opensim/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs

/*
 * 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:
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 *       notice, this list of conditions and the following disclaimer.
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 *       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;
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
using System;
using System.Reflection;
using System.Collections.Generic;
using System.Xml;
using log4net;
using OMV = OpenMetaverse;
using OpenSim.Framework;
using OpenSim.Region.Physics.Manager;
using OpenSim.Region.Physics.ConvexDecompositionDotNet;

namespace OpenSim.Region.Physics.BulletSPlugin
{
    [Serializable]
public sealed class BSPrim : PhysicsActor
{
    private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
    private static readonly string LogHeader = "[BULLETS PRIM]";

    private IMesh _mesh;
    private PrimitiveBaseShape _pbs;
    private ShapeData.PhysicsShapeType _shapeType;
    private ulong _meshKey;
    private ulong _hullKey;
    private List<ConvexResult> _hulls;

    private BSScene _scene;
    private String _avName;
    private uint _localID = 0;

    // _size is what the user passed. _scale is what we pass to the physics engine with the mesh.
    // Often _scale is unity because the meshmerizer will apply _size when creating the mesh.
    private OMV.Vector3 _size;  // the multiplier for each mesh dimension as passed by the user
    private OMV.Vector3 _scale; // the multiplier for each mesh dimension for the mesh as created by the meshmerizer

    private bool _stopped;
    private bool _grabbed;
    private bool _isSelected;
    private bool _isVolumeDetect;
    private OMV.Vector3 _position;
    private float _mass;
    private float _density;
    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 float _friction;
    private float _restitution;
    private bool _setAlwaysRun;
    private bool _throttleUpdates;
    private bool _isColliding;
    private bool _collidingGround;
    private bool _collidingObj;
    private bool _floatOnWater;
    private OMV.Vector3 _rotationalVelocity;
    private bool _kinematic;
    private float _buoyancy;
    private OMV.Vector3 _angularVelocity;

    private List<BSPrim> _childrenPrims;
    private BSPrim _parentPrim;

    private int _subscribedEventsMs = 0;
    private int _lastCollisionTime = 0;
    long _collidingStep;
    long _collidingGroundStep;

    private BSDynamics _vehicle;

    private OMV.Vector3 _PIDTarget;
    private bool _usePID;
    private float _PIDTau;
    private bool _useHoverPID;
    private float _PIDHoverHeight;
    private PIDHoverType _PIDHoverType;
    private float _PIDHoverTao;

    public BSPrim(uint localID, String primName, BSScene parent_scene, OMV.Vector3 pos, OMV.Vector3 size,
                       OMV.Quaternion rotation, PrimitiveBaseShape pbs, bool pisPhysical)
    {
        // m_log.DebugFormat("{0}: BSPrim creation of {1}, id={2}", LogHeader, primName, localID);
        _localID = localID;
        _avName = primName;
        _scene = parent_scene;
        _position = pos;
        _size = size;
        _scale = new OMV.Vector3(1f, 1f, 1f);   // the scale will be set by CreateGeom depending on object type
        _orientation = rotation;
        _buoyancy = 1f;
        _velocity = OMV.Vector3.Zero;
        _rotationalVelocity = OMV.Vector3.Zero;
        _angularVelocity = OMV.Vector3.Zero;
        _hullKey = 0;
        _meshKey = 0;
        _pbs = pbs;
        _isPhysical = pisPhysical;
        _isVolumeDetect = false;
        _subscribedEventsMs = 0;
        _friction = _scene.Params.defaultFriction; // TODO: compute based on object material
        _density = _scene.Params.defaultDensity; // TODO: compute based on object material
        _restitution = _scene.Params.defaultRestitution;
        _parentPrim = null;     // not a child or a parent
        _vehicle = new BSDynamics(this);    // add vehicleness
        _childrenPrims = new List<BSPrim>();
        if (_isPhysical)
            _mass = CalculateMass();
        else
            _mass = 0f;
        // do the actual object creation at taint time
        _scene.TaintedObject(delegate()
        {
            RecreateGeomAndObject();
        });
    }

    // called when this prim is being destroyed and we should free all the resources
    public void Destroy()
    {
        // m_log.DebugFormat("{0}: Destroy", LogHeader);
        // Undo any vehicle properties
        _vehicle.ProcessTypeChange(Vehicle.TYPE_NONE);
        _scene.RemoveVehiclePrim(this);     // just to make sure
        _scene.TaintedObject(delegate()
        {
            // everything in the C# world will get garbage collected. Tell the C++ world to free stuff.
            BulletSimAPI.DestroyObject(_scene.WorldID, _localID);
        });
    }
    
    public override bool Stopped { 
        get { return _stopped; } 
    }
    public override OMV.Vector3 Size { 
        get { return _size; } 
        set {
            _size = value;
            _scene.TaintedObject(delegate()
            {
                if (_isPhysical) _mass = CalculateMass();   // changing size changes the mass
                BulletSimAPI.SetObjectScaleMass(_scene.WorldID, _localID, _scale, _mass, _isPhysical);
                RecreateGeomAndObject();
            });
        } 
    }
    public override PrimitiveBaseShape Shape { 
        set {
            _pbs = value;
            _scene.TaintedObject(delegate()
            {
                if (_isPhysical) _mass = CalculateMass();   // changing the shape changes the mass
                RecreateGeomAndObject();
            });
        } 
    }
    public override uint LocalID { 
        set { _localID = value; }
        get { return _localID; }
    }
    public override bool Grabbed { 
        set { _grabbed = value; 
        } 
    }
    public override bool Selected { 
        set {
            _isSelected = value;
            _scene.TaintedObject(delegate()
            {
                SetObjectDynamic();
            });
        } 
    }
    public override void CrossingFailure() { return; }

    // link me to the specified parent
    public override void link(PhysicsActor obj) {
        BSPrim parent = (BSPrim)obj;
        // m_log.DebugFormat("{0}: link {1}/{2} to {3}", LogHeader, _avName, _localID, obj.LocalID);
        // TODO: decide if this parent checking needs to happen at taint time
        if (_parentPrim == null)
        {
            if (parent != null)
            {
                // I don't have a parent so I am joining a linkset
                parent.AddChildToLinkset(this);
            }
        }
        else
        {
            // I already have a parent, is parenting changing?
            if (parent != _parentPrim)
            {
                if (parent == null)
                {
                    // we are being removed from a linkset
                    _parentPrim.RemoveChildFromLinkset(this);
                }
                else
                {
                    // asking to reparent a prim should not happen
                    m_log.ErrorFormat("{0}: Reparenting a prim. ", LogHeader);
                }
            }
        }
        return; 
    }

    // delink me from my linkset
    public override void delink() {
        // TODO: decide if this parent checking needs to happen at taint time
        // Race condition here: if link() and delink() in same simulation tick, the delink will not happen
        // m_log.DebugFormat("{0}: delink {1}/{2}", LogHeader, _avName, _localID);
        if (_parentPrim != null)
        {
            _parentPrim.RemoveChildFromLinkset(this);
        }
        return; 
    }

    // I am the root of a linkset and a new child is being added
    public void AddChildToLinkset(BSPrim pchild)
    {
        BSPrim child = pchild;
        _scene.TaintedObject(delegate()
        {
            if (!_childrenPrims.Contains(child))
            {
                _childrenPrims.Add(child);
                child.ParentPrim = this;    // the child has gained a parent
                RecreateGeomAndObject();    // rebuild my shape with the new child added
            }
        });
        return;
    }

    // I am the root of a linkset and one of my children is being removed.
    // Safe to call even if the child is not really in my linkset.
    public void RemoveChildFromLinkset(BSPrim pchild)
    {
        BSPrim child = pchild;
        _scene.TaintedObject(delegate()
        {
            if (_childrenPrims.Contains(child))
            {
                BulletSimAPI.RemoveConstraint(_scene.WorldID, child.LocalID, this.LocalID);
                _childrenPrims.Remove(child);
                child.ParentPrim = null;    // the child has lost its parent
                RecreateGeomAndObject();    // rebuild my shape with the child removed
            }
            else
            {
                m_log.ErrorFormat("{0}: Asked to remove child from linkset that was not in linkset");
            }
        });
        return;
    }

    public BSPrim ParentPrim
    {
        set { _parentPrim = value; }
    }

    // return true if we are the root of a linkset (there are children to manage)
    public bool IsRootOfLinkset
    {
        get { return (_parentPrim == null && _childrenPrims.Count != 0); }
    }

    // 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.
    private void ZeroMotion()
    {
        Velocity = OMV.Vector3.Zero;
        _acceleration = OMV.Vector3.Zero;
        RotationalVelocity = OMV.Vector3.Zero;
        base.RequestPhysicsterseUpdate();
    }

    public override void LockAngularMotion(OMV.Vector3 axis) { return; }

    public override OMV.Vector3 Position { 
        get { 
            // don't do the following GetObjectPosition because this function is called a zillion times
            // _position = BulletSimAPI.GetObjectPosition(_scene.WorldID, _localID);
            return _position; 
        } 
        set {
            _position = value;
            _scene.TaintedObject(delegate()
            {
                BulletSimAPI.SetObjectTranslation(_scene.WorldID, _localID, _position, _orientation);
                // m_log.DebugFormat("{0}: setPosition: id={1}, position={2}", LogHeader, _localID, _position);
            });
        } 
    }
    public override float Mass { 
        get { return _mass; } 
    }
    public override OMV.Vector3 Force { 
        get { return _force; } 
        set {
            _force = value;
            _scene.TaintedObject(delegate()
            {
                BulletSimAPI.SetObjectForce(_scene.WorldID, _localID, _force);
            });
        } 
    }

    public override int VehicleType { 
        get {
            return (int)_vehicle.Type;   // if we are a vehicle, return that type
        } 
        set {
            Vehicle type = (Vehicle)value;
            _vehicle.ProcessTypeChange(type);
            _scene.TaintedObject(delegate()
            {
                if (type == Vehicle.TYPE_NONE)
                {
                    _scene.RemoveVehiclePrim(this);
                }
                else
                {
                    // make it so the scene will call us each tick to do vehicle things
                    _scene.AddVehiclePrim(this);
                }
                return;
            });
        } 
    }
    public override void VehicleFloatParam(int param, float value) 
    {
        _vehicle.ProcessFloatVehicleParam((Vehicle)param, value);
    }
    public override void VehicleVectorParam(int param, OMV.Vector3 value) 
    {
        _vehicle.ProcessVectorVehicleParam((Vehicle)param, value);
    }
    public override void VehicleRotationParam(int param, OMV.Quaternion rotation) 
    {
        _vehicle.ProcessRotationVehicleParam((Vehicle)param, rotation);
    }
    public override void VehicleFlags(int param, bool remove) 
    {
        _vehicle.ProcessVehicleFlags(param, remove);
    }
    // Called each simulation step to advance vehicle characteristics
    public void StepVehicle(float timeStep)
    {
        _vehicle.Step(timeStep, _scene);
    }

    // Allows the detection of collisions with inherently non-physical prims. see llVolumeDetect for more
    public override void SetVolumeDetect(int param) {
        bool newValue = (param != 0);
        if (_isVolumeDetect != newValue)
        {
            _isVolumeDetect = newValue;
            _scene.TaintedObject(delegate()
            {
                SetObjectDynamic();
            });
        }
        return; 
    }

    public override OMV.Vector3 GeometricCenter { get { return OMV.Vector3.Zero; } }
    public override OMV.Vector3 CenterOfMass { get { return OMV.Vector3.Zero; } }
    public override OMV.Vector3 Velocity { 
        get { return _velocity; } 
        set { _velocity = value; 
            _scene.TaintedObject(delegate()
            {
                BulletSimAPI.SetObjectVelocity(_scene.WorldID, LocalID, _velocity);
            });
        } 
    }
    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 Orientation { 
        get { return _orientation; } 
        set {
            _orientation = value;
            // m_log.DebugFormat("{0}: set orientation: id={1}, ori={2}", LogHeader, LocalID, _orientation);
            _scene.TaintedObject(delegate()
            {
                // _position = BulletSimAPI.GetObjectPosition(_scene.WorldID, _localID);
                BulletSimAPI.SetObjectTranslation(_scene.WorldID, _localID, _position, _orientation);
            });
        } 
    }
    public override int PhysicsActorType { 
        get { return _physicsActorType; } 
        set { _physicsActorType = value; 
        } 
    }
    public override bool IsPhysical { 
        get { return _isPhysical; } 
        set {
            _isPhysical = value;
            _scene.TaintedObject(delegate()
            {
                SetObjectDynamic();
            });
        } 
    }

    // An object is static (does not move) if selected or not physical
    private bool IsStatic
    {
        get { return _isSelected || !IsPhysical; }
    }

    // An object is solid if it's not phantom and if it's not doing VolumeDetect
    private bool IsSolid
    {
        get { return !IsPhantom && !_isVolumeDetect; }
    }

    // make gravity work if the object is physical and not selected
    // no locking here because only called when it is safe
    private void SetObjectDynamic()
    {
        // m_log.DebugFormat("{0}: ID={1}, SetObjectDynamic: IsStatic={2}, IsSolid={3}", LogHeader, _localID, IsStatic, IsSolid);
        // non-physical things work best with a mass of zero
        if (IsStatic)
        {
            _mass = 0f;
        }
        else
        {
            _mass = CalculateMass();
            // If it's dynamic, make sure the hull has been created for it
            // This shouldn't do much work if the object had previously been built
            RecreateGeomAndObject();

        }
        BulletSimAPI.SetObjectProperties(_scene.WorldID, LocalID, IsStatic, IsSolid, SubscribedEvents(), _mass);
    }

    // prims don't fly
    public override bool Flying { 
        get { return _flying; } 
        set { _flying = value; } 
    }
    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 == _scene.SimulationStep); } 
        set { _isColliding = value; } 
    }
    public override bool CollidingGround {
        get { return (_collidingGroundStep == _scene.SimulationStep); } 
        set { _collidingGround = value; } 
    }
    public override bool CollidingObj { 
        get { return _collidingObj; } 
        set { _collidingObj = value; } 
    }
    public bool IsPhantom {
        get {
            // SceneObjectPart removes phantom objects from the physics scene
            // so, although we could implement touching and such, we never
            // are invoked as a phantom object
            return false;
        }
    }
    public override bool FloatOnWater { 
        set { _floatOnWater = value; } 
    }
    public override OMV.Vector3 RotationalVelocity { 
        get { return _rotationalVelocity; } 
        set { _rotationalVelocity = value; 
            // m_log.DebugFormat("{0}: RotationalVelocity={1}", LogHeader, _rotationalVelocity);
            _scene.TaintedObject(delegate()
            {
                BulletSimAPI.SetObjectAngularVelocity(_scene.WorldID, LocalID, _rotationalVelocity);
            });
        } 
    }
    public OMV.Vector3 AngularVelocity { 
        get { return _angularVelocity; } 
        set { _angularVelocity = value; } 
    }
    public override bool Kinematic { 
        get { return _kinematic; } 
        set { _kinematic = value; 
            // m_log.DebugFormat("{0}: Kinematic={1}", LogHeader, _kinematic);
        } 
    }
    public override float Buoyancy { 
        get { return _buoyancy; } 
        set { _buoyancy = value;
        _scene.TaintedObject(delegate()
        {
            BulletSimAPI.SetObjectBuoyancy(_scene.WorldID, _localID, _buoyancy);
        });
        } 
    }

    // 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;
        }
        else
        {
            m_log.WarnFormat("{0}: Got a NaN force applied to a Character", LogHeader);
        }
        _scene.TaintedObject(delegate()
        {
            BulletSimAPI.SetObjectForce(_scene.WorldID, _localID, _force);
        });
    }

    public override void AddAngularForce(OMV.Vector3 force, bool pushforce) { 
        // m_log.DebugFormat("{0}: AddAngularForce. f={1}, push={2}", LogHeader, force, pushforce);
    }
    public override void SetMomentum(OMV.Vector3 momentum) { 
    }
    public override void SubscribeEvents(int ms) { 
        _subscribedEventsMs = ms;
        _lastCollisionTime = Util.EnvironmentTickCount() - _subscribedEventsMs; // make first collision happen
    }
    public override void UnSubscribeEvents() { 
        _subscribedEventsMs = 0;
    }
    public override bool SubscribedEvents() { 
        return (_subscribedEventsMs > 0);
    }

    #region Mass Calculation

    private float CalculateMass()
    {
        float volume = _size.X * _size.Y * _size.Z; // default
        float tmp;

        float returnMass = 0;
        float hollowAmount = (float)_pbs.ProfileHollow * 2.0e-5f;
        float hollowVolume = hollowAmount * hollowAmount; 
        
        switch (_pbs.ProfileShape)
        {
            case ProfileShape.Square:
                // default box

                if (_pbs.PathCurve == (byte)Extrusion.Straight)
                    {
                    if (hollowAmount > 0.0)
                        {
                        switch (_pbs.HollowShape)
                            {
                            case HollowShape.Square:
                            case HollowShape.Same:
                                break;

                            case HollowShape.Circle:

                                hollowVolume *= 0.78539816339f;
                                break;

                            case HollowShape.Triangle:

                                hollowVolume *= (0.5f * .5f);
                                break;

                            default:
                                hollowVolume = 0;
                                break;
                            }
                        volume *= (1.0f - hollowVolume);
                        }
                    }

                else if (_pbs.PathCurve == (byte)Extrusion.Curve1)
                    {
                    //a tube 

                    volume *= 0.78539816339e-2f * (float)(200 - _pbs.PathScaleX);
                    tmp= 1.0f -2.0e-2f * (float)(200 - _pbs.PathScaleY);
                    volume -= volume*tmp*tmp;
                    
                    if (hollowAmount > 0.0)
                        {
                        hollowVolume *= hollowAmount;
                        
                        switch (_pbs.HollowShape)
                            {
                            case HollowShape.Square:
                            case HollowShape.Same:
                                break;

                            case HollowShape.Circle:
                                hollowVolume *= 0.78539816339f;;
                                break;

                            case HollowShape.Triangle:
                                hollowVolume *= 0.5f * 0.5f;
                                break;
                            default:
                                hollowVolume = 0;
                                break;
                            }
                        volume *= (1.0f - hollowVolume);
                        }
                    }

                break;

            case ProfileShape.Circle:

                if (_pbs.PathCurve == (byte)Extrusion.Straight)
                    {
                    volume *= 0.78539816339f; // elipse base

                    if (hollowAmount > 0.0)
                        {
                        switch (_pbs.HollowShape)
                            {
                            case HollowShape.Same:
                            case HollowShape.Circle:
                                break;

                            case HollowShape.Square:
                                hollowVolume *= 0.5f * 2.5984480504799f;
                                break;

                            case HollowShape.Triangle:
                                hollowVolume *= .5f * 1.27323954473516f;
                                break;

                            default:
                                hollowVolume = 0;
                                break;
                            }
                        volume *= (1.0f - hollowVolume);
                        }
                    }

                else if (_pbs.PathCurve == (byte)Extrusion.Curve1)
                    {
                    volume *= 0.61685027506808491367715568749226e-2f * (float)(200 - _pbs.PathScaleX);
                    tmp = 1.0f - .02f * (float)(200 - _pbs.PathScaleY);
                    volume *= (1.0f - tmp * tmp);
                    
                    if (hollowAmount > 0.0)
                        {

                        // calculate the hollow volume by it's shape compared to the prim shape
                        hollowVolume *= hollowAmount;

                        switch (_pbs.HollowShape)
                            {
                            case HollowShape.Same:
                            case HollowShape.Circle:
                                break;

                            case HollowShape.Square:
                                hollowVolume *= 0.5f * 2.5984480504799f;
                                break;

                            case HollowShape.Triangle:
                                hollowVolume *= .5f * 1.27323954473516f;
                                break;

                            default:
                                hollowVolume = 0;
                                break;
                            }
                        volume *= (1.0f - hollowVolume);
                        }
                    }
                break;

            case ProfileShape.HalfCircle:
                if (_pbs.PathCurve == (byte)Extrusion.Curve1)
                {
                volume *= 0.52359877559829887307710723054658f;
                }
                break;

            case ProfileShape.EquilateralTriangle:

                if (_pbs.PathCurve == (byte)Extrusion.Straight)
                    {
                    volume *= 0.32475953f;

                    if (hollowAmount > 0.0)
                        {

                        // calculate the hollow volume by it's shape compared to the prim shape
                        switch (_pbs.HollowShape)
                            {
                            case HollowShape.Same:
                            case HollowShape.Triangle:
                                hollowVolume *= .25f;
                                break;

                            case HollowShape.Square:
                                hollowVolume *= 0.499849f * 3.07920140172638f;
                                break;

                            case HollowShape.Circle:
                                // Hollow shape is a perfect cyllinder in respect to the cube's scale
                                // Cyllinder hollow volume calculation

                                hollowVolume *= 0.1963495f * 3.07920140172638f;
                                break;

                            default:
                                hollowVolume = 0;
                                break;
                            }
                        volume *= (1.0f - hollowVolume);
                        }
                    }
                else if (_pbs.PathCurve == (byte)Extrusion.Curve1)
                    {
                    volume *= 0.32475953f;
                    volume *= 0.01f * (float)(200 - _pbs.PathScaleX);
                    tmp = 1.0f - .02f * (float)(200 - _pbs.PathScaleY);
                    volume *= (1.0f - tmp * tmp);

                    if (hollowAmount > 0.0)
                        {

                        hollowVolume *= hollowAmount;

                        switch (_pbs.HollowShape)
                            {
                            case HollowShape.Same:
                            case HollowShape.Triangle:
                                hollowVolume *= .25f;
                                break;

                            case HollowShape.Square:
                                hollowVolume *= 0.499849f * 3.07920140172638f;
                                break;

                            case HollowShape.Circle:

                                hollowVolume *= 0.1963495f * 3.07920140172638f;
                                break;

                            default:
                                hollowVolume = 0;
                                break;
                            }
                        volume *= (1.0f - hollowVolume);
                        }
                    }
                    break;

            default:
                break;
            }



        float taperX1;
        float taperY1;
        float taperX;
        float taperY;
        float pathBegin;
        float pathEnd;
        float profileBegin;
        float profileEnd;

        if (_pbs.PathCurve == (byte)Extrusion.Straight || _pbs.PathCurve == (byte)Extrusion.Flexible)
            {
            taperX1 = _pbs.PathScaleX * 0.01f;
            if (taperX1 > 1.0f)
                taperX1 = 2.0f - taperX1;
            taperX = 1.0f - taperX1;

            taperY1 = _pbs.PathScaleY * 0.01f;
            if (taperY1 > 1.0f)
                taperY1 = 2.0f - taperY1;
            taperY = 1.0f - taperY1;
            }
        else
            {
            taperX = _pbs.PathTaperX * 0.01f;
            if (taperX < 0.0f)
                taperX = -taperX;
            taperX1 = 1.0f - taperX;

            taperY = _pbs.PathTaperY * 0.01f;
            if (taperY < 0.0f)
                taperY = -taperY;
            taperY1 = 1.0f - taperY;

            }


        volume *= (taperX1 * taperY1 + 0.5f * (taperX1 * taperY + taperX * taperY1) + 0.3333333333f * taperX * taperY);

        pathBegin = (float)_pbs.PathBegin * 2.0e-5f;
        pathEnd = 1.0f - (float)_pbs.PathEnd * 2.0e-5f;
        volume *= (pathEnd - pathBegin);

        // this is crude aproximation
        profileBegin = (float)_pbs.ProfileBegin * 2.0e-5f;
        profileEnd = 1.0f - (float)_pbs.ProfileEnd * 2.0e-5f;
        volume *= (profileEnd - profileBegin);

        returnMass = _density * volume;

        if (IsRootOfLinkset)
        {
            foreach (BSPrim prim in _childrenPrims)
            {
                returnMass += prim.CalculateMass();
            }
        }

        if (returnMass <= 0)
            returnMass = 0.0001f;

        if (returnMass > _scene.MaximumObjectMass)
            returnMass = _scene.MaximumObjectMass;

        return returnMass;
    }// end CalculateMass
    #endregion Mass Calculation

    // Create the geometry information in Bullet for later use
    // The objects needs a hull if it's physical otherwise a mesh is enough
    // No locking here because this is done when we know physics is not simulating
    // if 'forceRebuild' is true, the geometry is rebuilt. Otherwise a previously built version is used
    private void CreateGeom(bool forceRebuild)
    {
        // the mesher thought this was too simple to mesh. Use a native Bullet collision shape.
        if (!_scene.NeedsMeshing(_pbs))
        {
            if (_pbs.ProfileShape == ProfileShape.HalfCircle && _pbs.PathCurve == (byte)Extrusion.Curve1)
            {
                if (_size.X == _size.Y && _size.Y == _size.Z && _size.X == _size.Z)
                {
                    // m_log.DebugFormat("{0}: CreateGeom: Defaulting to sphere of size {1}", LogHeader, _size);
                    _shapeType = ShapeData.PhysicsShapeType.SHAPE_SPHERE;
                    // Bullet native objects are scaled by the Bullet engine so pass the size in
                    _scale = _size;
                }
            }
            else
            {
                // m_log.DebugFormat("{0}: CreateGeom: Defaulting to box. lid={1}, size={2}", LogHeader, LocalID, _size);
                _shapeType = ShapeData.PhysicsShapeType.SHAPE_BOX;
                _scale = _size;
            }
        }
        else
        {
            if (IsPhysical)
            {
                if (forceRebuild || _hullKey == 0)
                {
                    // physical objects require a hull for interaction.
                    // This will create the mesh if it doesn't already exist
                    CreateGeomHull();
                }
            }
            else
            {
                if (forceRebuild || _meshKey == 0)
                {
                    // Static (non-physical) objects only need a mesh for bumping into
                    CreateGeomMesh();
                }
            }
        }
    }

    // No locking here because this is done when we know physics is not simulating
    private void CreateGeomMesh()
    {
        float lod = _pbs.SculptEntry ? _scene.SculptLOD : _scene.MeshLOD;
        ulong newMeshKey = (ulong)_pbs.GetMeshKey(_size, lod);
        // m_log.DebugFormat("{0}: CreateGeomMesh: lID={1}, oldKey={2}, newKey={3}", LogHeader, _localID, _meshKey, newMeshKey);

        // if this new shape is the same as last time, don't recreate the mesh
        if (_meshKey == newMeshKey) return;

        // Since we're recreating new, get rid of any previously generated shape
        if (_meshKey != 0)
        {
            // m_log.DebugFormat("{0}: CreateGeom: deleting old mesh. lID={1}, Key={2}", LogHeader, _localID, _meshKey);
            BulletSimAPI.DestroyMesh(_scene.WorldID, _meshKey);
            _mesh = null;
            _meshKey = 0;
        }

        _meshKey = newMeshKey;
        // always pass false for physicalness as this creates some sort of bounding box which we don't need
        _mesh = _scene.mesher.CreateMesh(_avName, _pbs, _size, lod, false);

        int[] indices = _mesh.getIndexListAsInt();
        List<OMV.Vector3> vertices = _mesh.getVertexList();

        float[] verticesAsFloats = new float[vertices.Count * 3];
        int vi = 0;
        foreach (OMV.Vector3 vv in vertices)
        {
            // m_log.DebugFormat("{0}:  {1}: <{2:0.00}, {3:0.00}, {4:0.00}>", LogHeader, vi / 3, vv.X, vv.Y, vv.Z);
            verticesAsFloats[vi++] = vv.X;
            verticesAsFloats[vi++] = vv.Y;
            verticesAsFloats[vi++] = vv.Z;
        }

        // m_log.DebugFormat("{0}: CreateGeomMesh: calling CreateMesh. lid={1}, key={2}, indices={3}, vertices={4}", 
        //                   LogHeader, _localID, _meshKey, indices.Length, vertices.Count);
        BulletSimAPI.CreateMesh(_scene.WorldID, _meshKey, indices.GetLength(0), indices, 
                                                        vertices.Count, verticesAsFloats);

        _shapeType = ShapeData.PhysicsShapeType.SHAPE_MESH;
        // meshes are already scaled by the meshmerizer
        _scale = new OMV.Vector3(1f, 1f, 1f);
        return;
    }

    // No locking here because this is done when we know physics is not simulating
    private void CreateGeomHull()
    {
        float lod = _pbs.SculptEntry ? _scene.SculptLOD : _scene.MeshLOD;
        ulong newHullKey = (ulong)_pbs.GetMeshKey(_size, lod);
        // m_log.DebugFormat("{0}: CreateGeomHull: lID={1}, oldKey={2}, newKey={3}", LogHeader, _localID, _hullKey, newHullKey);

        // if the hull hasn't changed, don't rebuild it
        if (newHullKey == _hullKey) return;

        // Since we're recreating new, get rid of any previously generated shape
        if (_hullKey != 0)
        {
            // m_log.DebugFormat("{0}: CreateGeom: deleting old hull. Key={1}", LogHeader, _hullKey);
            BulletSimAPI.DestroyHull(_scene.WorldID, _hullKey);
            _hullKey = 0;
            _hulls.Clear();
            BulletSimAPI.DestroyMesh(_scene.WorldID, _meshKey);
            _mesh = null;   // the mesh cannot match either
            _meshKey = 0;
        }

        _hullKey = newHullKey;
        if (_meshKey != _hullKey)
        {
            // if the underlying mesh has changed, rebuild it
            CreateGeomMesh();
        }

        int[] indices = _mesh.getIndexListAsInt();
        List<OMV.Vector3> vertices = _mesh.getVertexList();

        //format conversion from IMesh format to DecompDesc format
        List<int> convIndices = new List<int>();
        List<float3> convVertices = new List<float3>();
        for (int ii = 0; ii < indices.GetLength(0); ii++)
        {
            convIndices.Add(indices[ii]);
        }
        foreach (OMV.Vector3 vv in vertices)
        {
            convVertices.Add(new float3(vv.X, vv.Y, vv.Z));
        }

        // setup and do convex hull conversion
        _hulls = new List<ConvexResult>();
        DecompDesc dcomp = new DecompDesc();
        dcomp.mIndices = convIndices;
        dcomp.mVertices = convVertices;
        ConvexBuilder convexBuilder = new ConvexBuilder(HullReturn);
        // create the hull into the _hulls variable
        convexBuilder.process(dcomp);

        // Convert the vertices and indices for passing to unmanaged
        // The hull information is passed as a large floating point array. 
        // The format is:
        //  convHulls[0] = number of hulls
        //  convHulls[1] = number of vertices in first hull
        //  convHulls[2] = hull centroid X coordinate
        //  convHulls[3] = hull centroid Y coordinate
        //  convHulls[4] = hull centroid Z coordinate
        //  convHulls[5] = first hull vertex X
        //  convHulls[6] = first hull vertex Y
        //  convHulls[7] = first hull vertex Z
        //  convHulls[8] = second hull vertex X
        //  ...
        //  convHulls[n] = number of vertices in second hull
        //  convHulls[n+1] = second hull centroid X coordinate
        //  ...
        //
        // TODO: is is very inefficient. Someday change the convex hull generator to return
        //   data structures that do not need to be converted in order to pass to Bullet.
        //   And maybe put the values directly into pinned memory rather than marshaling.
        int hullCount = _hulls.Count;
        int totalVertices = 1;          // include one for the count of the hulls
        foreach (ConvexResult cr in _hulls)
        {
            totalVertices += 4;                         // add four for the vertex count and centroid
            totalVertices += cr.HullIndices.Count * 3;  // we pass just triangles
        }
        float[] convHulls = new float[totalVertices];

        convHulls[0] = (float)hullCount;
        int jj = 1;
        foreach (ConvexResult cr in _hulls)
        {
            // copy vertices for index access
            float3[] verts = new float3[cr.HullVertices.Count];
            int kk = 0;
            foreach (float3 ff in cr.HullVertices)
            {
                verts[kk++] = ff;
            }

            // add to the array one hull's worth of data
            convHulls[jj++] = cr.HullIndices.Count;
            convHulls[jj++] = 0f;   // centroid x,y,z
            convHulls[jj++] = 0f;
            convHulls[jj++] = 0f;
            foreach (int ind in cr.HullIndices)
            {
                convHulls[jj++] = verts[ind].x;
                convHulls[jj++] = verts[ind].y;
                convHulls[jj++] = verts[ind].z;
            }
        }

        // create the hull definition in Bullet
        // m_log.DebugFormat("{0}: CreateGeom: calling CreateHull. lid={1}, key={2}, hulls={3}", LogHeader, _localID, _hullKey, hullCount);
        BulletSimAPI.CreateHull(_scene.WorldID, _hullKey, hullCount, convHulls);
        _shapeType = ShapeData.PhysicsShapeType.SHAPE_HULL;
        // meshes are already scaled by the meshmerizer
        _scale = new OMV.Vector3(1f, 1f, 1f);
        return;
    }

    // Callback from convex hull creater with a newly created hull.
    // Just add it to the collection of hulls for this shape.
    private void HullReturn(ConvexResult result)
    {
        _hulls.Add(result);
        return;
    }

    // Create an object in Bullet
    // No locking here because this is done when the physics engine is not simulating
    private void CreateObject()
    {
        if (IsRootOfLinkset)
        {
            // Create a linkset around this object
            // CreateLinksetWithCompoundHull();
            CreateLinksetWithConstraints();
        }
        else
        {
            // simple object
            // the mesh or hull must have already been created in Bullet
            ShapeData shape;
            FillShapeInfo(out shape);
            // m_log.DebugFormat("{0}: CreateObject: lID={1}, shape={2}", LogHeader, _localID, shape.Type);
            BulletSimAPI.CreateObject(_scene.WorldID, shape);
        }
    }

    // Create a linkset by creating a compound hull at the root prim that consists of all
    // the children.
    // NOTE: This does not allow proper collisions with the children prims so it is not a workable solution
    void CreateLinksetWithCompoundHull()
    {
        // If I am the root prim of a linkset, replace my physical shape with all the
        // pieces of the children.
        // All of the children should have called CreateGeom so they have a hull
        // in the physics engine already. Here we pull together all of those hulls
        // into one shape.
        int totalPrimsInLinkset = _childrenPrims.Count + 1;
        // m_log.DebugFormat("{0}: CreateLinkset. Root prim={1}, prims={2}", LogHeader, LocalID, totalPrimsInLinkset);
        ShapeData[] shapes = new ShapeData[totalPrimsInLinkset];
        FillShapeInfo(out shapes[0]);
        int ii = 1;
        foreach (BSPrim prim in _childrenPrims)
        {
            // m_log.DebugFormat("{0}: CreateLinkset: adding prim {1}", LogHeader, prim.LocalID);
            prim.FillShapeInfo(out shapes[ii]);
            ii++;
        }
        BulletSimAPI.CreateLinkset(_scene.WorldID, totalPrimsInLinkset, shapes);
    }

    // Copy prim's info into the BulletSim shape description structure
    public void FillShapeInfo(out ShapeData shape)
    {
        shape.ID = _localID;
        shape.Type = _shapeType;
        shape.Position = _position;
        shape.Rotation = _orientation;
        shape.Velocity = _velocity;
        shape.Scale = _scale;
        shape.Mass = _isPhysical ? _mass : 0f;
        shape.Buoyancy = _buoyancy;
        shape.HullKey = _hullKey;
        shape.MeshKey = _meshKey;
        shape.Friction = _friction;
        shape.Restitution = _restitution;
        shape.Collidable = (!IsPhantom) ? ShapeData.numericTrue : ShapeData.numericFalse;
        shape.Static = _isPhysical ? ShapeData.numericFalse : ShapeData.numericTrue;
    }

    // Create the linkset by putting constraints between the objects of the set so they cannot move
    // relative to each other.
    // TODO: make this more effeicient: a large linkset gets rebuilt over and over and prims are added
    void CreateLinksetWithConstraints()
    {
        // m_log.DebugFormat("{0}: CreateLinkset. Root prim={1}, prims={2}", LogHeader, LocalID, _childrenPrims.Count+1);

        // remove any constraints that might be in place
        foreach (BSPrim prim in _childrenPrims)
        {
            // m_log.DebugFormat("{0}: CreateLinkset: RemoveConstraint between root prim {1} and child prim {2}", LogHeader, LocalID, prim.LocalID);
            BulletSimAPI.RemoveConstraint(_scene.WorldID, LocalID, prim.LocalID);
        }
        // create constraints between the root prim and each of the children
        foreach (BSPrim prim in _childrenPrims)
        {
            // m_log.DebugFormat("{0}: CreateLinkset: AddConstraint between root prim {1} and child prim {2}", LogHeader, LocalID, prim.LocalID);

            // Zero motion for children so they don't interpolate
            prim.ZeroMotion();

            // relative position normalized to the root prim
            OMV.Vector3 childRelativePosition = (prim._position - this._position) * OMV.Quaternion.Inverse(this._orientation);

            // relative rotation of the child to the parent
            OMV.Quaternion relativeRotation = OMV.Quaternion.Inverse(prim._orientation) * this._orientation;

            // this is a constraint that allows no freedom of movement between the two objects
            // http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818
            BulletSimAPI.AddConstraint(_scene.WorldID, LocalID, prim.LocalID, 
                childRelativePosition,
                relativeRotation,
                OMV.Vector3.Zero,
                OMV.Quaternion.Identity,
                OMV.Vector3.Zero, OMV.Vector3.Zero,
                OMV.Vector3.Zero, OMV.Vector3.Zero);
        }
    }

    // Rebuild the geometry and object.
    // This is called when the shape changes so we need to recreate the mesh/hull.
    // No locking here because this is done when the physics engine is not simulating
    private void RecreateGeomAndObject()
    {
        // m_log.DebugFormat("{0}: RecreateGeomAndObject. lID={1}", LogHeader, _localID);
        CreateGeom(true);
        CreateObject();
        return;
    }

    // The physics engine says that properties have updated. Update same and inform
    // the world that things have changed.
    // TODO: do we really need to check for changed? Maybe just copy values and call RequestPhysicsterseUpdate()
    enum UpdatedProperties {
        Position      = 1 << 0,
        Rotation      = 1 << 1,
        Velocity      = 1 << 2,
        Acceleration  = 1 << 3,
        RotationalVel = 1 << 4
    }

    const float ROTATION_TOLERANCE = 0.01f;
    const float VELOCITY_TOLERANCE = 0.001f;
    const float POSITION_TOLERANCE = 0.05f;
    const float ACCELERATION_TOLERANCE = 0.01f;
    const float ROTATIONAL_VELOCITY_TOLERANCE = 0.01f;
    const bool SHOULD_DAMP_UPDATES = false;

    public void UpdateProperties(EntityProperties entprop)
    {
        UpdatedProperties changed = 0;
        if (SHOULD_DAMP_UPDATES)
        {
            // assign to the local variables so the normal set action does not happen
            // if (_position != entprop.Position)
            if (!_position.ApproxEquals(entprop.Position, POSITION_TOLERANCE))
            {
                _position = entprop.Position;
                // m_log.DebugFormat("{0}: UpdateProperties: id={1}, pos = {2}", LogHeader, LocalID, _position);
                changed |= UpdatedProperties.Position;
            }
            // if (_orientation != entprop.Rotation)
            if (!_orientation.ApproxEquals(entprop.Rotation, ROTATION_TOLERANCE))
            {
                _orientation = entprop.Rotation;
                // m_log.DebugFormat("{0}: UpdateProperties: id={1}, rot = {2}", LogHeader, LocalID, _orientation);
                changed |= UpdatedProperties.Rotation;
            }
            // if (_velocity != entprop.Velocity)
            if (!_velocity.ApproxEquals(entprop.Velocity, VELOCITY_TOLERANCE))
            {
                _velocity = entprop.Velocity;
                // m_log.DebugFormat("{0}: UpdateProperties: velocity = {1}", LogHeader, _velocity);
                changed |= UpdatedProperties.Velocity;
            }
            // if (_acceleration != entprop.Acceleration)
            if (!_acceleration.ApproxEquals(entprop.Acceleration, ACCELERATION_TOLERANCE))
            {
                _acceleration = entprop.Acceleration;
                // m_log.DebugFormat("{0}: UpdateProperties: acceleration = {1}", LogHeader, _acceleration);
                changed |= UpdatedProperties.Acceleration;
            }
            // if (_rotationalVelocity != entprop.RotationalVelocity)
            if (!_rotationalVelocity.ApproxEquals(entprop.RotationalVelocity, ROTATIONAL_VELOCITY_TOLERANCE))
            {
                _rotationalVelocity = entprop.RotationalVelocity;
                // m_log.DebugFormat("{0}: UpdateProperties: rotationalVelocity = {1}", LogHeader, _rotationalVelocity);
                changed |= UpdatedProperties.RotationalVel;
            }
            if (changed != 0)
            {
                // m_log.DebugFormat("{0}: UpdateProperties: id={1}, c={2}, pos={3}, rot={4}", LogHeader, LocalID, changed, _position, _orientation);
                // Only update the position of single objects and linkset roots
                if (this._parentPrim == null)
                {
                    // m_log.DebugFormat("{0}: RequestTerseUpdate. id={1}, ch={2}, pos={3}, rot={4}", LogHeader, LocalID, changed, _position, _orientation);
                    base.RequestPhysicsterseUpdate();
                }
            }
        }
        else
        {
            // Don't check for damping here -- it's done in BulletSim and SceneObjectPart.

            // Only updates only for individual prims and for the root object of a linkset.
            if (this._parentPrim == null)
            {
                // Assign to the local variables so the normal set action does not happen
                _position = entprop.Position;
                _orientation = entprop.Rotation;
                _velocity = entprop.Velocity;
                _acceleration = entprop.Acceleration;
                _rotationalVelocity = entprop.RotationalVelocity;
                // m_log.DebugFormat("{0}: RequestTerseUpdate. id={1}, ch={2}, pos={3}, rot={4}", LogHeader, LocalID, changed, _position, _orientation);
                base.RequestPhysicsterseUpdate();
            }
        }
    }

    // I've collided with something
    public void Collide(uint collidingWith, ActorTypes type, OMV.Vector3 contactPoint, OMV.Vector3 contactNormal, float pentrationDepth)
    {
        // m_log.DebugFormat("{0}: Collide: ms={1}, id={2}, with={3}", LogHeader, _subscribedEventsMs, LocalID, collidingWith);

        // The following lines make IsColliding() and IsCollidingGround() work
        _collidingStep = _scene.SimulationStep;
        if (collidingWith == BSScene.TERRAIN_ID || collidingWith == BSScene.GROUNDPLANE_ID)
        {
            _collidingGroundStep = _scene.SimulationStep;
        }

        if (_subscribedEventsMs == 0) return;   // nothing in the object is waiting for collision events
        // throttle the collisions to the number of milliseconds specified in the subscription
        int nowTime = _scene.SimulationNowTime;
        if (nowTime < (_lastCollisionTime + _subscribedEventsMs)) return;
        _lastCollisionTime = nowTime;

        // create the event for the collision
        Dictionary<uint, ContactPoint> contactPoints = new Dictionary<uint, ContactPoint>();
        contactPoints.Add(collidingWith, new ContactPoint(contactPoint, contactNormal, pentrationDepth));
        CollisionEventUpdate args = new CollisionEventUpdate(contactPoints);
        base.SendCollisionUpdate(args);
    }
}
}