UT-1945 Import Settings Reset Fix (#531)

Add extra export option to preserve import settings and add methods to save metafile.
Add unit test.
Update image and docs.

Author: natalia-wh

com.unity.formats.fbx/Documentation~/exporting.md

@@ -218,6 +218,7 @@ When exporting an FBX file, the following **Export Options** window opens, displ
 | __Animated Skinned Mesh__ | Check this option to export animation on objects with skinned meshes.<br/><br/>If unchecked, the FBX Exporter does not export animation on skinned meshes. |
 | __Compatible Naming__     | Check this option to control renaming the GameObject and Materials during export. <br/><br/>The FBX Exporter ensures compatible naming with Autodesk® Maya® and Autodesk® Maya LT™ to avoid unexpected name changes between Unity and Autodesk® Maya® and Autodesk® Maya LT™. During export the FBX Exporter replaces characters in Unity names as follows:<br/> - Replaces invalid characters with underscores ("\_"). Invalid characters are all non-alphanumeric characters, except for the colon (":").<br/> - Adds an underscore ("\_") to names that begin with a number.<br/> - Replaces diacritics. For example, replaces "é" with “e”.<br/><br/>**NOTE:** If you have a Material with a space in its name, the space is replaced with an underscore ("_"). This results in a new Material being created when it is imported. For example, the Material named "Default Material" is exported as "Default_Material" and is created as a new Material when it is imported. If you want the exported Material to match an existing Material in the scene, you must manually rename the Material before exporting. |
 | __Export Unrendered__     | Check this option to export meshes that either don't have a renderer component, or that have a disabled renderer component. For example, a simplified mesh used as a Mesh collider. |
+|__Preserve Import Settings__ | Check this option to preserve all import settings applied to an existing fbx that will be overwritten in the export. If the GameObject is being exported as a new fbx, the import settings will not be carried over.|
 
 > **NOTE:** For FBX Model filenames, the FBX Exporter ensures that names do not contain invalid characters for the file system. The set of invalid characters may differ between file systems.
 

com.unity.formats.fbx/Documentation~/images/FBXExporter_ExportOptionsWindow.png

@@ -95,6 +95,12 @@ public override void OnInspectorGUI ()
             exportSettings.SetExportUnredererd(EditorGUILayout.Toggle(exportSettings.ExportUnrendered));
             EditorGUI.EndDisabledGroup ();
             GUILayout.EndHorizontal ();
+            
+            GUILayout.BeginHorizontal();
+            EditorGUILayout.LabelField(new GUIContent("Preserve Import Settings for Existing FBX",
+                "If checked, the import settings from the overwritten FBX will be carried over to the new version."), GUILayout.Width(LabelWidth - FieldOffset));
+            exportSettings.SetPreserveImportSettings(EditorGUILayout.Toggle(exportSettings.PreserveImportSettings));
+            GUILayout.EndHorizontal();
         }
     }
 
@@ -107,6 +113,7 @@ internal interface IExportOptions {
         bool UseMayaCompatibleNames { get; }
         bool AllowSceneModification { get; }
         bool ExportUnrendered { get; }
+        bool PreserveImportSettings { get; }
         Transform AnimationSource { get; }
         Transform AnimationDest { get; }
     }
@@ -152,6 +159,7 @@ internal abstract class ExportOptionsSettingsSerializeBase : IExportOptions
         public abstract ExportSettings.LODExportType LODExportType { get; }
         public abstract ExportSettings.ObjectPosition ObjectPosition { get; }
         public abstract bool ExportUnrendered { get; }
+        public virtual bool PreserveImportSettings { get;  }
         public abstract bool AllowSceneModification { get; }
     }
 
@@ -166,6 +174,7 @@ internal class ExportModelSettingsSerialize : ExportOptionsSettingsSerializeBase
         private ExportSettings.ObjectPosition objectPosition = ExportSettings.ObjectPosition.LocalCentered;
         [SerializeField]
         private bool exportUnrendered = true;
+        private bool preserveImportSettings = true;
 
         public override ExportSettings.Include ModelAnimIncludeOption { get { return include; } }
         public void SetModelAnimIncludeOption(ExportSettings.Include include) { this.include = include; }
@@ -175,6 +184,8 @@ internal class ExportModelSettingsSerialize : ExportOptionsSettingsSerializeBase
         public void SetObjectPosition(ExportSettings.ObjectPosition objPos){ this.objectPosition = objPos; }
         public override bool ExportUnrendered { get { return exportUnrendered; } }
         public void SetExportUnredererd(bool exportUnrendered){ this.exportUnrendered = exportUnrendered; }
+        public override bool PreserveImportSettings { get { return preserveImportSettings; } }
+        public void SetPreserveImportSettings(bool preserveImportSettings){ this.preserveImportSettings = preserveImportSettings; }
         public override bool AllowSceneModification { get { return false; } }
     }
 }

com.unity.formats.fbx/Editor/ExportModelSettings.cs

@@ -3643,9 +3643,23 @@ internal int ExportAll (
                     Debug.LogWarning ("Export Cancelled");
                     return 0;
                 }
+
+                // make a temporary copy of the original metafile
+                string originalMetafilePath = "";
+                if (ExportOptions.PreserveImportSettings && File.Exists(m_lastFilePath))
+                {
+                    originalMetafilePath = SaveMetafile();
+                }
+
                 // delete old file, move temp file
                 ReplaceFile();
                 AssetDatabase.Refresh();
+                
+                // replace with original metafile if specified to
+                if (ExportOptions.PreserveImportSettings && originalMetafilePath != "")
+                {
+                    ReplaceMetafile(originalMetafilePath);
+                }
 
                 return status == true ? NumNodes : 0;
             }
@@ -3729,6 +3743,71 @@ private void ReplaceFile ()
             }
         }
 
+        private string SaveMetafile()
+        {
+            var tempMetafilePath = Path.GetTempFileName();
+            
+            // Try as an absolute path
+            var fbxPath = m_lastFilePath;
+            if (AssetDatabase.LoadAssetAtPath(fbxPath, typeof(Object)) == null)
+            {
+                // Try as a relative path
+                fbxPath = "Assets" + m_lastFilePath.Substring(Application.dataPath.Length);
+                if (AssetDatabase.LoadAssetAtPath(fbxPath, typeof(Object)) == null)
+                {
+                    Debug.LogWarning(string.Format("Failed to find a valid asset at {0}. Import settings will be reset to default values.", m_lastFilePath));
+                    return "";
+                }
+            }
+            
+            // get metafile for original fbx file
+            var metafile = fbxPath + ".meta";
+
+#if UNITY_2019_1_OR_NEWER
+            metafile = VersionControl.Provider.GetAssetByPath(fbxPath).metaPath;
+#endif
+
+            // save it to a temp file
+            try {
+                File.Copy(metafile, tempMetafilePath, true);
+            } catch(IOException) {
+                Debug.LogWarning (string.Format("Failed to copy file {0} to {1}. Import settings will be reset to default values.", metafile, tempMetafilePath));
+                return "";
+            }
+
+            return tempMetafilePath;
+        }
+
+        private void ReplaceMetafile(string metafilePath)
+        {
+            // Try as an absolute path
+            var fbxPath = m_lastFilePath;
+            if (AssetDatabase.LoadAssetAtPath(fbxPath, typeof(Object)) == null)
+            {
+                // Try as a relative path
+                fbxPath = "Assets" + m_lastFilePath.Substring(Application.dataPath.Length);
+                if (AssetDatabase.LoadAssetAtPath(fbxPath, typeof(Object)) == null)
+                {
+                    Debug.LogWarning(string.Format("Failed to find a valid asset at {0}. Import settings will be reset to default values.", m_lastFilePath));
+                    return;
+                }
+            }
+            
+            // get metafile for new fbx file
+            var metafile = fbxPath + ".meta";
+
+#if UNITY_2019_1_OR_NEWER
+            metafile = VersionControl.Provider.GetAssetByPath(fbxPath).metaPath;
+#endif
+
+            // replace metafile with original one in temp file
+            try {
+                File.Copy(metafilePath, metafile, true);
+            } catch(IOException) {
+                Debug.LogWarning (string.Format("Failed to copy file {0} to {1}. Import settings will be reset to default values.", metafilePath, m_lastFilePath));
+            }
+        }
+
         /// <summary>
         /// GameObject/Export Selected Timeline Clip...
         /// </summary>

com.unity.formats.fbx/Editor/FbxExporter.cs

@@ -1034,5 +1034,44 @@ private void CompareGameObjectChildren(GameObject obj, HashSet<string> expectedC
                 expectedChildren.Remove (child.name);
             }
         }
+
+        [Test]
+        public void TestPreserveImportSettings()
+        {
+            // create a primitive object and export to an fbx
+            var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
+            var filename = GetRandomFbxFilePath();
+            ModelExporter.ExportObject(filename, cube);
+
+            // change an import setting
+            var importer = AssetImporter.GetAtPath(filename) as ModelImporter;
+            importer.importBlendShapes = !importer.importBlendShapes;
+            importer.SaveAndReimport();
+
+            // save original fbx's guid and import setting change
+            var originalGuid = AssetDatabase.AssetPathToGUID(filename);
+            var originalImportBlendShapes = importer.importBlendShapes;
+
+            // re-export with preserve import settings true and verify settings are the same
+            ModelExporter.ExportObjects(filename, new Object[] { cube });
+            importer.SaveAndReimport();
+            Assert.AreEqual(originalImportBlendShapes, importer.importBlendShapes);
+
+            // verify guids still match
+            var newGuid = AssetDatabase.AssetPathToGUID(filename);
+            Assert.AreEqual(originalGuid, newGuid);
+
+            // re-export with preserve import settings false and verify settings are different
+            var exportOptions = new ExportModelSettingsSerialize();
+
+            exportOptions.SetPreserveImportSettings(false);
+            ModelExporter.ExportObjects(filename, new Object[] { cube }, exportOptions);
+            importer.SaveAndReimport();
+            Assert.AreNotEqual(originalImportBlendShapes, importer.importBlendShapes);
+
+            // verify guids still match
+            newGuid = AssetDatabase.AssetPathToGUID(filename);
+            Assert.AreEqual(originalGuid, newGuid);
+        }
     }
 }