Make various tweaks to undo code in an effort to get things working better.

Undo rotation and position appear to be working.
Resizing a single prim appears to be working, though the undo has to be done twice.
Resizing a group of prims still does not work properly - possibly because in the UndoState we don't store a knowledge of when we're resizing a whole group rather than individual prims.
This needs to be addressed.

6 files changed, 217 insertions, 56 deletions

diff --git a/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs b/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
index 8414f8b..fa35bd8 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
@@ -11242,6 +11242,14 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                     }
                     else
                     {
+                        // Do this once since fetch parts creates a new array.
+                        SceneObjectPart[] parts = part.ParentGroup.Parts;
+                        for (int j = 0; j < parts.Length; j++)
+                        {
+                            part.StoreUndoState();
+                            parts[j].IgnoreUndoUpdate = true;
+                        }
+
                         // UUID partId = part.UUID;
                         UpdatePrimGroupRotation handlerUpdatePrimGroupRotation;
 
@@ -11257,6 +11265,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     handlerUpdatePrimSinglePosition(localId, pos1, this);
                                 }
                                 break;
+
                             case 2:
                                 Quaternion rot1 = new Quaternion(block.Data, 0, true);
 
@@ -11267,6 +11276,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     handlerUpdatePrimSingleRotation(localId, rot1, this);
                                 }
                                 break;
+
                             case 3:
                                 Vector3 rotPos = new Vector3(block.Data, 0);
                                 Quaternion rot2 = new Quaternion(block.Data, 12, true);
@@ -11279,6 +11289,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     handlerUpdatePrimSingleRotationPosition(localId, rot2, rotPos, this);
                                 }
                                 break;
+
                             case 4:
                             case 20:
                                 Vector3 scale4 = new Vector3(block.Data, 0);
@@ -11290,8 +11301,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     handlerUpdatePrimScale(localId, scale4, this);
                                 }
                                 break;
-                            case 5:
 
+                            case 5:
                                 Vector3 scale1 = new Vector3(block.Data, 12);
                                 Vector3 pos11 = new Vector3(block.Data, 0);
 
@@ -11308,6 +11319,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     }
                                 }
                                 break;
+
                             case 9:
                                 Vector3 pos2 = new Vector3(block.Data, 0);
 
@@ -11315,10 +11327,10 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
                                 if (handlerUpdateVector != null)
                                 {
-
                                     handlerUpdateVector(localId, pos2, this);
                                 }
                                 break;
+
                             case 10:
                                 Quaternion rot3 = new Quaternion(block.Data, 0, true);
 
@@ -11329,6 +11341,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     handlerUpdatePrimRotation(localId, rot3, this);
                                 }
                                 break;
+
                             case 11:
                                 Vector3 pos3 = new Vector3(block.Data, 0);
                                 Quaternion rot4 = new Quaternion(block.Data, 12, true);
@@ -11352,6 +11365,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     handlerUpdatePrimGroupScale(localId, scale7, this);
                                 }
                                 break;
+
                             case 13:
                                 Vector3 scale2 = new Vector3(block.Data, 12);
                                 Vector3 pos4 = new Vector3(block.Data, 0);
@@ -11371,6 +11385,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     }
                                 }
                                 break;
+
                             case 29:
                                 Vector3 scale5 = new Vector3(block.Data, 12);
                                 Vector3 pos5 = new Vector3(block.Data, 0);
@@ -11388,6 +11403,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     }
                                 }
                                 break;
+
                             case 21:
                                 Vector3 scale6 = new Vector3(block.Data, 12);
                                 Vector3 pos6 = new Vector3(block.Data, 0);
@@ -11404,13 +11420,18 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                                     }
                                 }
                                 break;
+
                             default:
-                                m_log.Debug("[CLIENT] MultipleObjUpdate recieved an unknown packet type: " + (block.Type));
+                                m_log.Debug("[CLIENT]: MultipleObjUpdate recieved an unknown packet type: " + (block.Type));
                                 break;
                         }
+
+                        for (int j = 0; j < parts.Length; j++)
+                            parts[j].IgnoreUndoUpdate = false;
                     }
                 }
             }
+
             return true;
         }
 
diff --git a/OpenSim/Region/Framework/Scenes/SceneGraph.cs b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
index bdb7f95..0a0bde8 100644
--- a/OpenSim/Region/Framework/Scenes/SceneGraph.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
@@ -564,6 +564,7 @@ namespace OpenSim.Region.Framework.Scenes
                     part.Undo();
             }
         }
+
         protected internal void HandleRedo(IClientAPI remoteClient, UUID primId)
         {
             if (primId != UUID.Zero)
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
index ce5db5f..7254992 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
@@ -1145,6 +1145,10 @@ namespace OpenSim.Region.Framework.Scenes
 
         public virtual void OnGrabPart(SceneObjectPart part, Vector3 offsetPos, IClientAPI remoteClient)
         {
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Processing OnGrabPart for {0} on {1} {2}, offsetPos {3}",
+//                remoteClient.Name, part.Name, part.LocalId, offsetPos);
+
             part.StoreUndoState();
             part.OnGrab(offsetPos, remoteClient);
         }
@@ -2611,17 +2615,14 @@ namespace OpenSim.Region.Framework.Scenes
 
         #region Resize
 
-
         /// <summary>
         /// Resize the entire group of prims.
         /// </summary>
         /// <param name="scale"></param>
         public void GroupResize(Vector3 scale)
         {
-//                m_log.DebugFormat(
-//                    "[SCENE OBJECT GROUP]: Group resizing {0} {1} from {2} to {3}", Name, localID, RootPart.Scale, scale);
-
-            RootPart.IgnoreUndoUpdate = true;
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Group resizing {0} {1} from {2} to {3}", Name, LocalId, RootPart.Scale, scale);
 
             scale.X = Math.Min(scale.X, Scene.m_maxNonphys);
             scale.Y = Math.Min(scale.Y, Scene.m_maxNonphys);
@@ -2647,7 +2648,7 @@ namespace OpenSim.Region.Framework.Scenes
                     SceneObjectPart obPart = parts[i];
                     if (obPart.UUID != m_rootPart.UUID)
                     {
-                        obPart.IgnoreUndoUpdate = true;
+//                        obPart.IgnoreUndoUpdate = true;
                         Vector3 oldSize = new Vector3(obPart.Scale);
 
                         float f = 1.0f;
@@ -2663,6 +2664,7 @@ namespace OpenSim.Region.Framework.Scenes
                                 y *= a;
                                 z *= a;
                             }
+
                             if (oldSize.Y * y > m_scene.m_maxPhys)
                             {
                                 f = m_scene.m_maxPhys / oldSize.Y;
@@ -2671,6 +2673,7 @@ namespace OpenSim.Region.Framework.Scenes
                                 y *= a;
                                 z *= a;
                             }
+
                             if (oldSize.Z * z > m_scene.m_maxPhys)
                             {
                                 f = m_scene.m_maxPhys / oldSize.Z;
@@ -2690,6 +2693,7 @@ namespace OpenSim.Region.Framework.Scenes
                                 y *= a;
                                 z *= a;
                             }
+
                             if (oldSize.Y * y > m_scene.m_maxNonphys)
                             {
                                 f = m_scene.m_maxNonphys / oldSize.Y;
@@ -2698,6 +2702,7 @@ namespace OpenSim.Region.Framework.Scenes
                                 y *= a;
                                 z *= a;
                             }
+
                             if (oldSize.Z * z > m_scene.m_maxNonphys)
                             {
                                 f = m_scene.m_maxNonphys / oldSize.Z;
@@ -2708,7 +2713,7 @@ namespace OpenSim.Region.Framework.Scenes
                             }
                         }
 
-                        obPart.IgnoreUndoUpdate = false;
+//                        obPart.IgnoreUndoUpdate = false;
                     }
                 }
             }
@@ -2723,7 +2728,7 @@ namespace OpenSim.Region.Framework.Scenes
             for (int i = 0; i < parts.Length; i++)
             {
                 SceneObjectPart obPart = parts[i];
-                obPart.IgnoreUndoUpdate = true;
+//                obPart.IgnoreUndoUpdate = true;
 
                 if (obPart.UUID != m_rootPart.UUID)
                 {
@@ -2738,16 +2743,18 @@ namespace OpenSim.Region.Framework.Scenes
                     newSize.Z *= z;
                     
                     obPart.Resize(newSize);
+
+                    obPart.IgnoreUndoUpdate = true;
                     obPart.UpdateOffSet(currentpos);
+                    obPart.IgnoreUndoUpdate = false;
                 }
 
-                obPart.IgnoreUndoUpdate = false;
-                obPart.StoreUndoState();
+//                obPart.IgnoreUndoUpdate = false;
+//                obPart.StoreUndoState();
             }
 
-            RootPart.IgnoreUndoUpdate = false;
-
-            RootPart.StoreUndoState();
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Finished group resizing {0} {1} to {2}", Name, LocalId, RootPart.Scale);
         }
 
         #endregion
@@ -2760,6 +2767,8 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="pos"></param>
         public void UpdateGroupPosition(Vector3 pos)
         {
+//            m_log.DebugFormat("[SCENE OBJECT GROUP]: Updating group position on {0} {1} to {2}", Name, LocalId, pos);
+
             SceneObjectPart[] parts = m_parts.GetArray();
             for (int i = 0; i < parts.Length; i++)
                 parts[i].StoreUndoState();
@@ -2805,6 +2814,9 @@ namespace OpenSim.Region.Framework.Scenes
 
             if (part != null)
             {
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT GROUP]: Updating single position of {0} {1} to {2}", part.Name, part.LocalId, pos);
+
                 if (part.UUID == m_rootPart.UUID)
                 {
                     UpdateRootPosition(pos);
@@ -2824,6 +2836,9 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="pos"></param>
         private void UpdateRootPosition(Vector3 pos)
         {
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Updating root position of {0} {1} to {2}", Name, LocalId, pos);
+
             SceneObjectPart[] parts = m_parts.GetArray();
             for (int i = 0; i < parts.Length; i++)
                 parts[i].StoreUndoState();
@@ -2868,6 +2883,9 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="rot"></param>
         public void UpdateGroupRotationR(Quaternion rot)
         {
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Updating group rotation R of {0} {1} to {2}", Name, LocalId, rot);
+
             SceneObjectPart[] parts = m_parts.GetArray();
             for (int i = 0; i < parts.Length; i++)
                 parts[i].StoreUndoState();
@@ -2892,6 +2910,9 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="rot"></param>
         public void UpdateGroupRotationPR(Vector3 pos, Quaternion rot)
         {
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Updating group rotation PR of {0} {1} to {2}", Name, LocalId, rot);
+
             SceneObjectPart[] parts = m_parts.GetArray();
             for (int i = 0; i < parts.Length; i++)
                 parts[i].StoreUndoState();
@@ -2926,6 +2947,9 @@ namespace OpenSim.Region.Framework.Scenes
 
             if (part != null)
             {
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT GROUP]: Updating single rotation of {0} {1} to {2}", part.Name, part.LocalId, rot);
+
                 if (part.UUID == m_rootPart.UUID)
                 {
                     UpdateRootRotation(rot);
@@ -2947,6 +2971,10 @@ namespace OpenSim.Region.Framework.Scenes
             SceneObjectPart part = GetChildPart(localID);
             if (part != null)
             {
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT GROUP]: Updating single position and rotation of {0} {1} to {2}",
+//                    part.Name, part.LocalId, rot);
+
                 if (part.UUID == m_rootPart.UUID)
                 {
                     UpdateRootRotation(rot);
@@ -2969,6 +2997,10 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="rot"></param>
         private void UpdateRootRotation(Quaternion rot)
         {
+//            m_log.DebugFormat(
+//                "[SCENE OBJECT GROUP]: Updating root rotation of {0} {1} to {2}",
+//                Name, LocalId, rot);
+
             Quaternion axRot = rot;
             Quaternion oldParentRot = m_rootPart.RotationOffset;
 
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs b/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
index a1200ee..aab83b8 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
@@ -1014,15 +1014,19 @@ namespace OpenSim.Region.Framework.Scenes
             get { return m_shape; }
             set { m_shape = value; }
         }
-        
+
+        /// <summary>
+        /// Change the scale of this part.
+        /// </summary>
         public Vector3 Scale
         {
             get { return m_shape.Scale; }
             set
             {
-                StoreUndoState();
                 if (m_shape != null)
                 {
+                    StoreUndoState();
+
                     m_shape.Scale = value;
 
                     PhysicsActor actor = PhysActor;
@@ -1033,11 +1037,16 @@ namespace OpenSim.Region.Framework.Scenes
                             if (m_parentGroup.Scene.PhysicsScene != null)
                             {
                                 actor.Size = m_shape.Scale;
-                                m_parentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(actor);
+
+                                if (((OpenMetaverse.SculptType)Shape.SculptType) == SculptType.Mesh)
+                                    CheckSculptAndLoad();
+                                else
+                                    ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(PhysActor);
                             }
                         }
                     }
                 }
+
                 TriggerScriptChangedEvent(Changed.SCALE);
             }
         }
@@ -2827,8 +2836,12 @@ namespace OpenSim.Region.Framework.Scenes
         }
 
         /// <summary>
-        /// Resize this part.
+        /// Set the scale of this part.
         /// </summary>
+        /// <remarks>
+        /// Unlike the scale property, this checks the new size against scene limits and schedules a full property
+        /// update to viewers.
+        /// </remarks>
         /// <param name="scale"></param>
         public void Resize(Vector3 scale)
         {
@@ -2836,33 +2849,18 @@ namespace OpenSim.Region.Framework.Scenes
             scale.Y = Math.Min(scale.Y, ParentGroup.Scene.m_maxNonphys);
             scale.Z = Math.Min(scale.Z, ParentGroup.Scene.m_maxNonphys);
 
-//            m_log.DebugFormat("[SCENE OBJECT PART]: Resizing {0} {1} to {2}", Name, LocalId, scale);
-
-            StoreUndoState();
-            m_shape.Scale = scale;
-
-            // If we're a mesh/sculpt, then we need to tell the physics engine about our new size.  To do this, we
-            // need to reinsert the sculpt data into the shape, since the physics engine deletes it when done to
-            // save memory
-            if (PhysActor != null)
+            if (PhysActor != null && PhysActor.IsPhysical)
             {
-                if (PhysActor.IsPhysical)
-                {
-                    scale.X = Math.Min(scale.X, ParentGroup.Scene.m_maxPhys);
-                    scale.Y = Math.Min(scale.Y, ParentGroup.Scene.m_maxPhys);
-                    scale.Z = Math.Min(scale.Z, ParentGroup.Scene.m_maxPhys);
-                }
+                scale.X = Math.Min(scale.X, ParentGroup.Scene.m_maxPhys);
+                scale.Y = Math.Min(scale.Y, ParentGroup.Scene.m_maxPhys);
+                scale.Z = Math.Min(scale.Z, ParentGroup.Scene.m_maxPhys);
+            }
 
-                PhysActor.Size = scale;
+//            m_log.DebugFormat("[SCENE OBJECT PART]: Resizing {0} {1} to {2}", Name, LocalId, scale);
 
-                if (((OpenMetaverse.SculptType)Shape.SculptType) == SculptType.Mesh)
-                    CheckSculptAndLoad();
-                else
-                    ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(PhysActor);
-            }
+            Scale = scale;
 
             ParentGroup.HasGroupChanged = true;
-            TriggerScriptChangedEvent(Changed.SCALE);
             ScheduleFullUpdate();
         }
         
@@ -3673,8 +3671,6 @@ namespace OpenSim.Region.Framework.Scenes
                 {
                     if (m_parentGroup != null)
                     {
-//                        m_log.DebugFormat("[SCENE OBJECT PART]: Storing undo state for {0} {1}", Name, LocalId);
-
                         lock (m_undo)
                         {
                             if (m_undo.Count > 0)
@@ -3683,15 +3679,29 @@ namespace OpenSim.Region.Framework.Scenes
                                 if (last != null)
                                 {
                                     if (last.Compare(this))
+                                    {
+//                                        m_log.DebugFormat(
+//                                            "[SCENE OBJECT PART]: Not storing undo for {0} {1} since current state is same as last undo state, initial stack size {2}",
+//                                            Name, LocalId, m_undo.Count);
+
                                         return;
+                                    }
                                 }
                             }
 
+//                            m_log.DebugFormat(
+//                                "[SCENE OBJECT PART]: Storing undo state for {0} {1}, initial stack size {2}",
+//                                Name, LocalId, m_undo.Count);
+
                             if (m_parentGroup.GetSceneMaxUndo() > 0)
                             {
                                 UndoState nUndo = new UndoState(this);
 
                                 m_undo.Push(nUndo);
+
+//                                m_log.DebugFormat(
+//                                    "[SCENE OBJECT PART]: Stored undo state for {0} {1}, stack size now {2}",
+//                                    Name, LocalId, m_undo.Count);
                             }
                         }
                     }
@@ -3703,7 +3713,8 @@ namespace OpenSim.Region.Framework.Scenes
             }
 //            else
 //            {
-//                m_log.DebugFormat("[SCENE OBJECT PART]: Ignoring undo store for {0} {1} since already undoing", Name, LocalId);
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT PART]: Ignoring undo store for {0} {1} since already undoing", Name, LocalId);
 //            }
         }
 
@@ -3721,10 +3732,12 @@ namespace OpenSim.Region.Framework.Scenes
 
         public void Undo()
         {
-//            m_log.DebugFormat("[SCENE OBJECT PART]: Handling undo request for {0} {1}", Name, LocalId);
-
             lock (m_undo)
             {
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT PART]: Handling undo request for {0} {1}, stack size {2}",
+//                    Name, LocalId, m_undo.Count);
+
                 if (m_undo.Count > 0)
                 {
                     UndoState nUndo = null;
@@ -3739,19 +3752,26 @@ namespace OpenSim.Region.Framework.Scenes
                     if (goback != null)
                     {
                         goback.PlaybackState(this);
+
                         if (nUndo != null)
                             m_redo.Push(nUndo);
                     }
                 }
+
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT PART]: Handled undo request for {0} {1}, stack size now {2}",
+//                    Name, LocalId, m_undo.Count);
             }
         }
 
         public void Redo()
         {
-//            m_log.DebugFormat("[SCENE OBJECT PART]: Handling redo request for {0} {1}", Name, LocalId);
-
             lock (m_redo)
             {
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT PART]: Handling redo request for {0} {1}, stack size {2}",
+//                    Name, LocalId, m_redo.Count);
+
                 if (m_parentGroup.GetSceneMaxUndo() > 0)
                 {
                     UndoState nUndo = new UndoState(this);
@@ -3763,11 +3783,17 @@ namespace OpenSim.Region.Framework.Scenes
 
                 if (gofwd != null)
                     gofwd.PlayfwdState(this);
+
+//                m_log.DebugFormat(
+//                    "[SCENE OBJECT PART]: Handled redo request for {0} {1}, stack size now {2}",
+//                    Name, LocalId, m_redo.Count);
             }
         }
 
         public void ClearUndoState()
         {
+//            m_log.DebugFormat("[SCENE OBJECT PART]: Clearing undo and redo stacks in {0} {1}", Name, LocalId);
+
             lock (m_undo)
             {
                 m_undo.Clear();
diff --git a/OpenSim/Region/Framework/Scenes/Tests/SceneObjectResizeTests.cs b/OpenSim/Region/Framework/Scenes/Tests/SceneObjectResizeTests.cs
index 6dbac3c..c4047ee 100644
--- a/OpenSim/Region/Framework/Scenes/Tests/SceneObjectResizeTests.cs
+++ b/OpenSim/Region/Framework/Scenes/Tests/SceneObjectResizeTests.cs
@@ -50,7 +50,7 @@ namespace OpenSim.Region.Framework.Scenes.Tests
         public void TestResizeSceneObject()
         {
             TestHelper.InMethod();
-            //log4net.Config.XmlConfigurator.Configure();
+//            log4net.Config.XmlConfigurator.Configure();
 
             Scene scene = SceneSetupHelpers.SetupScene();
             SceneObjectGroup g1 = SceneSetupHelpers.AddSceneObject(scene).ParentGroup;
diff --git a/OpenSim/Region/Framework/Scenes/UndoState.cs b/OpenSim/Region/Framework/Scenes/UndoState.cs
index 55e407e..38bbeb0 100644
--- a/OpenSim/Region/Framework/Scenes/UndoState.cs
+++ b/OpenSim/Region/Framework/Scenes/UndoState.cs
@@ -25,6 +25,9 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+using System;
+using System.Reflection;
+using log4net;
 using OpenMetaverse;
 using OpenSim.Region.Framework.Interfaces;
 
@@ -32,49 +35,80 @@ namespace OpenSim.Region.Framework.Scenes
 {
     public class UndoState
     {
+//        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+
         public Vector3 Position = Vector3.Zero;
         public Vector3 Scale = Vector3.Zero;
         public Quaternion Rotation = Quaternion.Identity;
 
+        /// <summary>
+        /// Constructor.
+        /// </summary>
+        /// <param name="part"></param>
         public UndoState(SceneObjectPart part)
         {
             if (part != null)
             {
                 if (part.ParentID == 0)
                 {
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Storing undo position {0} for root part", part.ParentGroup.AbsolutePosition);
                     Position = part.ParentGroup.AbsolutePosition;
+
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Storing undo rotation {0} for root part", part.RotationOffset);
                     Rotation = part.RotationOffset;
+
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Storing undo scale {0} for root part", part.Shape.Scale);
                     Scale = part.Shape.Scale;
                 }
                 else
                 {
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Storing undo position {0} for child part", part.OffsetPosition);
                     Position = part.OffsetPosition;
+
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Storing undo rotation {0} for child part", part.RotationOffset);
                     Rotation = part.RotationOffset;
+
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Storing undo scale {0} for child part", part.Shape.Scale);
                     Scale = part.Shape.Scale;
                 }
             }
         }
 
+        /// <summary>
+        /// Compare the relevant state in the given part to this state.
+        /// </summary>
+        /// <param name="part"></param>
+        /// <returns>true if both the part's position, rotation and scale match those in this undo state.  False otherwise.</returns>
         public bool Compare(SceneObjectPart part)
         {
             if (part != null)
             {
                 if (part.ParentID == 0)
                 {
-                    if (Position == part.ParentGroup.AbsolutePosition && Rotation == part.ParentGroup.Rotation)
+                    if (Position == part.ParentGroup.AbsolutePosition
+                        && Rotation == part.RotationOffset
+                        && Scale == part.Shape.Scale)
                         return true;
                     else
                         return false;
                 }
                 else
                 {
-                    if (Position == part.OffsetPosition && Rotation == part.RotationOffset && Scale == part.Shape.Scale)
+                    if (Position == part.OffsetPosition
+                        && Rotation == part.RotationOffset
+                        && Scale == part.Shape.Scale)
                         return true;
                     else
                         return false;
-
                 }
             }
+
             return false;
         }
 
@@ -87,24 +121,64 @@ namespace OpenSim.Region.Framework.Scenes
                 if (part.ParentID == 0)
                 {
                     if (Position != Vector3.Zero)
+                    {
+//                        m_log.DebugFormat(
+//                            "[UNDO STATE]: Undoing position {0} to {1} for root part {2} {3}",
+//                            part.ParentGroup.AbsolutePosition, Position, part.Name, part.LocalId);
+
                         part.ParentGroup.AbsolutePosition = Position;
+                    }
+
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Undoing rotation {0} to {1} for root part {2} {3}",
+//                        part.RotationOffset, Rotation, part.Name, part.LocalId);
+
                     part.RotationOffset = Rotation;
+
                     if (Scale != Vector3.Zero)
+                    {
+//                        m_log.DebugFormat(
+//                            "[UNDO STATE]: Undoing scale {0} to {1} for root part {2} {3}",
+//                            part.Shape.Scale, Scale, part.Name, part.LocalId);
+
                         part.Resize(Scale);
+                    }
+
                     part.ParentGroup.ScheduleGroupForTerseUpdate();
                 }
                 else
                 {
                     if (Position != Vector3.Zero)
+                    {
+//                        m_log.DebugFormat(
+//                            "[UNDO STATE]: Undoing position {0} to {1} for child part {2} {3}",
+//                            part.OffsetPosition, Position, part.Name, part.LocalId);
+
                         part.OffsetPosition = Position;
+                    }
+
+//                    m_log.DebugFormat(
+//                        "[UNDO STATE]: Undoing rotation {0} to {1} for child part {2} {3}",
+//                        part.RotationOffset, Rotation, part.Name, part.LocalId);
+
                     part.UpdateRotation(Rotation);
+
                     if (Scale != Vector3.Zero)
-                        part.Resize(Scale); part.ScheduleTerseUpdate();
+                    {
+//                        m_log.DebugFormat(
+//                            "[UNDO STATE]: Undoing scale {0} to {1} for child part {2} {3}",
+//                            part.Shape.Scale, Scale, part.Name, part.LocalId);
+
+                        part.Resize(Scale);
+                    }
+
+                    part.ScheduleTerseUpdate();
                 }
-                part.Undoing = false;
 
+                part.Undoing = false;
             }
         }
+
         public void PlayfwdState(SceneObjectPart part)
         {
             if (part != null)
@@ -115,27 +189,34 @@ namespace OpenSim.Region.Framework.Scenes
                 {
                     if (Position != Vector3.Zero)
                         part.ParentGroup.AbsolutePosition = Position;
+
                     if (Rotation != Quaternion.Identity)
                         part.UpdateRotation(Rotation);
+
                     if (Scale != Vector3.Zero)
                         part.Resize(Scale);
+
                     part.ParentGroup.ScheduleGroupForTerseUpdate();
                 }
                 else
                 {
                     if (Position != Vector3.Zero)
                         part.OffsetPosition = Position;
+
                     if (Rotation != Quaternion.Identity)
                         part.UpdateRotation(Rotation);
+
                     if (Scale != Vector3.Zero)
                         part.Resize(Scale);
+
                     part.ScheduleTerseUpdate();
                 }
-                part.Undoing = false;
 
+                part.Undoing = false;
             }
         }
     }
+
     public class LandUndoState
     {
         public ITerrainModule m_terrainModule;