BulletSim: move center of gravity of linkset to its geometric center.

Necessitated allowing simulator and physical position of a body to
get out of sync since Bullet assumes that <0,0,0> is the center of mass.
Update DLLs and SOs for the UpdateChildTransform so positions of
  individual prim in a linkset can be implemented.

1 files changed, 10 insertions, 0 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSPhysObject.cs b/OpenSim/Region/Physics/BulletSPlugin/BSPhysObject.cs
index 2c84293..185f111 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSPhysObject.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSPhysObject.cs
@@ -73,6 +73,8 @@ public abstract class BSPhysObject : PhysicsActor
 
         // A linkset of just me
         Linkset = BSLinkset.Factory(PhysicsScene, this);
+        PositionDisplacement = OMV.Vector3.Zero;
+
         LastAssetBuildFailed = false;
 
         // Default material type
@@ -157,6 +159,14 @@ public abstract class BSPhysObject : PhysicsActor
     public abstract OMV.Vector3 RawPosition { get; set; }
     public abstract OMV.Vector3 ForcePosition { get; set; }
 
+    // Position is what the simulator thinks the positions of the prim is.
+    // Because Bullet needs the zero coordinate to be the center of mass of the linkset,
+    //     sometimes it is necessary to displace the position the physics engine thinks
+    //     the position is. PositionDisplacement must be added and removed from the
+    //     position as the simulator position is stored and fetched from the physics
+    //     engine. 
+    public virtual OMV.Vector3 PositionDisplacement { get; set; }
+
     public abstract OMV.Quaternion RawOrientation { get; set; }
     public abstract OMV.Quaternion ForceOrientation { get; set; }