Initial update to OpenSim 0.8.2.1 source code.

1 files changed, 620 insertions, 0 deletions

diff --git a/OpenSim/Region/PhysicsModules/BulletS/BSPhysObject.cs b/OpenSim/Region/PhysicsModules/BulletS/BSPhysObject.cs
new file mode 100755
index 0000000..da3fc18
--- /dev/null
+++ b/OpenSim/Region/PhysicsModules/BulletS/BSPhysObject.cs
@@ -0,0 +1,620 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyrightD
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+using OMV = OpenMetaverse;
+using OpenSim.Framework;
+using OpenSim.Region.PhysicsModules.SharedBase;
+
+namespace OpenSim.Region.PhysicsModule.BulletS
+{
+/*
+ * Class to wrap all objects.
+ * The rest of BulletSim doesn't need to keep checking for avatars or prims
+ *        unless the difference is significant.
+ *
+ *  Variables in the physicsl objects are in three forms:
+ *      VariableName: used by the simulator and performs taint operations, etc
+ *      RawVariableName: direct reference to the BulletSim storage for the variable value
+ *      ForceVariableName: direct reference (store and fetch) to the value in the physics engine.
+ *  The last one should only be referenced in taint-time.
+ */
+
+/*
+ * As of 20121221, the following are the call sequences (going down) for different script physical functions:
+ * llApplyImpulse       llApplyRotImpulse           llSetTorque             llSetForce
+ * SOP.ApplyImpulse     SOP.ApplyAngularImpulse     SOP.SetAngularImpulse   SOP.SetForce
+ * SOG.ApplyImpulse     SOG.ApplyAngularImpulse     SOG.SetAngularImpulse
+ * PA.AddForce          PA.AddAngularForce          PA.Torque = v           PA.Force = v
+ * BS.ApplyCentralForce BS.ApplyTorque
+ */
+
+// Flags used to denote which properties updates when making UpdateProperties calls to linksets, etc.
+public enum UpdatedProperties : uint
+{
+    Position                = 1 << 0,
+    Orientation             = 1 << 1,
+    Velocity                = 1 << 2,
+    Acceleration            = 1 << 3,
+    RotationalVelocity      = 1 << 4,
+    EntPropUpdates          = Position | Orientation | Velocity | Acceleration | RotationalVelocity,
+}
+public abstract class BSPhysObject : PhysicsActor
+{
+    protected BSPhysObject()
+    {
+    }
+    protected BSPhysObject(BSScene parentScene, uint localID, string name, string typeName)
+    {
+        IsInitialized = false;
+
+        PhysScene = parentScene;
+        LocalID = localID;
+        PhysObjectName = name;
+        Name = name;    // PhysicsActor also has the name of the object. Someday consolidate.
+        TypeName = typeName;
+
+        // Oddity if object is destroyed and recreated very quickly it could still have the old body.
+        if (!PhysBody.HasPhysicalBody)
+            PhysBody = new BulletBody(localID);
+
+        // Clean out anything that might be in the physical actor list.
+        // Again, a workaround for destroying and recreating an object very quickly.
+        PhysicalActors.Dispose();
+
+        UserSetCenterOfMassDisplacement = null;
+
+        PrimAssetState = PrimAssetCondition.Unknown;
+
+        // Initialize variables kept in base.
+        // Beware that these cause taints to be queued whch can cause race conditions on startup.
+        GravModifier = 1.0f;
+        Gravity = new OMV.Vector3(0f, 0f, BSParam.Gravity);
+        HoverActive = false;
+
+        // Default material type. Also sets Friction, Restitution and Density.
+        SetMaterial((int)MaterialAttributes.Material.Wood);
+
+        CollisionsLastTickStep = -1;
+
+        SubscribedEventsMs = 0;
+        // Crazy values that will never be true
+        CollidingStep = BSScene.NotASimulationStep;
+        CollidingGroundStep = BSScene.NotASimulationStep;
+        CollisionAccumulation = BSScene.NotASimulationStep;
+        ColliderIsMoving = false;
+        CollisionScore = 0;
+
+        // All axis free.
+        LockedLinearAxis = LockedAxisFree;
+        LockedAngularAxis = LockedAxisFree;
+    }
+
+    // Tell the object to clean up.
+    public virtual void Destroy()
+    {
+        PhysicalActors.Enable(false);
+        PhysScene.TaintedObject(LocalID, "BSPhysObject.Destroy", delegate()
+        {
+            PhysicalActors.Dispose();
+        });
+    }
+
+    public BSScene PhysScene { get; protected set; }
+    // public override uint LocalID { get; set; } // Use the LocalID definition in PhysicsActor
+    public string PhysObjectName { get; protected set; }
+    public string TypeName { get; protected set; }
+
+    // Set to 'true' when the object is completely initialized.
+    // This mostly prevents property updates and collisions until the object is completely here.
+    public bool IsInitialized { get; protected set; }
+
+    // Set to 'true' if an object (mesh/linkset/sculpty) is not completely constructed.
+    // This test is used to prevent some updates to the object when it only partially exists.
+    // There are several reasons and object might be incomplete:
+    //     Its underlying mesh/sculpty is an asset which must be fetched from the asset store
+    //     It is a linkset who is being added to or removed from
+    //     It is changing state (static to physical, for instance) which requires rebuilding
+    // This is a computed value based on the underlying physical object construction
+    abstract public bool IsIncomplete { get; }
+
+    // Return the object mass without calculating it or having side effects
+    public abstract float RawMass { get; }
+    // Set the raw mass but also update physical mass properties (inertia, ...)
+    // 'inWorld' true if the object has already been added to the dynamic world.
+    public abstract void UpdatePhysicalMassProperties(float mass, bool inWorld);
+
+    // The gravity being applied to the object. A function of default grav, GravityModifier and Buoyancy.
+    public virtual OMV.Vector3 Gravity { get; set; }
+    // The last value calculated for the prim's inertia
+    public OMV.Vector3 Inertia { get; set; }
+
+    // Reference to the physical body (btCollisionObject) of this object
+    public BulletBody PhysBody = new BulletBody(0);
+    // Reference to the physical shape (btCollisionShape) of this object
+    public BSShape PhysShape = new BSShapeNull();
+
+    // The physical representation of the prim might require an asset fetch.
+    // The asset state is first 'Unknown' then 'Waiting' then either 'Failed' or 'Fetched'.
+    public enum PrimAssetCondition
+    {
+        Unknown, Waiting, FailedAssetFetch, FailedMeshing, Fetched
+    }
+    public PrimAssetCondition PrimAssetState { get; set; }
+    public virtual bool AssetFailed()
+    {
+        return ( (this.PrimAssetState == PrimAssetCondition.FailedAssetFetch)
+              || (this.PrimAssetState == PrimAssetCondition.FailedMeshing) );
+    }
+
+    // The objects base shape information. Null if not a prim type shape.
+    public PrimitiveBaseShape BaseShape { get; protected set; }
+
+    // When the physical properties are updated, an EntityProperty holds the update values.
+    // Keep the current and last EntityProperties to enable computation of differences
+    //      between the current update and the previous values.
+    public EntityProperties CurrentEntityProperties { get; set; }
+    public EntityProperties LastEntityProperties { get; set; }
+
+    public virtual OMV.Vector3 Scale { get; set; }
+
+    // It can be confusing for an actor to know if it should move or update an object
+    //    depeneding on the setting of 'selected', 'physical, ...
+    // This flag is the true test -- if true, the object is being acted on in the physical world
+    public abstract bool IsPhysicallyActive { get; }
+
+    // Detailed state of the object.
+    public abstract bool IsSolid { get; }
+    public abstract bool IsStatic { get; }
+    public abstract bool IsSelected { get; }
+    public abstract bool IsVolumeDetect { get; }
+
+    // Materialness
+    public MaterialAttributes.Material Material { get; private set; }
+    public override void SetMaterial(int material)
+    {
+        Material = (MaterialAttributes.Material)material;
+
+        // Setting the material sets the material attributes also.
+        // TODO: decide if this is necessary -- the simulator does this.
+        MaterialAttributes matAttrib = BSMaterials.GetAttributes(Material, false);
+        Friction = matAttrib.friction;
+        Restitution = matAttrib.restitution;
+        Density = matAttrib.density;
+        // DetailLog("{0},{1}.SetMaterial,Mat={2},frict={3},rest={4},den={5}", LocalID, TypeName, Material, Friction, Restitution, Density);
+    }
+
+    public override float Density
+    {
+        get
+        {
+            return base.Density;
+        }
+        set
+        {
+            DetailLog("{0},BSPhysObject.Density,set,den={1}", LocalID, value);
+            base.Density = value;
+        }
+    }
+
+    // Stop all physical motion.
+    public abstract void ZeroMotion(bool inTaintTime);
+    public abstract void ZeroAngularMotion(bool inTaintTime);
+
+    // Update the physical location and motion of the object. Called with data from Bullet.
+    public abstract void UpdateProperties(EntityProperties entprop);
+
+    public virtual OMV.Vector3 RawPosition { get; set; }
+    public abstract OMV.Vector3 ForcePosition { get; set; }
+
+    public virtual OMV.Quaternion RawOrientation { get; set; }
+    public abstract OMV.Quaternion ForceOrientation { get; set; }
+
+    public virtual OMV.Vector3 RawVelocity { get; set; }
+    public abstract OMV.Vector3 ForceVelocity { get; set; }
+
+    public OMV.Vector3 RawForce { get; set; }
+    public OMV.Vector3 RawTorque { get; set; }
+    public override void AddAngularForce(OMV.Vector3 force, bool pushforce)
+    {
+        AddAngularForce(force, pushforce, false);
+    }
+    public abstract void AddAngularForce(OMV.Vector3 force, bool pushforce, bool inTaintTime);
+    public abstract void AddForce(OMV.Vector3 force, bool pushforce, bool inTaintTime);
+
+    public abstract OMV.Vector3 ForceRotationalVelocity { get; set; }
+
+    public abstract float ForceBuoyancy { get; set; }
+
+    public virtual bool ForceBodyShapeRebuild(bool inTaintTime) { return false; }
+
+    public override bool PIDActive 
+    {
+        get { return MoveToTargetActive; }
+        set { MoveToTargetActive = value; } 
+    }
+
+    public override OMV.Vector3 PIDTarget { set { MoveToTargetTarget = value; } }
+    public override float PIDTau { set { MoveToTargetTau = value; } }
+
+    public bool MoveToTargetActive { get; set; }
+    public OMV.Vector3 MoveToTargetTarget { get; set; }
+    public float MoveToTargetTau { get; set; }
+
+    // Used for llSetHoverHeight and maybe vehicle height. Hover Height will override MoveTo target's Z
+    public override bool PIDHoverActive { set { HoverActive = value; } }
+    public override float PIDHoverHeight { set { HoverHeight = value; } }
+    public override PIDHoverType PIDHoverType { set { HoverType = value; } }
+    public override float PIDHoverTau { set { HoverTau = value; } }
+
+    public bool HoverActive { get; set; }
+    public float HoverHeight { get;  set; }
+    public PIDHoverType HoverType { get;  set; }
+    public float HoverTau { get; set; }
+
+    // For RotLookAt
+    public override OMV.Quaternion APIDTarget { set { return; } }
+    public override bool APIDActive { set { return; } }
+    public override float APIDStrength { set { return; } }
+    public override float APIDDamping { set { return; } }
+
+    // The current velocity forward
+    public virtual float ForwardSpeed
+    {
+        get
+        {
+            OMV.Vector3 characterOrientedVelocity = RawVelocity * OMV.Quaternion.Inverse(OMV.Quaternion.Normalize(RawOrientation));
+            return characterOrientedVelocity.X;
+        }
+    }
+    // The forward speed we are trying to achieve (TargetVelocity)
+    public virtual float TargetVelocitySpeed
+    {
+        get
+        {
+            OMV.Vector3 characterOrientedVelocity = TargetVelocity * OMV.Quaternion.Inverse(OMV.Quaternion.Normalize(RawOrientation));
+            return characterOrientedVelocity.X;
+        }
+    }
+
+    // The user can optionally set the center of mass. The user's setting will override any
+    //    computed center-of-mass (like in linksets).
+    // Note this is a displacement from the root's coordinates. Zero means use the root prim as center-of-mass.
+    public OMV.Vector3? UserSetCenterOfMassDisplacement { get; set; }
+
+    public OMV.Vector3 LockedLinearAxis;   // zero means locked. one means free.
+    public OMV.Vector3 LockedAngularAxis;  // zero means locked. one means free.
+    public const float FreeAxis = 1f;
+    public const float LockedAxis = 0f;
+    public readonly OMV.Vector3 LockedAxisFree = new OMV.Vector3(FreeAxis, FreeAxis, FreeAxis);  // All axis are free
+
+    // If an axis is locked (flagged above) then the limits of that axis are specified here.
+    // Linear axis limits are relative to the object's starting coordinates.
+    // Angular limits are limited to -PI to +PI
+    public OMV.Vector3 LockedLinearAxisLow;
+    public OMV.Vector3 LockedLinearAxisHigh;
+    public OMV.Vector3 LockedAngularAxisLow;
+    public OMV.Vector3 LockedAngularAxisHigh;
+
+    // Enable physical actions. Bullet will keep sleeping non-moving physical objects so
+    //     they need waking up when parameters are changed.
+    // Called in taint-time!!
+    public void ActivateIfPhysical(bool forceIt)
+    {
+        if (PhysBody.HasPhysicalBody)
+        {
+            if (IsPhysical)
+            {
+                // Physical objects might need activating
+                PhysScene.PE.Activate(PhysBody, forceIt);
+            }
+            else
+            {
+                // Clear the collision cache since we've changed some properties.
+                PhysScene.PE.ClearCollisionProxyCache(PhysScene.World, PhysBody);
+            }
+        }
+    }
+
+    // 'actors' act on the physical object to change or constrain its motion. These can range from
+    //       hovering to complex vehicle motion.
+    // May be called at non-taint time as this just adds the actor to the action list and the real
+    //    work is done during the simulation step.
+    // Note that, if the actor is already in the list and we are disabling same, the actor is just left
+    //    in the list disabled.
+    public delegate BSActor CreateActor();
+    public void EnableActor(bool enableActor, string actorName, CreateActor creator)
+    {
+        lock (PhysicalActors)
+        {
+            BSActor theActor;
+            if (PhysicalActors.TryGetActor(actorName, out theActor))
+            {
+                // The actor already exists so just turn it on or off
+                DetailLog("{0},BSPhysObject.EnableActor,enablingExistingActor,name={1},enable={2}", LocalID, actorName, enableActor);
+                theActor.Enabled = enableActor;
+            }
+            else
+            {
+                // The actor does not exist. If it should, create it.
+                if (enableActor)
+                {
+                    DetailLog("{0},BSPhysObject.EnableActor,creatingActor,name={1}", LocalID, actorName);
+                    theActor = creator();
+                    PhysicalActors.Add(actorName, theActor);
+                    theActor.Enabled = true;
+                }
+                else
+                {
+                    DetailLog("{0},BSPhysObject.EnableActor,notCreatingActorSinceNotEnabled,name={1}", LocalID, actorName);
+                }
+            }
+        }
+    }
+
+    #region Collisions
+
+    // Requested number of milliseconds between collision events. Zero means disabled.
+    protected int SubscribedEventsMs { get; set; }
+    // Given subscription, the time that a collision may be passed up
+    protected int NextCollisionOkTime { get; set; }
+    // The simulation step that last had a collision
+    protected long CollidingStep { get; set; }
+    // The simulation step that last had a collision with the ground
+    protected long CollidingGroundStep { get; set; }
+    // The simulation step that last collided with an object
+    protected long CollidingObjectStep { get; set; }
+    // The collision flags we think are set in Bullet
+    protected CollisionFlags CurrentCollisionFlags { get; set; }
+    // On a collision, check the collider and remember if the last collider was moving
+    //    Used to modify the standing of avatars (avatars on stationary things stand still)
+    public bool ColliderIsMoving;
+    // 'true' if the last collider was a volume detect object
+    public bool ColliderIsVolumeDetect;
+    // Used by BSCharacter to manage standing (and not slipping)
+    public bool IsStationary;
+
+    // Count of collisions for this object
+    protected long CollisionAccumulation { get; set; }
+
+    public override bool IsColliding {
+        get { return (CollidingStep == PhysScene.SimulationStep); }
+        set {
+            if (value)
+                CollidingStep = PhysScene.SimulationStep;
+            else
+                CollidingStep = BSScene.NotASimulationStep;
+            }
+    }
+    // Complex objects (like linksets) need to know if there is a collision on any part of
+    //    their shape. 'IsColliding' has an existing definition of reporting a collision on
+    //    only this specific prim or component of linksets.
+    // 'HasSomeCollision' is defined as reporting if there is a collision on any part of
+    //    the complex body that this prim is the root of.
+    public virtual bool HasSomeCollision
+    {
+        get { return IsColliding; }
+        set { IsColliding = value; }
+    }
+    public override bool CollidingGround {
+        get { return (CollidingGroundStep == PhysScene.SimulationStep); }
+        set
+        {
+            if (value)
+                CollidingGroundStep = PhysScene.SimulationStep;
+            else
+                CollidingGroundStep = BSScene.NotASimulationStep;
+        }
+    }
+    public override bool CollidingObj {
+        get { return (CollidingObjectStep == PhysScene.SimulationStep); }
+        set {
+            if (value)
+                CollidingObjectStep = PhysScene.SimulationStep;
+            else
+                CollidingObjectStep = BSScene.NotASimulationStep;
+        }
+    }
+
+    // The collisions that have been collected for the next collision reporting (throttled by subscription)
+    protected CollisionEventUpdate CollisionCollection = new CollisionEventUpdate();
+    // This is the collision collection last reported to the Simulator.
+    public CollisionEventUpdate CollisionsLastReported = new CollisionEventUpdate();
+    // Remember the collisions recorded in the last tick for fancy collision checking
+    //     (like a BSCharacter walking up stairs).
+    public CollisionEventUpdate CollisionsLastTick = new CollisionEventUpdate();
+    private long CollisionsLastTickStep = -1;
+
+    // The simulation step is telling this object about a collision.
+    // Return 'true' if a collision was processed and should be sent up.
+    // Return 'false' if this object is not enabled/subscribed/appropriate for or has already seen this collision.
+    // Called at taint time from within the Step() function
+    public delegate bool CollideCall(uint collidingWith, BSPhysObject collidee, OMV.Vector3 contactPoint, OMV.Vector3 contactNormal, float pentrationDepth);
+    public virtual bool Collide(uint collidingWith, BSPhysObject collidee,
+                    OMV.Vector3 contactPoint, OMV.Vector3 contactNormal, float pentrationDepth)
+    {
+        bool ret = false;
+
+        // The following lines make IsColliding(), CollidingGround() and CollidingObj work
+        CollidingStep = PhysScene.SimulationStep;
+        if (collidingWith <= PhysScene.TerrainManager.HighestTerrainID)
+        {
+            CollidingGroundStep = PhysScene.SimulationStep;
+        }
+        else
+        {
+            CollidingObjectStep = PhysScene.SimulationStep;
+        }
+
+        CollisionAccumulation++;
+
+        // For movement tests, remember if we are colliding with an object that is moving.
+        ColliderIsMoving = collidee != null ? (collidee.RawVelocity != OMV.Vector3.Zero) : false;
+        ColliderIsVolumeDetect = collidee != null ? (collidee.IsVolumeDetect) : false;
+
+        // Make a collection of the collisions that happened the last simulation tick.
+        // This is different than the collection created for sending up to the simulator as it is cleared every tick.
+        if (CollisionsLastTickStep != PhysScene.SimulationStep)
+        {
+            CollisionsLastTick = new CollisionEventUpdate();
+            CollisionsLastTickStep = PhysScene.SimulationStep;
+        }
+        CollisionsLastTick.AddCollider(collidingWith, new ContactPoint(contactPoint, contactNormal, pentrationDepth));
+
+        // If someone has subscribed for collision events log the collision so it will be reported up
+        if (SubscribedEvents()) {
+            lock (PhysScene.CollisionLock)
+            {
+                CollisionCollection.AddCollider(collidingWith, new ContactPoint(contactPoint, contactNormal, pentrationDepth));
+            }
+            DetailLog("{0},{1}.Collision.AddCollider,call,with={2},point={3},normal={4},depth={5},colliderMoving={6}",
+                            LocalID, TypeName, collidingWith, contactPoint, contactNormal, pentrationDepth, ColliderIsMoving);
+
+            ret = true;
+        }
+        return ret;
+    }
+
+    // Send the collected collisions into the simulator.
+    // Called at taint time from within the Step() function thus no locking problems
+    //      with CollisionCollection and ObjectsWithNoMoreCollisions.
+    // Called with BSScene.CollisionLock locked to protect the collision lists.
+    // Return 'true' if there were some actual collisions passed up
+    public virtual bool SendCollisions()
+    {
+        bool ret = true;
+
+        // If no collisions this call but there were collisions last call, force the collision
+        //     event to be happen right now so quick collision_end.
+        bool force = (CollisionCollection.Count == 0 && CollisionsLastReported.Count != 0);
+
+        // throttle the collisions to the number of milliseconds specified in the subscription
+        if (force || (PhysScene.SimulationNowTime >= NextCollisionOkTime))
+        {
+            NextCollisionOkTime = PhysScene.SimulationNowTime + SubscribedEventsMs;
+
+            // We are called if we previously had collisions. If there are no collisions
+            //   this time, send up one last empty event so OpenSim can sense collision end.
+            if (CollisionCollection.Count == 0)
+            {
+                // If I have no collisions this time, remove me from the list of objects with collisions.
+                ret = false;
+            }
+
+            DetailLog("{0},{1}.SendCollisionUpdate,call,numCollisions={2}", LocalID, TypeName, CollisionCollection.Count);
+            base.SendCollisionUpdate(CollisionCollection);
+
+            // Remember the collisions from this tick for some collision specific processing.
+            CollisionsLastReported = CollisionCollection;
+
+            // The CollisionCollection instance is passed around in the simulator.
+            // Make sure we don't have a handle to that one and that a new one is used for next time.
+            //    This fixes an interesting 'gotcha'. If we call CollisionCollection.Clear() here,
+            //    a race condition is created for the other users of this instance.
+            CollisionCollection = new CollisionEventUpdate();
+        }
+        return ret;
+    }
+
+    // Subscribe for collision events.
+    // Parameter is the millisecond rate the caller wishes collision events to occur.
+    public override void SubscribeEvents(int ms) {
+        // DetailLog("{0},{1}.SubscribeEvents,subscribing,ms={2}", LocalID, TypeName, ms);
+        SubscribedEventsMs = ms;
+        if (ms > 0)
+        {
+            // make sure first collision happens
+            NextCollisionOkTime = Util.EnvironmentTickCountSubtract(SubscribedEventsMs);
+
+            PhysScene.TaintedObject(LocalID, TypeName+".SubscribeEvents", delegate()
+            {
+                if (PhysBody.HasPhysicalBody)
+                    CurrentCollisionFlags = PhysScene.PE.AddToCollisionFlags(PhysBody, CollisionFlags.BS_SUBSCRIBE_COLLISION_EVENTS);
+            });
+        }
+        else
+        {
+            // Subscribing for zero or less is the same as unsubscribing
+            UnSubscribeEvents();
+        }
+    }
+    public override void UnSubscribeEvents() {
+        // DetailLog("{0},{1}.UnSubscribeEvents,unsubscribing", LocalID, TypeName);
+        SubscribedEventsMs = 0;
+        PhysScene.TaintedObject(LocalID, TypeName+".UnSubscribeEvents", delegate()
+        {
+            // Make sure there is a body there because sometimes destruction happens in an un-ideal order.
+            if (PhysBody.HasPhysicalBody)
+                CurrentCollisionFlags = PhysScene.PE.RemoveFromCollisionFlags(PhysBody, CollisionFlags.BS_SUBSCRIBE_COLLISION_EVENTS);
+        });
+    }
+    // Return 'true' if the simulator wants collision events
+    public override bool SubscribedEvents() {
+        return (SubscribedEventsMs > 0);
+    }
+    // Because 'CollisionScore' is called many times while sorting, it should not be recomputed
+    //    each time called. So this is built to be light weight for each collision and to do
+    //    all the processing when the user asks for the info.
+    public void ComputeCollisionScore()
+    {
+        // Scale the collision count by the time since the last collision.
+        // The "+1" prevents dividing by zero.
+        long timeAgo = PhysScene.SimulationStep - CollidingStep + 1;
+        CollisionScore = CollisionAccumulation / timeAgo;
+    }
+    public override float CollisionScore { get; set; }
+
+    #endregion // Collisions
+
+    #region Per Simulation Step actions
+
+    public BSActorCollection PhysicalActors = new BSActorCollection();
+
+    // When an update to the physical properties happens, this event is fired to let
+    //    different actors to modify the update before it is passed around
+    public delegate void PreUpdatePropertyAction(ref EntityProperties entprop);
+    public event PreUpdatePropertyAction OnPreUpdateProperty;
+    protected void TriggerPreUpdatePropertyAction(ref EntityProperties entprop)
+    {
+        PreUpdatePropertyAction actions = OnPreUpdateProperty;
+        if (actions != null)
+            actions(ref entprop);
+    }
+
+    #endregion // Per Simulation Step actions
+
+    // High performance detailed logging routine used by the physical objects.
+    protected void DetailLog(string msg, params Object[] args)
+    {
+        if (PhysScene.PhysicsLogging.Enabled)
+            PhysScene.DetailLog(msg, args);
+    }
+
+}
+}