             UnityEngine.Profiling.Profiler.BeginSample("USD: Xform Write");
             exportContext.scene.Write(objContext.path, sample);
             UnityEngine.Profiling.Profiler.EndSample();
@@ -55,7 +76,7 @@ public static void WriteSparseOverrides(Scene scene,
 
             try
             {
-                foreach (var path in scene.Find<XformableSample>())
+                foreach (var path in scene.Find<XformSample>())
                 {
                     GameObject go;
                     if (!primMap.TryGetValue(path, out go))