diff --git a/addon-modules/BulletSPlugin/BSCharacter.cs b/addon-modules/BulletSPlugin/BSCharacter.cs
index fa9fc8d4b9..3a278b3c97 100644
--- a/addon-modules/BulletSPlugin/BSCharacter.cs
+++ b/addon-modules/BulletSPlugin/BSCharacter.cs
@@ -93,6 +93,7 @@ public class BSCharacter : PhysicsActor
         _size = size;
         _orientation = Quaternion.Identity;
         _velocity = Vector3.Zero;
+        _buoyancy = 0f; // characters return a buoyancy of zero
         _scale = new Vector3(1f, 1f, 1f);
         float AVvolume = (float) (Math.PI*Math.Pow(CAPSULE_RADIUS, 2)*CAPSULE_LENGTH);
         _mass = _density*AVvolume;
@@ -105,8 +106,8 @@ public class BSCharacter : PhysicsActor
         shapeData.Velocity = _velocity;
         shapeData.Scale = _scale;
         shapeData.Mass = _mass;
-        shapeData.Flying = isFlying ? ShapeData.numericTrue : ShapeData.numericFalse;
-        shapeData.Dynamic = ShapeData.numericFalse;
+        shapeData.Buoyancy = isFlying ? 0f : 1f;
+        shapeData.Static = ShapeData.numericFalse;
 
         BulletSimAPI.CreateObject(parent_scene.WorldID, shapeData);
             
@@ -268,7 +269,8 @@ public class BSCharacter : PhysicsActor
             _flying = value;
             _scene.TaintedObject(delegate()
             {
-                BulletSimAPI.SetObjectFlying(_scene.WorldID, LocalID, _flying);
+                // simulate flying by changing the effect of gravity
+                BulletSimAPI.SetObjectBuoyancy(_scene.WorldID, LocalID, _flying ? 0f : 1f);
             });
         } 
     }
@@ -415,7 +417,7 @@ public class BSCharacter : PhysicsActor
     {
         // m_log.DebugFormat("{0}: Collide: ms={1}, id={2}, with={3}", LogHeader, _subscribedEventsMs, LocalID, collidingWith);
 
-        // The following says we're colliding this simulation step
+        // The following makes IsColliding() and IsCollidingGround() work
         _collidingStep = _scene.SimulationStep;
         if (collidingWith == BSScene.TERRAIN_ID || collidingWith == BSScene.GROUNDPLANE_ID)
         {
diff --git a/addon-modules/BulletSPlugin/BSPrim.cs b/addon-modules/BulletSPlugin/BSPrim.cs
index 06a8a03574..515c4dad61 100644
--- a/addon-modules/BulletSPlugin/BSPrim.cs
+++ b/addon-modules/BulletSPlugin/BSPrim.cs
@@ -106,6 +106,7 @@ public sealed class BSPrim : PhysicsActor
         _size = size;
         _scale = new OMV.Vector3(1f, 1f, 1f);   // the scale will be set by CreateGeom depending on object type
         _orientation = rotation;
+        _buoyancy = 1f;
         _mesh = mesh;
         _hullKey = 0;
         _pbs = pbs;
@@ -181,7 +182,6 @@ public sealed class BSPrim : PhysicsActor
             _isSelected = value;
             _scene.TaintedObject(delegate()
             {
-                m_log.DebugFormat("{0}: Selected={1}, localID={2}", LogHeader, _isSelected, _localID);
                 SetObjectDynamic();
                 // SyncUpdated = true;
             });
@@ -287,6 +287,7 @@ public sealed class BSPrim : PhysicsActor
 
     public override OMV.Vector3 Position { 
         get { 
+            // don't do the following GetObjectPosition because this function is called a zillion times
             // _position = BulletSimAPI.GetObjectPosition(_scene.WorldID, _localID);
             return _position; 
         } 
@@ -332,10 +333,7 @@ public sealed class BSPrim : PhysicsActor
             _isVolumeDetect = newValue;
             _scene.TaintedObject(delegate()
             {
-                // make the object ghostly or not (walk throughable)
-                BulletSimAPI.SetObjectGhost(_scene.WorldID, LocalID, _isVolumeDetect);
-                // set whether we hear about collisions
-                BulletSimAPI.SetObjectCollidable(_scene.WorldID, LocalID, !IsPhantom);
+                SetObjectDynamic();
             });
         }
         return; 
@@ -390,40 +388,39 @@ public sealed class BSPrim : PhysicsActor
             _scene.TaintedObject(delegate()
             {
                 SetObjectDynamic();
-                m_log.DebugFormat("{0}: ID={1}, IsPhysical={2}, IsSelected={3}, mass={4}", LogHeader, _localID, _isPhysical, _isSelected, _mass);
                 // SyncUpdated = true;
             });
         } 
     }
+
+    // An object is static (does not move) if selected or not physical
+    private bool IsStatic
+    {
+        get { return _isSelected || !IsPhysical; }
+    }
+
+    // An object is solid if it's not phantom and if it's not doing VolumeDetect
+    private bool IsSolid
+    {
+        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
     private void SetObjectDynamic()
     {
-        // a selected object is not physical
-        if (_isSelected || !_isPhysical)
-        {
-            _mass = 0f;  // non-physical things work best with a mass of zero
-            BulletSimAPI.SetObjectDynamic(_scene.WorldID, _localID, false, _mass);
-        }
-        else
-        {
-            _mass = CalculateMass();
-            BulletSimAPI.SetObjectDynamic(_scene.WorldID, _localID, true, _mass);
-        }
+        // non-physical things work best with a mass of zero
+        _mass = IsStatic ? 0f : CalculateMass();
+        BulletSimAPI.SetObjectProperties(_scene.WorldID, LocalID, IsStatic, IsSolid, SubscribedEvents(), _mass);
+        // m_log.DebugFormat("{0}: ID={1}, SetObjectDynamic: IsStatic={2}, IsSolid={3}, mass={4}", LogHeader, _localID, IsStatic, IsSolid, _mass);
     }
+
+    // prims don't fly
     public override bool Flying { 
         get { return _flying; } 
-        set {
-            _flying = value;
-            _scene.TaintedObject(delegate()
-            {
-                BulletSimAPI.SetObjectFlying(_scene.WorldID, LocalID, _flying);
-                // SyncUpdated = true;
-            });
-        } 
+        set { _flying = value; } 
     }
-    public override bool 
-        SetAlwaysRun { 
+    public override bool SetAlwaysRun { 
         get { return _setAlwaysRun; } 
         set { _setAlwaysRun = value; } 
     }
@@ -431,12 +428,12 @@ public sealed class BSPrim : PhysicsActor
         get { return _throttleUpdates; } 
         set { _throttleUpdates = value; } 
     }
-    public override bool IsColliding { 
-        get { return _isColliding; } 
+    public override bool IsColliding {
+        get { return (_collidingStep == _scene.SimulationStep); } 
         set { _isColliding = value; } 
     }
-    public override bool CollidingGround { 
-        get { return _collidingGround; } 
+    public override bool CollidingGround {
+        get { return (_collidingGroundStep == _scene.SimulationStep); } 
         set { _collidingGround = value; } 
     }
     public override bool CollidingObj { 
@@ -468,7 +465,12 @@ public sealed class BSPrim : PhysicsActor
     }
     public override float Buoyancy { 
         get { return _buoyancy; } 
-        set { _buoyancy = value; } 
+        set { _buoyancy = value;
+        _scene.TaintedObject(delegate()
+        {
+            BulletSimAPI.SetObjectBuoyancy(_scene.WorldID, _localID, _buoyancy);
+        });
+        } 
     }
 
     // Used for MoveTo
@@ -1003,11 +1005,11 @@ public sealed class BSPrim : PhysicsActor
         shape.Velocity = _velocity;
         shape.Scale = _scale;
         shape.Mass = _isPhysical ? _mass : 0f;
+        shape.Buoyancy = _buoyancy;
         shape.MeshKey = _hullKey;
         shape.Collidable = (!IsPhantom) ? ShapeData.numericTrue : ShapeData.numericFalse;
-        shape.Flying = _flying ? ShapeData.numericTrue : ShapeData.numericFalse; 
         shape.Friction = _friction;
-        shape.Dynamic = _isPhysical ? ShapeData.numericTrue : ShapeData.numericFalse;
+        shape.Static = _isPhysical ? ShapeData.numericFalse : ShapeData.numericTrue;
     }
 
     // Rebuild the geometry and object.
@@ -1044,7 +1046,7 @@ public sealed class BSPrim : PhysicsActor
     public void UpdateProperties(EntityProperties entprop)
     {
         bool changed = false;
-        // we assign to the local variables so the normal set action does not happen
+        // assign to the local variables so the normal set action does not happen
         if (_position != entprop.Position)
         {
             _position = entprop.Position;
diff --git a/addon-modules/BulletSPlugin/BSScene.cs b/addon-modules/BulletSPlugin/BSScene.cs
index a302b21139..d656b8aa24 100644
--- a/addon-modules/BulletSPlugin/BSScene.cs
+++ b/addon-modules/BulletSPlugin/BSScene.cs
@@ -35,23 +35,24 @@ using OpenSim.Region.Physics.Manager;
 using OpenMetaverse;
 using OpenSim.Region.Framework;
 
-// TODOs for BulletSim (both BSScene and BSPrim)
+// TODOs for BulletSim (for BSScene, BSPrim, BSCharacter and BulletSim)
 // Does NeedsMeshing() really need to exclude all the different shapes?
 // Based on material, set density and friction
 // More efficient memory usage in passing hull information from BSPrim to BulletSim
 // Four states of prim: Physical, regular, phantom and selected. Are we modeling these correctly?
 //     In SL one can set both physical and phantom (gravity, does not effect others, makes collisions with ground)
+//     At the moment, physical and phantom causes object to drop through the terrain
 // LinkSets
 //     Freeing of memory of linksets in BulletSim::DestroyObject
 //     Set child prims phantom since the physicality is handled by the parent prim
 //     Linked children need rotation relative to parent (passed as world rotation)
 // Should prim.link() and prim.delink() membership checking happen at taint time?
-// Pass collision enable flags to BulletSim code so collisions are not reported up unless they are really needed
-// Set bouyancy(). Maybe generalize SetFlying() to SetBouyancy() and use the factor to change the gravity effect
 // Test sculpties
 // Mesh sharing. Use meshHash to tell if we already have a hull of that shape and only create once
 // Do attachments need to be handled separately? Need collision events. Do not collide with VolumeDetect
 // Parameterize BulletSim. Pass a structure of parameters to the C++ code. Capsule size, friction, ...
+// Use event subscription times to reduce the number of events passed up (_subscribedEventMS)
+// Implement the genCollisions feature in BulletSim::SetObjectProperties (don't pass up unneeded collisions)
 // 
 namespace OpenSim.Region.Physics.BulletSPlugin
 {
diff --git a/addon-modules/BulletSPlugin/BulletSimAPI.cs b/addon-modules/BulletSPlugin/BulletSimAPI.cs
index b1f7bd314f..8d97f30bb1 100644
--- a/addon-modules/BulletSPlugin/BulletSimAPI.cs
+++ b/addon-modules/BulletSPlugin/BulletSimAPI.cs
@@ -59,11 +59,11 @@ public struct ShapeData
     public Vector3 Velocity;
     public Vector3 Scale;
     public float Mass;
+    public float Buoyancy;
     public System.UInt64 MeshKey;
     public int Collidable;
-    public int Flying;
     public float Friction;
-    public int Dynamic;
+    public int Static;  // true if a static object. Otherwise gravity, etc.
     // note that bools are passed as ints since bool size changes by language
 }
 public struct SweepHit 
@@ -148,7 +148,10 @@ public static extern bool SetObjectDynamic(uint worldID, uint id, bool isDynamic
 public static extern bool SetObjectGhost(uint worldID, uint id, bool ghostly);
 
 [DllImport("BulletSim", CallingConvention = CallingConvention.Cdecl), SuppressUnmanagedCodeSecurity]
-public static extern bool SetObjectFlying(uint worldID, uint id, bool flying);
+public static extern bool SetObjectProperties(uint worldID, uint id, bool isStatic, bool isSolid, bool genCollisions, float mass);
+
+[DllImport("BulletSim", CallingConvention = CallingConvention.Cdecl), SuppressUnmanagedCodeSecurity]
+public static extern bool SetObjectBuoyancy(uint worldID, uint id, float buoyancy);
 
 [DllImport("BulletSim", CallingConvention = CallingConvention.Cdecl), SuppressUnmanagedCodeSecurity]
 public static extern bool HasObject(uint worldID, uint id);
diff --git a/bin/BulletSim.dll b/bin/BulletSim.dll
index 02f1056f6c..45d81584f7 100755
Binary files a/bin/BulletSim.dll and b/bin/BulletSim.dll differ