1 files changed, 317 insertions, 297 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs b/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
index 130f1ca..a4ab702 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
@@ -42,6 +42,8 @@ public sealed class BSPrim : PhysicsActor
     private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
     private static readonly string LogHeader = "[BULLETS PRIM]";
 
+    private void DebugLog(string mm, params Object[] xx) { if (_scene.shouldDebugLog) m_log.DebugFormat(mm, xx); }
+
     private IMesh _mesh;
     private PrimitiveBaseShape _pbs;
     private ShapeData.PhysicsShapeType _shapeType;
@@ -50,6 +52,7 @@ public sealed class BSPrim : PhysicsActor
     private List<ConvexResult> _hulls;
 
     private BSScene _scene;
+    public BSScene Scene { get { return _scene; } }
     private String _avName;
     private uint _localID = 0;
 
@@ -63,7 +66,7 @@ public sealed class BSPrim : PhysicsActor
     private bool _isSelected;
     private bool _isVolumeDetect;
     private OMV.Vector3 _position;
-    private float _mass;
+    private float _mass;    // the mass of this object
     private float _density;
     private OMV.Vector3 _force;
     private OMV.Vector3 _velocity;
@@ -86,14 +89,25 @@ public sealed class BSPrim : PhysicsActor
     private bool _kinematic;
     private float _buoyancy;
 
-    private List<BSPrim> _childrenPrims;
-    private BSPrim _parentPrim;
+    // Membership in a linkset is controlled by this class.
+    private BSLinkset _linkset;
+    public BSLinkset Linkset
+    {
+        get { return _linkset; }
+        set { _linkset = value; }
+    }
 
     private int _subscribedEventsMs = 0;
     private int _nextCollisionOkTime = 0;
     long _collidingStep;
     long _collidingGroundStep;
 
+    private BulletBody m_body;
+    public BulletBody Body { 
+        get { return m_body; }
+        set { m_body = value; }
+    }
+
     private BSDynamics _vehicle;
 
     private OMV.Vector3 _PIDTarget;
@@ -127,17 +141,18 @@ public sealed class BSPrim : PhysicsActor
         _friction = _scene.Params.defaultFriction; // TODO: compute based on object material
         _density = _scene.Params.defaultDensity; // TODO: compute based on object material
         _restitution = _scene.Params.defaultRestitution;
-        _parentPrim = null;     // not a child or a parent
+        _linkset = new BSLinkset(_scene, this);     // a linkset of one
         _vehicle = new BSDynamics(this);    // add vehicleness
-        _childrenPrims = new List<BSPrim>();
-        if (_isPhysical)
-            _mass = CalculateMass();
-        else
-            _mass = 0f;
+        _mass = CalculateMass();
         // do the actual object creation at taint time
         _scene.TaintedObject(delegate()
         {
             RecreateGeomAndObject();
+
+            // Get the pointer to the physical body for this object.
+            // At the moment, we're still letting BulletSim manage the creation and destruction
+            //    of the object. Someday we'll move that into the C# code.
+            m_body = new BulletBody(LocalID, BulletSimAPI.GetBodyHandle2(_scene.World.Ptr, LocalID));
         });
     }
 
@@ -145,13 +160,19 @@ public sealed class BSPrim : PhysicsActor
     public void Destroy()
     {
         // m_log.DebugFormat("{0}: Destroy, id={1}", LogHeader, LocalID);
+        // DetailLog("{0},Destroy", LocalID);
+
         // Undo any vehicle properties
         _vehicle.ProcessTypeChange(Vehicle.TYPE_NONE);
         _scene.RemoveVehiclePrim(this);     // just to make sure
+
         _scene.TaintedObject(delegate()
         {
+            // Undo any links between me and any other object
+            _linkset = _linkset.RemoveMeFromLinkset(this);
+
             // everything in the C# world will get garbage collected. Tell the C++ world to free stuff.
-            BulletSimAPI.DestroyObject(_scene.WorldID, _localID);
+            BulletSimAPI.DestroyObject(_scene.WorldID, LocalID);
         });
     }
     
@@ -164,8 +185,9 @@ public sealed class BSPrim : PhysicsActor
             _size = value;
             _scene.TaintedObject(delegate()
             {
-                if (_isPhysical) _mass = CalculateMass();   // changing size changes the mass
-                BulletSimAPI.SetObjectScaleMass(_scene.WorldID, _localID, _scale, _mass, _isPhysical);
+                _mass = CalculateMass();   // changing size changes the mass
+                BulletSimAPI.SetObjectScaleMass(_scene.WorldID, _localID, _scale, (IsPhysical ? _mass : 0f), IsPhysical);
+                DetailLog("{0}: setSize: size={1}, mass={2}, physical={3}", LocalID, _size, _mass, IsPhysical);
                 RecreateGeomAndObject();
             });
         } 
@@ -175,7 +197,7 @@ public sealed class BSPrim : PhysicsActor
             _pbs = value;
             _scene.TaintedObject(delegate()
             {
-                if (_isPhysical) _mass = CalculateMass();   // changing the shape changes the mass
+                _mass = CalculateMass();   // changing the shape changes the mass
                 RecreateGeomAndObject();
             });
         } 
@@ -202,33 +224,10 @@ public sealed class BSPrim : PhysicsActor
     // link me to the specified parent
     public override void link(PhysicsActor obj) {
         BSPrim parent = obj as BSPrim;
-        // m_log.DebugFormat("{0}: link {1}/{2} to {3}", LogHeader, _avName, _localID, obj.LocalID);
-        // TODO: decide if this parent checking needs to happen at taint time
-        if (_parentPrim == null)
-        {
-            if (parent != null)
-            {
-                // I don't have a parent so I am joining a linkset
-                parent.AddChildToLinkset(this);
-            }
-        }
-        else
-        {
-            // I already have a parent, is parenting changing?
-            if (parent != _parentPrim)
-            {
-                if (parent == null)
-                {
-                    // we are being removed from a linkset
-                    _parentPrim.RemoveChildFromLinkset(this);
-                }
-                else
-                {
-                    // asking to reparent a prim should not happen
-                    m_log.ErrorFormat("{0}: Reparenting a prim. ", LogHeader);
-                }
-            }
-        }
+        DebugLog("{0}: link {1}/{2} to {3}", LogHeader, _avName, _localID, obj.LocalID);
+        DetailLog("{0},link,parent={1}", LocalID, obj.LocalID);
+
+        _linkset = _linkset.AddMeToLinkset(this, parent);
         return; 
     }
 
@@ -236,101 +235,92 @@ public sealed class BSPrim : PhysicsActor
     public override void delink() {
         // TODO: decide if this parent checking needs to happen at taint time
         // Race condition here: if link() and delink() in same simulation tick, the delink will not happen
-        // m_log.DebugFormat("{0}: delink {1}/{2}", LogHeader, _avName, _localID);
-        if (_parentPrim != null)
-        {
-            _parentPrim.RemoveChildFromLinkset(this);
-        }
-        return; 
-    }
-
-    // I am the root of a linkset and a new child is being added
-    public void AddChildToLinkset(BSPrim pchild)
-    {
-        BSPrim child = pchild;
-        _scene.TaintedObject(delegate()
-        {
-            if (!_childrenPrims.Contains(child))
-            {
-                _childrenPrims.Add(child);
-                child.ParentPrim = this;    // the child has gained a parent
-                RecreateGeomAndObject();    // rebuild my shape with the new child added
-            }
-        });
-        return;
-    }
-
-    // I am the root of a linkset and one of my children is being removed.
-    // Safe to call even if the child is not really in my linkset.
-    public void RemoveChildFromLinkset(BSPrim pchild)
-    {
-        BSPrim child = pchild;
-        _scene.TaintedObject(delegate()
-        {
-            if (_childrenPrims.Contains(child))
-            {
-                BulletSimAPI.RemoveConstraint(_scene.WorldID, child.LocalID, this.LocalID);
-                _childrenPrims.Remove(child);
-                child.ParentPrim = null;    // the child has lost its parent
-                RecreateGeomAndObject();    // rebuild my shape with the child removed
-            }
-            else
-            {
-                m_log.ErrorFormat("{0}: Asked to remove child from linkset that was not in linkset");
-            }
-        });
-        return;
-    }
-
-    public BSPrim ParentPrim
-    {
-        set { _parentPrim = value; }
-    }
+        DebugLog("{0}: delink {1}/{2}. Parent={3}", LogHeader, _avName, _localID, 
+                            _linkset.Root._avName+"/"+_linkset.Root.LocalID.ToString());
+        DetailLog("{0},delink,parent={1}", LocalID, _linkset.Root.LocalID.ToString());
 
-    // return true if we are the root of a linkset (there are children to manage)
-    public bool IsRootOfLinkset
-    {
-        get { return (_parentPrim == null && _childrenPrims.Count != 0); }
+        _linkset.RemoveMeFromLinkset(this);
+        return; 
     }
 
     // Set motion values to zero.
     // Do it to the properties so the values get set in the physics engine.
     // Push the setting of the values to the viewer.
-    private void ZeroMotion()
+    // Called at taint time!
+    public void ZeroMotion()
     {
-        Velocity = OMV.Vector3.Zero;
+        _velocity = OMV.Vector3.Zero;
         _acceleration = OMV.Vector3.Zero;
-        RotationalVelocity = OMV.Vector3.Zero;
-        base.RequestPhysicsterseUpdate();
+        _rotationalVelocity = OMV.Vector3.Zero;
+
+        // Zero some other properties directly into the physics engine
+        BulletSimAPI.SetVelocity2(Body.Ptr, OMV.Vector3.Zero);
+        BulletSimAPI.SetAngularVelocity2(Body.Ptr, OMV.Vector3.Zero);
+        BulletSimAPI.SetInterpolation2(Body.Ptr, OMV.Vector3.Zero, OMV.Vector3.Zero);
+        BulletSimAPI.ClearForces2(Body.Ptr);
     }
 
-    public override void LockAngularMotion(OMV.Vector3 axis) { return; }
+    public override void LockAngularMotion(OMV.Vector3 axis)
+    { 
+        DetailLog("{0},LockAngularMotion,call,axis={1}", LocalID, axis);
+        return;
+    }
 
     public override OMV.Vector3 Position { 
         get { 
-            // don't do the following GetObjectPosition because this function is called a zillion times
+            if (!_linkset.IsRoot(this))
+                // child prims move around based on their parent. Need to get the latest location
+                _position = BulletSimAPI.GetObjectPosition(_scene.WorldID, _localID);
+
+            // don't do the GetObjectPosition for root elements because this function is called a zillion times
             // _position = BulletSimAPI.GetObjectPosition(_scene.WorldID, _localID);
             return _position; 
         } 
         set {
             _position = value;
+            // TODO: what does it mean to set the position of a child prim?? Rebuild the constraint?
             _scene.TaintedObject(delegate()
             {
+                DetailLog("{0},SetPosition,taint,pos={1},orient={2}", LocalID, _position, _orientation);
                 BulletSimAPI.SetObjectTranslation(_scene.WorldID, _localID, _position, _orientation);
-                // m_log.DebugFormat("{0}: setPosition: id={1}, position={2}", LogHeader, _localID, _position);
             });
         } 
     }
-    public override float Mass { 
-        get { return _mass; } 
+
+    // Return the effective mass of the object.
+    // If there are multiple items in the linkset, add them together for the root
+    public override float Mass
+    { 
+        get
+        {
+            return _linkset.LinksetMass;
+        }
+    }
+
+    // used when we only want this prim's mass and not the linkset thing
+    public float MassRaw { get { return _mass; } }
+
+    // Is this used?
+    public override OMV.Vector3 CenterOfMass
+    {
+        get { return _linkset.CenterOfMass; }
+    }
+
+    // Is this used?
+    public override OMV.Vector3 GeometricCenter
+    {
+        get { return _linkset.GeometricCenter; }
     }
+
     public override OMV.Vector3 Force { 
         get { return _force; } 
         set {
             _force = value;
             _scene.TaintedObject(delegate()
             {
-                BulletSimAPI.SetObjectForce(_scene.WorldID, _localID, _force);
+                DetailLog("{0},SetForce,taint,force={1}", LocalID, _force);
+                // BulletSimAPI.SetObjectForce(_scene.WorldID, _localID, _force);
+                BulletSimAPI.SetObjectForce2(Body.Ptr, _force);
             });
         } 
     }
@@ -341,15 +331,22 @@ public sealed class BSPrim : PhysicsActor
         } 
         set {
             Vehicle type = (Vehicle)value;
-            _vehicle.ProcessTypeChange(type);
             _scene.TaintedObject(delegate()
             {
+                DetailLog("{0},SetVehicleType,taint,type={1}", LocalID, type);
+                _vehicle.ProcessTypeChange(type);
                 if (type == Vehicle.TYPE_NONE)
                 {
                     _scene.RemoveVehiclePrim(this);
                 }
                 else
                 {
+                    _scene.TaintedObject(delegate()
+                    {
+                        // Tell the physics engine to clear state
+                        BulletSimAPI.ClearForces2(this.Body.Ptr);
+                    });
+
                     // make it so the scene will call us each tick to do vehicle things
                     _scene.AddVehiclePrim(this);
                 }
@@ -359,47 +356,59 @@ public sealed class BSPrim : PhysicsActor
     }
     public override void VehicleFloatParam(int param, float value) 
     {
-        _vehicle.ProcessFloatVehicleParam((Vehicle)param, value);
+        _scene.TaintedObject(delegate()
+        {
+            _vehicle.ProcessFloatVehicleParam((Vehicle)param, value, _scene.LastSimulatedTimestep);
+        });
     }
     public override void VehicleVectorParam(int param, OMV.Vector3 value) 
     {
-        _vehicle.ProcessVectorVehicleParam((Vehicle)param, value);
+        _scene.TaintedObject(delegate()
+        {
+            _vehicle.ProcessVectorVehicleParam((Vehicle)param, value, _scene.LastSimulatedTimestep);
+        });
     }
     public override void VehicleRotationParam(int param, OMV.Quaternion rotation) 
     {
-        _vehicle.ProcessRotationVehicleParam((Vehicle)param, rotation);
+        _scene.TaintedObject(delegate()
+        {
+            _vehicle.ProcessRotationVehicleParam((Vehicle)param, rotation);
+        });
     }
     public override void VehicleFlags(int param, bool remove) 
     {
-        _vehicle.ProcessVehicleFlags(param, remove);
+        _scene.TaintedObject(delegate()
+        {
+            _vehicle.ProcessVehicleFlags(param, remove);
+        });
     }
-    // Called each simulation step to advance vehicle characteristics
+
+    // Called each simulation step to advance vehicle characteristics.
+    // Called from Scene when doing simulation step so we're in taint processing time.
     public void StepVehicle(float timeStep)
     {
-        _vehicle.Step(timeStep, _scene);
+        if (IsPhysical)
+            _vehicle.Step(timeStep);
     }
 
     // Allows the detection of collisions with inherently non-physical prims. see llVolumeDetect for more
     public override void SetVolumeDetect(int param) {
         bool newValue = (param != 0);
-        if (_isVolumeDetect != newValue)
+        _isVolumeDetect = newValue;
+        _scene.TaintedObject(delegate()
         {
-            _isVolumeDetect = newValue;
-            _scene.TaintedObject(delegate()
-            {
-                SetObjectDynamic();
-            });
-        }
+            SetObjectDynamic();
+        });
         return; 
     }
 
-    public override OMV.Vector3 GeometricCenter { get { return OMV.Vector3.Zero; } }
-    public override OMV.Vector3 CenterOfMass { get { return OMV.Vector3.Zero; } }
     public override OMV.Vector3 Velocity { 
         get { return _velocity; } 
-        set { _velocity = value; 
+        set {
+            _velocity = value;
             _scene.TaintedObject(delegate()
             {
+                DetailLog("{0},SetVelocity,taint,vel={1}", LocalID, _velocity);
                 BulletSimAPI.SetObjectVelocity(_scene.WorldID, LocalID, _velocity);
             });
         } 
@@ -407,6 +416,7 @@ public sealed class BSPrim : PhysicsActor
     public override OMV.Vector3 Torque { 
         get { return _torque; } 
         set { _torque = value; 
+            DetailLog("{0},SetTorque,call,torque={1}", LocalID, _torque);
         } 
     }
     public override float CollisionScore { 
@@ -419,13 +429,21 @@ public sealed class BSPrim : PhysicsActor
         set { _acceleration = value; }
     }
     public override OMV.Quaternion Orientation { 
-        get { return _orientation; } 
+        get {
+            if (!_linkset.IsRoot(this))
+            {
+                // Children move around because tied to parent. Get a fresh value.
+                _orientation = BulletSimAPI.GetObjectOrientation(_scene.WorldID, LocalID);
+            }
+            return _orientation;
+        } 
         set {
             _orientation = value;
-            // m_log.DebugFormat("{0}: set orientation: id={1}, ori={2}", LogHeader, LocalID, _orientation);
+            // TODO: what does it mean if a child in a linkset changes its orientation? Rebuild the constraint?
             _scene.TaintedObject(delegate()
             {
                 // _position = BulletSimAPI.GetObjectPosition(_scene.WorldID, _localID);
+                DetailLog("{0},SetOrientation,taint,pos={1},orient={2}", LocalID, _position, _orientation);
                 BulletSimAPI.SetObjectTranslation(_scene.WorldID, _localID, _position, _orientation);
             });
         } 
@@ -458,25 +476,24 @@ public sealed class BSPrim : PhysicsActor
         get { return !IsPhantom && !_isVolumeDetect; }
     }
 
-    // make gravity work if the object is physical and not selected
-    // no locking here because only called when it is safe
+    // Make gravity work if the object is physical and not selected
+    // No locking here because only called when it is safe
+    // Only called at taint time so it is save to call into Bullet.
     private void SetObjectDynamic()
     {
-        // m_log.DebugFormat("{0}: ID={1}, SetObjectDynamic: IsStatic={2}, IsSolid={3}", LogHeader, _localID, IsStatic, IsSolid);
-        // non-physical things work best with a mass of zero
-        if (IsStatic)
-        {
-            _mass = 0f;
-        }
-        else
-        {
-            _mass = CalculateMass();
-            // If it's dynamic, make sure the hull has been created for it
-            // This shouldn't do much work if the object had previously been built
-            RecreateGeomAndObject();
+        // RA: remove this for the moment.
+        // The problem is that dynamic objects are hulls so if we are becoming physical
+        //    the shape has to be checked and possibly built.
+        //    Maybe a VerifyCorrectPhysicalShape() routine?
+        // RecreateGeomAndObject();
 
-        }
-        BulletSimAPI.SetObjectProperties(_scene.WorldID, LocalID, IsStatic, IsSolid, SubscribedEvents(), _mass);
+        float mass = _mass;
+        // Bullet wants static objects have a mass of zero
+        if (IsStatic) 
+            mass = 0f;
+
+        DetailLog("{0},SetObjectDynamic,taint,static={1},solid={2},mass={3}", LocalID, IsStatic, IsSolid, mass);
+        BulletSimAPI.SetObjectProperties(_scene.WorldID, LocalID, IsStatic, IsSolid, SubscribedEvents(), mass);
     }
 
     // prims don't fly
@@ -516,11 +533,24 @@ public sealed class BSPrim : PhysicsActor
         set { _floatOnWater = value; } 
     }
     public override OMV.Vector3 RotationalVelocity { 
-        get { return _rotationalVelocity; } 
-        set { _rotationalVelocity = value; 
+        get {
+            /*
+            OMV.Vector3 pv = OMV.Vector3.Zero;
+            // if close to zero, report zero
+            // This is copied from ODE but I'm not sure why it returns zero but doesn't
+            //    zero the property in the physics engine.
+            if (_rotationalVelocity.ApproxEquals(pv, 0.2f))
+                return pv;
+             */
+
+            return _rotationalVelocity;
+        } 
+        set {
+            _rotationalVelocity = value;
             // m_log.DebugFormat("{0}: RotationalVelocity={1}", LogHeader, _rotationalVelocity);
             _scene.TaintedObject(delegate()
             {
+                DetailLog("{0},SetRotationalVel,taint,rotvel={1}", LocalID, _rotationalVelocity);
                 BulletSimAPI.SetObjectAngularVelocity(_scene.WorldID, LocalID, _rotationalVelocity);
             });
         } 
@@ -533,11 +563,13 @@ public sealed class BSPrim : PhysicsActor
     }
     public override float Buoyancy { 
         get { return _buoyancy; } 
-        set { _buoyancy = value;
-        _scene.TaintedObject(delegate()
-        {
-            BulletSimAPI.SetObjectBuoyancy(_scene.WorldID, _localID, _buoyancy);
-        });
+        set {
+            _buoyancy = value;
+            _scene.TaintedObject(delegate()
+            {
+                DetailLog("{0},SetBuoyancy,taint,buoy={1}", LocalID, _buoyancy);
+                BulletSimAPI.SetObjectBuoyancy(_scene.WorldID, _localID, _buoyancy);
+            });
         } 
     }
 
@@ -573,27 +605,45 @@ public sealed class BSPrim : PhysicsActor
     public override float APIDStrength { set { return; } }
     public override float APIDDamping { set { return; } }
 
+    private List<OMV.Vector3> m_accumulatedForces = new List<OMV.Vector3>();
     public override void AddForce(OMV.Vector3 force, bool pushforce) {
         if (force.IsFinite())
         {
-            _force.X += force.X;
-            _force.Y += force.Y;
-            _force.Z += force.Z;
+            // _force += force;
+            lock (m_accumulatedForces)
+                m_accumulatedForces.Add(new OMV.Vector3(force));
         }
         else
         {
             m_log.WarnFormat("{0}: Got a NaN force applied to a Character", LogHeader);
+            return;
         }
         _scene.TaintedObject(delegate()
         {
-            BulletSimAPI.SetObjectForce(_scene.WorldID, _localID, _force);
+            lock (m_accumulatedForces)
+            {
+                if (m_accumulatedForces.Count > 0)
+                {
+                    OMV.Vector3 fSum = OMV.Vector3.Zero;
+                    foreach (OMV.Vector3 v in m_accumulatedForces)
+                    {
+                        fSum += v;
+                    }
+                    m_accumulatedForces.Clear();
+
+                    DetailLog("{0},SetObjectForce,taint,force={1}", LocalID, fSum);
+                    BulletSimAPI.SetObjectForce(_scene.WorldID, _localID, fSum);
+                }
+            }
         });
     }
 
     public override void AddAngularForce(OMV.Vector3 force, bool pushforce) { 
+        DetailLog("{0},AddAngularForce,call,angForce={1},push={2}", LocalID, force, pushforce);
         // m_log.DebugFormat("{0}: AddAngularForce. f={1}, push={2}", LogHeader, force, pushforce);
     }
     public override void SetMomentum(OMV.Vector3 momentum) { 
+        DetailLog("{0},SetMomentum,call,mom={1}", LocalID, momentum);
     }
     public override void SubscribeEvents(int ms) { 
         _subscribedEventsMs = ms;
@@ -885,6 +935,9 @@ public sealed class BSPrim : PhysicsActor
 
         returnMass = _density * volume;
 
+        /*
+         * This change means each object keeps its own mass and the Mass property
+         * will return the sum if we're part of a linkset.
         if (IsRootOfLinkset)
         {
             foreach (BSPrim prim in _childrenPrims)
@@ -892,6 +945,7 @@ public sealed class BSPrim : PhysicsActor
                 returnMass += prim.CalculateMass();
             }
         }
+         */
 
         if (returnMass <= 0)
             returnMass = 0.0001f;
@@ -907,9 +961,11 @@ public sealed class BSPrim : PhysicsActor
     // The objects needs a hull if it's physical otherwise a mesh is enough
     // No locking here because this is done when we know physics is not simulating
     // if 'forceRebuild' is true, the geometry is rebuilt. Otherwise a previously built version is used
-    private void CreateGeom(bool forceRebuild)
+    // Returns 'true' if the geometry was rebuilt
+    private bool CreateGeom(bool forceRebuild)
     {
         // the mesher thought this was too simple to mesh. Use a native Bullet collision shape.
+        bool ret = false;
         if (!_scene.NeedsMeshing(_pbs))
         {
             if (_pbs.ProfileShape == ProfileShape.HalfCircle && _pbs.PathCurve == (byte)Extrusion.Curve1)
@@ -917,16 +973,28 @@ public sealed class BSPrim : PhysicsActor
                 if (_size.X == _size.Y && _size.Y == _size.Z && _size.X == _size.Z)
                 {
                     // m_log.DebugFormat("{0}: CreateGeom: Defaulting to sphere of size {1}", LogHeader, _size);
-                    _shapeType = ShapeData.PhysicsShapeType.SHAPE_SPHERE;
-                    // Bullet native objects are scaled by the Bullet engine so pass the size in
-                    _scale = _size;
+                    if (forceRebuild || (_shapeType != ShapeData.PhysicsShapeType.SHAPE_SPHERE))
+                    {
+                        DetailLog("{0},CreateGeom,sphere", LocalID);
+                        _shapeType = ShapeData.PhysicsShapeType.SHAPE_SPHERE;
+                        // Bullet native objects are scaled by the Bullet engine so pass the size in
+                        _scale = _size;
+                        // TODO: do we need to check for and destroy a mesh or hull that might have been left from before?
+                        ret = true;
+                    }
                 }
             }
             else
             {
-                // m_log.DebugFormat("{0}: CreateGeom: Defaulting to box. lid={1}, size={2}", LogHeader, LocalID, _size);
-                _shapeType = ShapeData.PhysicsShapeType.SHAPE_BOX;
-                _scale = _size;
+                // m_log.DebugFormat("{0}: CreateGeom: Defaulting to box. lid={1}, type={2}, size={3}", LogHeader, LocalID, _shapeType, _size);
+                if (forceRebuild || (_shapeType != ShapeData.PhysicsShapeType.SHAPE_BOX))
+                {
+                    DetailLog("{0},CreateGeom,box", LocalID);
+                    _shapeType = ShapeData.PhysicsShapeType.SHAPE_BOX;
+                    _scale = _size;
+                    // TODO: do we need to check for and destroy a mesh or hull that might have been left from before?
+                    ret = true;
+                }
             }
         }
         else
@@ -938,6 +1006,7 @@ public sealed class BSPrim : PhysicsActor
                     // physical objects require a hull for interaction.
                     // This will create the mesh if it doesn't already exist
                     CreateGeomHull();
+                    ret = true;
                 }
             }
             else
@@ -946,9 +1015,11 @@ public sealed class BSPrim : PhysicsActor
                 {
                     // Static (non-physical) objects only need a mesh for bumping into
                     CreateGeomMesh();
+                    ret = true;
                 }
             }
         }
+        return ret;
     }
 
     // No locking here because this is done when we know physics is not simulating
@@ -961,10 +1032,12 @@ public sealed class BSPrim : PhysicsActor
         // if this new shape is the same as last time, don't recreate the mesh
         if (_meshKey == newMeshKey) return;
 
+        DetailLog("{0},CreateGeomMesh,create,key={1}", LocalID, _meshKey);
         // Since we're recreating new, get rid of any previously generated shape
         if (_meshKey != 0)
         {
             // m_log.DebugFormat("{0}: CreateGeom: deleting old mesh. lID={1}, Key={2}", LogHeader, _localID, _meshKey);
+            DetailLog("{0},CreateGeomMesh,deleteOld,key={1}", LocalID, _meshKey);
             BulletSimAPI.DestroyMesh(_scene.WorldID, _meshKey);
             _mesh = null;
             _meshKey = 0;
@@ -981,7 +1054,6 @@ public sealed class BSPrim : PhysicsActor
         int vi = 0;
         foreach (OMV.Vector3 vv in vertices)
         {
-            // m_log.DebugFormat("{0}:  {1}: <{2:0.00}, {3:0.00}, {4:0.00}>", LogHeader, vi / 3, vv.X, vv.Y, vv.Z);
             verticesAsFloats[vi++] = vv.X;
             verticesAsFloats[vi++] = vv.Y;
             verticesAsFloats[vi++] = vv.Z;
@@ -995,6 +1067,7 @@ public sealed class BSPrim : PhysicsActor
         _shapeType = ShapeData.PhysicsShapeType.SHAPE_MESH;
         // meshes are already scaled by the meshmerizer
         _scale = new OMV.Vector3(1f, 1f, 1f);
+        DetailLog("{0},CreateGeomMesh,done", LocalID);
         return;
     }
 
@@ -1008,13 +1081,17 @@ public sealed class BSPrim : PhysicsActor
         // if the hull hasn't changed, don't rebuild it
         if (newHullKey == _hullKey) return;
 
+        DetailLog("{0},CreateGeomHull,create,key={1}", LocalID, _meshKey);
+        
         // Since we're recreating new, get rid of any previously generated shape
         if (_hullKey != 0)
         {
             // m_log.DebugFormat("{0}: CreateGeom: deleting old hull. Key={1}", LogHeader, _hullKey);
+            DetailLog("{0},CreateGeomHull,deleteOldHull,key={1}", LocalID, _meshKey);
             BulletSimAPI.DestroyHull(_scene.WorldID, _hullKey);
             _hullKey = 0;
             _hulls.Clear();
+            DetailLog("{0},CreateGeomHull,deleteOldMesh,key={1}", LocalID, _meshKey);
             BulletSimAPI.DestroyMesh(_scene.WorldID, _meshKey);
             _mesh = null;   // the mesh cannot match either
             _meshKey = 0;
@@ -1111,6 +1188,7 @@ public sealed class BSPrim : PhysicsActor
         _shapeType = ShapeData.PhysicsShapeType.SHAPE_HULL;
         // meshes are already scaled by the meshmerizer
         _scale = new OMV.Vector3(1f, 1f, 1f);
+        DetailLog("{0},CreateGeomHull,done", LocalID);
         return;
     }
 
@@ -1124,47 +1202,21 @@ public sealed class BSPrim : PhysicsActor
 
     // Create an object in Bullet if it has not already been created
     // No locking here because this is done when the physics engine is not simulating
-    private void CreateObject()
+    // Returns 'true' if an object was actually created.
+    private bool CreateObject()
     {
-        if (IsRootOfLinkset)
-        {
-            // Create a linkset around this object
-            // CreateLinksetWithCompoundHull();
-            CreateLinksetWithConstraints();
-        }
-        else
-        {
-            // simple object
-            // the mesh or hull must have already been created in Bullet
-            ShapeData shape;
-            FillShapeInfo(out shape);
-            // m_log.DebugFormat("{0}: CreateObject: lID={1}, shape={2}", LogHeader, _localID, shape.Type);
-            BulletSimAPI.CreateObject(_scene.WorldID, shape);
-        }
-    }
+        // this routine is called when objects are rebuilt. 
 
-    // Create a linkset by creating a compound hull at the root prim that consists of all
-    // the children.
-    // NOTE: This does not allow proper collisions with the children prims so it is not a workable solution
-    void CreateLinksetWithCompoundHull()
-    {
-        // If I am the root prim of a linkset, replace my physical shape with all the
-        // pieces of the children.
-        // All of the children should have called CreateGeom so they have a hull
-        // in the physics engine already. Here we pull together all of those hulls
-        // into one shape.
-        int totalPrimsInLinkset = _childrenPrims.Count + 1;
-        // m_log.DebugFormat("{0}: CreateLinkset. Root prim={1}, prims={2}", LogHeader, LocalID, totalPrimsInLinkset);
-        ShapeData[] shapes = new ShapeData[totalPrimsInLinkset];
-        FillShapeInfo(out shapes[0]);
-        int ii = 1;
-        foreach (BSPrim prim in _childrenPrims)
-        {
-            // m_log.DebugFormat("{0}: CreateLinkset: adding prim {1}", LogHeader, prim.LocalID);
-            prim.FillShapeInfo(out shapes[ii]);
-            ii++;
-        }
-        BulletSimAPI.CreateLinkset(_scene.WorldID, totalPrimsInLinkset, shapes);
+        // the mesh or hull must have already been created in Bullet
+        ShapeData shape;
+        FillShapeInfo(out shape);
+        // m_log.DebugFormat("{0}: CreateObject: lID={1}, shape={2}", LogHeader, _localID, shape.Type);
+        bool ret = BulletSimAPI.CreateObject(_scene.WorldID, shape);
+
+        // the CreateObject() may have recreated the rigid body. Make sure we have the latest.
+        m_body.Ptr = BulletSimAPI.GetBodyHandle2(_scene.World.Ptr, LocalID);
+
+        return ret;
     }
 
     // Copy prim's info into the BulletSim shape description structure
@@ -1186,44 +1238,6 @@ public sealed class BSPrim : PhysicsActor
         shape.Static = _isPhysical ? ShapeData.numericFalse : ShapeData.numericTrue;
     }
 
-    // Create the linkset by putting constraints between the objects of the set so they cannot move
-    // relative to each other.
-    // TODO: make this more effeicient: a large linkset gets rebuilt over and over and prims are added
-    void CreateLinksetWithConstraints()
-    {
-        // m_log.DebugFormat("{0}: CreateLinkset. Root prim={1}, prims={2}", LogHeader, LocalID, _childrenPrims.Count+1);
-
-        // remove any constraints that might be in place
-        foreach (BSPrim prim in _childrenPrims)
-        {
-            // m_log.DebugFormat("{0}: CreateLinkset: RemoveConstraint between root prim {1} and child prim {2}", LogHeader, LocalID, prim.LocalID);
-            BulletSimAPI.RemoveConstraint(_scene.WorldID, LocalID, prim.LocalID);
-        }
-        // create constraints between the root prim and each of the children
-        foreach (BSPrim prim in _childrenPrims)
-        {
-            // m_log.DebugFormat("{0}: CreateLinkset: AddConstraint between root prim {1} and child prim {2}", LogHeader, LocalID, prim.LocalID);
-
-            // Zero motion for children so they don't interpolate
-            prim.ZeroMotion();
-
-            // relative position normalized to the root prim
-            OMV.Vector3 childRelativePosition = (prim._position - this._position) * OMV.Quaternion.Inverse(this._orientation);
-
-            // relative rotation of the child to the parent
-            OMV.Quaternion relativeRotation = OMV.Quaternion.Inverse(prim._orientation) * this._orientation;
-
-            // this is a constraint that allows no freedom of movement between the two objects
-            // http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818
-            BulletSimAPI.AddConstraint(_scene.WorldID, LocalID, prim.LocalID, 
-                childRelativePosition,
-                relativeRotation,
-                OMV.Vector3.Zero,
-                OMV.Quaternion.Identity,
-                OMV.Vector3.Zero, OMV.Vector3.Zero,
-                OMV.Vector3.Zero, OMV.Vector3.Zero);
-        }
-    }
 
     // Rebuild the geometry and object.
     // This is called when the shape changes so we need to recreate the mesh/hull.
@@ -1231,8 +1245,8 @@ public sealed class BSPrim : PhysicsActor
     private void RecreateGeomAndObject()
     {
         // m_log.DebugFormat("{0}: RecreateGeomAndObject. lID={1}", LogHeader, _localID);
-        CreateGeom(true);
-        CreateObject();
+        if (CreateGeom(true))
+            CreateObject();
         return;
     }
 
@@ -1252,78 +1266,78 @@ public sealed class BSPrim : PhysicsActor
     const float POSITION_TOLERANCE = 0.05f;
     const float ACCELERATION_TOLERANCE = 0.01f;
     const float ROTATIONAL_VELOCITY_TOLERANCE = 0.01f;
-    const bool SHOULD_DAMP_UPDATES = false;
 
     public void UpdateProperties(EntityProperties entprop)
     {
+        /*
         UpdatedProperties changed = 0;
-        if (SHOULD_DAMP_UPDATES)
+        // assign to the local variables so the normal set action does not happen
+        // if (_position != entprop.Position)
+        if (!_position.ApproxEquals(entprop.Position, POSITION_TOLERANCE))
         {
-            // assign to the local variables so the normal set action does not happen
-            // if (_position != entprop.Position)
-            if (!_position.ApproxEquals(entprop.Position, POSITION_TOLERANCE))
-            {
-                _position = entprop.Position;
-                // m_log.DebugFormat("{0}: UpdateProperties: id={1}, pos = {2}", LogHeader, LocalID, _position);
-                changed |= UpdatedProperties.Position;
-            }
-            // if (_orientation != entprop.Rotation)
-            if (!_orientation.ApproxEquals(entprop.Rotation, ROTATION_TOLERANCE))
-            {
-                _orientation = entprop.Rotation;
-                // m_log.DebugFormat("{0}: UpdateProperties: id={1}, rot = {2}", LogHeader, LocalID, _orientation);
-                changed |= UpdatedProperties.Rotation;
-            }
-            // if (_velocity != entprop.Velocity)
-            if (!_velocity.ApproxEquals(entprop.Velocity, VELOCITY_TOLERANCE))
-            {
-                _velocity = entprop.Velocity;
-                // m_log.DebugFormat("{0}: UpdateProperties: velocity = {1}", LogHeader, _velocity);
-                changed |= UpdatedProperties.Velocity;
-            }
-            // if (_acceleration != entprop.Acceleration)
-            if (!_acceleration.ApproxEquals(entprop.Acceleration, ACCELERATION_TOLERANCE))
-            {
-                _acceleration = entprop.Acceleration;
-                // m_log.DebugFormat("{0}: UpdateProperties: acceleration = {1}", LogHeader, _acceleration);
-                changed |= UpdatedProperties.Acceleration;
-            }
-            // if (_rotationalVelocity != entprop.RotationalVelocity)
-            if (!_rotationalVelocity.ApproxEquals(entprop.RotationalVelocity, ROTATIONAL_VELOCITY_TOLERANCE))
-            {
-                _rotationalVelocity = entprop.RotationalVelocity;
-                // m_log.DebugFormat("{0}: UpdateProperties: rotationalVelocity = {1}", LogHeader, _rotationalVelocity);
-                changed |= UpdatedProperties.RotationalVel;
-            }
-            if (changed != 0)
-            {
-                // m_log.DebugFormat("{0}: UpdateProperties: id={1}, c={2}, pos={3}, rot={4}", LogHeader, LocalID, changed, _position, _orientation);
-                // Only update the position of single objects and linkset roots
-                if (this._parentPrim == null)
-                {
-                    // m_log.DebugFormat("{0}: RequestTerseUpdate. id={1}, ch={2}, pos={3}, rot={4}", LogHeader, LocalID, changed, _position, _orientation);
-                    base.RequestPhysicsterseUpdate();
-                }
-            }
+            _position = entprop.Position;
+            changed |= UpdatedProperties.Position;
         }
-        else
+        // if (_orientation != entprop.Rotation)
+        if (!_orientation.ApproxEquals(entprop.Rotation, ROTATION_TOLERANCE))
         {
-            // Don't check for damping here -- it's done in BulletSim and SceneObjectPart.
-
-            // Only updates only for individual prims and for the root object of a linkset.
+            _orientation = entprop.Rotation;
+            changed |= UpdatedProperties.Rotation;
+        }
+        // if (_velocity != entprop.Velocity)
+        if (!_velocity.ApproxEquals(entprop.Velocity, VELOCITY_TOLERANCE))
+        {
+            _velocity = entprop.Velocity;
+            changed |= UpdatedProperties.Velocity;
+        }
+        // if (_acceleration != entprop.Acceleration)
+        if (!_acceleration.ApproxEquals(entprop.Acceleration, ACCELERATION_TOLERANCE))
+        {
+            _acceleration = entprop.Acceleration;
+            changed |= UpdatedProperties.Acceleration;
+        }
+        // if (_rotationalVelocity != entprop.RotationalVelocity)
+        if (!_rotationalVelocity.ApproxEquals(entprop.RotationalVelocity, ROTATIONAL_VELOCITY_TOLERANCE))
+        {
+            _rotationalVelocity = entprop.RotationalVelocity;
+            changed |= UpdatedProperties.RotationalVel;
+        }
+        if (changed != 0)
+        {
+            // Only update the position of single objects and linkset roots
             if (this._parentPrim == null)
             {
-                // Assign to the local variables so the normal set action does not happen
-                _position = entprop.Position;
-                _orientation = entprop.Rotation;
-                _velocity = entprop.Velocity;
-                _acceleration = entprop.Acceleration;
-                _rotationalVelocity = entprop.RotationalVelocity;
-                // m_log.DebugFormat("{0}: RequestTerseUpdate. id={1}, ch={2}, pos={3}, rot={4}, vel={5}, acc={6}, rvel={7}", 
-                //         LogHeader, LocalID, changed, _position, _orientation, _velocity, _acceleration, _rotationalVelocity);
                 base.RequestPhysicsterseUpdate();
             }
         }
+        */
+
+        // Don't check for damping here -- it's done in BulletSim and SceneObjectPart.
+
+        // Updates only for individual prims and for the root object of a linkset.
+        if (_linkset.IsRoot(this))
+        {
+            // Assign to the local variables so the normal set action does not happen
+            _position = entprop.Position;
+            _orientation = entprop.Rotation;
+            _velocity = entprop.Velocity;
+            _acceleration = entprop.Acceleration;
+            _rotationalVelocity = entprop.RotationalVelocity;
+
+            // m_log.DebugFormat("{0}: RequestTerseUpdate. id={1}, ch={2}, pos={3}, rot={4}, vel={5}, acc={6}, rvel={7}", 
+            //         LogHeader, LocalID, changed, _position, _orientation, _velocity, _acceleration, _rotationalVelocity);
+            DetailLog("{0},UpdateProperties,call,pos={1},orient={2},vel={3},accel={4},rotVel={5}",
+                    LocalID, _position, _orientation, _velocity, _acceleration, _rotationalVelocity);
+
+            base.RequestPhysicsterseUpdate();
+        }
+        else
+        {
+            // For debugging, we can also report the movement of children
+            DetailLog("{0},UpdateProperties,child,pos={1},orient={2},vel={3},accel={4},rotVel={5}",
+                    LocalID, entprop.Position, entprop.Rotation, entprop.Velocity, 
+                    entprop.Acceleration, entprop.RotationalVelocity);
+        }
     }
 
     // I've collided with something
@@ -1362,5 +1376,11 @@ public sealed class BSPrim : PhysicsActor
             collisionCollection.Clear();
         }
     }
+
+    // Invoke the detailed logger and output something if it's enabled.
+    private void DetailLog(string msg, params Object[] args)
+    {
+        Scene.PhysicsLogging.Write(msg, args);
+    }
 }
 }