* 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, 814 insertions, 0 deletions

diff --git a/OpenSim/Region/Physics/BulletSNPlugin/BSCharacter.cs b/OpenSim/Region/Physics/BulletSNPlugin/BSCharacter.cs
new file mode 100644
index 0000000..4c4e950
--- /dev/null
+++ b/OpenSim/Region/Physics/BulletSNPlugin/BSCharacter.cs
@@ -0,0 +1,814 @@
+/*
+ * 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.Reflection;
+using log4net;
+using OMV = OpenMetaverse;
+using OpenSim.Framework;
+using OpenSim.Region.Physics.Manager;
+
+namespace OpenSim.Region.Physics.BulletSNPlugin
+{
+public sealed class BSCharacter : BSPhysObject
+{
+    private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+    private static readonly string LogHeader = "[BULLETS CHAR]";
+
+    // private bool _stopped;
+    private OMV.Vector3 _size;
+    private bool _grabbed;
+    private bool _selected;
+    private OMV.Vector3 _position;
+    private float _mass;
+    private float _avatarDensity;
+    private float _avatarVolume;
+    private OMV.Vector3 _force;
+    private OMV.Vector3 _velocity;
+    private OMV.Vector3 _torque;
+    private float _collisionScore;
+    private OMV.Vector3 _acceleration;
+    private OMV.Quaternion _orientation;
+    private int _physicsActorType;
+    private bool _isPhysical;
+    private bool _flying;
+    private bool _setAlwaysRun;
+    private bool _throttleUpdates;
+    private bool _isColliding;
+    private bool _collidingObj;
+    private bool _floatOnWater;
+    private OMV.Vector3 _rotationalVelocity;
+    private bool _kinematic;
+    private float _buoyancy;
+
+    // The friction and velocity of the avatar is modified depending on whether walking or not.
+    private OMV.Vector3 _appliedVelocity;   // the last velocity applied to the avatar
+    private float _currentFriction;         // the friction currently being used (changed by setVelocity).
+
+    private BSVMotor _velocityMotor;
+
+    private OMV.Vector3 _PIDTarget;
+    private bool _usePID;
+    private float _PIDTau;
+    private bool _useHoverPID;
+    private float _PIDHoverHeight;
+    private PIDHoverType _PIDHoverType;
+    private float _PIDHoverTao;
+
+    public BSCharacter(uint localID, String avName, BSScene parent_scene, OMV.Vector3 pos, OMV.Vector3 size, bool isFlying)
+            : base(parent_scene, localID, avName, "BSCharacter")
+    {
+        _physicsActorType = (int)ActorTypes.Agent;
+        _position = pos;
+
+        // Old versions of ScenePresence passed only the height. If width and/or depth are zero,
+        //     replace with the default values.
+        _size = size;
+        if (_size.X == 0f) _size.X = BSParam.AvatarCapsuleDepth;
+        if (_size.Y == 0f) _size.Y = BSParam.AvatarCapsuleWidth;
+
+        // A motor to control the acceleration and deceleration of the avatar movement.
+        // _velocityMotor = new BSVMotor("BSCharacter.Velocity", 3f, 5f, BSMotor.InfiniteVector, 1f);
+        // _velocityMotor = new BSPIDVMotor("BSCharacter.Velocity", 3f, 5f, BSMotor.InfiniteVector, 1f);
+        // Infinite decay and timescale values so motor only changes current to target values.
+        _velocityMotor = new BSVMotor("BSCharacter.Velocity", 
+                                            0.2f,                       // time scale
+                                            BSMotor.Infinite,           // decay time scale
+                                            BSMotor.InfiniteVector,     // friction timescale
+                                            1f                          // efficiency
+        );
+        _velocityMotor.PhysicsScene = PhysicsScene; // DEBUG DEBUG so motor will output detail log messages.
+
+        _flying = isFlying;
+        _orientation = OMV.Quaternion.Identity;
+        _velocity = OMV.Vector3.Zero;
+        _appliedVelocity = OMV.Vector3.Zero;
+        _buoyancy = ComputeBuoyancyFromFlying(isFlying);
+        _currentFriction = BSParam.AvatarStandingFriction;
+        _avatarDensity = BSParam.AvatarDensity;
+
+        // The dimensions of the avatar capsule are kept in the scale.
+        // Physics creates a unit capsule which is scaled by the physics engine.
+        ComputeAvatarScale(_size);
+        // set _avatarVolume and _mass based on capsule size, _density and Scale
+        ComputeAvatarVolumeAndMass();
+        DetailLog("{0},BSCharacter.create,call,size={1},scale={2},density={3},volume={4},mass={5}",
+                            LocalID, _size, Scale, _avatarDensity, _avatarVolume, RawMass);
+
+        // do actual creation in taint time
+        PhysicsScene.TaintedObject("BSCharacter.create", delegate()
+        {
+            DetailLog("{0},BSCharacter.create,taint", LocalID);
+            // New body and shape into PhysBody and PhysShape
+            PhysicsScene.Shapes.GetBodyAndShape(true, PhysicsScene.World, this);
+
+            SetPhysicalProperties();
+        });
+        return;
+    }
+
+    // called when this character is being destroyed and the resources should be released
+    public override void Destroy()
+    {
+        base.Destroy();
+
+        DetailLog("{0},BSCharacter.Destroy", LocalID);
+        PhysicsScene.TaintedObject("BSCharacter.destroy", delegate()
+        {
+            PhysicsScene.Shapes.DereferenceBody(PhysBody, true, null);
+            PhysBody.Clear();
+            PhysicsScene.Shapes.DereferenceShape(PhysShape, true, null);
+            PhysShape.Clear();
+        });
+    }
+
+    private void SetPhysicalProperties()
+    {
+        BulletSimAPI.RemoveObjectFromWorld2(PhysicsScene.World.ptr, PhysBody.ptr);
+
+        ZeroMotion(true);
+        ForcePosition = _position;
+        // Set the velocity and compute the proper friction
+        ForceVelocity = _velocity;
+        // Setting the current and target in the motor will cause it to start computing any deceleration.
+        _velocityMotor.Reset();
+        _velocityMotor.SetCurrent(_velocity);
+        _velocityMotor.SetTarget(_velocity);
+        _velocityMotor.Enabled = false;
+
+        // This will enable or disable the flying buoyancy of the avatar.
+        // Needs to be reset especially when an avatar is recreated after crossing a region boundry.
+        Flying = _flying;
+
+        BulletSimAPI.SetRestitution2(PhysBody.ptr, BSParam.AvatarRestitution);
+        BulletSimAPI.SetMargin2(PhysShape.ptr, PhysicsScene.Params.collisionMargin);
+        BulletSimAPI.SetLocalScaling2(PhysShape.ptr, Scale);
+        BulletSimAPI.SetContactProcessingThreshold2(PhysBody.ptr, BSParam.ContactProcessingThreshold);
+        if (BSParam.CcdMotionThreshold > 0f)
+        {
+            BulletSimAPI.SetCcdMotionThreshold2(PhysBody.ptr, BSParam.CcdMotionThreshold);
+            BulletSimAPI.SetCcdSweptSphereRadius2(PhysBody.ptr, BSParam.CcdSweptSphereRadius);
+        }
+
+        UpdatePhysicalMassProperties(RawMass);
+
+        // Make so capsule does not fall over
+        BulletSimAPI.SetAngularFactorV2(PhysBody.ptr, OMV.Vector3.Zero);
+
+        BulletSimAPI.AddToCollisionFlags2(PhysBody.ptr, CollisionFlags.CF_CHARACTER_OBJECT);
+
+        BulletSimAPI.AddObjectToWorld2(PhysicsScene.World.ptr, PhysBody.ptr, _position, _orientation);
+
+        // BulletSimAPI.ForceActivationState2(BSBody.ptr, ActivationState.ACTIVE_TAG);
+        BulletSimAPI.ForceActivationState2(PhysBody.ptr, ActivationState.DISABLE_DEACTIVATION);
+        BulletSimAPI.UpdateSingleAabb2(PhysicsScene.World.ptr, PhysBody.ptr);
+
+        // Do this after the object has been added to the world
+        PhysBody.collisionType = CollisionType.Avatar;
+        PhysBody.ApplyCollisionMask();
+    }
+
+    public override void RequestPhysicsterseUpdate()
+    {
+        base.RequestPhysicsterseUpdate();
+    }
+    // No one calls this method so I don't know what it could possibly mean
+    public override bool Stopped { get { return false; } }
+
+    public override OMV.Vector3 Size {
+        get
+        {
+            // Avatar capsule size is kept in the scale parameter.
+            return _size;
+        }
+
+        set {
+            // When an avatar's size is set, only the height is changed.
+            _size = value;
+            // Old versions of ScenePresence passed only the height. If width and/or depth are zero,
+            //     replace with the default values.
+            if (_size.X == 0f) _size.X = BSParam.AvatarCapsuleDepth;
+            if (_size.Y == 0f) _size.Y = BSParam.AvatarCapsuleWidth;
+
+            ComputeAvatarScale(_size);
+            ComputeAvatarVolumeAndMass();
+            DetailLog("{0},BSCharacter.setSize,call,size={1},scale={2},density={3},volume={4},mass={5}",
+                            LocalID, _size, Scale, _avatarDensity, _avatarVolume, RawMass);
+
+            PhysicsScene.TaintedObject("BSCharacter.setSize", delegate()
+            {
+                if (PhysBody.HasPhysicalBody && PhysShape.HasPhysicalShape)
+                {
+                    BulletSimAPI.SetLocalScaling2(PhysShape.ptr, Scale);
+                    UpdatePhysicalMassProperties(RawMass);
+                    // Make sure this change appears as a property update event
+                    BulletSimAPI.PushUpdate2(PhysBody.ptr);
+                }
+            });
+
+        }
+    }
+
+    public override PrimitiveBaseShape Shape
+    {
+        set { BaseShape = value; }
+    }
+    // I want the physics engine to make an avatar capsule
+    public override BSPhysicsShapeType PreferredPhysicalShape
+    {
+        get {return BSPhysicsShapeType.SHAPE_CAPSULE; }
+    }
+
+    public override bool Grabbed {
+        set { _grabbed = value; }
+    }
+    public override bool Selected {
+        set { _selected = value; }
+    }
+    public override void CrossingFailure() { return; }
+    public override void link(PhysicsActor obj) { return; }
+    public override void delink() { return; }
+
+    // Set motion values to zero.
+    // Do it to the properties so the values get set in the physics engine.
+    // Push the setting of the values to the viewer.
+    // Called at taint time!
+    public override void ZeroMotion(bool inTaintTime)
+    {
+        _velocity = OMV.Vector3.Zero;
+        _velocityMotor.Zero();
+        _acceleration = OMV.Vector3.Zero;
+        _rotationalVelocity = OMV.Vector3.Zero;
+
+        // Zero some other properties directly into the physics engine
+        PhysicsScene.TaintedObject(inTaintTime, "BSCharacter.ZeroMotion", delegate()
+        {
+            if (PhysBody.HasPhysicalBody)
+                BulletSimAPI.ClearAllForces2(PhysBody.ptr);
+        });
+    }
+    public override void ZeroAngularMotion(bool inTaintTime)
+    {
+        _rotationalVelocity = OMV.Vector3.Zero;
+
+        PhysicsScene.TaintedObject(inTaintTime, "BSCharacter.ZeroMotion", delegate()
+        {
+            if (PhysBody.HasPhysicalBody)
+            {
+                BulletSimAPI.SetInterpolationAngularVelocity2(PhysBody.ptr, OMV.Vector3.Zero);
+                BulletSimAPI.SetAngularVelocity2(PhysBody.ptr, OMV.Vector3.Zero);
+                // The next also get rid of applied linear force but the linear velocity is untouched.
+                BulletSimAPI.ClearForces2(PhysBody.ptr);
+            }
+        });
+    }
+
+
+    public override void LockAngularMotion(OMV.Vector3 axis) { return; }
+
+    public override OMV.Vector3 RawPosition
+    {
+        get { return _position; }
+        set { _position = value; }
+    }
+    public override OMV.Vector3 Position {
+        get {
+            // Don't refetch the position because this function is called a zillion times
+            // _position = BulletSimAPI.GetObjectPosition2(Scene.World.ptr, LocalID);
+            return _position;
+        }
+        set {
+            _position = value;
+            PositionSanityCheck();
+
+            PhysicsScene.TaintedObject("BSCharacter.setPosition", delegate()
+            {
+                DetailLog("{0},BSCharacter.SetPosition,taint,pos={1},orient={2}", LocalID, _position, _orientation);
+                if (PhysBody.HasPhysicalBody)
+                    BulletSimAPI.SetTranslation2(PhysBody.ptr, _position, _orientation);
+            });
+        }
+    }
+    public override OMV.Vector3 ForcePosition {
+        get {
+            _position = BulletSimAPI.GetPosition2(PhysBody.ptr);
+            return _position;
+        }
+        set {
+            _position = value;
+            PositionSanityCheck();
+            BulletSimAPI.SetTranslation2(PhysBody.ptr, _position, _orientation);
+        }
+    }
+
+
+    // Check that the current position is sane and, if not, modify the position to make it so.
+    // Check for being below terrain or on water.
+    // Returns 'true' of the position was made sane by some action.
+    private bool PositionSanityCheck()
+    {
+        bool ret = false;
+
+        // TODO: check for out of bounds
+        if (!PhysicsScene.TerrainManager.IsWithinKnownTerrain(_position))
+        {
+            // The character is out of the known/simulated area.
+            // Upper levels of code will handle the transition to other areas so, for
+            //     the time, we just ignore the position.
+            return ret;
+        }
+
+        // If below the ground, move the avatar up
+        float terrainHeight = PhysicsScene.TerrainManager.GetTerrainHeightAtXYZ(_position);
+        if (Position.Z < terrainHeight)
+        {
+            DetailLog("{0},BSCharacter.PositionAdjustUnderGround,call,pos={1},terrain={2}", LocalID, _position, terrainHeight);
+            _position.Z = terrainHeight + 2.0f;
+            ret = true;
+        }
+        if ((CurrentCollisionFlags & CollisionFlags.BS_FLOATS_ON_WATER) != 0)
+        {
+            float waterHeight = PhysicsScene.TerrainManager.GetWaterLevelAtXYZ(_position);
+            if (Position.Z < waterHeight)
+            {
+                _position.Z = waterHeight;
+                ret = true;
+            }
+        }
+
+        return ret;
+    }
+
+    // A version of the sanity check that also makes sure a new position value is
+    //    pushed back to the physics engine. This routine would be used by anyone
+    //    who is not already pushing the value.
+    private bool PositionSanityCheck(bool inTaintTime)
+    {
+        bool ret = false;
+        if (PositionSanityCheck())
+        {
+            // The new position value must be pushed into the physics engine but we can't
+            //    just assign to "Position" because of potential call loops.
+            PhysicsScene.TaintedObject(inTaintTime, "BSCharacter.PositionSanityCheck", delegate()
+            {
+                DetailLog("{0},BSCharacter.PositionSanityCheck,taint,pos={1},orient={2}", LocalID, _position, _orientation);
+                if (PhysBody.HasPhysicalBody)
+                    BulletSimAPI.SetTranslation2(PhysBody.ptr, _position, _orientation);
+            });
+            ret = true;
+        }
+        return ret;
+    }
+
+    public override float Mass { get { return _mass; } }
+
+    // used when we only want this prim's mass and not the linkset thing
+    public override float RawMass { 
+        get {return _mass; }
+    }
+    public override void UpdatePhysicalMassProperties(float physMass)
+    {
+        OMV.Vector3 localInertia = BulletSimAPI.CalculateLocalInertia2(PhysShape.ptr, physMass);
+        BulletSimAPI.SetMassProps2(PhysBody.ptr, physMass, localInertia);
+    }
+
+    public override OMV.Vector3 Force {
+        get { return _force; }
+        set {
+            _force = value;
+            // m_log.DebugFormat("{0}: Force = {1}", LogHeader, _force);
+            PhysicsScene.TaintedObject("BSCharacter.SetForce", delegate()
+            {
+                DetailLog("{0},BSCharacter.setForce,taint,force={1}", LocalID, _force);
+                if (PhysBody.HasPhysicalBody)
+                    BulletSimAPI.SetObjectForce2(PhysBody.ptr, _force);
+            });
+        }
+    }
+
+    public bool TouchingGround()
+    {
+        bool ret = BulletSimAPI.RayCastGround(PhysicsScene.World.ptr,_position,_size.Z * 0.55f, PhysBody.ptr);
+        return ret;
+    }
+    // Avatars don't do vehicles
+    public override int VehicleType { get { return (int)Vehicle.TYPE_NONE; } set { return; } }
+    public override void VehicleFloatParam(int param, float value) { }
+    public override void VehicleVectorParam(int param, OMV.Vector3 value) {}
+    public override void VehicleRotationParam(int param, OMV.Quaternion rotation) { }
+    public override void VehicleFlags(int param, bool remove) { }
+
+    // Allows the detection of collisions with inherently non-physical prims. see llVolumeDetect for more
+    public override void SetVolumeDetect(int param) { return; }
+
+    public override OMV.Vector3 GeometricCenter { get { return OMV.Vector3.Zero; } }
+    public override OMV.Vector3 CenterOfMass { get { return OMV.Vector3.Zero; } }
+
+    // Sets the target in the motor. This starts the changing of the avatar's velocity.
+    public override OMV.Vector3 TargetVelocity
+    {
+        get
+        {
+            return _velocityMotor.TargetValue;
+        }
+        set
+        {
+            DetailLog("{0},BSCharacter.setTargetVelocity,call,vel={1}", LocalID, value);
+
+            if (!_flying)
+                if ((value.Z >= 0.0001f) || (value.Z <= -0.0001f) || _velocity.Z < -0.0001f)
+                    if (!TouchingGround())
+                        value.Z = _velocity.Z;
+            if (_setAlwaysRun)
+                value *= 1.3f;
+
+            OMV.Vector3 targetVel = value;
+
+            PhysicsScene.TaintedObject("BSCharacter.setTargetVelocity", delegate()
+            {
+                                                                                
+                _velocityMotor.Reset();
+                _velocityMotor.SetTarget(targetVel);
+                _velocityMotor.SetCurrent(_velocity);
+                _velocityMotor.Enabled = true;
+
+                // Make sure a property update happens next step so the motor gets incorporated.
+                BulletSimAPI.PushUpdate2(PhysBody.ptr);
+            });
+        }
+    }
+    // Directly setting velocity means this is what the user really wants now.
+    public override OMV.Vector3 Velocity {
+        get { return _velocity; }
+        set {
+            _velocity = value;
+            // m_log.DebugFormat("{0}: set velocity = {1}", LogHeader, _velocity);
+            PhysicsScene.TaintedObject("BSCharacter.setVelocity", delegate()
+            {
+                _velocityMotor.Reset();
+                _velocityMotor.SetCurrent(_velocity);
+                _velocityMotor.SetTarget(_velocity);
+                // Even though the motor is initialized, it's not used and the velocity goes straight into the avatar.
+                _velocityMotor.Enabled = false;
+
+                DetailLog("{0},BSCharacter.setVelocity,taint,vel={1}", LocalID, _velocity);
+                ForceVelocity = _velocity;
+            });
+        }
+    }
+    public override OMV.Vector3 ForceVelocity {
+        get { return _velocity; }
+        set {
+            PhysicsScene.AssertInTaintTime("BSCharacter.ForceVelocity");
+
+            _velocity = value;
+            // Depending on whether the avatar is moving or not, change the friction
+            //    to keep the avatar from slipping around
+            if (_velocity.Length() == 0)
+            {
+                if (_currentFriction != BSParam.AvatarStandingFriction)
+                {
+                    _currentFriction = BSParam.AvatarStandingFriction;
+                    if (PhysBody.HasPhysicalBody)
+                        BulletSimAPI.SetFriction2(PhysBody.ptr, _currentFriction);
+                }
+            }
+            else
+            {
+                if (_currentFriction != BSParam.AvatarFriction)
+                {
+                    _currentFriction = BSParam.AvatarFriction;
+                    if (PhysBody.HasPhysicalBody)
+                        BulletSimAPI.SetFriction2(PhysBody.ptr, _currentFriction);
+                }
+            }
+            // Remember the set velocity so we can suppress the reduction by friction, ...
+            _appliedVelocity = value;
+
+            BulletSimAPI.SetLinearVelocity2(PhysBody.ptr, _velocity);
+            BulletSimAPI.Activate2(PhysBody.ptr, true);
+        }
+    }
+    public override OMV.Vector3 Torque {
+        get { return _torque; }
+        set { _torque = value;
+        }
+    }
+    public override float CollisionScore {
+        get { return _collisionScore; }
+        set { _collisionScore = value;
+        }
+    }
+    public override OMV.Vector3 Acceleration {
+        get { return _acceleration; }
+        set { _acceleration = value; }
+    }
+    public override OMV.Quaternion RawOrientation
+    {
+        get { return _orientation; }
+        set { _orientation = value; }
+    }
+    public override OMV.Quaternion Orientation {
+        get { return _orientation; }
+        set {
+            _orientation = value;
+            // m_log.DebugFormat("{0}: set orientation to {1}", LogHeader, _orientation);
+            PhysicsScene.TaintedObject("BSCharacter.setOrientation", delegate()
+            {
+                if (PhysBody.HasPhysicalBody)
+                {
+                    // _position = BulletSimAPI.GetPosition2(BSBody.ptr);
+                    BulletSimAPI.SetTranslation2(PhysBody.ptr, _position, _orientation);
+                }
+            });
+        }
+    }
+    // Go directly to Bullet to get/set the value.
+    public override OMV.Quaternion ForceOrientation
+    {
+        get
+        {
+            _orientation = BulletSimAPI.GetOrientation2(PhysBody.ptr);
+            return _orientation;
+        }
+        set
+        {
+            _orientation = value;
+            BulletSimAPI.SetTranslation2(PhysBody.ptr, _position, _orientation);
+        }
+    }
+    public override int PhysicsActorType {
+        get { return _physicsActorType; }
+        set { _physicsActorType = value;
+        }
+    }
+    public override bool IsPhysical {
+        get { return _isPhysical; }
+        set { _isPhysical = value;
+        }
+    }
+    public override bool IsSolid {
+        get { return true; }
+    }
+    public override bool IsStatic {
+        get { return false; }
+    }
+    public override bool Flying {
+        get { return _flying; }
+        set {
+            _flying = value;
+
+            // simulate flying by changing the effect of gravity
+            Buoyancy = ComputeBuoyancyFromFlying(_flying);
+        }
+    }
+    // Flying is implimented by changing the avatar's buoyancy.
+    // Would this be done better with a vehicle type?
+    private float ComputeBuoyancyFromFlying(bool ifFlying) {
+        return ifFlying ? 1f : 0f;
+    }
+    public override bool
+        SetAlwaysRun {
+        get { return _setAlwaysRun; }
+        set { _setAlwaysRun = value; }
+    }
+    public override bool ThrottleUpdates {
+        get { return _throttleUpdates; }
+        set { _throttleUpdates = value; }
+    }
+    public override bool IsColliding {
+        get { return (CollidingStep == PhysicsScene.SimulationStep); }
+        set { _isColliding = value; }
+    }
+    public override bool CollidingGround {
+        get { return (CollidingGroundStep == PhysicsScene.SimulationStep); }
+        set { CollidingGround = value; }
+    }
+    public override bool CollidingObj {
+        get { return _collidingObj; }
+        set { _collidingObj = value; }
+    }
+    public override bool FloatOnWater {
+        set {
+            _floatOnWater = value;
+            PhysicsScene.TaintedObject("BSCharacter.setFloatOnWater", delegate()
+            {
+                if (PhysBody.HasPhysicalBody)
+                {
+                    if (_floatOnWater)
+                        CurrentCollisionFlags = BulletSimAPI.AddToCollisionFlags2(PhysBody.ptr, CollisionFlags.BS_FLOATS_ON_WATER);
+                    else
+                        CurrentCollisionFlags = BulletSimAPI.RemoveFromCollisionFlags2(PhysBody.ptr, CollisionFlags.BS_FLOATS_ON_WATER);
+                }
+            });
+        }
+    }
+    public override OMV.Vector3 RotationalVelocity {
+        get { return _rotationalVelocity; }
+        set { _rotationalVelocity = value; }
+    }
+    public override OMV.Vector3 ForceRotationalVelocity {
+        get { return _rotationalVelocity; }
+        set { _rotationalVelocity = value; }
+    }
+    public override bool Kinematic {
+        get { return _kinematic; }
+        set { _kinematic = value; }
+    }
+    // neg=fall quickly, 0=1g, 1=0g, pos=float up
+    public override float Buoyancy {
+        get { return _buoyancy; }
+        set { _buoyancy = value;
+            PhysicsScene.TaintedObject("BSCharacter.setBuoyancy", delegate()
+            {
+                DetailLog("{0},BSCharacter.setBuoyancy,taint,buoy={1}", LocalID, _buoyancy);
+                ForceBuoyancy = _buoyancy;
+            });
+        }
+    }
+    public override float ForceBuoyancy {
+        get { return _buoyancy; }
+        set { 
+            PhysicsScene.AssertInTaintTime("BSCharacter.ForceBuoyancy");
+
+            _buoyancy = value;
+            DetailLog("{0},BSCharacter.setForceBuoyancy,taint,buoy={1}", LocalID, _buoyancy);
+            // Buoyancy is faked by changing the gravity applied to the object
+            float grav = PhysicsScene.Params.gravity * (1f - _buoyancy);
+            if (PhysBody.HasPhysicalBody)
+                BulletSimAPI.SetGravity2(PhysBody.ptr, new OMV.Vector3(0f, 0f, grav));
+        }
+    }
+
+    // Used for MoveTo
+    public override OMV.Vector3 PIDTarget {
+        set { _PIDTarget = value; }
+    }
+    public override bool PIDActive {
+        set { _usePID = value; }
+    }
+    public override float PIDTau {
+        set { _PIDTau = value; }
+    }
+
+    // Used for llSetHoverHeight and maybe vehicle height
+    // Hover Height will override MoveTo target's Z
+    public override bool PIDHoverActive {
+        set { _useHoverPID = value; }
+    }
+    public override float PIDHoverHeight {
+        set { _PIDHoverHeight = value; }
+    }
+    public override PIDHoverType PIDHoverType {
+        set { _PIDHoverType = value; }
+    }
+    public override float PIDHoverTau {
+        set { _PIDHoverTao = value; }
+    }
+
+    // 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; } }
+
+    public override void AddForce(OMV.Vector3 force, bool pushforce) {
+        if (force.IsFinite())
+        {
+            _force.X += force.X;
+            _force.Y += force.Y;
+            _force.Z += force.Z;
+            // m_log.DebugFormat("{0}: AddForce. adding={1}, newForce={2}", LogHeader, force, _force);
+            PhysicsScene.TaintedObject("BSCharacter.AddForce", delegate()
+            {
+                DetailLog("{0},BSCharacter.setAddForce,taint,addedForce={1}", LocalID, _force);
+                if (PhysBody.HasPhysicalBody)
+                    BulletSimAPI.SetObjectForce2(PhysBody.ptr, _force);
+            });
+        }
+        else
+        {
+            m_log.ErrorFormat("{0}: Got a NaN force applied to a Character", LogHeader);
+        }
+        //m_lastUpdateSent = false;
+    }
+
+    public override void AddAngularForce(OMV.Vector3 force, bool pushforce) {
+    }
+    public override void SetMomentum(OMV.Vector3 momentum) {
+    }
+
+    private void ComputeAvatarScale(OMV.Vector3 size)
+    {
+        OMV.Vector3 newScale = size;
+        // newScale.X = PhysicsScene.Params.avatarCapsuleWidth;
+        // newScale.Y = PhysicsScene.Params.avatarCapsuleDepth;
+
+        // From the total height, remove the capsule half spheres that are at each end
+        // The 1.15f came from ODE. Not sure what this factors in.
+        // newScale.Z = (size.Z * 1.15f) - (newScale.X + newScale.Y);
+
+        // The total scale height is the central cylindar plus the caps on the two ends.
+        newScale.Z = size.Z + (Math.Min(size.X, size.Y) * 2f);
+
+        // Convert diameters to radii and height to half height -- the way Bullet expects it.
+        Scale = newScale / 2f;
+    }
+
+    // set _avatarVolume and _mass based on capsule size, _density and Scale
+    private void ComputeAvatarVolumeAndMass()
+    {
+        _avatarVolume = (float)(
+                        Math.PI
+                        * Scale.X
+                        * Scale.Y    // the area of capsule cylinder
+                        * Scale.Z    // times height of capsule cylinder
+                      + 1.33333333f
+                        * Math.PI
+                        * Scale.X
+                        * Math.Min(Scale.X, Scale.Y)
+                        * Scale.Y    // plus the volume of the capsule end caps
+                        );
+        _mass = _avatarDensity * _avatarVolume;
+    }
+
+    // The physics engine says that properties have updated. Update same and inform
+    // the world that things have changed.
+    public override void UpdateProperties(EntityProperties entprop)
+    {
+        _position = entprop.Position;
+        _orientation = entprop.Rotation;
+        _velocity = entprop.Velocity;
+        _acceleration = entprop.Acceleration;
+        _rotationalVelocity = entprop.RotationalVelocity;
+
+        // Do some sanity checking for the avatar. Make sure it's above ground and inbounds.
+        PositionSanityCheck(true);
+
+        if (_velocityMotor.Enabled)
+        {
+            // TODO: Decide if the step parameters should be changed depending on the avatar's
+            //     state (flying, colliding, ...).
+
+            OMV.Vector3 stepVelocity = _velocityMotor.Step(PhysicsScene.LastTimeStep);
+
+            // If falling, we keep the world's downward vector no matter what the other axis specify.
+            if (!Flying && !IsColliding)
+            {
+                stepVelocity.Z = entprop.Velocity.Z;
+                DetailLog("{0},BSCharacter.UpdateProperties,taint,overrideStepZWithWorldZ,stepVel={1}", LocalID, stepVelocity);
+            }
+
+            // If the user has said stop and we've stopped applying velocity correction,
+            //     the motor can be turned off. Set the velocity to zero so the zero motion is sent to the viewer.
+            if (_velocityMotor.TargetValue.ApproxEquals(OMV.Vector3.Zero, 0.01f) && _velocityMotor.ErrorIsZero)
+            {
+                stepVelocity = OMV.Vector3.Zero;
+                _velocityMotor.Enabled = false;
+                DetailLog("{0},BSCharacter.UpdateProperties,taint,disableVelocityMotor,m={1}", LocalID, _velocityMotor);
+            }
+
+            _velocity = stepVelocity;
+            entprop.Velocity = _velocity;
+            BulletSimAPI.SetLinearVelocity2(PhysBody.ptr, _velocity);
+        }
+
+        // remember the current and last set values
+        LastEntityProperties = CurrentEntityProperties;
+        CurrentEntityProperties = entprop;
+
+        // Tell the linkset about value changes
+        Linkset.UpdateProperties(this, true);
+
+        // Avatars don't report their changes the usual way. Changes are checked for in the heartbeat loop.
+        // base.RequestPhysicsterseUpdate();
+
+        DetailLog("{0},BSCharacter.UpdateProperties,call,pos={1},orient={2},vel={3},accel={4},rotVel={5}",
+                LocalID, _position, _orientation, _velocity, _acceleration, _rotationalVelocity);
+    }
+}
+}