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*       derived from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS AND ANY
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*/
using System;
using System.Threading;
using System.Collections.Generic;
using Axiom.Math;
using Ode.NET;
using OpenSim.Region.Physics.Manager;

namespace OpenSim.Region.Physics.OdePlugin
{
    /// <summary>
    /// ODE plugin 
    /// </summary>
    public class OdePlugin : IPhysicsPlugin
    {
        private OdeScene _mScene;

        public OdePlugin()
        {

        }

        public bool Init()
        {
            return true;
        }

        public PhysicsScene GetScene()
        {
            if (_mScene == null)
            {
                _mScene = new OdeScene();
            }
            return (_mScene);
        }

        public string GetName()
        {
            return ("OpenDynamicsEngine");
        }

        public void Dispose()
        {

        }
    }

    public class OdeScene : PhysicsScene
    {
        private IntPtr contactgroup;
        private IntPtr LandGeom;
        private double[] _heightmap;
        private d.NearCallback nearCallback;
        private List<OdeCharacter> _characters = new List<OdeCharacter>();
        private List<OdePrim> _prims = new List<OdePrim>();
        private d.ContactGeom[] contacts = new d.ContactGeom[30];
        private d.Contact contact;

        public IntPtr world;
        public IntPtr space;
        public static Object OdeLock = new Object();

        public OdeScene()
        {
            nearCallback = near;
            contact.surface.mode |= d.ContactFlags.Approx1 | d.ContactFlags.SoftCFM | d.ContactFlags.SoftERP;
            contact.surface.mu = 10.0f;
            contact.surface.bounce = 0.9f;
            contact.surface.soft_erp = 0.005f;
            contact.surface.soft_cfm = 0.00003f;

            lock (OdeLock)
            {
                world = d.WorldCreate();
                space = d.HashSpaceCreate(IntPtr.Zero);
                contactgroup = d.JointGroupCreate(0);
                d.WorldSetGravity(world, 0.0f, 0.0f, -10.0f);
                d.WorldSetAutoDisableFlag(world, false);
                d.WorldSetContactSurfaceLayer(world, 0.001f);
            }

            _heightmap = new double[65536];
        }

        // This function blatantly ripped off from BoxStack.cs
        private void near(IntPtr space, IntPtr g1, IntPtr g2)
        {
            //  no lock here!  It's invoked from within Simulate(), which is thread-locked
            IntPtr b1 = d.GeomGetBody(g1);
            IntPtr b2 = d.GeomGetBody(g2);
            if (b1 != IntPtr.Zero && b2 != IntPtr.Zero && d.AreConnectedExcluding(b1, b2, d.JointType.Contact))
                return;

            int count = d.Collide(g1, g2, 500, contacts, d.ContactGeom.SizeOf);
            for (int i = 0; i < count; i++)
            {
                contact.geom = contacts[i];
                IntPtr joint = d.JointCreateContact(world, contactgroup, ref contact);
                d.JointAttach(joint, b1, b2);
            }

        }

        private void collision_optimized()
        {
            foreach (OdeCharacter chr in _characters)
            {
                d.SpaceCollide2(space, chr.capsule_geom, IntPtr.Zero, nearCallback);
                foreach (OdeCharacter ch2 in _characters)           /// should be a separate space -- lots of avatars will be N**2 slow
                {
                    d.SpaceCollide2(chr.capsule_geom, ch2.capsule_geom, IntPtr.Zero, nearCallback);
                }
            }
        }

        public override PhysicsActor AddAvatar(PhysicsVector position)
        {
            PhysicsVector pos = new PhysicsVector();
            pos.X = position.X;
            pos.Y = position.Y;
            pos.Z = position.Z;
            OdeCharacter newAv = new OdeCharacter(this, pos);
            _characters.Add(newAv);
            return newAv;
        }

        public override void RemoveAvatar(PhysicsActor actor)
        {
            OdeCharacter och = (OdeCharacter)actor;
            d.BodyDestroy(och.BoundingCapsule);
            _characters.Remove(och);
        }

        public override void RemovePrim(PhysicsActor prim)
        {
            if (prim is OdePrim)
            {
                lock (OdeLock)
                {
                    d.GeomDestroy(((OdePrim)prim).prim_geom);
                    _prims.Remove((OdePrim)prim);
                }
            }
        }

        public override PhysicsActor AddPrim(PhysicsVector position, PhysicsVector size, Quaternion rotation)
        {
            PhysicsVector pos = new PhysicsVector();
            pos.X = position.X;
            pos.Y = position.Y;
            pos.Z = position.Z;
            PhysicsVector siz = new PhysicsVector();
            siz.X = size.X;
            siz.Y = size.Y;
            siz.Z = size.Z;
            Quaternion rot = new Quaternion();
            rot.w = rotation.w;
            rot.x = rotation.x;
            rot.y = rotation.y;
            rot.z = rotation.z;
            OdePrim newPrim;
            lock (OdeLock)
            {
                newPrim = new OdePrim(this, pos, siz, rot);
            }
            _prims.Add(newPrim);
            return newPrim;
        }

        public override void Simulate(float timeStep)
        {
            lock (OdeLock)
            {
                foreach (OdePrim p in _prims)
                {
                }
                foreach (OdeCharacter actor in _characters)
                {
                    actor.Move(timeStep);
                }
                collision_optimized();
                for (int i = 0; i < 50; i++)
                {
                    d.WorldQuickStep(world, timeStep * 0.02f);
                }

                d.JointGroupEmpty(contactgroup);
                foreach (OdeCharacter actor in _characters)
                {
                    actor.UpdatePosition();
                }
            }
        }

        public override void GetResults()
        {

        }

        public override bool IsThreaded
        {
            get
            {
                return (false); // for now we won't be multithreaded
            }
        }

        public override void SetTerrain(float[] heightMap)
        {
            for (int i = 0; i < 65536; i++)
            {
                // this._heightmap[i] = (double)heightMap[i];
                // dbm (danx0r) -- heightmap x,y must be swapped for Ode (should fix ODE, but for now...)
                int x = i & 0xff;
                int y = i >> 8;
                _heightmap[i] = (double)heightMap[x * 256 + y];
            }

            lock (OdeLock)
            {
                IntPtr HeightmapData = d.GeomHeightfieldDataCreate();
                d.GeomHeightfieldDataBuildDouble(HeightmapData, _heightmap, 0, 256, 256, 256, 256, 1.0f, 0.0f, 2.0f, 0);
                d.GeomHeightfieldDataSetBounds(HeightmapData, 256, 256);
                LandGeom = d.CreateHeightfield(space, HeightmapData, 1);
                d.Matrix3 R = new d.Matrix3();

                Quaternion q1 = Quaternion.FromAngleAxis(1.5707f, new Vector3(1, 0, 0));
                Quaternion q2 = Quaternion.FromAngleAxis(1.5707f, new Vector3(0, 1, 0));
                //Axiom.Math.Quaternion q3 = Axiom.Math.Quaternion.FromAngleAxis(3.14f, new Axiom.Math.Vector3(0, 0, 1));

                q1 = q1 * q2;
                //q1 = q1 * q3;
                Vector3 v3 = new Vector3();
                float angle = 0;
                q1.ToAngleAxis(ref angle, ref v3);

                d.RFromAxisAndAngle(out R, v3.x, v3.y, v3.z, angle);
                d.GeomSetRotation(LandGeom, ref R);
                d.GeomSetPosition(LandGeom, 128, 128, 0);
            }
        }

        public override void DeleteTerrain()
        {

        }
    }

    public class OdeCharacter : PhysicsActor
    {
        private PhysicsVector _position;
        private d.Vector3 _zeroPosition;
        private bool _zeroFlag=false;
        private PhysicsVector _velocity;
        private PhysicsVector _acceleration;
        private bool flying = false;
        //private float gravityAccel;
        public IntPtr BoundingCapsule;
        private OdeScene _parent_scene;
        public IntPtr capsule_geom;
        public d.Mass capsule_mass;

        public OdeCharacter(OdeScene parent_scene, PhysicsVector pos)
        {
            _velocity = new PhysicsVector();
            _position = pos;
            _acceleration = new PhysicsVector();
            _parent_scene = parent_scene;
            lock (OdeScene.OdeLock)
            {
                d.MassSetCapsule(out capsule_mass, 50.0f, 3, 0.5f, 2f);
                capsule_geom = d.CreateSphere(parent_scene.space, 1.0f);        /// not a typo!  Spheres roll, capsules tumble
                BoundingCapsule = d.BodyCreate(parent_scene.world);
                d.BodySetMass(BoundingCapsule, ref capsule_mass);
                d.BodySetPosition(BoundingCapsule, pos.X, pos.Y, pos.Z);
                d.GeomSetBody(capsule_geom, BoundingCapsule);
            }
        }

        public override bool Flying
        {
            get
            {
                return flying;
            }
            set
            {
                flying = value;
            }
        }

        public override PhysicsVector Position
        {
            get
            {
                return _position;
            }
            set
            {
                lock (OdeScene.OdeLock)
                {
                    d.BodySetPosition(BoundingCapsule, value.X, value.Y, value.Z);
                    _position = value;
                }
            }
        }

        public override PhysicsVector Size
        {
            get
            {
                return new PhysicsVector(0,0,0);
            }
            set
            {
            }
        }


        public override PhysicsVector Velocity
        {
            get
            {
                return _velocity;
            }
            set
            {
                _velocity = value;
            }
        }

        public override bool Kinematic
        {
            get
            {
                return false;
            }
            set
            {

            }
        }

        public override Quaternion Orientation
        {
            get
            {
                return Quaternion.Identity;
            }
            set
            {

            }
        }

        public override PhysicsVector Acceleration
        {
            get
            {
                return _acceleration;
            }

        }
        public void SetAcceleration(PhysicsVector accel)
        {
            _acceleration = accel;
        }

        public override void AddForce(PhysicsVector force)
        {

        }

        public override void SetMomentum(PhysicsVector momentum)
        {

        }

        public void Move(float timeStep)
        {
            //  no lock; for now it's only called from within Simulate()
            PhysicsVector vec = new PhysicsVector();
            d.Vector3 vel = d.BodyGetLinearVel(BoundingCapsule);

            //  if velocity is zero, use position control; otherwise, velocity control
            if (_velocity.X == 0.0f & _velocity.Y == 0.0f & _velocity.Z == 0.0f & !flying)
            {
                //  keep track of where we stopped.  No more slippin' & slidin'
                if (!_zeroFlag)
                {
                    _zeroFlag = true;
                    _zeroPosition = d.BodyGetPosition(BoundingCapsule);
                }
                d.Vector3 pos = d.BodyGetPosition(BoundingCapsule);
                vec.X = (_velocity.X - vel.X) * 75000.0f + (_zeroPosition.X - pos.X) * 120000.0f;
                vec.Y = (_velocity.Y - vel.Y) * 75000.0f + (_zeroPosition.Y - pos.Y) * 120000.0f;
            }
            else
            {
                _zeroFlag = false;
                vec.X = (_velocity.X - vel.X) * 75000.0f;
                vec.Y = (_velocity.Y - vel.Y) * 75000.0f;
                if (flying)
                {
                    vec.Z = (_velocity.Z - vel.Z) * 75000.0f;
                }
            }
            d.BodyAddForce(this.BoundingCapsule, vec.X, vec.Y, vec.Z);
        }

        public void UpdatePosition()
        {
            //  no lock; called from Simulate() -- if you call this from elsewhere, gotta lock or do Monitor.Enter/Exit!
            d.Vector3 vec = d.BodyGetPosition(BoundingCapsule);

            //  kluge to keep things in bounds.  ODE lets dead avatars drift away (they should be removed!)
            if (vec.X < 0.0f) vec.X = 0.0f;
            if (vec.Y < 0.0f) vec.Y = 0.0f;
            if (vec.X > 255.95f) vec.X = 255.95f;
            if (vec.Y > 255.95f) vec.Y = 255.95f;

            this._position.X = vec.X;
            this._position.Y = vec.Y;
            this._position.Z = vec.Z;
        }
    }

    public class OdePrim : PhysicsActor
    {
        private PhysicsVector _position;
        private PhysicsVector _velocity;
        private PhysicsVector _size;
        private PhysicsVector _acceleration;
        private Quaternion _orientation;
        public IntPtr prim_geom;

        public OdePrim(OdeScene parent_scene, PhysicsVector pos, PhysicsVector size, Quaternion rotation)
        {
            _velocity = new PhysicsVector();
            _position = pos;
            _size = size;
            _acceleration = new PhysicsVector();
            _orientation = rotation;
            lock (OdeScene.OdeLock)
            {
                prim_geom = d.CreateBox(parent_scene.space, _size.X, _size.Y, _size.Z);
                d.GeomSetPosition(prim_geom, _position.X, _position.Y, _position.Z);
                d.Quaternion myrot = new d.Quaternion();
                myrot.W = rotation.w;
                myrot.X = rotation.x;
                myrot.Y = rotation.y;
                myrot.Z = rotation.z;
                d.GeomSetQuaternion(prim_geom, ref myrot);
            }
        }

        public override bool Flying
        {
            get
            {
                return false; //no flying prims for you
            }
            set
            {
            }
        }

        public override PhysicsVector Position
        {
            get
            {
                return _position;
            }
            set
            {
                _position = value;
                lock (OdeScene.OdeLock)
                {
                    d.GeomSetPosition(prim_geom, _position.X, _position.Y, _position.Z);
                }
            }
        }

        public override PhysicsVector Size
        {
            get
            {
                return _size;
            }
            set
            {
                _size = value;
                lock (OdeScene.OdeLock)
                {
                    d.GeomBoxSetLengths(prim_geom, _size.X, _size.Y, _size.Z);
                }
            }
        }

        public override PhysicsVector Velocity
        {
            get
            {
                return _velocity;
            }
            set
            {
                _velocity = value;
            }
        }

        public override bool Kinematic
        {
            get
            {
                return false;
            }
            set
            {
            }
        }

        public override Quaternion Orientation
        {
            get
            {
                return _orientation;
            }
            set
            {
                _orientation = value;
                lock (OdeScene.OdeLock)
                {
                    d.Quaternion myrot = new d.Quaternion();
                    myrot.W = _orientation.w;
                    myrot.X = _orientation.x;
                    myrot.Y = _orientation.y;
                    myrot.Z = _orientation.z;
                    d.GeomSetQuaternion(prim_geom, ref myrot);
                }
            }
        }

        public override PhysicsVector Acceleration
        {
            get
            {
                return _acceleration;
            }
        }

        public void SetAcceleration(PhysicsVector accel)
        {
            this._acceleration = accel;
        }

        public override void AddForce(PhysicsVector force)
        {
        }

        public override void SetMomentum(PhysicsVector momentum)
        {
        }
    }
}