1 files changed, 139 insertions, 226 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSLinksetCompound.cs b/OpenSim/Region/Physics/BulletSPlugin/BSLinksetCompound.cs
index e05562a..6359046 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSLinksetCompound.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSLinksetCompound.cs
@@ -35,81 +35,55 @@ using OMV = OpenMetaverse;
 namespace OpenSim.Region.Physics.BulletSPlugin
 {
 
-// When a child is linked, the relationship position of the child to the parent
-//    is remembered so the child's world position can be recomputed when it is
-//    removed from the linkset.
-sealed class BSLinksetCompoundInfo : BSLinksetInfo
+public sealed class BSLinksetCompound : BSLinkset
 {
-    public int Index;
-    public OMV.Vector3 OffsetFromRoot;
-    public OMV.Vector3 OffsetFromCenterOfMass;
-    public OMV.Quaternion OffsetRot;
-    public BSLinksetCompoundInfo(int indx, OMV.Vector3 p, OMV.Quaternion r)
+    private static string LogHeader = "[BULLETSIM LINKSET COMPOUND]";
+
+    public BSLinksetCompound(BSScene scene, BSPrimLinkable parent)
+        : base(scene, parent)
     {
-        Index = indx;
-        OffsetFromRoot = p;
-        OffsetFromCenterOfMass = p;
-        OffsetRot = r;
     }
-    // 'centerDisplacement' is the distance from the root the the center-of-mass (Bullet 'zero' of the shape)
-    public BSLinksetCompoundInfo(int indx, BSPrimLinkable root, BSPrimLinkable child, OMV.Vector3 centerDisplacement)
+
+    // ================================================================
+    // Changing the physical property of the linkset only needs to change the root
+    public override void SetPhysicalFriction(float friction)
     {
-        // Each child position and rotation is given relative to the center-of-mass.
-        OMV.Quaternion invRootOrientation = OMV.Quaternion.Inverse(root.RawOrientation);
-        OMV.Vector3 displacementFromRoot = (child.RawPosition - root.RawPosition) * invRootOrientation;
-        OMV.Vector3 displacementFromCOM = displacementFromRoot - centerDisplacement;
-        OMV.Quaternion displacementRot = child.RawOrientation * invRootOrientation;
-
-        // Save relative position for recomputing child's world position after moving linkset.
-        Index = indx;
-        OffsetFromRoot = displacementFromRoot;
-        OffsetFromCenterOfMass = displacementFromCOM;
-        OffsetRot = displacementRot;
+        if (LinksetRoot.PhysBody.HasPhysicalBody)
+            m_physicsScene.PE.SetFriction(LinksetRoot.PhysBody, friction);
     }
-    public override void Clear()
+    public override void SetPhysicalRestitution(float restitution)
     {
-        Index = 0;
-        OffsetFromRoot = OMV.Vector3.Zero;
-        OffsetFromCenterOfMass = OMV.Vector3.Zero;
-        OffsetRot = OMV.Quaternion.Identity;
+        if (LinksetRoot.PhysBody.HasPhysicalBody)
+            m_physicsScene.PE.SetRestitution(LinksetRoot.PhysBody, restitution);
     }
-    public override string ToString()
+    public override void SetPhysicalGravity(OMV.Vector3 gravity)
     {
-        StringBuilder buff = new StringBuilder();
-        buff.Append("<i=");
-        buff.Append(Index.ToString());
-        buff.Append(",p=");
-        buff.Append(OffsetFromRoot.ToString());
-        buff.Append(",m=");
-        buff.Append(OffsetFromCenterOfMass.ToString());
-        buff.Append(",r=");
-        buff.Append(OffsetRot.ToString());
-        buff.Append(">");
-        return buff.ToString();
+        if (LinksetRoot.PhysBody.HasPhysicalBody)
+            m_physicsScene.PE.SetGravity(LinksetRoot.PhysBody, gravity);
     }
-};
-
-public sealed class BSLinksetCompound : BSLinkset
-{
-    private static string LogHeader = "[BULLETSIM LINKSET COMPOUND]";
-
-    public BSLinksetCompound(BSScene scene, BSPrimLinkable parent)
-        : base(scene, parent)
+    public override void ComputeAndSetLocalInertia(OMV.Vector3 inertiaFactor, float linksetMass)
     {
+        OMV.Vector3 inertia = m_physicsScene.PE.CalculateLocalInertia(LinksetRoot.PhysShape.physShapeInfo, linksetMass);
+        LinksetRoot.Inertia = inertia * inertiaFactor;
+        m_physicsScene.PE.SetMassProps(LinksetRoot.PhysBody, linksetMass, LinksetRoot.Inertia);
+        m_physicsScene.PE.UpdateInertiaTensor(LinksetRoot.PhysBody);
     }
-
-    // For compound implimented linksets, if there are children, use compound shape for the root.
-    public override BSPhysicsShapeType PreferredPhysicalShape(BSPrimLinkable requestor)
-    { 
-        // Returning 'unknown' means we don't have a preference.
-        BSPhysicsShapeType ret = BSPhysicsShapeType.SHAPE_UNKNOWN;
-        if (IsRoot(requestor) && HasAnyChildren)
-        {
-            ret = BSPhysicsShapeType.SHAPE_COMPOUND;
-        }
-        // DetailLog("{0},BSLinksetCompound.PreferredPhysicalShape,call,shape={1}", LinksetRoot.LocalID, ret);
-        return ret;
+    public override void SetPhysicalCollisionFlags(CollisionFlags collFlags)
+    {
+        if (LinksetRoot.PhysBody.HasPhysicalBody)
+            m_physicsScene.PE.SetCollisionFlags(LinksetRoot.PhysBody, collFlags);
+    }
+    public override void AddToPhysicalCollisionFlags(CollisionFlags collFlags)
+    {
+        if (LinksetRoot.PhysBody.HasPhysicalBody)
+            m_physicsScene.PE.AddToCollisionFlags(LinksetRoot.PhysBody, collFlags);
+    }
+    public override void RemoveFromPhysicalCollisionFlags(CollisionFlags collFlags)
+    {
+        if (LinksetRoot.PhysBody.HasPhysicalBody)
+            m_physicsScene.PE.RemoveFromCollisionFlags(LinksetRoot.PhysBody, collFlags);
     }
+    // ================================================================
 
     // When physical properties are changed the linkset needs to recalculate
     //   its internal properties.
@@ -124,14 +98,15 @@ public sealed class BSLinksetCompound : BSLinkset
     // Schedule a refresh to happen after all the other taint processing.
     private void ScheduleRebuild(BSPrimLinkable requestor)
     {
-        DetailLog("{0},BSLinksetCompound.ScheduleRebuild,,rebuilding={1},hasChildren={2},actuallyScheduling={3}", 
+        DetailLog("{0},BSLinksetCompound.ScheduleRebuild,,rebuilding={1},hasChildren={2},actuallyScheduling={3}",
                             requestor.LocalID, Rebuilding, HasAnyChildren, (!Rebuilding && HasAnyChildren));
+
         // When rebuilding, it is possible to set properties that would normally require a rebuild.
         //    If already rebuilding, don't request another rebuild.
         //    If a linkset with just a root prim (simple non-linked prim) don't bother rebuilding.
         if (!Rebuilding && HasAnyChildren)
         {
-            PhysicsScene.PostTaintObject("BSLinksetCompound.ScheduleRebuild", LinksetRoot.LocalID, delegate()
+            m_physicsScene.PostTaintObject("BSLinksetCompound.ScheduleRebuild", LinksetRoot.LocalID, delegate()
             {
                 if (HasAnyChildren)
                     RecomputeLinksetCompound();
@@ -153,46 +128,23 @@ public sealed class BSLinksetCompound : BSLinkset
             // The root is going dynamic. Rebuild the linkset so parts and mass get computed properly.
             ScheduleRebuild(LinksetRoot);
         }
-        else
-        {
-            // The origional prims are removed from the world as the shape of the root compound
-            //     shape takes over.
-            PhysicsScene.PE.AddToCollisionFlags(child.PhysBody, CollisionFlags.CF_NO_CONTACT_RESPONSE);
-            PhysicsScene.PE.ForceActivationState(child.PhysBody, ActivationState.DISABLE_SIMULATION);
-            // We don't want collisions from the old linkset children.
-            PhysicsScene.PE.RemoveFromCollisionFlags(child.PhysBody, CollisionFlags.BS_SUBSCRIBE_COLLISION_EVENTS);
-
-            child.PhysBody.collisionType = CollisionType.LinksetChild;
-
-            ret = true;
-        }
         return ret;
     }
 
-    // The object is going static (non-physical). Do any setup necessary for a static linkset.
+    // The object is going static (non-physical). We do not do anything for static linksets.
     // Return 'true' if any properties updated on the passed object.
-    // This doesn't normally happen -- OpenSim removes the objects from the physical
-    //     world if it is a static linkset.
     // Called at taint-time!
     public override bool MakeStatic(BSPrimLinkable child)
     {
         bool ret = false;
+
         DetailLog("{0},BSLinksetCompound.MakeStatic,call,IsRoot={1}", child.LocalID, IsRoot(child));
+        child.ClearDisplacement();
         if (IsRoot(child))
         {
+            // Schedule a rebuild to verify that the root shape is set to the real shape.
             ScheduleRebuild(LinksetRoot);
         }
-        else
-        {
-            // The non-physical children can come back to life.
-            PhysicsScene.PE.RemoveFromCollisionFlags(child.PhysBody, CollisionFlags.CF_NO_CONTACT_RESPONSE);
-
-            child.PhysBody.collisionType = CollisionType.LinksetChild;
-
-            // Don't force activation so setting of DISABLE_SIMULATION can stay if used.
-            PhysicsScene.PE.Activate(child.PhysBody, false);
-            ret = true;
-        }
         return ret;
     }
 
@@ -200,13 +152,20 @@ public sealed class BSLinksetCompound : BSLinkset
     // Called at taint-time.
     public override void UpdateProperties(UpdatedProperties whichUpdated, BSPrimLinkable updated)
     {
+        if (!LinksetRoot.IsPhysicallyActive)
+        {
+            // No reason to do this physical stuff for static linksets.
+            DetailLog("{0},BSLinksetCompound.UpdateProperties,notPhysical", LinksetRoot.LocalID);
+            return;
+        }
+
         // The user moving a child around requires the rebuilding of the linkset compound shape
         // One problem is this happens when a border is crossed -- the simulator implementation
         //    stores the position into the group which causes the move of the object
         //    but it also means all the child positions get updated.
         //    What would cause an unnecessary rebuild so we make sure the linkset is in a
         //    region before bothering to do a rebuild.
-        if (!IsRoot(updated) && PhysicsScene.TerrainManager.IsWithinKnownTerrain(LinksetRoot.RawPosition))
+        if (!IsRoot(updated) && m_physicsScene.TerrainManager.IsWithinKnownTerrain(LinksetRoot.RawPosition))
         {
             // If a child of the linkset is updating only the position or rotation, that can be done
             //    without rebuilding the linkset.
@@ -218,22 +177,22 @@ public sealed class BSLinksetCompound : BSLinkset
             //     and that is caused by us updating the object.
             if ((whichUpdated & ~(UpdatedProperties.Position | UpdatedProperties.Orientation)) == 0)
             {
-                    // Find the physical instance of the child 
-                if (LinksetRoot.PhysShape.HasPhysicalShape && PhysicsScene.PE.IsCompound(LinksetRoot.PhysShape))
+                // Find the physical instance of the child
+                if (LinksetRoot.PhysShape.HasPhysicalShape && m_physicsScene.PE.IsCompound(LinksetRoot.PhysShape.physShapeInfo))
                 {
                     // It is possible that the linkset is still under construction and the child is not yet
                     //    inserted into the compound shape. A rebuild of the linkset in a pre-step action will
                     //    build the whole thing with the new position or rotation.
                     // The index must be checked because Bullet references the child array but does no validity
                     //    checking of the child index passed.
-                    int numLinksetChildren = PhysicsScene.PE.GetNumberOfCompoundChildren(LinksetRoot.PhysShape);
+                    int numLinksetChildren = m_physicsScene.PE.GetNumberOfCompoundChildren(LinksetRoot.PhysShape.physShapeInfo);
                     if (updated.LinksetChildIndex < numLinksetChildren)
                     {
-                        BulletShape linksetChildShape = PhysicsScene.PE.GetChildShapeFromCompoundShapeIndex(LinksetRoot.PhysShape, updated.LinksetChildIndex);
+                        BulletShape linksetChildShape = m_physicsScene.PE.GetChildShapeFromCompoundShapeIndex(LinksetRoot.PhysShape.physShapeInfo, updated.LinksetChildIndex);
                         if (linksetChildShape.HasPhysicalShape)
                         {
                             // Found the child shape within the compound shape
-                            PhysicsScene.PE.UpdateChildTransform(LinksetRoot.PhysShape, updated.LinksetChildIndex,
+                            m_physicsScene.PE.UpdateChildTransform(LinksetRoot.PhysShape.physShapeInfo, updated.LinksetChildIndex,
                                                                         updated.RawPosition - LinksetRoot.RawPosition,
                                                                         updated.RawOrientation * OMV.Quaternion.Inverse(LinksetRoot.RawOrientation),
                                                                         true /* shouldRecalculateLocalAabb */);
@@ -267,7 +226,6 @@ public sealed class BSLinksetCompound : BSLinkset
                     //    there will already be a rebuild scheduled.
                     DetailLog("{0},BSLinksetCompound.UpdateProperties,couldNotUpdateChild.schedulingRebuild,whichUpdated={1}",
                                                                     updated.LocalID, whichUpdated);
-                    updated.LinksetInfo = null; // setting to 'null' causes relative position to be recomputed.
                     ScheduleRebuild(updated);
                 }
             }
@@ -275,75 +233,22 @@ public sealed class BSLinksetCompound : BSLinkset
     }
 
     // Routine called when rebuilding the body of some member of the linkset.
-    // Since we don't keep in world relationships, do nothing unless it's a child changing.
+    // If one of the bodies is being changed, the linkset needs rebuilding.
+    // For instance, a linkset is built and then a mesh asset is read in and the mesh is recreated.
     // Returns 'true' of something was actually removed and would need restoring
     // Called at taint-time!!
-    public override bool RemoveBodyDependencies(BSPrimLinkable child)
+    public override bool RemoveDependencies(BSPrimLinkable child)
     {
         bool ret = false;
 
         DetailLog("{0},BSLinksetCompound.RemoveBodyDependencies,refreshIfChild,rID={1},rBody={2},isRoot={3}",
                         child.LocalID, LinksetRoot.LocalID, LinksetRoot.PhysBody, IsRoot(child));
 
-        if (!IsRoot(child))
-        {
-            // Because it is a convenient time, recompute child world position and rotation based on
-            //    its position in the linkset.
-            RecomputeChildWorldPosition(child, true /* inTaintTime */);
-            child.LinksetInfo = null;
-        }
-
-        // Cannot schedule a refresh/rebuild here because this routine is called when
-        //     the linkset is being rebuilt.
-        // InternalRefresh(LinksetRoot);
+        ScheduleRebuild(child);
 
         return ret;
     }
 
-    // When the linkset is built, the child shape is added to the compound shape relative to the
-    //    root shape. The linkset then moves around but this does not move the actual child
-    //    prim. The child prim's location must be recomputed based on the location of the root shape.
-    private void RecomputeChildWorldPosition(BSPrimLinkable child, bool inTaintTime)
-    {
-        // For the moment (20130201), disable this computation (converting the child physical addr back to
-        //    a region address) until we have a good handle on center-of-mass offsets and what the physics
-        //    engine moving a child actually means.
-        // The simulator keeps track of where children should be as the linkset moves. Setting
-        //    the pos/rot here does not effect that knowledge as there is no good way for the
-        //    physics engine to send the simulator an update for a child.
-
-        /*
-        BSLinksetCompoundInfo lci = child.LinksetInfo as BSLinksetCompoundInfo;
-        if (lci != null)
-        {
-            if (inTaintTime)
-            {
-                OMV.Vector3 oldPos = child.RawPosition;
-                child.ForcePosition = LinksetRoot.RawPosition + lci.OffsetFromRoot;
-                child.ForceOrientation = LinksetRoot.RawOrientation * lci.OffsetRot;
-                DetailLog("{0},BSLinksetCompound.RecomputeChildWorldPosition,oldPos={1},lci={2},newPos={3}",
-                                            child.LocalID, oldPos, lci, child.RawPosition);
-            }
-            else
-            {
-                // TaintedObject is not used here so the raw position is set now and not at taint-time.
-                child.Position = LinksetRoot.RawPosition + lci.OffsetFromRoot;
-                child.Orientation = LinksetRoot.RawOrientation * lci.OffsetRot;
-            }
-        }
-        else
-        {
-            // This happens when children have been added to the linkset but the linkset
-            //     has not been constructed yet. So like, at taint time, adding children to a linkset
-            //     and then changing properties of the children (makePhysical, for instance)
-            //     but the post-print action of actually rebuilding the linkset has not yet happened.
-            // PhysicsScene.Logger.WarnFormat("{0} Restoring linkset child position failed because of no relative position computed. ID={1}",
-            //                                 LogHeader, child.LocalID);
-            DetailLog("{0},BSLinksetCompound.recomputeChildWorldPosition,noRelativePositonInfo", child.LocalID);
-        }
-        */
-    }
-
     // ================================================================
 
     // Add a new child to the linkset.
@@ -376,8 +281,6 @@ public sealed class BSLinksetCompound : BSLinkset
                             child.LocalID, child.PhysBody.AddrString);
 
             // Cause the child's body to be rebuilt and thus restored to normal operation
-            RecomputeChildWorldPosition(child, false);
-            child.LinksetInfo = null;
             child.ForceBodyShapeRebuild(false);
 
             if (!HasAnyChildren)
@@ -399,108 +302,118 @@ public sealed class BSLinksetCompound : BSLinkset
     // Constraint linksets are rebuilt every time.
     // Note that this works for rebuilding just the root after a linkset is taken apart.
     // Called at taint time!!
-    private bool disableCOM = true;     // DEBUG DEBUG: disable until we get this debugged
+    private bool UseBulletSimRootOffsetHack = false;    // Attempt to have Bullet track the coords of root compound shape
     private void RecomputeLinksetCompound()
     {
         try
         {
-            // Suppress rebuilding while rebuilding. (We know rebuilding is on only one thread.)
             Rebuilding = true;
 
-            // Cause the root shape to be rebuilt as a compound object with just the root in it
-            LinksetRoot.ForceBodyShapeRebuild(true /* inTaintTime */);
+            // No matter what is being done, force the root prim's PhysBody and PhysShape to get set
+            //     to what they should be as if the root was not in a linkset.
+            // Not that bad since we only get into this routine if there are children in the linkset and
+            //     something has been updated/changed.
+            // Have to do the rebuild before checking for physical because this might be a linkset
+            //     being destructed and going non-physical.
+            LinksetRoot.ForceBodyShapeRebuild(true);
 
-            // The center of mass for the linkset is the geometric center of the group.
-            // Compute a displacement for each component so it is relative to the center-of-mass.
-            // Bullet presumes an object's origin (relative <0,0,0>) is its center-of-mass
-            OMV.Vector3 centerOfMassW = LinksetRoot.RawPosition;
-            if (!disableCOM)                             // DEBUG DEBUG
+            // There is no reason to build all this physical stuff for a non-physical linkset.
+            if (!LinksetRoot.IsPhysicallyActive)
             {
-                // Compute a center-of-mass in world coordinates.
-                centerOfMassW = ComputeLinksetCenterOfMass();
+                DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,notPhysical", LinksetRoot.LocalID);
+                return; // Note the 'finally' clause at the botton which will get executed.
             }
 
-            OMV.Quaternion invRootOrientation = OMV.Quaternion.Inverse(LinksetRoot.RawOrientation);
+            // Get a new compound shape to build the linkset shape in.
+            BSShape linksetShape = BSShapeCompound.GetReference(m_physicsScene);
 
-            // 'centerDisplacement' is the value to subtract from children to give physical offset position
-            OMV.Vector3 centerDisplacement = (centerOfMassW - LinksetRoot.RawPosition) * invRootOrientation;
-            LinksetRoot.SetEffectiveCenterOfMassW(centerDisplacement);
-
-            // This causes the physical position of the root prim to be offset to accomodate for the displacements
-            LinksetRoot.ForcePosition = LinksetRoot.RawPosition;
+            // Compute a displacement for each component so it is relative to the center-of-mass.
+            // Bullet presumes an object's origin (relative <0,0,0>) is its center-of-mass
+            OMV.Vector3 centerOfMassW = ComputeLinksetCenterOfMass();
 
-            // Update the local transform for the root child shape so it is offset from the <0,0,0> which is COM
-            PhysicsScene.PE.UpdateChildTransform(LinksetRoot.PhysShape, 0 /* childIndex */,
-                                                -centerDisplacement,
-                                                OMV.Quaternion.Identity, // LinksetRoot.RawOrientation,
-                                                false /* shouldRecalculateLocalAabb (is done later after linkset built) */);
+            OMV.Quaternion invRootOrientation = OMV.Quaternion.Normalize(OMV.Quaternion.Inverse(LinksetRoot.RawOrientation));
+            OMV.Vector3 origRootPosition = LinksetRoot.RawPosition;
 
-            DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,COM,com={1},rootPos={2},centerDisp={3}",
-                                    LinksetRoot.LocalID, centerOfMassW, LinksetRoot.RawPosition, centerDisplacement);
+            // 'centerDisplacementV' is the vehicle relative distance from the simulator root position to the center-of-mass
+            OMV.Vector3 centerDisplacementV = (centerOfMassW - LinksetRoot.RawPosition) * invRootOrientation;
+            if (UseBulletSimRootOffsetHack || !BSParam.LinksetOffsetCenterOfMass)
+            {
+                // Zero everything if center-of-mass displacement is not being done.
+                centerDisplacementV = OMV.Vector3.Zero;
+                LinksetRoot.ClearDisplacement();
+            }
+            else
+            {
+                // The actual center-of-mass could have been set by the user.
+                centerDisplacementV = LinksetRoot.SetEffectiveCenterOfMassDisplacement(centerDisplacementV);
+            }
 
-            DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,start,rBody={1},rShape={2},numChildren={3}",
-                            LinksetRoot.LocalID, LinksetRoot.PhysBody, LinksetRoot.PhysShape, NumberOfChildren);
+            DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,COM,rootPos={1},com={2},comDisp={3}",
+                                LinksetRoot.LocalID, origRootPosition, centerOfMassW, centerDisplacementV);
 
-            // Add a shape for each of the other children in the linkset
+            // Add the shapes of all the components of the linkset
             int memberIndex = 1;
             ForEachMember(delegate(BSPrimLinkable cPrim)
             {
                 if (IsRoot(cPrim))
                 {
+                    // Root shape is always index zero.
                     cPrim.LinksetChildIndex = 0;
                 }
                 else
                 {
                     cPrim.LinksetChildIndex = memberIndex;
+                    memberIndex++;
+                }
 
-                    if (cPrim.PhysShape.isNativeShape)
-                    {
-                        // A native shape is turned into a hull collision shape because native
-                        //    shapes are not shared so we have to hullify it so it will be tracked
-                        //    and freed at the correct time. This also solves the scaling problem
-                        //    (native shapes scale but hull/meshes are assumed to not be).
-                        // TODO: decide of the native shape can just be used in the compound shape.
-                        //    Use call to CreateGeomNonSpecial().
-                        BulletShape saveShape = cPrim.PhysShape;
-                        cPrim.PhysShape.Clear();        // Don't let the create free the child's shape
-                        PhysicsScene.Shapes.CreateGeomMeshOrHull(cPrim, null);
-                        BulletShape newShape = cPrim.PhysShape;
-                        cPrim.PhysShape = saveShape;
-
-                        OMV.Vector3 offsetPos = (cPrim.RawPosition - LinksetRoot.RawPosition) * invRootOrientation - centerDisplacement;
-                        OMV.Quaternion offsetRot = cPrim.RawOrientation * invRootOrientation;
-                        PhysicsScene.PE.AddChildShapeToCompoundShape(LinksetRoot.PhysShape, newShape, offsetPos, offsetRot);
-                        DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,addNative,indx={1},rShape={2},cShape={3},offPos={4},offRot={5}",
-                                    LinksetRoot.LocalID, memberIndex, LinksetRoot.PhysShape, newShape, offsetPos, offsetRot);
-                    }
-                    else
-                    {
-                        // For the shared shapes (meshes and hulls), just use the shape in the child.
-                        // The reference count added here will be decremented when the compound shape
-                        //     is destroyed in BSShapeCollection (the child shapes are looped over and dereferenced).
-                        if (PhysicsScene.Shapes.ReferenceShape(cPrim.PhysShape))
-                        {
-                            PhysicsScene.Logger.ErrorFormat("{0} Rebuilt sharable shape when building linkset! Region={1}, primID={2}, shape={3}",
-                                                LogHeader, PhysicsScene.RegionName, cPrim.LocalID, cPrim.PhysShape);
-                        }
-                        OMV.Vector3 offsetPos = (cPrim.RawPosition - LinksetRoot.RawPosition) * invRootOrientation - centerDisplacement;
-                        OMV.Quaternion offsetRot = cPrim.RawOrientation * invRootOrientation;
-                        PhysicsScene.PE.AddChildShapeToCompoundShape(LinksetRoot.PhysShape, cPrim.PhysShape, offsetPos, offsetRot);
-                        DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,addNonNative,indx={1},rShape={2},cShape={3},offPos={4},offRot={5}",
-                                    LinksetRoot.LocalID, memberIndex, LinksetRoot.PhysShape, cPrim.PhysShape, offsetPos, offsetRot);
+                // Get a reference to the shape of the child for adding of that shape to the linkset compound shape
+                BSShape childShape = cPrim.PhysShape.GetReference(m_physicsScene, cPrim);
 
-                    }
-                    memberIndex++;
+                // Offset the child shape from the center-of-mass and rotate it to vehicle relative.
+                OMV.Vector3 offsetPos = (cPrim.RawPosition - origRootPosition) * invRootOrientation - centerDisplacementV;
+                OMV.Quaternion offsetRot = OMV.Quaternion.Normalize(cPrim.RawOrientation) * invRootOrientation;
+
+                // Add the child shape to the compound shape being built
+                m_physicsScene.PE.AddChildShapeToCompoundShape(linksetShape.physShapeInfo, childShape.physShapeInfo, offsetPos, offsetRot);
+                DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,addChild,indx={1},cShape={2},offPos={3},offRot={4}",
+                                    LinksetRoot.LocalID, cPrim.LinksetChildIndex, childShape, offsetPos, offsetRot);
+
+                // Since we are borrowing the shape of the child, disable the origional child body
+                if (!IsRoot(cPrim))
+                {
+                    m_physicsScene.PE.AddToCollisionFlags(cPrim.PhysBody, CollisionFlags.CF_NO_CONTACT_RESPONSE);
+                    m_physicsScene.PE.ForceActivationState(cPrim.PhysBody, ActivationState.DISABLE_SIMULATION);
+                    // We don't want collisions from the old linkset children.
+                    m_physicsScene.PE.RemoveFromCollisionFlags(cPrim.PhysBody, CollisionFlags.BS_SUBSCRIBE_COLLISION_EVENTS);
+                    cPrim.PhysBody.collisionType = CollisionType.LinksetChild;
                 }
+
                 return false;   // 'false' says to move onto the next child in the list
             });
 
+            // Replace the root shape with the built compound shape.
+            // Object removed and added to world to get collision cache rebuilt for new shape.
+            LinksetRoot.PhysShape.Dereference(m_physicsScene);
+            LinksetRoot.PhysShape = linksetShape;
+            m_physicsScene.PE.RemoveObjectFromWorld(m_physicsScene.World, LinksetRoot.PhysBody);
+            m_physicsScene.PE.SetCollisionShape(m_physicsScene.World, LinksetRoot.PhysBody, linksetShape.physShapeInfo);
+            m_physicsScene.PE.AddObjectToWorld(m_physicsScene.World, LinksetRoot.PhysBody);
+            DetailLog("{0},BSLinksetCompound.RecomputeLinksetCompound,addBody,body={1},shape={2}",
+                                        LinksetRoot.LocalID, LinksetRoot.PhysBody, linksetShape);
+
             // With all of the linkset packed into the root prim, it has the mass of everyone.
             LinksetMass = ComputeLinksetMass();
             LinksetRoot.UpdatePhysicalMassProperties(LinksetMass, true);
 
-            // Enable the physical position updator to return the position and rotation of the root shape
-            PhysicsScene.PE.AddToCollisionFlags(LinksetRoot.PhysBody, CollisionFlags.BS_RETURN_ROOT_COMPOUND_SHAPE);
+            if (UseBulletSimRootOffsetHack)
+            {
+                // Enable the physical position updator to return the position and rotation of the root shape.
+                // This enables a feature in the C++ code to return the world coordinates of the first shape in the
+                //     compound shape. This aleviates the need to offset the returned physical position by the
+                //     center-of-mass offset.
+                // TODO: either debug this feature or remove it.
+                m_physicsScene.PE.AddToCollisionFlags(LinksetRoot.PhysBody, CollisionFlags.BS_RETURN_ROOT_COMPOUND_SHAPE);
+            }
         }
         finally
         {
@@ -508,7 +421,7 @@ public sealed class BSLinksetCompound : BSLinkset
         }
 
         // See that the Aabb surrounds the new shape
-        PhysicsScene.PE.RecalculateCompoundShapeLocalAabb(LinksetRoot.PhysShape);
+        m_physicsScene.PE.RecalculateCompoundShapeLocalAabb(LinksetRoot.PhysShape.physShapeInfo);
     }
 }
 }
\ No newline at end of file