* Initial commit of BulletSimN (BulletSNPlugin). Purely C# implementation of BulletSim. This is designed to be /as close as possible/ to the BulletSim plugin while still being entirely in the managed space to make keeping it up to date easy as possible (no thinking work). This implementation is /slower/ then the c++ version just because it's fully managed, so it's not appropriate for huge sims, but it will run small ones OK. At the moment, it supports all known features of BulletSim. Think of it like.. POS but everything works. To use this plugin, set the physics plugin to BulletSimN.

1 files changed, 954 insertions, 0 deletions

diff --git a/OpenSim/Region/Physics/BulletSNPlugin/BSScene.cs b/OpenSim/Region/Physics/BulletSNPlugin/BSScene.cs
new file mode 100644
index 0000000..6bcea3f
--- /dev/null
+++ b/OpenSim/Region/Physics/BulletSNPlugin/BSScene.cs
@@ -0,0 +1,954 @@
+/*
+ * 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.Runtime.InteropServices;
+using System.Text;
+using System.Threading;
+using OpenSim.Framework;
+using OpenSim.Region.Framework;
+using OpenSim.Region.CoreModules;
+using Logging = OpenSim.Region.CoreModules.Framework.Statistics.Logging;
+using OpenSim.Region.Physics.Manager;
+using Nini.Config;
+using log4net;
+using OpenMetaverse;
+
+// TODOs for BulletSim (for BSScene, BSPrim, BSCharacter and BulletSim)
+// Based on material, set density and friction
+// More efficient memory usage when passing hull information from BSPrim to BulletSim
+// Do attachments need to be handled separately? Need collision events. Do not collide with VolumeDetect
+// Implement LockAngularMotion
+// Add PID movement operations. What does ScenePresence.MoveToTarget do?
+// Check terrain size. 128 or 127?
+// Raycast
+//
+namespace OpenSim.Region.Physics.BulletSNPlugin
+{
+public sealed class BSScene : PhysicsScene, IPhysicsParameters
+{
+    private static readonly ILog m_log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
+    private static readonly string LogHeader = "[BULLETS SCENE]";
+
+    // The name of the region we're working for.
+    public string RegionName { get; private set; }
+
+    public string BulletSimVersion = "?";
+
+    public Dictionary<uint, BSPhysObject> PhysObjects;
+    public BSShapeCollection Shapes;
+
+    // Keeping track of the objects with collisions so we can report begin and end of a collision
+    public HashSet<BSPhysObject> ObjectsWithCollisions = new HashSet<BSPhysObject>();
+    public HashSet<BSPhysObject> ObjectsWithNoMoreCollisions = new HashSet<BSPhysObject>();
+    // Keep track of all the avatars so we can send them a collision event
+    //    every tick so OpenSim will update its animation.
+    private HashSet<BSPhysObject> m_avatars = new HashSet<BSPhysObject>();
+
+    // let my minuions use my logger
+    public ILog Logger { get { return m_log; } }
+
+    public IMesher mesher;
+    public uint WorldID { get; private set; }
+    public BulletSim World { get; private set; }
+
+    // All the constraints that have been allocated in this instance.
+    public BSConstraintCollection Constraints { get; private set; }
+
+    // Simulation parameters
+    internal int m_maxSubSteps;
+    internal float m_fixedTimeStep;
+    internal long m_simulationStep = 0;
+    public long SimulationStep { get { return m_simulationStep; } }
+    internal int m_taintsToProcessPerStep;
+    internal float LastTimeStep { get; private set; }
+
+    // Physical objects can register for prestep or poststep events
+    public delegate void PreStepAction(float timeStep);
+    public delegate void PostStepAction(float timeStep);
+    public event PreStepAction BeforeStep;
+    public event PreStepAction AfterStep;
+
+    // A value of the time now so all the collision and update routines do not have to get their own
+    // Set to 'now' just before all the prims and actors are called for collisions and updates
+    public int SimulationNowTime { get; private set; }
+
+    // True if initialized and ready to do simulation steps
+    private bool m_initialized = false;
+
+    // Flag which is true when processing taints.
+    // Not guaranteed to be correct all the time (don't depend on this) but good for debugging.
+    public bool InTaintTime { get; private set; }
+
+    // Pinned memory used to pass step information between managed and unmanaged
+    internal int m_maxCollisionsPerFrame;
+    private List<BulletXNA.CollisionDesc> m_collisionArray;
+    //private GCHandle m_collisionArrayPinnedHandle;
+
+    internal int m_maxUpdatesPerFrame;
+    private List<BulletXNA.EntityProperties> m_updateArray;
+    //private GCHandle m_updateArrayPinnedHandle;
+
+
+    public const uint TERRAIN_ID = 0;       // OpenSim senses terrain with a localID of zero
+    public const uint GROUNDPLANE_ID = 1;
+    public const uint CHILDTERRAIN_ID = 2;  // Terrain allocated based on our mega-prim childre start here
+
+    public float SimpleWaterLevel { get; set; }
+    public BSTerrainManager TerrainManager { get; private set; }
+
+    public ConfigurationParameters Params
+    {
+        get { return UnmanagedParams[0]; }
+    }
+    public Vector3 DefaultGravity
+    {
+        get { return new Vector3(0f, 0f, Params.gravity); }
+    }
+    // Just the Z value of the gravity
+    public float DefaultGravityZ
+    {
+        get { return Params.gravity; }
+    }
+
+    // When functions in the unmanaged code must be called, it is only
+    //   done at a known time just before the simulation step. The taint
+    //   system saves all these function calls and executes them in
+    //   order before the simulation.
+    public delegate void TaintCallback();
+    private struct TaintCallbackEntry
+    {
+        public String ident;
+        public TaintCallback callback;
+        public TaintCallbackEntry(string i, TaintCallback c)
+        {
+            ident = i;
+            callback = c;
+        }
+    }
+    private Object _taintLock = new Object();   // lock for using the next object
+    private List<TaintCallbackEntry> _taintOperations;
+    private Dictionary<string, TaintCallbackEntry> _postTaintOperations;
+    private List<TaintCallbackEntry> _postStepOperations;
+
+    // A pointer to an instance if this structure is passed to the C++ code
+    // Used to pass basic configuration values to the unmanaged code.
+    internal ConfigurationParameters[] UnmanagedParams;
+    //GCHandle m_paramsHandle;
+
+    // Handle to the callback used by the unmanaged code to call into the managed code.
+    // Used for debug logging.
+    // Need to store the handle in a persistant variable so it won't be freed.
+    private BulletSimAPI.DebugLogCallback m_DebugLogCallbackHandle;
+
+    // Sometimes you just have to log everything.
+    public Logging.LogWriter PhysicsLogging;
+    private bool m_physicsLoggingEnabled;
+    private string m_physicsLoggingDir;
+    private string m_physicsLoggingPrefix;
+    private int m_physicsLoggingFileMinutes;
+    private bool m_physicsLoggingDoFlush;
+    // 'true' of the vehicle code is to log lots of details
+    public bool VehicleLoggingEnabled { get; private set; }
+    public bool VehiclePhysicalLoggingEnabled { get; private set; }
+
+    #region Construction and Initialization
+    public BSScene(string identifier)
+    {
+        m_initialized = false;
+        // we are passed the name of the region we're working for.
+        RegionName = identifier;
+    }
+
+    public override void Initialise(IMesher meshmerizer, IConfigSource config)
+    {
+        mesher = meshmerizer;
+        _taintOperations = new List<TaintCallbackEntry>();
+        _postTaintOperations = new Dictionary<string, TaintCallbackEntry>();
+        _postStepOperations = new List<TaintCallbackEntry>();
+        PhysObjects = new Dictionary<uint, BSPhysObject>();
+        Shapes = new BSShapeCollection(this);
+
+        // Allocate pinned memory to pass parameters.
+        UnmanagedParams = new ConfigurationParameters[1];
+        //m_paramsHandle = GCHandle.Alloc(UnmanagedParams, GCHandleType.Pinned);
+
+        // Set default values for physics parameters plus any overrides from the ini file
+        GetInitialParameterValues(config);
+
+        // allocate more pinned memory close to the above in an attempt to get the memory all together
+        m_collisionArray = new List<BulletXNA.CollisionDesc>();
+        //m_collisionArrayPinnedHandle = GCHandle.Alloc(m_collisionArray, GCHandleType.Pinned);
+        m_updateArray = new List<BulletXNA.EntityProperties>();
+        //m_updateArrayPinnedHandle = GCHandle.Alloc(m_updateArray, GCHandleType.Pinned);
+
+        // Enable very detailed logging.
+        // By creating an empty logger when not logging, the log message invocation code
+        //     can be left in and every call doesn't have to check for null.
+        if (m_physicsLoggingEnabled)
+        {
+            PhysicsLogging = new Logging.LogWriter(m_physicsLoggingDir, m_physicsLoggingPrefix, m_physicsLoggingFileMinutes);
+            PhysicsLogging.ErrorLogger = m_log; // for DEBUG. Let's the logger output error messages.
+        }
+        else
+        {
+            PhysicsLogging = new Logging.LogWriter();
+        }
+
+        // If Debug logging level, enable logging from the unmanaged code
+        m_DebugLogCallbackHandle = null;
+        if (m_log.IsDebugEnabled || PhysicsLogging.Enabled)
+        {
+            m_log.DebugFormat("{0}: Initialize: Setting debug callback for unmanaged code", LogHeader);
+            if (PhysicsLogging.Enabled)
+                // The handle is saved in a variable to make sure it doesn't get freed after this call
+                m_DebugLogCallbackHandle = new BulletSimAPI.DebugLogCallback(BulletLoggerPhysLog);
+            else
+                m_DebugLogCallbackHandle = new BulletSimAPI.DebugLogCallback(BulletLogger);
+        }
+
+        // Get the version of the DLL
+        // TODO: this doesn't work yet. Something wrong with marshaling the returned string.
+        // BulletSimVersion = BulletSimAPI.GetVersion();
+        // m_log.WarnFormat("{0}: BulletSim.dll version='{1}'", LogHeader, BulletSimVersion);
+
+        // The bounding box for the simulated world. The origin is 0,0,0 unless we're
+        //    a child in a mega-region.
+        // Bullet actually doesn't care about the extents of the simulated
+        //    area. It tracks active objects no matter where they are.
+        Vector3 worldExtent = new Vector3(Constants.RegionSize, Constants.RegionSize, Constants.RegionHeight);
+
+        // m_log.DebugFormat("{0}: Initialize: Calling BulletSimAPI.Initialize.", LogHeader);
+
+        World = new BulletSim(0, this, BulletSimAPI.Initialize2(worldExtent, UnmanagedParams,
+                                        m_maxCollisionsPerFrame, ref m_collisionArray,
+                                        m_maxUpdatesPerFrame,ref m_updateArray,
+                                        m_DebugLogCallbackHandle));
+
+        Constraints = new BSConstraintCollection(World);
+
+        TerrainManager = new BSTerrainManager(this);
+        TerrainManager.CreateInitialGroundPlaneAndTerrain();
+
+        m_log.WarnFormat("{0} Linksets implemented with {1}", LogHeader, (BSLinkset.LinksetImplementation)BSParam.LinksetImplementation);
+
+        InTaintTime = false;
+        m_initialized = true;
+    }
+
+    // All default parameter values are set here. There should be no values set in the
+    // variable definitions.
+    private void GetInitialParameterValues(IConfigSource config)
+    {
+        ConfigurationParameters parms = new ConfigurationParameters();
+        UnmanagedParams[0] = parms;
+
+        BSParam.SetParameterDefaultValues(this);
+
+        if (config != null)
+        {
+            // If there are specifications in the ini file, use those values
+            IConfig pConfig = config.Configs["BulletSim"];
+            if (pConfig != null)
+            {
+                BSParam.SetParameterConfigurationValues(this, pConfig);
+
+                // Very detailed logging for physics debugging
+                m_physicsLoggingEnabled = pConfig.GetBoolean("PhysicsLoggingEnabled", false);
+                m_physicsLoggingDir = pConfig.GetString("PhysicsLoggingDir", ".");
+                m_physicsLoggingPrefix = pConfig.GetString("PhysicsLoggingPrefix", "physics-%REGIONNAME%-");
+                m_physicsLoggingFileMinutes = pConfig.GetInt("PhysicsLoggingFileMinutes", 5);
+                m_physicsLoggingDoFlush = pConfig.GetBoolean("PhysicsLoggingDoFlush", false);
+                // Very detailed logging for vehicle debugging
+                VehicleLoggingEnabled = pConfig.GetBoolean("VehicleLoggingEnabled", false);
+                VehiclePhysicalLoggingEnabled = pConfig.GetBoolean("VehiclePhysicalLoggingEnabled", false);
+
+                // Do any replacements in the parameters
+                m_physicsLoggingPrefix = m_physicsLoggingPrefix.Replace("%REGIONNAME%", RegionName);
+            }
+
+            // The material characteristics.
+            BSMaterials.InitializeFromDefaults(Params);
+            if (pConfig != null)
+            {
+                // Let the user add new and interesting material property values.
+                BSMaterials.InitializefromParameters(pConfig);
+            }
+        }
+    }
+
+    // A helper function that handles a true/false parameter and returns the proper float number encoding
+    float ParamBoolean(IConfig config, string parmName, float deflt)
+    {
+        float ret = deflt;
+        if (config.Contains(parmName))
+        {
+            ret = ConfigurationParameters.numericFalse;
+            if (config.GetBoolean(parmName, false))
+            {
+                ret = ConfigurationParameters.numericTrue;
+            }
+        }
+        return ret;
+    }
+
+    // Called directly from unmanaged code so don't do much
+    private void BulletLogger(string msg)
+    {
+        m_log.Debug("[BULLETS UNMANAGED]:" + msg);
+    }
+
+    // Called directly from unmanaged code so don't do much
+    private void BulletLoggerPhysLog(string msg)
+    {
+        DetailLog("[BULLETS UNMANAGED]:" + msg);
+    }
+
+    public override void Dispose()
+    {
+        // m_log.DebugFormat("{0}: Dispose()", LogHeader);
+
+        // make sure no stepping happens while we're deleting stuff
+        m_initialized = false;
+
+        foreach (KeyValuePair<uint, BSPhysObject> kvp in PhysObjects)
+        {
+            kvp.Value.Destroy();
+        }
+        PhysObjects.Clear();
+
+        // Now that the prims are all cleaned up, there should be no constraints left
+        if (Constraints != null)
+        {
+            Constraints.Dispose();
+            Constraints = null;
+        }
+
+        if (Shapes != null)
+        {
+            Shapes.Dispose();
+            Shapes = null;
+        }
+
+        if (TerrainManager != null)
+        {
+            TerrainManager.ReleaseGroundPlaneAndTerrain();
+            TerrainManager.Dispose();
+            TerrainManager = null;
+        }
+
+        // Anything left in the unmanaged code should be cleaned out
+        BulletSimAPI.Shutdown2(World.ptr);
+
+        // Not logging any more
+        PhysicsLogging.Close();
+    }
+    #endregion // Construction and Initialization
+
+    #region Prim and Avatar addition and removal
+
+    public override PhysicsActor AddAvatar(string avName, Vector3 position, Vector3 size, bool isFlying)
+    {
+        m_log.ErrorFormat("{0}: CALL TO AddAvatar in BSScene. NOT IMPLEMENTED", LogHeader);
+        return null;
+    }
+
+    public override PhysicsActor AddAvatar(uint localID, string avName, Vector3 position, Vector3 size, bool isFlying)
+    {
+        // m_log.DebugFormat("{0}: AddAvatar: {1}", LogHeader, avName);
+
+        if (!m_initialized) return null;
+
+        BSCharacter actor = new BSCharacter(localID, avName, this, position, size, isFlying);
+        lock (PhysObjects) PhysObjects.Add(localID, actor);
+
+        // TODO: Remove kludge someday.
+        // We must generate a collision for avatars whether they collide or not.
+        // This is required by OpenSim to update avatar animations, etc.
+        lock (m_avatars) m_avatars.Add(actor);
+
+        return actor;
+    }
+
+    public override void RemoveAvatar(PhysicsActor actor)
+    {
+        // m_log.DebugFormat("{0}: RemoveAvatar", LogHeader);
+
+        if (!m_initialized) return;
+
+        BSCharacter bsactor = actor as BSCharacter;
+        if (bsactor != null)
+        {
+            try
+            {
+                lock (PhysObjects) PhysObjects.Remove(actor.LocalID);
+                // Remove kludge someday
+                lock (m_avatars) m_avatars.Remove(bsactor);
+            }
+            catch (Exception e)
+            {
+                m_log.WarnFormat("{0}: Attempt to remove avatar that is not in physics scene: {1}", LogHeader, e);
+            }
+            bsactor.Destroy();
+            // bsactor.dispose();
+        }
+    }
+
+    public override void RemovePrim(PhysicsActor prim)
+    {
+        if (!m_initialized) return;
+
+        BSPrim bsprim = prim as BSPrim;
+        if (bsprim != null)
+        {
+            DetailLog("{0},RemovePrim,call", bsprim.LocalID);
+            // m_log.DebugFormat("{0}: RemovePrim. id={1}/{2}", LogHeader, bsprim.Name, bsprim.LocalID);
+            try
+            {
+                lock (PhysObjects) PhysObjects.Remove(bsprim.LocalID);
+            }
+            catch (Exception e)
+            {
+                m_log.ErrorFormat("{0}: Attempt to remove prim that is not in physics scene: {1}", LogHeader, e);
+            }
+            bsprim.Destroy();
+            // bsprim.dispose();
+        }
+        else
+        {
+            m_log.ErrorFormat("{0}: Attempt to remove prim that is not a BSPrim type.", LogHeader);
+        }
+    }
+
+    public override PhysicsActor AddPrimShape(string primName, PrimitiveBaseShape pbs, Vector3 position,
+                                              Vector3 size, Quaternion rotation, bool isPhysical, uint localID)
+    {
+        // m_log.DebugFormat("{0}: AddPrimShape2: {1}", LogHeader, primName);
+
+        if (!m_initialized) return null;
+
+        DetailLog("{0},AddPrimShape,call", localID);
+
+        BSPrim prim = new BSPrim(localID, primName, this, position, size, rotation, pbs, isPhysical);
+        lock (PhysObjects) PhysObjects.Add(localID, prim);
+        return prim;
+    }
+
+    // This is a call from the simulator saying that some physical property has been updated.
+    // The BulletSim driver senses the changing of relevant properties so this taint
+    // information call is not needed.
+    public override void AddPhysicsActorTaint(PhysicsActor prim) { }
+
+    #endregion // Prim and Avatar addition and removal
+
+    #region Simulation
+    // Simulate one timestep
+    public override float Simulate(float timeStep)
+    {
+        // prevent simulation until we've been initialized
+        if (!m_initialized) return 5.0f;
+
+        LastTimeStep = timeStep;
+
+        int updatedEntityCount = 0;
+        //Object updatedEntitiesPtr;
+        int collidersCount = 0;
+        //Object collidersPtr;
+
+        int beforeTime = 0;
+        int simTime = 0;
+
+        // update the prim states while we know the physics engine is not busy
+        int numTaints = _taintOperations.Count;
+
+        InTaintTime = true; // Only used for debugging so locking is not necessary.
+
+        ProcessTaints();
+
+        // Some of the physical objects requre individual, pre-step calls
+        TriggerPreStepEvent(timeStep);
+
+        // the prestep actions might have added taints
+        ProcessTaints();
+
+        InTaintTime = false; // Only used for debugging so locking is not necessary.
+
+        // step the physical world one interval
+        m_simulationStep++;
+        int numSubSteps = 0;
+
+        try
+        {
+            //if (VehicleLoggingEnabled) DumpVehicles();  // DEBUG
+            if (PhysicsLogging.Enabled) beforeTime = Util.EnvironmentTickCount();
+
+            numSubSteps = BulletSimAPI.PhysicsStep2(World.ptr, timeStep, m_maxSubSteps, m_fixedTimeStep,
+                        out updatedEntityCount, out m_updateArray, out collidersCount, out m_collisionArray);
+
+            if (PhysicsLogging.Enabled) simTime = Util.EnvironmentTickCountSubtract(beforeTime);
+            DetailLog("{0},Simulate,call, frame={1}, nTaints={2}, simTime={3}, substeps={4}, updates={5}, colliders={6}, objWColl={7}",
+                                    DetailLogZero, m_simulationStep, numTaints, simTime, numSubSteps, 
+                                    updatedEntityCount, collidersCount, ObjectsWithCollisions.Count);
+        }
+        catch (Exception e)
+        {
+            m_log.WarnFormat("{0},PhysicsStep Exception: nTaints={1}, substeps={2}, updates={3}, colliders={4}, e={5}",
+                        LogHeader, numTaints, numSubSteps, updatedEntityCount, collidersCount, e);
+            DetailLog("{0},PhysicsStepException,call, nTaints={1}, substeps={2}, updates={3}, colliders={4}",
+                        DetailLogZero, numTaints, numSubSteps, updatedEntityCount, collidersCount);
+            updatedEntityCount = 0;
+            collidersCount = 0;
+        }
+
+        // Don't have to use the pointers passed back since we know it is the same pinned memory we passed in.
+
+        // Get a value for 'now' so all the collision and update routines don't have to get their own.
+        SimulationNowTime = Util.EnvironmentTickCount();
+
+        // If there were collisions, process them by sending the event to the prim.
+        // Collisions must be processed before updates.
+        if (collidersCount > 0)
+        {
+            for (int ii = 0; ii < collidersCount; ii++)
+            {
+                uint cA = m_collisionArray[ii].aID;
+                uint cB = m_collisionArray[ii].bID;
+                Vector3 point = new Vector3(m_collisionArray[ii].point.X, m_collisionArray[ii].point.Y,
+                                            m_collisionArray[ii].point.Z);
+                Vector3 normal = new Vector3(m_collisionArray[ii].normal.X, m_collisionArray[ii].normal.Y,
+                                            m_collisionArray[ii].normal.Z); 
+                SendCollision(cA, cB, point, normal, 0.01f);
+                SendCollision(cB, cA, point, -normal, 0.01f);
+            }
+        }
+
+        // The above SendCollision's batch up the collisions on the objects.
+        //      Now push the collisions into the simulator.
+        if (ObjectsWithCollisions.Count > 0)
+        {
+            foreach (BSPhysObject bsp in ObjectsWithCollisions)
+                if (!bsp.SendCollisions())
+                {
+                    // If the object is done colliding, see that it's removed from the colliding list
+                    ObjectsWithNoMoreCollisions.Add(bsp);
+                }
+        }
+
+        // This is a kludge to get avatar movement updates.
+        // The simulator expects collisions for avatars even if there are have been no collisions.
+        //    The event updates avatar animations and stuff.
+        // If you fix avatar animation updates, remove this overhead and let normal collision processing happen.
+        foreach (BSPhysObject bsp in m_avatars)
+            if (!ObjectsWithCollisions.Contains(bsp))   // don't call avatars twice
+                bsp.SendCollisions();
+
+        // Objects that are done colliding are removed from the ObjectsWithCollisions list.
+        // Not done above because it is inside an iteration of ObjectWithCollisions.
+        // This complex collision processing is required to create an empty collision
+        //     event call after all collisions have happened on an object. This enables
+        //     the simulator to generate the 'collision end' event.
+        if (ObjectsWithNoMoreCollisions.Count > 0)
+        {
+            foreach (BSPhysObject po in ObjectsWithNoMoreCollisions)
+                ObjectsWithCollisions.Remove(po);
+            ObjectsWithNoMoreCollisions.Clear();
+        }
+        // Done with collisions.
+
+        // If any of the objects had updated properties, tell the object it has been changed by the physics engine
+        if (updatedEntityCount > 0)
+        {
+            for (int ii = 0; ii < updatedEntityCount; ii++)
+            {
+
+                BulletXNA.EntityProperties entprop = m_updateArray[ii];
+                BSPhysObject pobj;
+                if (PhysObjects.TryGetValue(entprop.ID, out pobj))
+                {
+                    EntityProperties prop = new EntityProperties()
+                                                {
+                                                    Acceleration = new Vector3(entprop.Acceleration.X, entprop.Acceleration.Y, entprop.Acceleration.Z),
+                                                    ID = entprop.ID,
+                                                    Position = new Vector3(entprop.Position.X,entprop.Position.Y,entprop.Position.Z),
+                                                    Rotation = new Quaternion(entprop.Rotation.X,entprop.Rotation.Y,entprop.Rotation.Z,entprop.Rotation.W),
+                                                    RotationalVelocity = new Vector3(entprop.AngularVelocity.X,entprop.AngularVelocity.Y,entprop.AngularVelocity.Z),
+                                                    Velocity = new Vector3(entprop.Velocity.X,entprop.Velocity.Y,entprop.Velocity.Z)
+                                                };
+                    //m_log.Debug(pobj.Name + ":" + prop.ToString() + "\n");
+                    pobj.UpdateProperties(prop);
+                }
+            }
+        }
+
+        TriggerPostStepEvent(timeStep);
+
+        // The following causes the unmanaged code to output ALL the values found in ALL the objects in the world.
+        // Only enable this in a limited test world with few objects.
+        // BulletSimAPI.DumpAllInfo2(World.ptr);    // DEBUG DEBUG DEBUG
+
+        // The physics engine returns the number of milliseconds it simulated this call.
+        // These are summed and normalized to one second and divided by 1000 to give the reported physics FPS.
+        // Multiply by 55 to give a nominal frame rate of 55.
+        return (float)numSubSteps * m_fixedTimeStep * 1000f * 55f;
+    }
+
+    // Something has collided
+    private void SendCollision(uint localID, uint collidingWith, Vector3 collidePoint, Vector3 collideNormal, float penetration)
+    {
+        if (localID <= TerrainManager.HighestTerrainID)
+        {
+            return;         // don't send collisions to the terrain
+        }
+
+        BSPhysObject collider;
+        if (!PhysObjects.TryGetValue(localID, out collider))
+        {
+            // If the object that is colliding cannot be found, just ignore the collision.
+            DetailLog("{0},BSScene.SendCollision,colliderNotInObjectList,id={1},with={2}", DetailLogZero, localID, collidingWith);
+            return;
+        }
+
+        // The terrain is not in the physical object list so 'collidee' can be null when Collide() is called.
+        BSPhysObject collidee = null;
+        PhysObjects.TryGetValue(collidingWith, out collidee);
+
+        // DetailLog("{0},BSScene.SendCollision,collide,id={1},with={2}", DetailLogZero, localID, collidingWith);
+
+        if (collider.Collide(collidingWith, collidee, collidePoint, collideNormal, penetration))
+        {
+            // If a collision was posted, remember to send it to the simulator
+            ObjectsWithCollisions.Add(collider);
+        }
+
+        return;
+    }
+
+    #endregion // Simulation
+
+    public override void GetResults() { }
+
+    #region Terrain
+
+    public override void SetTerrain(float[] heightMap) {
+        TerrainManager.SetTerrain(heightMap);
+    }
+
+    public override void SetWaterLevel(float baseheight)
+    {
+        SimpleWaterLevel = baseheight;
+    }
+
+    public override void DeleteTerrain()
+    {
+        // m_log.DebugFormat("{0}: DeleteTerrain()", LogHeader);
+    }
+
+    // Although no one seems to check this, I do support combining.
+    public override bool SupportsCombining()
+    {
+        return TerrainManager.SupportsCombining();
+    }
+    // This call says I am a child to region zero in a mega-region. 'pScene' is that
+    //    of region zero, 'offset' is my offset from regions zero's origin, and
+    //    'extents' is the largest XY that is handled in my region.
+    public override void Combine(PhysicsScene pScene, Vector3 offset, Vector3 extents)
+    {
+        TerrainManager.Combine(pScene, offset, extents);
+    }
+
+    // Unhook all the combining that I know about.
+    public override void UnCombine(PhysicsScene pScene)
+    {
+        TerrainManager.UnCombine(pScene);
+    }
+
+    #endregion // Terrain
+
+    public override Dictionary<uint, float> GetTopColliders()
+    {
+        return new Dictionary<uint, float>();
+    }
+
+    public override bool IsThreaded { get { return false;  } }
+
+    #region Taints
+    // The simulation execution order is:
+    // Simulate()
+    //    DoOneTimeTaints
+    //    TriggerPreStepEvent
+    //    DoOneTimeTaints
+    //    Step()
+    //       ProcessAndForwardCollisions
+    //       ProcessAndForwardPropertyUpdates
+    //    TriggerPostStepEvent
+
+    // Calls to the PhysicsActors can't directly call into the physics engine
+    //       because it might be busy. We delay changes to a known time.
+    // We rely on C#'s closure to save and restore the context for the delegate.
+    public void TaintedObject(String ident, TaintCallback callback)
+    {
+        if (!m_initialized) return;
+
+        lock (_taintLock)
+        {
+            _taintOperations.Add(new TaintCallbackEntry(ident, callback));
+        }
+
+        return;
+    }
+
+    // Sometimes a potentially tainted operation can be used in and out of taint time.
+    // This routine executes the command immediately if in taint-time otherwise it is queued.
+    public void TaintedObject(bool inTaintTime, string ident, TaintCallback callback)
+    {
+        if (inTaintTime)
+            callback();
+        else
+            TaintedObject(ident, callback);
+    }
+
+    private void TriggerPreStepEvent(float timeStep)
+    {
+        PreStepAction actions = BeforeStep;
+        if (actions != null)
+            actions(timeStep);
+
+    }
+
+    private void TriggerPostStepEvent(float timeStep)
+    {
+        PreStepAction actions = AfterStep;
+        if (actions != null)
+            actions(timeStep);
+
+    }
+
+    // When someone tries to change a property on a BSPrim or BSCharacter, the object queues
+    // a callback into itself to do the actual property change. That callback is called
+    // here just before the physics engine is called to step the simulation.
+    public void ProcessTaints()
+    {
+        ProcessRegularTaints();
+        ProcessPostTaintTaints();
+    }
+
+    private void ProcessRegularTaints()
+    {
+        if (_taintOperations.Count > 0)  // save allocating new list if there is nothing to process
+        {
+            // swizzle a new list into the list location so we can process what's there
+            List<TaintCallbackEntry> oldList;
+            lock (_taintLock)
+            {
+                oldList = _taintOperations;
+                _taintOperations = new List<TaintCallbackEntry>();
+            }
+
+            foreach (TaintCallbackEntry tcbe in oldList)
+            {
+                try
+                {
+                    DetailLog("{0},BSScene.ProcessTaints,doTaint,id={1}", DetailLogZero, tcbe.ident); // DEBUG DEBUG DEBUG
+                    tcbe.callback();
+                }
+                catch (Exception e)
+                {
+                    m_log.ErrorFormat("{0}: ProcessTaints: {1}: Exception: {2}", LogHeader, tcbe.ident, e);
+                }
+            }
+            oldList.Clear();
+        }
+    }
+
+    // Schedule an update to happen after all the regular taints are processed.
+    // Note that new requests for the same operation ("ident") for the same object ("ID")
+    //     will replace any previous operation by the same object.
+    public void PostTaintObject(String ident, uint ID, TaintCallback callback)
+    {
+        string uniqueIdent = ident + "-" + ID.ToString();
+        lock (_taintLock)
+        {
+            _postTaintOperations[uniqueIdent] = new TaintCallbackEntry(uniqueIdent, callback);
+        }
+
+        return;
+    }
+
+    // Taints that happen after the normal taint processing but before the simulation step.
+    private void ProcessPostTaintTaints()
+    {
+        if (_postTaintOperations.Count > 0)
+        {
+            Dictionary<string, TaintCallbackEntry> oldList;
+            lock (_taintLock)
+            {
+                oldList = _postTaintOperations;
+                _postTaintOperations = new Dictionary<string, TaintCallbackEntry>();
+            }
+
+            foreach (KeyValuePair<string,TaintCallbackEntry> kvp in oldList)
+            {
+                try
+                {
+                    DetailLog("{0},BSScene.ProcessPostTaintTaints,doTaint,id={1}", DetailLogZero, kvp.Key); // DEBUG DEBUG DEBUG
+                    kvp.Value.callback();
+                }
+                catch (Exception e)
+                {
+                    m_log.ErrorFormat("{0}: ProcessPostTaintTaints: {1}: Exception: {2}", LogHeader, kvp.Key, e);
+                }
+            }
+            oldList.Clear();
+        }
+    }
+
+    // Only used for debugging. Does not change state of anything so locking is not necessary.
+    public bool AssertInTaintTime(string whereFrom)
+    {
+        if (!InTaintTime)
+        {
+            DetailLog("{0},BSScene.AssertInTaintTime,NOT IN TAINT TIME,Region={1},Where={2}", DetailLogZero, RegionName, whereFrom);
+            m_log.ErrorFormat("{0} NOT IN TAINT TIME!! Region={1}, Where={2}", LogHeader, RegionName, whereFrom);
+            Util.PrintCallStack();  // Prints the stack into the DEBUG log file.
+        }
+        return InTaintTime;
+    }
+
+    #endregion // Taints
+
+    #region INI and command line parameter processing
+
+    #region IPhysicsParameters
+    // Get the list of parameters this physics engine supports
+    public PhysParameterEntry[] GetParameterList()
+    {
+        BSParam.BuildParameterTable();
+        return BSParam.SettableParameters;
+    }
+
+    // Set parameter on a specific or all instances.
+    // Return 'false' if not able to set the parameter.
+    // Setting the value in the m_params block will change the value the physics engine
+    //   will use the next time since it's pinned and shared memory.
+    // Some of the values require calling into the physics engine to get the new
+    //   value activated ('terrainFriction' for instance).
+    public bool SetPhysicsParameter(string parm, float val, uint localID)
+    {
+        bool ret = false;
+        BSParam.ParameterDefn theParam;
+        if (BSParam.TryGetParameter(parm, out theParam))
+        {
+            theParam.setter(this, parm, localID, val);
+            ret = true;
+        }
+        return ret;
+    }
+
+    // update all the localIDs specified
+    // If the local ID is APPLY_TO_NONE, just change the default value
+    // If the localID is APPLY_TO_ALL change the default value and apply the new value to all the lIDs
+    // If the localID is a specific object, apply the parameter change to only that object
+    internal delegate void AssignVal(float x);
+    internal void UpdateParameterObject(AssignVal setDefault, string parm, uint localID, float val)
+    {
+        List<uint> objectIDs = new List<uint>();
+        switch (localID)
+        {
+            case PhysParameterEntry.APPLY_TO_NONE:
+                setDefault(val);            // setting only the default value
+                // This will cause a call into the physical world if some operation is specified (SetOnObject).
+                objectIDs.Add(TERRAIN_ID);
+                TaintedUpdateParameter(parm, objectIDs, val);
+                break;
+            case PhysParameterEntry.APPLY_TO_ALL:
+                setDefault(val);  // setting ALL also sets the default value
+                lock (PhysObjects) objectIDs = new List<uint>(PhysObjects.Keys);
+                TaintedUpdateParameter(parm, objectIDs, val);
+                break;
+            default:
+                // setting only one localID
+                objectIDs.Add(localID);
+                TaintedUpdateParameter(parm, objectIDs, val);
+                break;
+        }
+    }
+
+    // schedule the actual updating of the paramter to when the phys engine is not busy
+    private void TaintedUpdateParameter(string parm, List<uint> lIDs, float val)
+    {
+        float xval = val;
+        List<uint> xlIDs = lIDs;
+        string xparm = parm;
+        TaintedObject("BSScene.UpdateParameterSet", delegate() {
+            BSParam.ParameterDefn thisParam;
+            if (BSParam.TryGetParameter(xparm, out thisParam))
+            {
+                if (thisParam.onObject != null)
+                {
+                    foreach (uint lID in xlIDs)
+                    {
+                        BSPhysObject theObject = null;
+                        PhysObjects.TryGetValue(lID, out theObject);
+                        thisParam.onObject(this, theObject, xval);
+                    }
+                }
+            }
+        });
+    }
+
+    // Get parameter.
+    // Return 'false' if not able to get the parameter.
+    public bool GetPhysicsParameter(string parm, out float value)
+    {
+        float val = 0f;
+        bool ret = false;
+        BSParam.ParameterDefn theParam;
+        if (BSParam.TryGetParameter(parm, out theParam))
+        {
+            val = theParam.getter(this);
+            ret = true;
+        }
+        value = val;
+        return ret;
+    }
+
+    #endregion IPhysicsParameters
+
+    #endregion Runtime settable parameters
+
+    // Invoke the detailed logger and output something if it's enabled.
+    public void DetailLog(string msg, params Object[] args)
+    {
+        PhysicsLogging.Write(msg, args);
+        // Add the Flush() if debugging crashes. Gets all the messages written out.
+        if (m_physicsLoggingDoFlush) PhysicsLogging.Flush();
+    }
+    // Used to fill in the LocalID when there isn't one. It's the correct number of characters.
+    public const string DetailLogZero = "0000000000";
+
+}
+}