add utility for reverting transform hierarchy, simplify hash compare

Editor/Utility/PrefabTransformHierarchyEditor.cs

 			var root = target as PrefabTransformHierarchy;
 			if (root != null)
 			{
-				EditorGUI.BeginDisabledGroup(Application.isPlaying);
+				if (GUILayout.Button("Revert transform hierarchy"))
-					if (GUILayout.Button("Revert transform hierarchy"))
+					if (Application.isPlaying)
+					{
+						root.LoadDefaults();
+					}
+					else
 					{
 						var transforms = root.GetComponentsInChildren<Transform>(includeInactive: true);
 						for (int i = 0; i != transforms.Length; i++)
 								PrefabUtility.RevertObjectOverride(transforms[i], InteractionMode.UserAction);
 							}
 						}
+					}
-						EditorUtility.ClearProgressBar();
-					}
+					EditorUtility.ClearProgressBar();
-				EditorGUI.EndDisabledGroup();
 			}
 		}
 	}

Runtime/SkinAttachment.cs

 			return new Hash128(checksum0, checksum1);
 		}
 
+		public bool ChecksumCompare(in SkinAttachmentData data)
+		{
+			return (checksum0 == data.checksum0) && (checksum1 == data.checksum1);
+		}
+
 		public void RevertVertexData()
 		{
 			if (meshAsset != null)

Runtime/SkinAttachmentTarget.cs

 
 			for (int i = 0, n = subjects.Count; i != n; i++)
 			{
-				if (subjects[i].Checksum() != attachData.Checksum())
+				if (subjects[i].ChecksumCompare(attachData) == false)
 					return true;
 			}
 
 			for (int i = 0, n = subjects.Count; i != n; i++)
 			{
 				var subject = subjects[i];
-				if (subject.Checksum() != attachData.Checksum())
+				if (subject.ChecksumCompare(attachData) == false)
 					continue;
 
 				int attachmentIndex = subject.attachmentIndex;
 				for (int i = 0, n = subjects.Count; i != n; i++)
 				{
 					var subject = subjects[i];
-					if (subject.Checksum() != attachData.Checksum())
+					if (subject.ChecksumCompare(attachData) == false)
 						continue;
 
 					var stillRunning = (stagingJobs[i].IsCompleted == false);

Runtime/Utility/PrefabTransformHierarchy.cs

-using UnityEngine;
+using System;
+using UnityEngine;
+#if UNITY_EDITOR
+using UnityEditor.Experimental.SceneManagement;
+#endif
+		[Serializable]
+		public struct TransformDefaults
+		{
+			public Transform transform;
+			public Vector3 localPosition;
+			public Quaternion localRotation;
+		}
+
+		public TransformDefaults[] data;
+
+		public void LoadDefaults()
+		{
+			if (data == null)
+				return;
+
+			for (int i = 0; i != data.Length; i++)
+			{
+				if (data[i].transform == null)
+					continue;
+
+				data[i].transform.localPosition = data[i].localPosition;
+				data[i].transform.localRotation = data[i].localRotation;
+			}
+		}
+
+		public void SaveDefaults()
+		{
+			var transforms = this.transform.GetComponentsInChildren<Transform>(includeInactive: true);
+			var transformCount = transforms.Length;
+
+			data = new TransformDefaults[transformCount];
+
+			for (int i = 0; i != transformCount; i++)
+			{
+				data[i].transform = transforms[i];
+				data[i].localPosition = transforms[i].localPosition;
+				data[i].localRotation = transforms[i].localRotation;
+			}
+		}
+
+#if UNITY_EDITOR
+		static PrefabTransformHierarchy()
+		{
+			PrefabStage.prefabSaving += (GameObject prefab) =>
+			{
+				var prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
+				if (prefabStage != null)
+				{
+					var roots = prefab.GetComponentsInChildren<PrefabTransformHierarchy>(includeInactive: true);
+					foreach (var root in roots)
+					{
+						root.SaveDefaults();
+					}
+				}
+			};
+		}
+#endif
 	}
 }