Eliminate race condition where many callers would check SOP.PhysicsActor != null then assume it was still not null in later code.

Another thread could come and turn off physics for a part (null PhysicsActor) at any point.
Had to turn off localCopy on warp3D CoreModules section in prebuild.xml since on current nant this copies all DLLs in bin/ which can be a very large number with compiled DLLs
No obvious reason for doing that copy - nothing else does it.

5 files changed, 208 insertions, 154 deletions

diff --git a/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs b/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs
index 427a49d..86e10d4 100644
--- a/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs
+++ b/OpenSim/Region/CoreModules/Framework/EntityTransfer/EntityTransferModule.cs
@@ -36,6 +36,7 @@ using OpenSim.Framework.Capabilities;
 using OpenSim.Framework.Client;
 using OpenSim.Region.Framework.Interfaces;
 using OpenSim.Region.Framework.Scenes;
+using OpenSim.Region.Physics.Manager;
 using OpenSim.Services.Interfaces;
 
 using GridRegion = OpenSim.Services.Interfaces.GridRegion;
@@ -1803,10 +1804,9 @@ namespace OpenSim.Region.CoreModules.Framework.EntityTransfer
                 {
                     if (!grp.IsDeleted)
                     {
-                        if (grp.RootPart.PhysActor != null)
-                        {
-                            grp.RootPart.PhysActor.CrossingFailure();
-                        }
+                        PhysicsActor pa = grp.RootPart.PhysActor;
+                        if (pa != null)
+                            pa.CrossingFailure();
                     }
 
                     m_log.ErrorFormat("[ENTITY TRANSFER MODULE]: Prim crossing failed for {0}", grp);
diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index 06f7c0f..29825a2 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -642,10 +642,6 @@ namespace OpenSim.Region.Framework.Scenes
 
             #endregion Region Settings
 
-            MainConsole.Instance.Commands.AddCommand("Estates", false, "reload estate",
-                                          "reload estate",
-                                          "Reload the estate data", HandleReloadEstate);
-
             //Bind Storage Manager functions to some land manager functions for this scene
             EventManager.OnLandObjectAdded +=
                 new EventManager.LandObjectAdded(simDataService.StoreLandObject);
diff --git a/OpenSim/Region/Framework/Scenes/SceneGraph.cs b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
index 8a05772..0098add 100644
--- a/OpenSim/Region/Framework/Scenes/SceneGraph.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
@@ -306,7 +306,8 @@ namespace OpenSim.Region.Framework.Scenes
             if (rot != null)
                 sceneObject.UpdateGroupRotationR((Quaternion)rot);
 
-            if (sceneObject.RootPart.PhysActor != null && sceneObject.RootPart.PhysActor.IsPhysical && vel != Vector3.Zero)
+            PhysicsActor pa = sceneObject.RootPart.PhysActor;
+            if (pa != null && pa.IsPhysical && vel != Vector3.Zero)
             {
                 sceneObject.RootPart.ApplyImpulse((vel * sceneObject.GetMass()), false);
                 sceneObject.Velocity = vel;
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
index 04b3766..87fdc41 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
@@ -523,16 +523,21 @@ namespace OpenSim.Region.Framework.Scenes
             {
                 m_isSelected = value;
                 // Tell physics engine that group is selected
-                if (m_rootPart.PhysActor != null)
+
+                PhysicsActor pa = m_rootPart.PhysActor;
+                if (pa != null)
                 {
-                    m_rootPart.PhysActor.Selected = value;
+                    pa.Selected = value;
+
                     // Pass it on to the children.
                     SceneObjectPart[] parts = m_parts.GetArray();
                     for (int i = 0; i < parts.Length; i++)
                     {
                         SceneObjectPart child = parts[i];
-                        if (child.PhysActor != null)
-                            child.PhysActor.Selected = value;
+
+                        PhysicsActor childPa = child.PhysActor;
+                        if (childPa != null)
+                            childPa.Selected = value;
                     }
                 }
             }
@@ -1478,7 +1483,8 @@ namespace OpenSim.Region.Framework.Scenes
                 }
 
                 // Need to duplicate the physics actor as well
-                if (part.PhysActor != null && userExposed)
+                PhysicsActor originalPartPa = part.PhysActor;
+                if (originalPartPa != null && userExposed)
                 {
                     PrimitiveBaseShape pbs = newPart.Shape;
     
@@ -1489,10 +1495,10 @@ namespace OpenSim.Region.Framework.Scenes
                             newPart.AbsolutePosition,
                             newPart.Scale,
                             newPart.RotationOffset,
-                            part.PhysActor.IsPhysical,
+                            originalPartPa.IsPhysical,
                             newPart.LocalId);
     
-                    newPart.DoPhysicsPropertyUpdate(part.PhysActor.IsPhysical, true);
+                    newPart.DoPhysicsPropertyUpdate(originalPartPa.IsPhysical, true);
                 }
             }
             
@@ -1564,45 +1570,53 @@ namespace OpenSim.Region.Framework.Scenes
             }
             else
             {
-                if (RootPart.PhysActor != null)
+                PhysicsActor pa = RootPart.PhysActor;
+
+                if (pa != null)
                 {
-                    RootPart.PhysActor.AddForce(impulse, true);
-                    m_scene.PhysicsScene.AddPhysicsActorTaint(RootPart.PhysActor);
+                    pa.AddForce(impulse, true);
+                    m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
                 }
             }
         }
 
         public void applyAngularImpulse(Vector3 impulse)
         {
-            if (RootPart.PhysActor != null)
+            PhysicsActor pa = RootPart.PhysActor;
+
+            if (pa != null)
             {
                 if (!IsAttachment)
                 {
-                    RootPart.PhysActor.AddAngularForce(impulse, true);
-                    m_scene.PhysicsScene.AddPhysicsActorTaint(RootPart.PhysActor);
+                    pa.AddAngularForce(impulse, true);
+                    m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
                 }
             }
         }
 
         public void setAngularImpulse(Vector3 impulse)
         {
-            if (RootPart.PhysActor != null)
+            PhysicsActor pa = RootPart.PhysActor;
+
+            if (pa != null)
             {
                 if (!IsAttachment)
                 {
-                    RootPart.PhysActor.Torque = impulse;
-                    m_scene.PhysicsScene.AddPhysicsActorTaint(RootPart.PhysActor);
+                    pa.Torque = impulse;
+                    m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
                 }
             }
         }
 
         public Vector3 GetTorque()
         {
-            if (RootPart.PhysActor != null)
+            PhysicsActor pa = RootPart.PhysActor;
+
+            if (pa != null)
             {
                 if (!IsAttachment)
                 {
-                    Vector3 torque = RootPart.PhysActor.Torque;
+                    Vector3 torque = pa.Torque;
                     return torque;
                 }
             }
@@ -1622,19 +1636,23 @@ namespace OpenSim.Region.Framework.Scenes
             }
             else
             {
-                if (RootPart.PhysActor != null)
+                PhysicsActor pa = RootPart.PhysActor;
+
+                if (pa != null)
                 {
-                    RootPart.PhysActor.PIDTarget = target;
-                    RootPart.PhysActor.PIDTau = tau;
-                    RootPart.PhysActor.PIDActive = true;
+                    pa.PIDTarget = target;
+                    pa.PIDTau = tau;
+                    pa.PIDActive = true;
                 }
             }
         }
 
         public void stopMoveToTarget()
         {
-            if (RootPart.PhysActor != null)
-                RootPart.PhysActor.PIDActive = false;
+            PhysicsActor pa = RootPart.PhysActor;
+
+            if (pa != null)
+                pa.PIDActive = false;
         }
         
         /// <summary>
@@ -1645,18 +1663,20 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="tau">Number of seconds over which to reach target</param>
         public void SetHoverHeight(float height, PIDHoverType hoverType, float tau)
         {
-            if (RootPart.PhysActor != null)
+            PhysicsActor pa = RootPart.PhysActor;
+
+            if (pa != null)
             {
                 if (height != 0f)
                 {
-                    RootPart.PhysActor.PIDHoverHeight = height;
-                    RootPart.PhysActor.PIDHoverType = hoverType;
-                    RootPart.PhysActor.PIDTau = tau;
-                    RootPart.PhysActor.PIDHoverActive = true;
+                    pa.PIDHoverHeight = height;
+                    pa.PIDHoverType = hoverType;
+                    pa.PIDTau = tau;
+                    pa.PIDHoverActive = true;
                 }
                 else
                 {
-                    RootPart.PhysActor.PIDHoverActive = false;
+                    pa.PIDHoverActive = false;
                 }
             }
         }
@@ -2094,10 +2114,10 @@ namespace OpenSim.Region.Framework.Scenes
             linkPart.ParentID = 0;
             linkPart.LinkNum = 0;
 
-            if (linkPart.PhysActor != null)
-            {
-                m_scene.PhysicsScene.RemovePrim(linkPart.PhysActor);
-            }
+            PhysicsActor linkPartPa = linkPart.PhysActor;
+
+            if (linkPartPa != null)
+                m_scene.PhysicsScene.RemovePrim(linkPartPa);
 
             // We need to reset the child part's position
             // ready for life as a separate object after being a part of another object
@@ -2188,17 +2208,19 @@ namespace OpenSim.Region.Framework.Scenes
         {
             if (m_scene.EventManager.TriggerGroupMove(UUID, pos))
             {
-                if (m_rootPart.PhysActor != null)
+                PhysicsActor pa = m_rootPart.PhysActor;
+
+                if (pa != null)
                 {
-                    if (m_rootPart.PhysActor.IsPhysical)
+                    if (pa.IsPhysical)
                     {
                         if (!m_rootPart.BlockGrab)
                         {
                             Vector3 llmoveforce = pos - AbsolutePosition;
                             Vector3 grabforce = llmoveforce;
-                            grabforce = (grabforce / 10) * m_rootPart.PhysActor.Mass;
-                            m_rootPart.PhysActor.AddForce(grabforce, true);
-                            m_scene.PhysicsScene.AddPhysicsActorTaint(m_rootPart.PhysActor);
+                            grabforce = (grabforce / 10) * pa.Mass;
+                            pa.AddForce(grabforce, true);
+                            m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
                         }
                     }
                     else
@@ -2228,9 +2250,11 @@ namespace OpenSim.Region.Framework.Scenes
         {
             if (m_scene.EventManager.TriggerGroupSpinStart(UUID))
             {
-                if (m_rootPart.PhysActor != null)
+                PhysicsActor pa = m_rootPart.PhysActor;
+
+                if (pa != null)
                 {
-                    if (m_rootPart.PhysActor.IsPhysical)
+                    if (pa.IsPhysical)
                     {
                         m_rootPart.IsWaitingForFirstSpinUpdatePacket = true;
                     }
@@ -2271,12 +2295,13 @@ namespace OpenSim.Region.Framework.Scenes
             // but it will result in over-shoot or under-shoot of the target orientation.
             // For the end user, this means that ctrl+shift+drag can be used for relative,
             // but not absolute, adjustments of orientation for physical prims.
-          
             if (m_scene.EventManager.TriggerGroupSpin(UUID, newOrientation))
             {
-                if (m_rootPart.PhysActor != null)
+                PhysicsActor pa = m_rootPart.PhysActor;
+
+                if (pa != null)
                 {
-                    if (m_rootPart.PhysActor.IsPhysical)
+                    if (pa.IsPhysical)
                     {
                         if (m_rootPart.IsWaitingForFirstSpinUpdatePacket)
                         {
@@ -2302,9 +2327,9 @@ namespace OpenSim.Region.Framework.Scenes
 
                           //m_log.Error("SCENE OBJECT GROUP]: rotation axis is " + rotationAxis);
                           Vector3 spinforce = new Vector3(rotationAxis.X, rotationAxis.Y, rotationAxis.Z);
-                          spinforce = (spinforce/8) * m_rootPart.PhysActor.Mass; // 8 is an arbitrary torque scaling factor
-                          m_rootPart.PhysActor.AddAngularForce(spinforce,true);
-                          m_scene.PhysicsScene.AddPhysicsActorTaint(m_rootPart.PhysActor);
+                          spinforce = (spinforce/8) * pa.Mass; // 8 is an arbitrary torque scaling factor
+                          pa.AddAngularForce(spinforce,true);
+                          m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
                         }
                     }
                     else
@@ -2478,8 +2503,10 @@ namespace OpenSim.Region.Framework.Scenes
             {
                 part.UpdateShape(shapeBlock);
 
-                if (part.PhysActor != null)
-                    m_scene.PhysicsScene.AddPhysicsActorTaint(part.PhysActor);
+                PhysicsActor pa = m_rootPart.PhysActor;
+
+                if (pa != null)
+                    m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
             }
         }
 
@@ -2502,7 +2529,9 @@ namespace OpenSim.Region.Framework.Scenes
             scale.Y = Math.Min(scale.Y, Scene.m_maxNonphys);
             scale.Z = Math.Min(scale.Z, Scene.m_maxNonphys);
 
-            if (RootPart.PhysActor != null && RootPart.PhysActor.IsPhysical)
+            PhysicsActor pa = m_rootPart.PhysActor;
+
+            if (pa != null && pa.IsPhysical)
             {
                 scale.X = Math.Min(scale.X, Scene.m_maxPhys);
                 scale.Y = Math.Min(scale.Y, Scene.m_maxPhys);
@@ -2528,7 +2557,7 @@ namespace OpenSim.Region.Framework.Scenes
                         float f = 1.0f;
                         float a = 1.0f;
 
-                        if (RootPart.PhysActor != null && RootPart.PhysActor.IsPhysical)
+                        if (pa != null && pa.IsPhysical)
                         {
                             if (oldSize.X * x > m_scene.m_maxPhys)
                             {
@@ -2893,10 +2922,13 @@ namespace OpenSim.Region.Framework.Scenes
 
             m_rootPart.StoreUndoState();
             m_rootPart.UpdateRotation(rot);
-            if (m_rootPart.PhysActor != null)
+
+            PhysicsActor pa = m_rootPart.PhysActor;
+
+            if (pa != null)
             {
-                m_rootPart.PhysActor.Orientation = m_rootPart.RotationOffset;
-                m_scene.PhysicsScene.AddPhysicsActorTaint(m_rootPart.PhysActor);
+                pa.Orientation = m_rootPart.RotationOffset;
+                m_scene.PhysicsScene.AddPhysicsActorTaint(pa);
             }
 
             SceneObjectPart[] parts = m_parts.GetArray();
diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs b/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
index 439b718..2b1fba0 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectPart.cs
@@ -151,6 +151,14 @@ namespace OpenSim.Region.Framework.Scenes
         public int[] PayPrice = {-2,-2,-2,-2,-2};
 
         [XmlIgnore]
+        /// <summary>
+        /// The representation of this part in the physics scene.
+        /// </summary>
+        /// <remarks>
+        /// If you use this property more than once in a section of code then you must take a reference and use that.
+        /// If another thread is simultaneously turning physics off on this part then this refernece could become
+        /// null at any time.
+        /// </remarks>
         public PhysicsActor PhysActor
         {
             get { return m_physActor; }
@@ -522,10 +530,11 @@ namespace OpenSim.Region.Framework.Scenes
             set 
             { 
                 m_name = value;
-                if (PhysActor != null)
-                {
-                    PhysActor.SOPName = value;
-                }
+
+                PhysicsActor pa = PhysActor;
+
+                if (pa != null)
+                    pa.SOPName = value;
             }
         }
 
@@ -535,10 +544,11 @@ namespace OpenSim.Region.Framework.Scenes
             set
             {
                 m_material = (Material)value;
-                if (PhysActor != null)
-                {
-                    PhysActor.SetMaterial((int)value);
-                }
+
+                PhysicsActor pa = PhysActor;
+
+                if (pa != null)
+                    pa.SetMaterial((int)value);
             }
         }
 
@@ -669,9 +679,7 @@ namespace OpenSim.Region.Framework.Scenes
                 // If this is a linkset, we don't want the physics engine mucking up our group position here.
                 PhysicsActor actor = PhysActor;
                 if (actor != null && ParentID == 0)
-                {
                     m_groupPosition = actor.Position;
-                }
 
                 if (ParentGroup.IsAttachment)
                 {
@@ -979,7 +987,7 @@ namespace OpenSim.Region.Framework.Scenes
                                 if (Shape.SculptEntry)
                                     CheckSculptAndLoad();
                                 else
-                                    ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(PhysActor);
+                                    ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(actor);
                             }
                         }
                     }
@@ -1505,12 +1513,14 @@ namespace OpenSim.Region.Framework.Scenes
                     }
 
                     // Basic Physics can also return null as well as an exception catch.
-                    if (PhysActor != null)
+                    PhysicsActor pa = PhysActor;
+
+                    if (pa != null)
                     {
-                        PhysActor.SOPName = this.Name; // save object into the PhysActor so ODE internals know the joint/body info
-                        PhysActor.SetMaterial(Material);
+                        pa.SOPName = this.Name; // save object into the PhysActor so ODE internals know the joint/body info
+                        pa.SetMaterial(Material);
                         DoPhysicsPropertyUpdate(RigidBody, true);
-                        PhysActor.SetVolumeDetect(VolumeDetectActive ? 1 : 0);
+                        pa.SetVolumeDetect(VolumeDetectActive ? 1 : 0);
                     }
                 }
             }
@@ -1731,23 +1741,25 @@ namespace OpenSim.Region.Framework.Scenes
             }
             else
             {
-                if (PhysActor != null)
+                PhysicsActor pa = PhysActor;
+
+                if (pa != null)
                 {
-                    if (UsePhysics != PhysActor.IsPhysical || isNew)
+                    if (UsePhysics != pa.IsPhysical || isNew)
                     {
-                        if (PhysActor.IsPhysical) // implies UsePhysics==false for this block
+                        if (pa.IsPhysical) // implies UsePhysics==false for this block
                         {
                             if (!isNew)
                                 ParentGroup.Scene.RemovePhysicalPrim(1);
 
-                            PhysActor.OnRequestTerseUpdate -= PhysicsRequestingTerseUpdate;
-                            PhysActor.OnOutOfBounds -= PhysicsOutOfBounds;
-                            PhysActor.delink();
+                            pa.OnRequestTerseUpdate -= PhysicsRequestingTerseUpdate;
+                            pa.OnOutOfBounds -= PhysicsOutOfBounds;
+                            pa.delink();
 
                             if (ParentGroup.Scene.PhysicsScene.SupportsNINJAJoints && (!isNew))
                             {
                                 // destroy all joints connected to this now deactivated body
-                                ParentGroup.Scene.PhysicsScene.RemoveAllJointsConnectedToActorThreadLocked(PhysActor);
+                                ParentGroup.Scene.PhysicsScene.RemoveAllJointsConnectedToActorThreadLocked(pa);
                             }
 
                             // stop client-side interpolation of all joint proxy objects that have just been deleted
@@ -1766,7 +1778,7 @@ namespace OpenSim.Region.Framework.Scenes
                             //RotationalVelocity = new Vector3(0, 0, 0);
                         }
 
-                        PhysActor.IsPhysical = UsePhysics;
+                        pa.IsPhysical = UsePhysics;
 
                         // If we're not what we're supposed to be in the physics scene, recreate ourselves.
                         //m_parentGroup.Scene.PhysicsScene.RemovePrim(PhysActor);
@@ -1779,13 +1791,15 @@ namespace OpenSim.Region.Framework.Scenes
                             {
                                 ParentGroup.Scene.AddPhysicalPrim(1);
 
-                                PhysActor.OnRequestTerseUpdate += PhysicsRequestingTerseUpdate;
-                                PhysActor.OnOutOfBounds += PhysicsOutOfBounds;
+                                pa.OnRequestTerseUpdate += PhysicsRequestingTerseUpdate;
+                                pa.OnOutOfBounds += PhysicsOutOfBounds;
                                 if (ParentID != 0 && ParentID != LocalId)
                                 {
-                                    if (ParentGroup.RootPart.PhysActor != null)
+                                    PhysicsActor parentPa = ParentGroup.RootPart.PhysActor;
+
+                                    if (parentPa != null)
                                     {
-                                        PhysActor.link(ParentGroup.RootPart.PhysActor);
+                                        pa.link(parentPa);
                                     }
                                 }
                             }
@@ -1797,7 +1811,7 @@ namespace OpenSim.Region.Framework.Scenes
                     if (Shape.SculptEntry)
                         CheckSculptAndLoad();
                     else
-                        ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(PhysActor);
+                        ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(pa);
                 }
             }
         }
@@ -1908,24 +1922,30 @@ namespace OpenSim.Region.Framework.Scenes
 
         public Vector3 GetGeometricCenter()
         {
-            if (PhysActor != null)
-                return new Vector3(PhysActor.CenterOfMass.X, PhysActor.CenterOfMass.Y, PhysActor.CenterOfMass.Z);
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                return new Vector3(pa.CenterOfMass.X, pa.CenterOfMass.Y, pa.CenterOfMass.Z);
             else
                 return new Vector3(0, 0, 0);
         }
 
         public float GetMass()
         {
-            if (PhysActor != null)
-                return PhysActor.Mass;
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                return pa.Mass;
             else
                 return 0;
         }
 
         public Vector3 GetForce()
         {
-            if (PhysActor != null)
-                return PhysActor.Force;
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                return pa.Force;
             else
                 return Vector3.Zero;
         }
@@ -2556,9 +2576,11 @@ namespace OpenSim.Region.Framework.Scenes
 
         public void PhysicsRequestingTerseUpdate()
         {
-            if (PhysActor != null)
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
             {
-                Vector3 newpos = new Vector3(PhysActor.Position.GetBytes(), 0);
+                Vector3 newpos = new Vector3(pa.Position.GetBytes(), 0);
                 
                 if (ParentGroup.Scene.TestBorderCross(newpos, Cardinals.N)
                     | ParentGroup.Scene.TestBorderCross(newpos, Cardinals.S)
@@ -2570,6 +2592,7 @@ namespace OpenSim.Region.Framework.Scenes
                 }
                 //ParentGroup.RootPart.m_groupPosition = newpos;
             }
+
             ScheduleTerseUpdate();
         }
 
@@ -2660,7 +2683,9 @@ 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);
 
-            if (PhysActor != null && PhysActor.IsPhysical)
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null && pa.IsPhysical)
             {
                 scale.X = Math.Min(scale.X, ParentGroup.Scene.m_maxPhys);
                 scale.Y = Math.Min(scale.Y, ParentGroup.Scene.m_maxPhys);
@@ -2809,12 +2834,14 @@ namespace OpenSim.Region.Framework.Scenes
                         m_shape.SculptData = texture.Data;
                     }
 
-                    if (PhysActor != null)
+                    PhysicsActor pa = PhysActor;
+
+                    if (pa != null)
                     {
                         // Update the physics actor with the new loaded sculpt data and set the taint signal.
-                        PhysActor.Shape = m_shape;
+                        pa.Shape = m_shape;
 
-                        ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(PhysActor);
+                        ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(pa);
                     }
                 }
             }
@@ -3072,10 +3099,10 @@ namespace OpenSim.Region.Framework.Scenes
 
         public void SetBuoyancy(float fvalue)
         {
-            if (PhysActor != null)
-            {
-                PhysActor.Buoyancy = fvalue;
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.Buoyancy = fvalue;
         }
 
         public void SetDieAtEdge(bool p)
@@ -3088,57 +3115,50 @@ namespace OpenSim.Region.Framework.Scenes
 
         public void SetFloatOnWater(int floatYN)
         {
-            if (PhysActor != null)
-            {
-                if (floatYN == 1)
-                {
-                    PhysActor.FloatOnWater = true;
-                }
-                else
-                {
-                    PhysActor.FloatOnWater = false;
-                }
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.FloatOnWater = floatYN == 1;
         }
 
         public void SetForce(Vector3 force)
         {
-            if (PhysActor != null)
-            {
-                PhysActor.Force = force;
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.Force = force;
         }
 
         public void SetVehicleType(int type)
         {
-            if (PhysActor != null)
-            {
-                PhysActor.VehicleType = type;
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.VehicleType = type;
         }
 
         public void SetVehicleFloatParam(int param, float value)
         {
-            if (PhysActor != null)
-            {
-                PhysActor.VehicleFloatParam(param, value);
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.VehicleFloatParam(param, value);
         }
 
         public void SetVehicleVectorParam(int param, Vector3 value)
         {
-            if (PhysActor != null)
-            {
-                PhysActor.VehicleVectorParam(param, value);
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.VehicleVectorParam(param, value);
         }
 
         public void SetVehicleRotationParam(int param, Quaternion rotation)
         {
-            if (PhysActor != null)
-            {
-                PhysActor.VehicleRotationParam(param, rotation);
-            }
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
+                pa.VehicleRotationParam(param, rotation);
         }
 
         /// <summary>
@@ -4226,6 +4246,8 @@ namespace OpenSim.Region.Framework.Scenes
             if ((UsePhysics == wasUsingPhysics) && (wasTemporary == SetTemporary) && (wasPhantom == SetPhantom) && (SetVD == wasVD))
                 return;
 
+            PhysicsActor pa = PhysActor;
+
             // Special cases for VD. VD can only be called from a script 
             // and can't be combined with changes to other states. So we can rely
             // that...
@@ -4241,8 +4263,9 @@ namespace OpenSim.Region.Framework.Scenes
                 {
                     SetVD = false;               // Switch it of for the course of this routine
                     VolumeDetectActive = false; // and also permanently
-                    if (PhysActor != null)
-                        PhysActor.SetVolumeDetect(0);   // Let physics know about it too
+
+                    if (pa != null)
+                        pa.SetVolumeDetect(0);   // Let physics know about it too
                 }
                 else
                 {
@@ -4357,9 +4380,9 @@ namespace OpenSim.Region.Framework.Scenes
                 // Defensive programming calls for a check here.
                 // Better would be throwing an exception that could be catched by a unit test as the internal 
                 // logic should make sure, this Physactor is always here.
-                if (this.PhysActor != null)
+                if (pa != null)
                 {
-                    PhysActor.SetVolumeDetect(1);
+                    pa.SetVolumeDetect(1);
                     AddFlag(PrimFlags.Phantom); // We set this flag also if VD is active
                     this.VolumeDetectActive = true;
                 }
@@ -4368,11 +4391,8 @@ namespace OpenSim.Region.Framework.Scenes
             {
                 // Remove VolumeDetect in any case. Note, it's safe to call SetVolumeDetect as often as you like
                 // (mumbles, well, at least if you have infinte CPU powers :-))
-                PhysicsActor pa = this.PhysActor;
                 if (pa != null)
-                {
                     PhysActor.SetVolumeDetect(0);
-                }
 
                 this.VolumeDetectActive = false;
             }
@@ -4385,6 +4405,7 @@ namespace OpenSim.Region.Framework.Scenes
             {
                 RemFlag(PrimFlags.TemporaryOnRez);
             }
+
             //            m_log.Debug("Update:  PHY:" + UsePhysics.ToString() + ", T:" + IsTemporary.ToString() + ", PHA:" + IsPhantom.ToString() + " S:" + CastsShadows.ToString());
 
             if (ParentGroup != null)
@@ -4453,10 +4474,12 @@ namespace OpenSim.Region.Framework.Scenes
             m_shape.PathTwist = shapeBlock.PathTwist;
             m_shape.PathTwistBegin = shapeBlock.PathTwistBegin;
 
-            if (PhysActor != null)
+            PhysicsActor pa = PhysActor;
+
+            if (pa != null)
             {
-                PhysActor.Shape = m_shape;
-                ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(PhysActor);
+                pa.Shape = m_shape;
+                ParentGroup.Scene.PhysicsScene.AddPhysicsActorTaint(pa);
             }
 
             // This is what makes vehicle trailers work
@@ -4598,6 +4621,8 @@ namespace OpenSim.Region.Framework.Scenes
                 objectflagupdate |= (uint) PrimFlags.AllowInventoryDrop;
             }
 
+            PhysicsActor pa = PhysActor;
+
             if (
                 ((AggregateScriptEvents & scriptEvents.collision) != 0) ||
                 ((AggregateScriptEvents & scriptEvents.collision_end) != 0) ||
@@ -4609,18 +4634,18 @@ namespace OpenSim.Region.Framework.Scenes
                 )
             {
                 // subscribe to physics updates.
-                if (PhysActor != null)
+                if (pa != null)
                 {
-                    PhysActor.OnCollisionUpdate += PhysicsCollision;
-                    PhysActor.SubscribeEvents(1000);
+                    pa.OnCollisionUpdate += PhysicsCollision;
+                    pa.SubscribeEvents(1000);
                 }
             }
             else
             {
-                if (PhysActor != null)
+                if (pa != null)
                 {
-                    PhysActor.UnSubscribeEvents();
-                    PhysActor.OnCollisionUpdate -= PhysicsCollision;
+                    pa.UnSubscribeEvents();
+                    pa.OnCollisionUpdate -= PhysicsCollision;
                 }
             }