RVOCoreSimulator.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using Pathfinding;
using Pathfinding.RVO.Sampled;

#if NETFX_CORE
using Thread = Pathfinding.WindowsStore.Thread;
using ParameterizedThreadStart = Pathfinding.WindowsStore.ParameterizedThreadStart;
using ThreadStart = Pathfinding.WindowsStore.ThreadStart;
#else
using Thread = System.Threading.Thread;
using ParameterizedThreadStart = System.Threading.ParameterizedThreadStart;
using ThreadStart = System.Threading.ThreadStart;
#endif

/** Local avoidance related classes */
namespace Pathfinding.RVO {

    /** Exposes properties of an Agent class.
      * \astarpro */
    public interface IAgent {
        /** Interpolated position of agent.
         * Will be interpolated if the interpolation setting is enabled on the simulator.
         */
        Vector3 InterpolatedPosition {get;}

        /** Position of the agent.
         * This can be changed manually if you need to reposition the agent, but if you are reading from InterpolatedPosition, it will not update interpolated position
         * until the next simulation step.
         * \see Position
         */
        Vector3 Position {get; set;}

        /** Desired velocity of the agent.
         * Usually you set this once per frame. The agent will try move as close to the desired velocity as possible.
         * Will take effect at the next simulation step.
         */
        Vector3 DesiredVelocity {get; set;}
        /** Velocity of the agent.
         * Can be used to set the rotation of the rendered agent.
         * But smoothing is recommended if you do so since it might be a bit unstable when the velocity is very low.
         *
         * You can set this variable manually,but it is not recommended to do so unless
         * you have good reasons since it might degrade the quality of the simulation.
         */
        Vector3 Velocity {get; set;}

        /** Locked agents will not move */
        bool Locked {get; set;}

        /** Radius of the agent.
         * Agents are modelled as circles/cylinders */
        float Radius {get; set;}

        /** Height of the agent */
        float Height {get; set;}

        /** Max speed of the agent. In units per second  */
        float MaxSpeed {get; set;}

        /** Max distance to other agents to take them into account.
         * Decreasing this value can lead to better performance, increasing it can lead to better quality of the simulation.
         */
        float NeighbourDist {get; set;}

        /** Max number of estimated seconds to look into the future for collisions with agents.
          * As it turns out, this variable is also very good for controling agent avoidance priorities.
          * Agents with lower values will avoid other agents less and thus you can make 'high priority agents' by
          * giving them a lower value.
          */
        float AgentTimeHorizon {get; set;}
        /** Max number of estimated seconds to look into the future for collisions with obstacles */
        float ObstacleTimeHorizon {get; set;}

        /** Specifies the avoidance layer for this agent.
         * The #CollidesWith mask on other agents will determine if they will avoid this agent.
         */
        RVOLayer Layer {get; set;}

        /** Layer mask specifying which layers this agent will avoid.
         * You can set it as CollidesWith = RVOLayer.DefaultAgent | RVOLayer.Layer3 | RVOLayer.Layer6 ...
         *
         * \see http://en.wikipedia.org/wiki/Mask_(computing)
         */
        RVOLayer CollidesWith {get; set;}

        /** Debug drawing */
        bool DebugDraw {get; set;}

        /** Max number of agents to take into account.
         * Decreasing this value can lead to better performance, increasing it can lead to better quality of the simulation.
         */
        int MaxNeighbours {get; set;}

        /** List of obstacle segments which were close to the agent during the last simulation step.
         * Can be used to apply additional wall avoidance forces for example.
         * Segments are formed by the obstacle vertex and its .next property.
         */
        List<ObstacleVertex> NeighbourObstacles {get; }

        /** Teleports the agent to a new position.
         * Just setting the position can cause strange effects when using interpolation.
         */
        void Teleport (Vector3 pos);


    }

    [System.Flags]
    public enum RVOLayer {
        DefaultAgent = 1 << 0,
        DefaultObstacle = 1 << 1,
        Layer2 = 1 << 2,
        Layer3 = 1 << 3,
        Layer4 = 1 << 4,
        Layer5 = 1 << 5,
        Layer6 = 1 << 6,
        Layer7 = 1 << 7,
        Layer8 = 1 << 8,
        Layer9 = 1 << 9,
        Layer10 = 1 << 10,
        Layer11 = 1 << 11,
        Layer12 = 1 << 12,
        Layer13 = 1 << 13,
        Layer14 = 1 << 14,
        Layer15 = 1 << 15,
        Layer16 = 1 << 16,
        Layer17 = 1 << 17,
        Layer18 = 1 << 18,
        Layer19 = 1 << 19,
        Layer20 = 1 << 20,
        Layer21 = 1 << 21,
        Layer22 = 1 << 22,
        Layer23 = 1 << 23,
        Layer24 = 1 << 24,
        Layer25 = 1 << 25,
        Layer26 = 1 << 26,
        Layer27 = 1 << 27,
        Layer28 = 1 << 28,
        Layer29 = 1 << 29,
        Layer30 = 1 << 30
    }

    /** Local Avoidance %Simulator.
     * This class handles local avoidance simulation for a number of agents using
     * Reciprocal Velocity Obstacles (RVO) and Optimal Reciprocal Collision Avoidance (ORCA).
     *
     * This class will handle calculation of velocities from desired velocities supplied by a script.
     * It is, however, not responsible for moving any objects in a Unity Scene. For that there are other scripts (see below).
     *
     * Obstacles can be added and removed from the simulation, agents can also be added and removed at any time.
     * \see
     * RVOSimulator
     * RVOAgent
     * Pathfinding.RVO.IAgent
     *
     * The implementation is based on the RVO2 Library (http://gamma.cs.unc.edu/RVO2/) extended with many new features.
     *
     * You will most likely mostly use the wrapper class RVOSimulator.
     *
     * \astarpro
     */
    public class Simulator {

        /** Use Double Buffering.
         * \see DoubleBuffering */
        private bool doubleBuffering = true;

        /** Inverse desired simulation fps.
         * \see DesiredDeltaTime
         */
        private float desiredDeltaTime = 0.05f;

        /** Use Interpolation.
         * \see Interpolation */
        private bool interpolation = true;

        /** Worker threads */
        Worker[] workers;

        /** Agents in this simulation */
        List<Agent> agents;

        /** Obstacles in this simulation */
        List<ObstacleVertex> obstacles;

        public enum SamplingAlgorithm {
            AdaptiveSampling,
            GradientDecent
        }

        /** What sampling algorithm to use.
         * \see "Reciprocal Velocity Obstacles for Real-Time Multi-Agent Navigation"
         * \see https://en.wikipedia.org/wiki/Gradient_descent
         * \see http://digestingduck.blogspot.se/2010/04/adaptive-rvo-sampling.html
         * \see http://digestingduck.blogspot.se/2010/10/rvo-sample-pattern.html
          */
        public SamplingAlgorithm algorithm = SamplingAlgorithm.AdaptiveSampling;

#if !AstarRelease
        /** KDTree for this simulation */
        KDTree kdTree;
#endif

        RVOQuadtree quadtree = new RVOQuadtree();

        public float qualityCutoff = 0.05f;
        public float stepScale = 1.5f;

#if !AstarRelease
        /** KDTree for this simulation.
         * Used internally by the simulation.
         * Please only read from this tree, do not rebuild it since that can interfere with the simulation.
         * It is rebuilt when needed.
         *
         */
        public KDTree KDTree { get { return kdTree; } }
#endif

        /** Quadtree for this simulation.
         * Used internally by the simulation to perform fast neighbour lookups for each agent.
         * Please only read from this tree, do not rebuild it since that can interfere with the simulation.
         * It is rebuilt when needed.
         */
        public RVOQuadtree Quadtree { get { return quadtree; } }

        private float deltaTime;
        private float prevDeltaTime = 0;

        private float lastStep = -99999;
        private float lastStepInterpolationReference = -9999;
        private float lastFrame = 0;

        private bool doUpdateObstacles = false;
        private bool doCleanObstacles = false;

        private bool oversampling = false;

        private int frameTimeBufferIndex = 0;
        private float[] frameTimeBuffer = new float[1];

        public float DeltaTime { get { return deltaTime; } }
        public float PrevDeltaTime { get { return prevDeltaTime; } }

        /** Is using multithreading */
        public bool Multithreading { get { return workers != null && workers.Length > 0; }}

        /** Time in seconds between each simulation step.
         * This is the desired delta time, the simulation will never run at a higher fps than
         * the rate at which the Update function is called.
         */
        public float DesiredDeltaTime { get { return desiredDeltaTime; } set { desiredDeltaTime = System.Math.Max (value,0.0f); }}

        /** Use Interpolation.
         * If interpolation is enabled, agent positions will be interpolated on frames when no rvo calculation is done.
         * This has a very small overhead, but usually yields much smoother looking movement.
         */
        public bool Interpolation { get { return interpolation; } set { interpolation = value; }}

        public bool Oversampling { get { return oversampling; } set { oversampling = value; }}

        //internal int textureWidth;
        //internal Texture2D tex;
        //internal float textureSize;
        //internal float colorScale = 0.05f;
        //Color[] colors;

        //bool dirtyColors = false;

        /** Get a list of all agents.
         *
         * This is an internal list.
         * I'm not going to be restrictive so you may access it since it is better for performance
         * but please do not modify it since that can cause errors in the simulation.
         *
         * \warning Do not modify this list! */
        public List<Agent> GetAgents () {
            return agents;
        }

        /** Get a list of all obstacles.
         * This is a list of obstacle vertices.
         * Each vertex is part of a doubly linked list loop
         * forming an obstacle polygon.
         *
         * \warning Do not modify this list!
         *
         * \see AddObstacle
         * \see RemoveObstacle
         */
        public List<ObstacleVertex> GetObstacles () {
            return obstacles;
        }

        /** Create a new simulator.
         *
         * \param workers Use the specified number of worker threads.\n
         * When the number zero is specified, no multithreading will be used.
         * A good number is the number of cores on the machine.
         *
         * \param doubleBuffering Use Double Buffering for calculations.
         * Testing done with 5000 agents and 0.1 desired delta time showed that with double buffering enabled
         * the game ran at 50 fps for most frames, dropping to 10 fps during calculation frames. But without double buffering
         * it ran at around 10 fps all the time.\n
         * This will let threads calculate while the game progresses instead of waiting for the calculations
         * to finish.
         * \note Will only have effect if using multithreading
         *
         * \see #Multithreading
         */
        public Simulator (int workers, bool doubleBuffering) {
            this.workers = new Simulator.Worker[workers];
            this.doubleBuffering = doubleBuffering;

            for (int i=0;i<workers;i++) this.workers[i] = new Simulator.Worker(this);

            //kdTree = new KDTree(this);
            agents = new List<Agent>();
            obstacles = new List<ObstacleVertex>();

        }

        /*internal void DebugPlot ( Vector2 p, Color col ) {
            if ( colors == null ) {
                tex = new Texture2D(textureWidth,textureWidth);
                //mat.mainTexture = tex;
                colors = new Color[tex.width*tex.height];
            }

            int x = Mathf.RoundToInt (p.x*tex.width/textureSize);
            int y = Mathf.RoundToInt (p.y*tex.height/textureSize);

            if ( x >= 0 && y >= 0 && x < tex.width && y < tex.height ) {
                dirtyColors = true;
                colors[x+y*tex.width] = col;
            }
        }*/

        /** Removes all agents from the simulation */
        public void ClearAgents () {

            //Bad to update agents while processing of current agents might be done
            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            for (int i=0;i<agents.Count;i++) {
                agents[i].simulator = null;
            }
            agents.Clear ();

#if !AstarRelease
            if (kdTree != null ) kdTree.RebuildAgents ();
#endif
        }

        public void OnDestroy () {
            if (workers != null) {
                for (int i=0;i<workers.Length;i++) workers[i].Terminate ();
            }
        }

        /** Terminates any worker threads */
        ~Simulator () {
            OnDestroy ();
        }

        /** Add a previously removed agent to the simulation.
          * An agent can only be in one simulation at a time, any attempt to add an agent to two simulations
          * or multiple times to the same simulation will result in an exception being thrown.
          *
          * \see RemoveAgent
          */
        public IAgent AddAgent (IAgent agent) {
            if (agent == null) throw new System.ArgumentNullException ("Agent must not be null");

            Agent agentReal = agent as Agent;
            if (agentReal == null) throw new System.ArgumentException ("The agent must be of type Agent. Agent was of type "+agent.GetType ());


            if (agentReal.simulator != null && agentReal.simulator == this) throw new System.ArgumentException ("The agent is already in the simulation");
            else if (agentReal.simulator != null) throw new System.ArgumentException ("The agent is already added to another simulation");
            agentReal.simulator = this;

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            agents.Add (agentReal);

#if !AstarRelease
            if ( kdTree != null ) kdTree.RebuildAgents ();
#endif

            return agent;
        }

        /** Add an agent at the specified position.
         * You can use the returned interface to read several parameters such as position and velocity
         * and set for example radius and desired velocity.
         *
         * \see RemoveAgent
         */
        public IAgent AddAgent (Vector3 position) {

            Agent agent = new Agent (position);

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            agents.Add (agent);
#if !AstarRelease
            if ( kdTree != null ) kdTree.RebuildAgents ();
#endif
            agent.simulator = this;

            return agent;
        }

        /** Removes a specified agent from this simulation.
         * The agent can be added again later by using AddAgent.
         *
         * \see AddAgent(IAgent)
         * \see ClearAgents
         */
        public void RemoveAgent (IAgent agent) {
            if (agent == null) throw new System.ArgumentNullException ("Agent must not be null");

            Agent agentReal = agent as Agent;
            if (agentReal == null) throw new System.ArgumentException ("The agent must be of type Agent. Agent was of type "+agent.GetType ());

            if (agentReal.simulator != this) throw new System.ArgumentException ("The agent is not added to this simulation");

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            agentReal.simulator = null;

            if (!agents.Remove (agentReal)) {
                throw new System.ArgumentException ("Critical Bug! This should not happen. Please report this.");
            }
        }

        /** Adds a previously removed obstacle.
         * This does not check if the obstacle is already added to the simulation, so please do not add an obstacle multiple times.
         *
         * It is assumed that this is a valid obstacle.
         */
        public ObstacleVertex AddObstacle (ObstacleVertex v) {
            if (v == null) throw new System.ArgumentNullException ("Obstacle must not be null");

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            obstacles.Add (v);
            UpdateObstacles ();
            return v;
        }

        /** Adds an obstacle described by the vertices.
         *
         * \see RemoveObstacle
         */
        public ObstacleVertex AddObstacle (Vector3[] vertices, float height) {

            return AddObstacle (vertices, height, Matrix4x4.identity);

            /*if (vertices == null) throw new System.ArgumentNullException ("Vertices must not be null");

            if (vertices.Length < 2) throw new System.ArgumentException ("Less than 2 vertices in an obstacle");

            ObstacleVertex first = null;
            ObstacleVertex prev = null;

            for (int i=0;i<vertices.Length;i++) {
                ObstacleVertex v = new ObstacleVertex();
                if (first == null) first = v;
                else prev.next = v;

                v.prev = prev;
                v.position = vertices[i];
                //v.thin = thin;
                v.height = height;
                prev = v;
            }

            prev.next = first;
            first.prev = prev;

            ObstacleVertex c = first;
            do {
                Vector3 dir = c.next.position - c.position;
                v.dir =  new Vector2 (dir.x,dir.z).normalized;

                if (vertices.Length == 2) {
                    v.convex = true;
                } else {
                    v.convex = Polygon.IsClockwiseMargin (c.prev.position,c.position, c.next.position);
                }

                c = c.next;
            } while (c != first);

            obstacles.Add (first);

            UpdateObstacles ();
            return first;*/
        }

        /** Adds an obstacle described by the vertices.
         *
         * \see RemoveObstacle
         */
        public ObstacleVertex AddObstacle (Vector3[] vertices, float height, Matrix4x4 matrix) {

            if (vertices == null) throw new System.ArgumentNullException ("Vertices must not be null");

            if (vertices.Length < 2) throw new System.ArgumentException ("Less than 2 vertices in an obstacle");

            ObstacleVertex first = null;
            ObstacleVertex prev = null;

            bool identity = matrix == Matrix4x4.identity;

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            for (int i=0;i<vertices.Length;i++) {
                ObstacleVertex v = new ObstacleVertex();
                if (first == null) first = v;
                else prev.next = v;

                v.prev = prev;

                //Premature optimization ftw!
                v.position = identity ? vertices[i] : matrix.MultiplyPoint3x4(vertices[i]);

                //v.thin = thin;
                v.height = height;

                prev = v;
            }

            prev.next = first;
            first.prev = prev;

            ObstacleVertex c = first;
            do {
                Vector3 dir = c.next.position - c.position;
                c.dir = new Vector2 (dir.x,dir.z).normalized;

                if (vertices.Length == 2) {
                    c.convex = true;
                } else {
                    c.convex = Polygon.IsClockwiseMargin (c.next.position,c.position, c.prev.position);
                }

                c = c.next;
            } while (c != first);

            obstacles.Add (first);

            UpdateObstacles ();
            return first;
        }

        /**
         * Adds a line obstacle with a specified height.
         *
         * \see RemoveObstacle
         */
        public ObstacleVertex AddObstacle (Vector3 a, Vector3 b, float height) {
            ObstacleVertex first = new ObstacleVertex ();
            ObstacleVertex second = new ObstacleVertex ();

            first.prev = second;
            second.prev = first;
            first.next = second;
            second.next = first;

            first.position = a;
            second.position = b;
            first.height = height;
            second.height = height;

            first.convex = true;
            second.convex = true;

            first.dir = new Vector2 (b.x-a.x,b.z-a.z).normalized;
            second.dir = -first.dir;

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            obstacles.Add (first);

            UpdateObstacles ();
            return first;
        }

        /** Updates the vertices of an obstacle.
         * \param obstacle %Obstacle to update
         * \param vertices New vertices for the obstacle, must have at least the number of vertices in the original obstacle
         * \param matrix %Matrix to multiply vertices with before updating obstacle
         *
         * The number of vertices in an obstacle cannot be changed, existing vertices can only be moved.
         */
        public void UpdateObstacle (ObstacleVertex obstacle, Vector3[] vertices, Matrix4x4 matrix) {

            if (vertices == null) throw new System.ArgumentNullException ("Vertices must not be null");
            if (obstacle == null) throw new System.ArgumentNullException ("Obstacle must not be null");

            if (vertices.Length < 2) throw new System.ArgumentException ("Less than 2 vertices in an obstacle");

            if (obstacle.split) throw new System.ArgumentException ("Obstacle is not a start vertex. You should only pass those ObstacleVertices got from AddObstacle method calls");

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            //Compact obstacle and count
            int count = 0;

            ObstacleVertex c = obstacle;
            do {
                while (c.next.split) {
                    c.next = c.next.next;
                    c.next.prev = c;
                }

                if (count >= vertices.Length) {
                    Debug.DrawLine (c.prev.position, c.position,Color.red);
                    throw new System.ArgumentException ("Obstacle has more vertices than supplied for updating (" + vertices.Length+ " supplied)");
                }
                c.position = matrix.MultiplyPoint3x4 (vertices[count]);
                count++;
                c = c.next;
            } while (c != obstacle);

            c = obstacle;
            do {
                Vector3 dir = c.next.position - c.position;
                c.dir =  new Vector2 (dir.x,dir.z).normalized;

                if (vertices.Length == 2) {
                    c.convex = true;
                } else {
                    c.convex = Polygon.IsClockwiseMargin (c.next.position,c.position, c.prev.position);
                }

                c = c.next;
            } while (c != obstacle);

            ScheduleCleanObstacles ();
            UpdateObstacles();
        }

        private void ScheduleCleanObstacles () {
            doCleanObstacles = true;
        }

        private void CleanObstacles () {

            for (int i=0;i<obstacles.Count;i++) {
                ObstacleVertex first = obstacles[i];
                ObstacleVertex c = first;
                do {
                    while (c.next.split) {
                        c.next = c.next.next;
                        c.next.prev = c;
                    }
                    c = c.next;
                } while (c != first);
            }
        }

        /** Removes the obstacle identified by the vertex.
          * This must be the same vertex as the one returned by the AddObstacle call.
          *
          * \see AddObstacle
          */
        public void RemoveObstacle (ObstacleVertex v) {
            if (v == null) throw new System.ArgumentNullException ("Vertex must not be null");

            //Don't interfere with ongoing calculations
            if (Multithreading && doubleBuffering) for (int j=0;j<workers.Length;j++) workers[j].WaitOne();

            obstacles.Remove (v);
            UpdateObstacles ();
        }

        /** Rebuilds the obstacle tree at next simulation frame.
         * Add and remove obstacle functions call this automatically.
         */
        public void UpdateObstacles () {
            //Update obstacles at next frame
            doUpdateObstacles = true;
        }

        void BuildQuadtree () {
            quadtree.Clear ();
            if ( agents.Count > 0 ) {
                Rect bounds = Rect.MinMaxRect (agents[0].position.x, agents[0].position.y, agents[0].position.x, agents[0].position.y);
                for ( int i = 1; i < agents.Count; i++ ) {
                    Vector3 p = agents[i].position;
                    bounds = Rect.MinMaxRect ( Mathf.Min(bounds.xMin, p.x), Mathf.Min(bounds.yMin, p.z), Mathf.Max(bounds.xMax, p.x), Mathf.Max(bounds.yMax, p.z) );
                }
                quadtree.SetBounds (bounds);

                for (int i=0;i<agents.Count;i++) {
                    quadtree.Insert (agents[i]);
                }

                //quadtree.DebugDraw ();
            }
        }

        private WorkerContext coroutineWorkerContext = new WorkerContext();

        /** Should be called once per frame */
        public void Update () {

            //Initialize last step
            if (lastStep < 0) {
                lastStep = Time.time;
                deltaTime = DesiredDeltaTime;
                lastStepInterpolationReference = lastStep;
            }

            if (Time.time - lastStep >= DesiredDeltaTime) {

                prevDeltaTime = DeltaTime;
                deltaTime = Time.time - lastStep;
                lastStep = Time.time;

                frameTimeBufferIndex++;
                frameTimeBufferIndex %= frameTimeBuffer.Length;
                frameTimeBuffer[frameTimeBufferIndex] = deltaTime;

                // Implements averaging of delta times
                // Disabled for now because it seems to have caused more issues than it solved
                // Might re-enable later
                /*float sum = 0;
                float mn = float.PositiveInfinity;
                float mx = float.NegativeInfinity;
                for (int i=0;i<frameTimeBuffer.Length;i++) {
                    sum += frameTimeBuffer[i];
                    mn = Mathf.Min (mn, frameTimeBuffer[i]);
                    mx = Mathf.Max (mx, frameTimeBuffer[i]);
                }
                sum -= mn;
                sum -= mx;
                sum /= (frameTimeBuffer.Length-2);
                sum = frame
                deltaTime = sum;*/

                //Calculate smooth delta time
                //Disabled because it seemed to cause more problems than it solved
                //deltaTime = (Time.time - frameTimeBuffer[(frameTimeBufferIndex-1+frameTimeBuffer.Length)%frameTimeBuffer.Length]) / frameTimeBuffer.Length;

                //Prevent a zero delta time
                deltaTime = System.Math.Max (deltaTime, 1.0f/2000f);

                // Time reference for the interpolation
                // If delta time would not be subtracted, the character would have a zero velocity
                // during all frames when the velocity was recalculated
                lastStepInterpolationReference = lastStep - Time.deltaTime;

                if (Multithreading) {

                    if (doubleBuffering) {
                        for (int i=0;i<workers.Length;i++) workers[i].WaitOne();
                        if (!Interpolation) for (int i=0;i<agents.Count;i++) agents[i].Interpolate (1.0f);
                    }


                    if (doCleanObstacles) {
                        CleanObstacles();
                        doCleanObstacles = false;
                        doUpdateObstacles = true;
                    }

                    if (doUpdateObstacles) {
                        doUpdateObstacles = false;
#if !AstarRelease
                        if ( kdTree != null ) kdTree.BuildObstacleTree ();
#endif
                    }


                    BuildQuadtree ();

                    for (int i=0;i<workers.Length;i++) {
                        workers[i].start = i*agents.Count / workers.Length;
                        workers[i].end = (i+1)*agents.Count / workers.Length;
                    }

                    //Update
                    //BufferSwitch
                    for (int i=0;i<workers.Length;i++) workers[i].Execute (1);
                    for (int i=0;i<workers.Length;i++) workers[i].WaitOne();

                    //Calculate New Velocity
                    for (int i=0;i<workers.Length;i++) workers[i].Execute (0);

                    if (!doubleBuffering) {
                        for (int i=0;i<workers.Length;i++) workers[i].WaitOne();
                        if (!Interpolation) for (int i=0;i<agents.Count;i++) agents[i].Interpolate (1.0f);
                    }
                } else {

                    if (doCleanObstacles) {
                        CleanObstacles();
                        doCleanObstacles = false;
                        doUpdateObstacles = true;
                    }

                    if (doUpdateObstacles) {
                        doUpdateObstacles = false;
#if !AstarRelease
                        if ( kdTree != null ) kdTree.BuildObstacleTree ();
#endif
                    }

                    BuildQuadtree ();

                    for (int i=0;i<agents.Count;i++) {
                        agents[i].Update ();
                        agents[i].BufferSwitch ();
                    }


                    for (int i=0;i<agents.Count;i++) {
                        agents[i].CalculateNeighbours ();
                        agents[i].CalculateVelocity ( coroutineWorkerContext );
                    }

                    if ( oversampling ) {
                        for (int i=0;i<agents.Count;i++) {
                            agents[i].Velocity = agents[i].newVelocity;
                        }

                        for (int i=0;i<agents.Count;i++) {
                            Vector3 vel = agents[i].newVelocity;
                            agents[i].CalculateVelocity ( coroutineWorkerContext );
                            agents[i].newVelocity = (vel + agents[i].newVelocity)*0.5f;
                        }
                    }

                    if (!Interpolation) for (int i=0;i<agents.Count;i++) agents[i].Interpolate (1.0f);
                }
            }

            lastFrame = Time.time;

            if (Interpolation) {
                for (int i=0;i<agents.Count;i++) {
                    agents[i].Interpolate ((Time.time - lastStepInterpolationReference)/DeltaTime);
                }
            }
        }

        internal class WorkerContext {
            public Agent.VO[] vos = new Agent.VO[20];

            public const int KeepCount = 3;
            public Vector2[] bestPos = new Vector2[KeepCount];
            public float[] bestSizes = new float[KeepCount];
            public float[] bestScores = new float[KeepCount+1];

            public Vector2[] samplePos = new Vector2[50];
            public float[] sampleSize = new float[50];

        }

        private class Worker {
            public Thread thread;
            public int start, end;
            public int task = 0;

            public AutoResetEvent runFlag = new AutoResetEvent(false);

            public ManualResetEvent waitFlag = new ManualResetEvent(true);

            public Simulator simulator;

            private bool terminate = false;

            private WorkerContext context = new WorkerContext();

            public Worker (Simulator sim) {
                this.simulator = sim;
                thread = new Thread (new ThreadStart (Run));
                thread.IsBackground = true;
                thread.Name = "RVO Simulator Thread";
                thread.Start ();
            }

            public void Execute (int task) {
                this.task = task;
                waitFlag.Reset ();
                runFlag.Set ();
            }

            public void WaitOne () {
                waitFlag.WaitOne ();
            }

            public void Terminate () {
                terminate = true;
            }

            public void Run () {

                runFlag.WaitOne ();

                while (!terminate) {
                    try {
                        List<Agent> agents = simulator.GetAgents ();
                        if (task == 0) {
                            for (int i=start;i<end;i++) {
                                agents[i].CalculateNeighbours ();
                                agents[i].CalculateVelocity ( context );
                            }

                        } else if (task == 1) {
                            for (int i=start;i<end;i++) {
                                agents[i].Update ();
                                agents[i].BufferSwitch ();
                            }
                        } else if ( task  == 2 ) {
                            simulator.BuildQuadtree ();
                        /*} else if (task == 2) {
                            for (int i=start;i<end;i++) {
                                agents[i].BufferSwitch ();
                            }*/
                        } else {
                            Debug.LogError ("Invalid Task Number: " + task);
                            throw new System.Exception ("Invalid Task Number: " + task);
                        }
                    } catch (System.Exception e) {
                        Debug.LogError (e);
                    }
                    waitFlag.Set ();
                    runFlag.WaitOne ();
                }
            }
        }
    }
}