BulletSim: Reduce idle region physics overhead where there are MANY

    static objects by more restrictive selection of objects that collide
    with static objects.
Rename collision mask fuctions from 'filter' to 'group' so it is clear
    what is being set.
Rename BulletSimAPI.SetCollisionFilterMask() to SetCollisionGroupMask to match above.
Restore passing of time step to linear and angular motion component routines.
Use buffering vehicle physical parameter get/set routines consistantly.
Make range enforcement clearer by using ClampInRange() function for parameter setting.
Remove commented out experimental vehicle calculations.

7 files changed, 95 insertions, 80 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs b/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs
index 1dfc420..21aa9be 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs
@@ -165,8 +165,8 @@ public sealed class BSCharacter : BSPhysObject
         BulletSimAPI.UpdateSingleAabb2(PhysicsScene.World.ptr, PhysBody.ptr);
 
         // Do this after the object has been added to the world
-        BulletSimAPI.SetCollisionFilterMask2(PhysBody.ptr,
-                        (uint)CollisionFilterGroups.AvatarFilter,
+        BulletSimAPI.SetCollisionGroupMask2(PhysBody.ptr,
+                        (uint)CollisionFilterGroups.AvatarGroup,
                         (uint)CollisionFilterGroups.AvatarMask);
     }
 
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs b/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
index 525aac4..be8a502 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
@@ -161,7 +161,7 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                     m_angularMotor.TimeScale = m_angularMotorTimescale;
                     break;
                 case Vehicle.BANKING_EFFICIENCY:
-                    m_bankingEfficiency = Math.Max(-1f, Math.Min(pValue, 1f));
+                    m_bankingEfficiency = ClampInRange(-1f, pValue, 1f);
                     break;
                 case Vehicle.BANKING_MIX:
                     m_bankingMix = Math.Max(pValue, 0.01f);
@@ -170,10 +170,10 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                     m_bankingTimescale = Math.Max(pValue, 0.01f);
                     break;
                 case Vehicle.BUOYANCY:
-                    m_VehicleBuoyancy = Math.Max(-1f, Math.Min(pValue, 1f));
+                    m_VehicleBuoyancy = ClampInRange(-1f, pValue, 1f);
                     break;
                 case Vehicle.HOVER_EFFICIENCY:
-                    m_VhoverEfficiency = Math.Max(0f, Math.Min(pValue, 1f));
+                    m_VhoverEfficiency = ClampInRange(0f, pValue, 1f);
                     break;
                 case Vehicle.HOVER_HEIGHT:
                     m_VhoverHeight = pValue;
@@ -188,7 +188,7 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                     m_linearDeflectionTimescale = Math.Max(pValue, 0.01f);
                     break;
                 case Vehicle.LINEAR_MOTOR_DECAY_TIMESCALE:
-                    m_linearMotorDecayTimescale = Math.Max(0.01f, Math.Min(pValue,120));
+                    m_linearMotorDecayTimescale = ClampInRange(0.01f, pValue, 120);
                     m_linearMotor.TargetValueDecayTimeScale = m_linearMotorDecayTimescale;
                     break;
                 case Vehicle.LINEAR_MOTOR_TIMESCALE:
@@ -196,7 +196,7 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                     m_linearMotor.TimeScale = m_linearMotorTimescale;
                     break;
                 case Vehicle.VERTICAL_ATTRACTION_EFFICIENCY:
-                    m_verticalAttractionEfficiency = Math.Max(0.1f, Math.Min(pValue, 1f));
+                    m_verticalAttractionEfficiency = ClampInRange(0.1f, pValue, 1f);
                     m_verticalAttractionMotor.Efficiency = m_verticalAttractionEfficiency;
                     break;
                 case Vehicle.VERTICAL_ATTRACTION_TIMESCALE:
@@ -607,10 +607,15 @@ namespace OpenSim.Region.Physics.BulletSPlugin
         }
 
         #region Known vehicle value functions
+        // Vehicle physical parameters that we buffer from constant getting and setting.
+        // The "m_known*" variables are initialized to 'null', fetched only if referenced
+        //      and stored back into the physics engine only if updated.
+        //      This does two things: 1) saves continuious calls into unmanaged code, and
+        //      2) signals when a physics property update must happen back to the simulator
+        //      to update values modified for the vehicle.
         private int m_knownChanged;
         private float? m_knownTerrainHeight;
         private float? m_knownWaterLevel;
-
         private Vector3? m_knownPosition;
         private Vector3? m_knownVelocity;
         private Quaternion? m_knownOrientation;
@@ -642,7 +647,10 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                 if ((m_knownChanged & m_knownChangedVelocity) != 0)
                     Prim.ForceVelocity = VehicleVelocity;
                 if ((m_knownChanged & m_knownChangedRotationalVelocity) != 0)
+                {
                     Prim.ForceRotationalVelocity = VehicleRotationalVelocity;
+                    BulletSimAPI.SetInterpolationAngularVelocity2(Prim.PhysBody.ptr, VehicleRotationalVelocity);
+                }
                 // If we set one of the values (ie, the physics engine didn't do it) we must force
                 //      an UpdateProperties event to send the changes up to the simulator.
                 BulletSimAPI.PushUpdate2(Prim.PhysBody.ptr);
@@ -766,15 +774,13 @@ namespace OpenSim.Region.Physics.BulletSPlugin
             // m_VehicleBuoyancy: -1=2g; 0=1g; 1=0g;
             Vector3 grav = Prim.PhysicsScene.DefaultGravity * (1f - m_VehicleBuoyancy);
 
-            Vector3 pos = VehiclePosition;
-
-            Vector3 terrainHeightContribution = ComputeLinearTerrainHeightCorrection(ref pos);
+            Vector3 terrainHeightContribution = ComputeLinearTerrainHeightCorrection(pTimestep);
 
-            Vector3 hoverContribution = ComputeLinearHover(ref pos);
+            Vector3 hoverContribution = ComputeLinearHover(pTimestep);
 
-            ComputeLinearBlockingEndPoint(ref pos);
+            ComputeLinearBlockingEndPoint(pTimestep);
 
-            Vector3 limitMotorUpContribution = ComputeLinearMotorUp(pos);
+            Vector3 limitMotorUpContribution = ComputeLinearMotorUp(pTimestep);
 
             // ==================================================================
             Vector3 newVelocity = linearMotorContribution
@@ -820,22 +826,21 @@ namespace OpenSim.Region.Physics.BulletSPlugin
 
         } // end MoveLinear()
 
-        public Vector3 ComputeLinearTerrainHeightCorrection(ref Vector3 pos)
+        public Vector3 ComputeLinearTerrainHeightCorrection(float pTimestep)
         {
             Vector3 ret = Vector3.Zero;
             // If below the terrain, move us above the ground a little.
             // TODO: Consider taking the rotated size of the object or possibly casting a ray.
-            if (pos.Z < GetTerrainHeight(pos))
+            if (VehiclePosition.Z < GetTerrainHeight(VehiclePosition))
             {
                 // TODO: correct position by applying force rather than forcing position.
-                pos.Z = GetTerrainHeight(pos) + 2;
-                VehiclePosition = pos;
-                VDetailLog("{0},  MoveLinear,terrainHeight,terrainHeight={1},pos={2}", Prim.LocalID, GetTerrainHeight(pos), pos);
+                VehiclePosition += new Vector3(0f, 0f, GetTerrainHeight(VehiclePosition) + 2f);
+                VDetailLog("{0},  MoveLinear,terrainHeight,terrainHeight={1},pos={2}", Prim.LocalID, GetTerrainHeight(VehiclePosition), VehiclePosition);
             }
             return ret;
         }
 
-        public Vector3 ComputeLinearHover(ref Vector3 pos)
+        public Vector3 ComputeLinearHover(float pTimestep)
         {
             Vector3 ret = Vector3.Zero;
 
@@ -846,11 +851,11 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                 // We should hover, get the target height
                 if ((m_flags & VehicleFlag.HOVER_WATER_ONLY) != 0)
                 {
-                    m_VhoverTargetHeight = GetWaterLevel(pos) + m_VhoverHeight;
+                    m_VhoverTargetHeight = GetWaterLevel(VehiclePosition) + m_VhoverHeight;
                 }
                 if ((m_flags & VehicleFlag.HOVER_TERRAIN_ONLY) != 0)
                 {
-                    m_VhoverTargetHeight = GetTerrainHeight(pos) + m_VhoverHeight;
+                    m_VhoverTargetHeight = GetTerrainHeight(VehiclePosition) + m_VhoverHeight;
                 }
                 if ((m_flags & VehicleFlag.HOVER_GLOBAL_HEIGHT) != 0)
                 {
@@ -860,14 +865,15 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                 if ((m_flags & VehicleFlag.HOVER_UP_ONLY) != 0)
                 {
                     // If body is already heigher, use its height as target height
-                    if (pos.Z > m_VhoverTargetHeight)
-                        m_VhoverTargetHeight = pos.Z;
+                    if (VehiclePosition.Z > m_VhoverTargetHeight)
+                        m_VhoverTargetHeight = VehiclePosition.Z;
                 }
                 
                 if ((m_flags & VehicleFlag.LOCK_HOVER_HEIGHT) != 0)
                 {
-                    if (Math.Abs(pos.Z - m_VhoverTargetHeight) > 0.2f)
+                    if (Math.Abs(VehiclePosition.Z - m_VhoverTargetHeight) > 0.2f)
                     {
+                        Vector3 pos = VehiclePosition;
                         pos.Z = m_VhoverTargetHeight;
                         VehiclePosition = pos;
                     }
@@ -875,7 +881,7 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                 else
                 {
                     // Error is positive if below the target and negative if above.
-                    float verticalError = m_VhoverTargetHeight - pos.Z;
+                    float verticalError = m_VhoverTargetHeight - VehiclePosition.Z;
                     float verticalCorrectionVelocity = verticalError / m_VhoverTimescale;
 
                     // TODO: implement m_VhoverEfficiency correctly
@@ -886,16 +892,17 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                 }
 
                 VDetailLog("{0},  MoveLinear,hover,pos={1},ret={2},hoverTS={3},height={4},target={5}",
-                                Prim.LocalID, pos, ret, m_VhoverTimescale, m_VhoverHeight, m_VhoverTargetHeight);
+                                Prim.LocalID, VehiclePosition, ret, m_VhoverTimescale, m_VhoverHeight, m_VhoverTargetHeight);
             }
 
             return ret;
         }
 
-        public bool ComputeLinearBlockingEndPoint(ref Vector3 pos)
+        public bool ComputeLinearBlockingEndPoint(float pTimestep)
         {
             bool changed = false;
 
+            Vector3 pos = VehiclePosition;
             Vector3 posChange = pos - m_lastPositionVector;
             if (m_BlockingEndPoint != Vector3.Zero)
             {
@@ -941,14 +948,14 @@ namespace OpenSim.Region.Physics.BulletSPlugin
         //    VEHICLE_BANKING_TIMESCALE. This is to help prevent ground vehicles from steering
         //    when they are in mid jump. 
         // TODO: this code is wrong. Also, what should it do for boats?
-        public Vector3 ComputeLinearMotorUp(Vector3 pos)
+        public Vector3 ComputeLinearMotorUp(float pTimestep)
         {
             Vector3 ret = Vector3.Zero;
             if ((m_flags & (VehicleFlag.LIMIT_MOTOR_UP)) != 0)
             {
                 // If the vehicle is motoring into the sky, get it going back down.
                 // float distanceAboveGround = pos.Z - Math.Max(GetTerrainHeight(pos), GetWaterLevel(pos));
-                float distanceAboveGround = pos.Z - GetTerrainHeight(pos);
+                float distanceAboveGround = VehiclePosition.Z - GetTerrainHeight(VehiclePosition);
                 if (distanceAboveGround > 1f)
                 {
                     // downForce = new Vector3(0, 0, (-distanceAboveGround / m_bankingTimescale) * pTimestep);
@@ -969,12 +976,13 @@ namespace OpenSim.Region.Physics.BulletSPlugin
         // =======================================================================
         // =======================================================================
         // Apply the effect of the angular motor.
-        // The 'contribution' is how much angular correction each function wants.
+        // The 'contribution' is how much angular correction velocity each function wants.
         //     All the contributions are added together and the orientation of the vehicle
         //     is changed by all the contributed corrections.
         private void MoveAngular(float pTimestep)
         {
-            Vector3 angularMotorContribution = m_angularMotor.Step();
+            // The user wants how many radians per second angular change?
+            Vector3 angularMotorContribution = m_angularMotor.Step(pTimestep);
 
             // ==================================================================
             // From http://wiki.secondlife.com/wiki/LlSetVehicleFlags :
@@ -1006,14 +1014,11 @@ namespace OpenSim.Region.Physics.BulletSPlugin
 
             // ==================================================================
             // The correction is applied to the current orientation.
-            // Any angular velocity on the vehicle is not us so zero the current value.
-            VehicleRotationalVelocity = Vector3.Zero;
             if (!m_lastAngularCorrection.ApproxEquals(Vector3.Zero, 0.01f))
             {
                 Vector3 scaledCorrection = m_lastAngularCorrection * pTimestep;
-                Quaternion quatCorrection = Quaternion.CreateFromEulers(scaledCorrection);
 
-                VehicleOrientation = Quaternion.Add(VehicleOrientation, quatCorrection);
+                VehicleRotationalVelocity = scaledCorrection;
 
                 VDetailLog("{0},  MoveAngular,done,nonZero,angMotorContrib={1},vertAttrContrib={2},bankContrib={3},deflectContrib={4},totalContrib={5},scaledCorr={6}",
                                     Prim.LocalID,
@@ -1022,6 +1027,12 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                                     m_lastAngularCorrection, scaledCorrection
                                     );
             }
+            else
+            {
+                // The vehicle is not adding anything velocity wise.
+                VehicleRotationalVelocity = Vector3.Zero;
+                VDetailLog("{0},  MoveAngular,done,zero", Prim.LocalID);
+            }
 
             // ==================================================================
             //Offset section
@@ -1065,7 +1076,7 @@ namespace OpenSim.Region.Physics.BulletSPlugin
             {
                 // Take a vector pointing up and convert it from world to vehicle relative coords.
                 Vector3 verticalError = Vector3.UnitZ * VehicleOrientation;
-                // verticalError.Normalize();
+                verticalError.Normalize();
 
                 // If vertical attraction correction is needed, the vector that was pointing up (UnitZ)
                 //    is now leaning to one side (rotated around the X axis) and the Y value will
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs b/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
index 42a362f..ea1f71a 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
@@ -646,9 +646,13 @@ public sealed class BSPrim : BSPhysObject
         BulletSimAPI.UpdateSingleAabb2(PhysicsScene.World.ptr, PhysBody.ptr);
 
         // Collision filter can be set only when the object is in the world
-        if (PhysBody.collisionFilter != 0 || PhysBody.collisionMask != 0)
+        if (PhysBody.collisionGroup != 0 || PhysBody.collisionMask != 0)
         {
-            BulletSimAPI.SetCollisionFilterMask2(PhysBody.ptr, (uint)PhysBody.collisionFilter, (uint)PhysBody.collisionMask);
+            if (!BulletSimAPI.SetCollisionGroupMask2(PhysBody.ptr, (uint)PhysBody.collisionGroup, (uint)PhysBody.collisionMask))
+            {
+                PhysicsScene.Logger.ErrorFormat("{0} Failure setting prim collision mask. localID={1}, grp={2:X}, mask={3:X}",
+                                LogHeader, LocalID, PhysBody.collisionGroup, PhysBody.collisionMask);
+            }
         }
 
         // Recompute any linkset parameters.
@@ -691,7 +695,7 @@ public sealed class BSPrim : BSPhysObject
             // Start it out sleeping and physical actions could wake it up.
             BulletSimAPI.ForceActivationState2(PhysBody.ptr, ActivationState.ISLAND_SLEEPING);
 
-            PhysBody.collisionFilter = CollisionFilterGroups.StaticObjectFilter;
+            PhysBody.collisionGroup = CollisionFilterGroups.StaticObjectGroup;
             PhysBody.collisionMask = CollisionFilterGroups.StaticObjectMask;
         }
         else
@@ -737,7 +741,7 @@ public sealed class BSPrim : BSPhysObject
             BulletSimAPI.ForceActivationState2(PhysBody.ptr, ActivationState.ACTIVE_TAG);
             // BulletSimAPI.Activate2(BSBody.ptr, true);
 
-            PhysBody.collisionFilter = CollisionFilterGroups.ObjectFilter;
+            PhysBody.collisionGroup = CollisionFilterGroups.ObjectGroup;
             PhysBody.collisionMask = CollisionFilterGroups.ObjectMask;
         }
     }
@@ -765,7 +769,7 @@ public sealed class BSPrim : BSPhysObject
                 m_log.ErrorFormat("{0} MakeSolid: physical body of wrong type for non-solidness. id={1}, type={2}", LogHeader, LocalID, bodyType);
             }
             CurrentCollisionFlags = BulletSimAPI.AddToCollisionFlags2(PhysBody.ptr, CollisionFlags.CF_NO_CONTACT_RESPONSE);
-            PhysBody.collisionFilter = CollisionFilterGroups.VolumeDetectFilter;
+            PhysBody.collisionGroup = CollisionFilterGroups.VolumeDetectGroup;
             PhysBody.collisionMask = CollisionFilterGroups.VolumeDetectMask;
         }
     }
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSTerrainHeightmap.cs b/OpenSim/Region/Physics/BulletSPlugin/BSTerrainHeightmap.cs
index 0cb151e..83b9c37 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSTerrainHeightmap.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSTerrainHeightmap.cs
@@ -121,8 +121,8 @@ public sealed class BSTerrainHeightmap : BSTerrainPhys
         // redo its bounding box now that it is in the world
         BulletSimAPI.UpdateSingleAabb2(PhysicsScene.World.ptr, m_mapInfo.terrainBody.ptr);
 
-        BulletSimAPI.SetCollisionFilterMask2(m_mapInfo.terrainBody.ptr,
-                            (uint)CollisionFilterGroups.TerrainFilter,
+        BulletSimAPI.SetCollisionGroupMask2(m_mapInfo.terrainBody.ptr,
+                            (uint)CollisionFilterGroups.TerrainGroup,
                             (uint)CollisionFilterGroups.TerrainMask);
 
         // Make it so the terrain will not move or be considered for movement.
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSTerrainManager.cs b/OpenSim/Region/Physics/BulletSPlugin/BSTerrainManager.cs
index 17d9536..83df360 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSTerrainManager.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSTerrainManager.cs
@@ -140,8 +140,8 @@ public sealed class BSTerrainManager
         // Ground plane does not move
         BulletSimAPI.ForceActivationState2(m_groundPlane.ptr, ActivationState.DISABLE_SIMULATION);
         // Everything collides with the ground plane.
-        BulletSimAPI.SetCollisionFilterMask2(m_groundPlane.ptr,
-                        (uint)CollisionFilterGroups.GroundPlaneFilter, (uint)CollisionFilterGroups.GroundPlaneMask);
+        BulletSimAPI.SetCollisionGroupMask2(m_groundPlane.ptr,
+                        (uint)CollisionFilterGroups.GroundPlaneGroup, (uint)CollisionFilterGroups.GroundPlaneMask);
 
         // Build an initial terrain and put it in the world. This quickly gets replaced by the real region terrain.
         BSTerrainPhys initialTerrain = new BSTerrainHeightmap(PhysicsScene, Vector3.Zero, BSScene.TERRAIN_ID, DefaultRegionSize);
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSTerrainMesh.cs b/OpenSim/Region/Physics/BulletSPlugin/BSTerrainMesh.cs
index 7e93ab4..6ce767d 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSTerrainMesh.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSTerrainMesh.cs
@@ -130,8 +130,8 @@ public sealed class BSTerrainMesh : BSTerrainPhys
         // Redo its bounding box now that it is in the world
         BulletSimAPI.UpdateSingleAabb2(PhysicsScene.World.ptr, m_terrainBody.ptr);
 
-        BulletSimAPI.SetCollisionFilterMask2(m_terrainBody.ptr,
-                            (uint)CollisionFilterGroups.TerrainFilter,
+        BulletSimAPI.SetCollisionGroupMask2(m_terrainBody.ptr,
+                            (uint)CollisionFilterGroups.TerrainGroup,
                             (uint)CollisionFilterGroups.TerrainMask);
 
         // Make it so the terrain will not move or be considered for movement.
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BulletSimAPI.cs b/OpenSim/Region/Physics/BulletSPlugin/BulletSimAPI.cs
index 21bc6a3..a5acfd1 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BulletSimAPI.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BulletSimAPI.cs
@@ -57,12 +57,12 @@ public struct BulletBody
     {
         ID = id;
         ptr = xx;
-        collisionFilter = 0;
+        collisionGroup = 0;
         collisionMask = 0;
     }
     public IntPtr ptr;
     public uint ID;
-    public CollisionFilterGroups collisionFilter;
+    public CollisionFilterGroups collisionGroup;
     public CollisionFilterGroups collisionMask;
     public override string ToString()
     {
@@ -71,10 +71,10 @@ public struct BulletBody
         buff.Append(ID.ToString());
         buff.Append(",p=");
         buff.Append(ptr.ToString("X"));
-        if (collisionFilter != 0 || collisionMask != 0)
+        if (collisionGroup != 0 || collisionMask != 0)
         {
-            buff.Append(",f=");
-            buff.Append(collisionFilter.ToString("X"));
+            buff.Append(",g=");
+            buff.Append(collisionGroup.ToString("X"));
             buff.Append(",m=");
             buff.Append(collisionMask.ToString("X"));
         }
@@ -376,36 +376,36 @@ public enum CollisionFilterGroups : uint
     // Don't use the bit definitions!!  Define the use in a
     //   filter/mask definition below. This way collision interactions
     //   are more easily debugged.
-    BNoneFilter              = 0,
-    BDefaultFilter           = 1 << 0,
-    BStaticFilter            = 1 << 1,
-    BKinematicFilter         = 1 << 2,
-    BDebrisFilter            = 1 << 3,
-    BSensorTrigger           = 1 << 4,
-    BCharacterFilter         = 1 << 5,
-    BAllFilter               = 0xFFFFFFFF,
+    BNoneGroup              = 0,
+    BDefaultGroup           = 1 << 0,
+    BStaticGroup            = 1 << 1,
+    BKinematicGroup         = 1 << 2,
+    BDebrisGroup            = 1 << 3,
+    BSensorTrigger          = 1 << 4,
+    BCharacterGroup         = 1 << 5,
+    BAllGroup               = 0xFFFFFFFF,
     // Filter groups defined by BulletSim
-    BGroundPlaneFilter       = 1 << 10,
-    BTerrainFilter           = 1 << 11,
-    BRaycastFilter           = 1 << 12,
-    BSolidFilter             = 1 << 13,
-    BLinksetFilter           = 1 << 14,
+    BGroundPlaneGroup       = 1 << 10,
+    BTerrainGroup           = 1 << 11,
+    BRaycastGroup           = 1 << 12,
+    BSolidGroup             = 1 << 13,
+    BLinksetGroup           = 1 << 14,
 
     // The collsion filters and masked are defined in one place -- don't want them scattered
-    AvatarFilter            = BCharacterFilter,
-    AvatarMask              = BAllFilter,
-    ObjectFilter            = BSolidFilter,
-    ObjectMask              = BAllFilter,
-    StaticObjectFilter      = BStaticFilter,
-    StaticObjectMask        = BAllFilter & ~BStaticFilter,   // static objects don't collide with each other
-    LinksetFilter           = BLinksetFilter,
-    LinksetMask             = BAllFilter & ~BLinksetFilter, // linkset objects don't collide with each other
-    VolumeDetectFilter      = BSensorTrigger,
+    AvatarGroup             = BCharacterGroup,
+    AvatarMask              = BAllGroup,
+    ObjectGroup             = BSolidGroup,
+    ObjectMask              = BAllGroup,
+    StaticObjectGroup       = BStaticGroup,
+    StaticObjectMask        = AvatarGroup | ObjectGroup,    // static things don't interact with much
+    LinksetGroup            = BLinksetGroup,
+    LinksetMask             = BAllGroup & ~BLinksetGroup, // linkset objects don't collide with each other
+    VolumeDetectGroup       = BSensorTrigger,
     VolumeDetectMask        = ~BSensorTrigger,
-    TerrainFilter           = BTerrainFilter,
-    TerrainMask             = BAllFilter & ~BStaticFilter,  // static objects on the ground don't collide
-    GroundPlaneFilter       = BGroundPlaneFilter,
-    GroundPlaneMask         = BAllFilter
+    TerrainGroup            = BTerrainGroup,
+    TerrainMask             = BAllGroup & ~BStaticGroup,  // static objects on the ground don't collide
+    GroundPlaneGroup        = BGroundPlaneGroup,
+    GroundPlaneMask         = BAllGroup
 
 };
 
@@ -945,7 +945,7 @@ public static extern IntPtr GetConstraintRef2(IntPtr obj, int index);
 public static extern int GetNumConstraintRefs2(IntPtr obj);
 
 [DllImport("BulletSim", CallingConvention = CallingConvention.Cdecl), SuppressUnmanagedCodeSecurity]
-public static extern void SetCollisionFilterMask2(IntPtr body, uint filter, uint mask);
+public static extern bool SetCollisionGroupMask2(IntPtr body, uint filter, uint mask);
 
 // =====================================================================================
 // btCollisionShape entries