random-walk-2d-outdoor-mobility-model.cc

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2006,2007 INRIA
 * Copyright (c) 2019 University of Padova
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
 * Author: Michele Polese <michele.polese@gmail.com>
 */
#include "random-walk-2d-outdoor-mobility-model.h"
#include "ns3/enum.h"
#include "ns3/double.h"
#include "ns3/uinteger.h"
#include "ns3/string.h"
#include "ns3/pointer.h"
#include "ns3/simulator.h"
#include "ns3/log.h"
#include "ns3/building.h"
#include "ns3/building-list.h"
#include <cmath>

namespace ns3 {

NS_LOG_COMPONENT_DEFINE ("RandomWalk2dOutdoor");

NS_OBJECT_ENSURE_REGISTERED (RandomWalk2dOutdoorMobilityModel);

TypeId
RandomWalk2dOutdoorMobilityModel::GetTypeId (void)
{
  static TypeId tid = TypeId ("ns3::RandomWalk2dOutdoorMobilityModel")
    .SetParent<MobilityModel> ()
    .SetGroupName ("Mobility")
    .AddConstructor<RandomWalk2dOutdoorMobilityModel> ()
    .AddAttribute ("Bounds",
                   "Bounds of the area to cruise.",
                   RectangleValue (Rectangle (0.0, 100.0, 0.0, 100.0)),
                   MakeRectangleAccessor (&RandomWalk2dOutdoorMobilityModel::m_bounds),
                   MakeRectangleChecker ())
    .AddAttribute ("Time",
                   "Change current direction and speed after moving for this delay.",
                   TimeValue (Seconds (20.0)),
                   MakeTimeAccessor (&RandomWalk2dOutdoorMobilityModel::m_modeTime),
                   MakeTimeChecker ())
    .AddAttribute ("Distance",
                   "Change current direction and speed after moving for this distance.",
                   DoubleValue (30.0),
                   MakeDoubleAccessor (&RandomWalk2dOutdoorMobilityModel::m_modeDistance),
                   MakeDoubleChecker<double> ())
    .AddAttribute ("Mode",
                   "The mode indicates the condition used to "
                   "change the current speed and direction",
                   EnumValue (RandomWalk2dOutdoorMobilityModel::MODE_DISTANCE),
                   MakeEnumAccessor (&RandomWalk2dOutdoorMobilityModel::m_mode),
                   MakeEnumChecker (RandomWalk2dOutdoorMobilityModel::MODE_DISTANCE, "Distance",
                                    RandomWalk2dOutdoorMobilityModel::MODE_TIME, "Time"))
    .AddAttribute ("Direction",
                   "A random variable used to pick the direction (radians).",
                   StringValue ("ns3::UniformRandomVariable[Min=0.0|Max=6.283184]"),
                   MakePointerAccessor (&RandomWalk2dOutdoorMobilityModel::m_direction),
                   MakePointerChecker<RandomVariableStream> ())
    .AddAttribute ("Speed",
                   "A random variable used to pick the speed (m/s)."
                   "The default value is taken from Figure 1 of the paper"
                   "Henderson, L.F., 1971. The statistics of crowd fluids. nature, 229(5284), p.381.",
                   StringValue ("ns3::NormalRandomVariable[Mean=1.53|Variance=0.040401]"),
                   MakePointerAccessor (&RandomWalk2dOutdoorMobilityModel::m_speed),
                   MakePointerChecker<RandomVariableStream> ())
    .AddAttribute ("Tolerance",
                   "Tolerance for the intersection point with buildings (m)."
                   "It represents a small distance from where the building limit"
                   "is actually placed, for example to represent a sidewalk.",
                   DoubleValue (1e-6),
                   MakeDoubleAccessor (&RandomWalk2dOutdoorMobilityModel::m_epsilon),
                   MakeDoubleChecker<double> ())
    .AddAttribute ("MaxIterations",
                   "Maximum number of attempts to find an alternative next position"
                   "if the original one is inside a building.",
                   UintegerValue (100),
                   MakeUintegerAccessor (&RandomWalk2dOutdoorMobilityModel::m_maxIter),
                   MakeUintegerChecker<uint32_t> ())
  ;
  return tid;
}

void
RandomWalk2dOutdoorMobilityModel::DoInitialize (void)
{
  DoInitializePrivate ();
  MobilityModel::DoInitialize ();
}

void
RandomWalk2dOutdoorMobilityModel::DoInitializePrivate (void)
{
  m_helper.Update ();
  double speed = m_speed->GetValue ();
  double direction = m_direction->GetValue ();
  Vector vector (std::cos (direction) * speed,
                 std::sin (direction) * speed,
                 0.0);
  m_helper.SetVelocity (vector);
  m_helper.Unpause ();

  Time delayLeft;
  if (m_mode == RandomWalk2dOutdoorMobilityModel::MODE_TIME)
    {
      delayLeft = m_modeTime;
    }
  else
    {
      delayLeft = Seconds (m_modeDistance / speed);
    }
  DoWalk (delayLeft);
}

void
RandomWalk2dOutdoorMobilityModel::DoWalk (Time delayLeft)
{
  NS_LOG_FUNCTION (this << delayLeft.GetSeconds ());

  Vector position = m_helper.GetCurrentPosition ();
  Vector speed = m_helper.GetVelocity ();
  Vector nextPosition = position;
  nextPosition.x += speed.x * delayLeft.GetSeconds ();
  nextPosition.y += speed.y * delayLeft.GetSeconds ();
  m_event.Cancel ();

  // check if the nextPosition is inside a building, or if the line
  // from position to the next position intersects a building
  auto outdoorBuilding = IsLineClearOfBuildings (position, nextPosition);
  bool outdoor = std::get<0> (outdoorBuilding);
  Ptr<Building> building = std::get<1> (outdoorBuilding);

  if (m_bounds.IsInside (nextPosition))
    {
      if (outdoor)
        {
          m_event = Simulator::Schedule (delayLeft, &RandomWalk2dOutdoorMobilityModel::DoInitializePrivate, this);
        }
      else
        {
          NS_LOG_LOGIC ("NextPosition would lead into a building");
          nextPosition = CalculateIntersectionFromOutside (position, nextPosition, building->GetBoundaries ());
          Time delay = Seconds ((nextPosition.x - position.x) / speed.x);
          m_event = Simulator::Schedule (delay, &RandomWalk2dOutdoorMobilityModel::AvoidBuilding, this,
                                         delayLeft - delay,
                                         nextPosition
                                         );
        }
    }
  else
    {
      NS_LOG_LOGIC ("Out of bounding box");
      nextPosition = m_bounds.CalculateIntersection (position, speed);
      // check that this nextPosition is outdoor
      auto outdoorBuilding = IsLineClearOfBuildings (position, nextPosition);
      bool outdoor = std::get<0> (outdoorBuilding);
      Ptr<Building> building = std::get<1> (outdoorBuilding);

      if (outdoor)
        {
          Time delay = Seconds ((nextPosition.x - position.x) / speed.x);
          m_event = Simulator::Schedule (delay, &RandomWalk2dOutdoorMobilityModel::Rebound, this,
                                         delayLeft - delay);
        }
      else
        {
          NS_LOG_LOGIC ("NextPosition would lead into a building");
          nextPosition = CalculateIntersectionFromOutside (position, nextPosition, building->GetBoundaries ());
          Time delay = Seconds ((nextPosition.x - position.x) / speed.x);
          m_event = Simulator::Schedule (delay, &RandomWalk2dOutdoorMobilityModel::AvoidBuilding, this,
                                         delayLeft - delay,
                                         nextPosition
                                         );
        }
    }
  NS_LOG_LOGIC ("Position " << position << " NextPosition " << nextPosition);

  // store the previous position
  m_prevPosition = position;
  NotifyCourseChange ();
}

std::pair<bool, Ptr<Building> >
RandomWalk2dOutdoorMobilityModel::IsLineClearOfBuildings ( Vector currentPosition, Vector nextPosition ) const
{
  NS_LOG_FUNCTION (this << currentPosition << nextPosition);

  bool intersectBuilding = false;
  double minIntersectionDistance = std::numeric_limits<double>::max ();
  Ptr<Building> minIntersectionDistanceBuilding;

  for (BuildingList::Iterator bit = BuildingList::Begin (); bit != BuildingList::End (); ++bit)
    {
      // check if this building intersects the line between the current and next positions
      // this checks also if the next position is inside the building
      if ((*bit)->IsIntersect (currentPosition, nextPosition))
        {
          NS_LOG_LOGIC ("Building " << (*bit)->GetBoundaries ()
                                    << " intersects the line between " << currentPosition
                                    << " and " << nextPosition);
          auto intersection = CalculateIntersectionFromOutside (
            currentPosition, nextPosition, (*bit)->GetBoundaries ());
          double distance = CalculateDistance (intersection, currentPosition);
          intersectBuilding = true;
          if (distance < minIntersectionDistance)
            {
              minIntersectionDistance = distance;
              minIntersectionDistanceBuilding = (*bit);
            }
        }
    }

  return std::make_pair (!intersectBuilding, minIntersectionDistanceBuilding);
}

Vector
RandomWalk2dOutdoorMobilityModel::CalculateIntersectionFromOutside (const Vector &current, const Vector &next, Box boundaries) const
{
  NS_LOG_FUNCTION (this << " current " << current << " next " << next);
  bool inside = boundaries.IsInside (current);
  NS_ASSERT (!inside);

  // get the closest side
  Rectangle rect = Rectangle (boundaries.xMin, boundaries.xMax, boundaries.yMin, boundaries.yMax);
  NS_LOG_INFO ("rect " << rect);
  Rectangle::Side closestSide = rect.GetClosestSide (current);

  double xIntersect  = 0;
  double yIntersect = 0;

  switch (closestSide)
    {
      case Rectangle::RIGHT:
        NS_LOG_INFO ("The closest side is RIGHT");
        NS_ABORT_MSG_IF (next.x - current.x == 0, "x position not updated");
        xIntersect = boundaries.xMax + m_epsilon;
        yIntersect =
          (next.y - current.y) / (next.x - current.x) * (xIntersect - current.x) + current.y;
        break;
      case Rectangle::LEFT:
        NS_LOG_INFO ("The closest side is LEFT");
        xIntersect = boundaries.xMin - m_epsilon;
        NS_ABORT_MSG_IF (next.x - current.x == 0, "x position not updated");
        yIntersect =
          (next.y - current.y) / (next.x - current.x) * (xIntersect - current.x) + current.y;
        break;
      case Rectangle::TOP:
        NS_LOG_INFO ("The closest side is TOP");
        yIntersect = boundaries.yMax + m_epsilon;
        NS_ABORT_MSG_IF (next.y - current.y == 0, "y position not updated");
        xIntersect =
          (next.x - current.x) / (next.y - current.y) * (yIntersect - current.y) + current.x;
        break;
      case Rectangle::BOTTOM:
        NS_LOG_INFO ("The closest side is BOTTOM");
        yIntersect = boundaries.yMin - m_epsilon;
        NS_ABORT_MSG_IF (next.y - current.y == 0, "y position not updated");
        xIntersect =
          (next.x - current.x) / (next.y - current.y) * (yIntersect - current.y) + current.x;
        break;
    }
  NS_LOG_INFO ("xIntersect " << xIntersect << " yIntersect " << yIntersect);
  return Vector (xIntersect, yIntersect, 0);
}

void
RandomWalk2dOutdoorMobilityModel::Rebound (Time delayLeft)
{
  NS_LOG_FUNCTION (this << delayLeft.GetSeconds ());
  m_helper.UpdateWithBounds (m_bounds);
  Vector position = m_helper.GetCurrentPosition ();
  Vector speed = m_helper.GetVelocity ();
  switch (m_bounds.GetClosestSide (position))
    {
      case Rectangle::RIGHT:
        NS_LOG_INFO ("The closest side is RIGHT");
      case Rectangle::LEFT:
        NS_LOG_INFO ("The closest side is LEFT");
        speed.x = -speed.x;
        break;
      case Rectangle::TOP:
        NS_LOG_INFO ("The closest side is TOP");
      case Rectangle::BOTTOM:
        NS_LOG_INFO ("The closest side is BOTTOM");
        speed.y = -speed.y;
        break;
    }
  m_helper.SetVelocity (speed);
  m_helper.Unpause ();
  DoWalk (delayLeft);
}

void
RandomWalk2dOutdoorMobilityModel::AvoidBuilding (Time delayLeft, Vector intersectPosition)
{
  NS_LOG_FUNCTION (this << delayLeft.GetSeconds ());
  m_helper.Update ();

  bool nextWouldBeInside = true;
  uint32_t iter = 0;

  while (nextWouldBeInside && iter < m_maxIter)
    {
      NS_LOG_INFO ("The next position would be inside a building, compute an alternative");
      iter++;
      double speed = m_speed->GetValue ();
      double direction = m_direction->GetValue ();
      Vector velocityVector (std::cos (direction) * speed,
                             std::sin (direction) * speed,
                             0.0);
      m_helper.SetVelocity (velocityVector);

      Vector nextPosition = intersectPosition;
      nextPosition.x += velocityVector.x * delayLeft.GetSeconds ();
      nextPosition.y += velocityVector.y * delayLeft.GetSeconds ();

      // check if this is inside the current buildingBox
      auto outdoorBuilding = IsLineClearOfBuildings (intersectPosition, nextPosition);
      bool outdoor = std::get<0> (outdoorBuilding);

      if (!outdoor)
        {
          NS_LOG_LOGIC ("inside loop intersect " << intersectPosition << " nextPosition "
                                                 << nextPosition << " " << outdoor << " building " << std::get<1> (outdoorBuilding)->GetBoundaries ());
        }
      else
        {
          NS_LOG_LOGIC ("inside loop intersect " << intersectPosition << " nextPosition "
                                                 << nextPosition << " " << outdoor);
        }

      if (outdoor && m_bounds.IsInside (nextPosition))
        {
          nextWouldBeInside = false;
        }
    }

  // after m_maxIter iterations, the positions tested are all inside
  // to avoid increasing m_maxIter too much, it is possible to perform a step back
  // to the previous position and continue from there
  if (iter >= m_maxIter)
    {
      NS_LOG_INFO ("Move back to the previous position");

      // compute the difference between the previous position and the intersection
      Vector posDiff = m_prevPosition - intersectPosition;
      // compute the distance
      double distance = CalculateDistance (m_prevPosition, intersectPosition);
      double speed = distance / delayLeft.GetSeconds (); // compute the speed

      NS_LOG_LOGIC ("prev " << m_prevPosition
                            << " intersectPosition " << intersectPosition
                            << " diff " << posDiff << " dist " << distance
                    );

      Vector velocityVector (posDiff.x / distance * speed,
                             posDiff.y / distance * speed,
                             0.0);
      m_helper.SetVelocity (velocityVector);

      Vector nextPosition = intersectPosition;
      nextPosition.x += velocityVector.x * delayLeft.GetSeconds ();
      nextPosition.y += velocityVector.y * delayLeft.GetSeconds ();

      // check if the path is clear
      auto outdoorBuilding = IsLineClearOfBuildings (intersectPosition, nextPosition);
      bool outdoor = std::get<0> (outdoorBuilding);
      if (!outdoor)
        {
          NS_LOG_LOGIC ("The position is still inside after "
                        << m_maxIter + 1 << " iterations, loop intersect "
                        << intersectPosition << " nextPosition "
                        << nextPosition << " " << outdoor
                        << " building " << std::get<1> (outdoorBuilding)->GetBoundaries ());
          // This error may be due to buildings being attached to one another, or to the boundary of the scenario.
          NS_FATAL_ERROR ("Not able to find an outdoor position. Try to increase the attribute MaxIterations and check the position of the buildings in the scenario.");
        }
      else
        {
          NS_LOG_LOGIC ("inside loop intersect " << intersectPosition << " nextPosition "
                                                 << nextPosition << " " << outdoor);
        }
    }

  m_helper.Unpause ();

  DoWalk (delayLeft);
}

void
RandomWalk2dOutdoorMobilityModel::DoDispose (void)
{
  // chain up
  MobilityModel::DoDispose ();
}
Vector
RandomWalk2dOutdoorMobilityModel::DoGetPosition (void) const
{
  m_helper.UpdateWithBounds (m_bounds);
  return m_helper.GetCurrentPosition ();
}
void
RandomWalk2dOutdoorMobilityModel::DoSetPosition (const Vector &position)
{
  NS_ASSERT (m_bounds.IsInside (position));
  m_helper.SetPosition (position);
  Simulator::Remove (m_event);
  m_event = Simulator::ScheduleNow (&RandomWalk2dOutdoorMobilityModel::DoInitializePrivate, this);
}
Vector
RandomWalk2dOutdoorMobilityModel::DoGetVelocity (void) const
{
  return m_helper.GetVelocity ();
}
int64_t
RandomWalk2dOutdoorMobilityModel::DoAssignStreams (int64_t stream)
{
  m_speed->SetStream (stream);
  m_direction->SetStream (stream + 1);
  return 2;
}


} // namespace ns3