2 files changed, 30 insertions, 55 deletions

diff --git a/OpenSim/Region/Framework/Scenes/SceneGraph.cs b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
index a3206015..3cd4a10 100644
--- a/OpenSim/Region/Framework/Scenes/SceneGraph.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneGraph.cs
@@ -230,27 +230,9 @@ namespace OpenSim.Region.Framework.Scenes
                 if (sp.IsChildAgent)
                     continue;
 
-                if (sp.ParentID != 0)
-                {
-                    // sitting avatar
-                    SceneObjectPart sop = m_parentScene.GetSceneObjectPart(sp.ParentID);
-                    if (sop != null)
-                    {
-                        coarseLocations.Add(sop.AbsolutePosition + sp.OffsetPosition);
-                        avatarUUIDs.Add(sp.UUID);
-                    }
-                    else
-                    {
-                        // we can't find the parent..  ! arg!
-                        coarseLocations.Add(sp.AbsolutePosition);
-                        avatarUUIDs.Add(sp.UUID);
-                    }
-                }
-                else
-                {
-                    coarseLocations.Add(sp.AbsolutePosition);
-                    avatarUUIDs.Add(sp.UUID);
-                }
+                coarseLocations.Add(sp.AbsolutePosition);
+
+                avatarUUIDs.Add(sp.UUID);
             }
         }
 
diff --git a/OpenSim/Region/Framework/Scenes/ScenePresence.cs b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
index 4190cf6..c4aaebe 100644
--- a/OpenSim/Region/Framework/Scenes/ScenePresence.cs
+++ b/OpenSim/Region/Framework/Scenes/ScenePresence.cs
@@ -438,7 +438,7 @@ namespace OpenSim.Region.Framework.Scenes
         {
             get
             {
-                if (PhysicsActor != null && m_parentID == 0)
+                if (PhysicsActor != null)
                 {
                     m_pos = PhysicsActor.Position;
 
@@ -461,12 +461,12 @@ namespace OpenSim.Region.Framework.Scenes
                     // in the sim unless the avatar is on a sit target. While
                     // on a sit target, m_pos will contain the desired offset
                     // without the parent rotation applied.
-                    if (ParentID != 0)
-                    {
-                        SceneObjectPart part = ParentPart;
-                            return part.AbsolutePosition + (m_pos * part.GetWorldRotation());
-                    }
+                    SceneObjectPart sitPart = ParentPart;
+
+                    if (sitPart != null)
+                        return sitPart.AbsolutePosition + (m_pos * sitPart.GetWorldRotation());
                 }
+                
                 return m_pos;
             }
             set
@@ -483,7 +483,7 @@ namespace OpenSim.Region.Framework.Scenes
                     }
                 }
 
-                // Don't update while sitting
+                // Don't update while sitting.  The PhysicsActor above is null whilst sitting.
                 if (ParentID == 0)
                 {
                     m_pos = value;
@@ -510,6 +510,7 @@ namespace OpenSim.Region.Framework.Scenes
                 // There is no offset position when not seated
                 if (ParentID == 0)
                     return;
+
                 m_pos = value;
             }
         }
@@ -568,12 +569,10 @@ namespace OpenSim.Region.Framework.Scenes
 
         public bool IsChildAgent { get; set; }
 
-        public uint ParentID
-        {
-            get { return m_parentID; }
-            set { m_parentID = value; }
-        }
-        private uint m_parentID;
+        /// <summary>
+        /// If the avatar is sitting, the local ID of the prim that it's sitting on.  If not sitting then zero.
+        /// </summary>
+        public uint ParentID { get; set; }
 
         public UUID ParentUUID
         {
@@ -582,12 +581,13 @@ namespace OpenSim.Region.Framework.Scenes
         }
         private UUID m_parentUUID = UUID.Zero;
 
-        public SceneObjectPart ParentPart
-        {
-            get { return m_parentPart; }
-            set { m_parentPart = value; }
-        }
-        private SceneObjectPart m_parentPart = null;
+        /// <summary>
+        /// If the avatar is sitting, the prim that it's sitting on.  If not sitting then null.
+        /// </summary>
+        /// <remarks>
+        /// If you use this property then you must take a reference since another thread could set it to null.
+        /// </remarks>
+        public SceneObjectPart ParentPart { get; set; }
 
         public float Health
         {
@@ -2285,23 +2285,16 @@ namespace OpenSim.Region.Framework.Scenes
 //                            "[SCENE PRESENCE]: Sitting {0} at position {1} ({2} + {3}) on part {4} {5} without sit target",
 //                            Name, part.AbsolutePosition, m_pos, ParentPosition, part.Name, part.LocalId);
                 }
-            }
-            else
-            {
-                return;
-            }
-
-            ParentPart = m_scene.GetSceneObjectPart(m_requestedSitTargetID);
-            if (ParentPart == null)
-                return;
 
-            ParentID = m_requestedSitTargetID;
+                ParentPart = m_scene.GetSceneObjectPart(m_requestedSitTargetID);
+                ParentID = m_requestedSitTargetID;
 
-            Velocity = Vector3.Zero;
-            RemoveFromPhysicalScene();
-
-            Animator.TrySetMovementAnimation(sitAnimation);
-            SendAvatarDataToAllAgents();
+                Velocity = Vector3.Zero;
+                RemoveFromPhysicalScene();
+        
+                Animator.TrySetMovementAnimation(sitAnimation);
+                SendAvatarDataToAllAgents();
+            }
         }
 
         public void HandleAgentSitOnGround()