Program Listing for File obstacles.cpp

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#include <hateb_local_planner/obstacles.h>
#include <ros/assert.h>
#include <ros/console.h>
// #include <hateb_local_planner/misc.h>

namespace hateb_local_planner {

void PolygonObstacle::fixPolygonClosure() {
  if (vertices_.size() < 2) {
    return;
  }

  if (vertices_.front().isApprox(vertices_.back())) {
    vertices_.pop_back();
  }
}

void PolygonObstacle::calcCentroid() {
  if (vertices_.empty()) {
    centroid_.setConstant(NAN);
    ROS_WARN("PolygonObstacle::calcCentroid(): number of vertices is empty. the resulting centroid is a vector of NANs.");
    return;
  }

  // if polygon is a point
  if (noVertices() == 1) {
    centroid_ = vertices_.front();
    return;
  }

  // if polygon is a line:
  if (noVertices() == 2) {
    centroid_ = 0.5 * (vertices_.front() + vertices_.back());
    return;
  }

  // otherwise:

  centroid_.setZero();

  // calculate centroid (see wikipedia http://de.wikipedia.org/wiki/Geometrischer_Schwerpunkt#Polygon)
  double A = 0;  // A = 0.5 * sum_0_n-1 (x_i * y_{i+1} - x_{i+1} * y_i)
  for (int i = 0; i < noVertices() - 1; ++i) {
    A += vertices_.at(i).coeffRef(0) * vertices_.at(i + 1).coeffRef(1) - vertices_.at(i + 1).coeffRef(0) * vertices_.at(i).coeffRef(1);
  }
  A += vertices_.at(noVertices() - 1).coeffRef(0) * vertices_.at(0).coeffRef(1) - vertices_.at(0).coeffRef(0) * vertices_.at(noVertices() - 1).coeffRef(1);
  A *= 0.5;

  if (A != 0) {
    for (int i = 0; i < noVertices() - 1; ++i) {
      double aux = ((vertices_.at(i).coeffRef(0) * vertices_.at(i + 1).coeffRef(1)) - (vertices_.at(i + 1).coeffRef(0) * vertices_.at(i).coeffRef(1)));
      centroid_ += (vertices_.at(i) + vertices_.at(i + 1)) * aux;
    }
    double aux = ((vertices_.at(noVertices() - 1).coeffRef(0) * vertices_.at(0).coeffRef(1)) - (vertices_.at(0).coeffRef(0) * vertices_.at(noVertices() - 1).coeffRef(1)));
    centroid_ += (vertices_.at(noVertices() - 1) + vertices_.at(0)) * aux;
    centroid_ /= (6 * A);
  } else  // A == 0 -> all points are placed on a 'perfect' line
  {
    // seach for the two outer points of the line with the maximum distance inbetween
    int i_cand = 0;
    int j_cand = 0;
    double max_dist = 0;
    for (int i = 0; i < noVertices(); ++i) {
      for (int j = i + 1; j < noVertices(); ++j)  // start with j=i+1
      {
        double dist = (vertices_[j] - vertices_[i]).norm();
        if (dist > max_dist) {
          max_dist = dist;
          i_cand = i;
          j_cand = j;
        }
      }
    }
    // calc centroid of that line
    centroid_ = 0.5 * (vertices_[i_cand] + vertices_[j_cand]);
  }
}

Eigen::Vector2d PolygonObstacle::getClosestPoint(const Eigen::Vector2d& position) const {
  // the polygon is a point
  if (noVertices() == 1) {
    return vertices_.front();
  }

  if (noVertices() > 1) {
    Eigen::Vector2d new_pt = closest_point_on_line_segment_2d(position, vertices_.at(0), vertices_.at(1));

    if (noVertices() > 2) {  // real polygon and not a line
      double dist = (new_pt - position).norm();
      Eigen::Vector2d closest_pt = new_pt;

      // check each polygon edge
      for (int i = 1; i < noVertices() - 1; ++i)  // skip the first one, since we already checked it (new_pt)
      {
        new_pt = closest_point_on_line_segment_2d(position, vertices_.at(i), vertices_.at(i + 1));
        double new_dist = (new_pt - position).norm();
        if (new_dist < dist) {
          dist = new_dist;
          closest_pt = new_pt;
        }
      }
      // afterwards we check the edge between goal and start (close polygon)
      new_pt = closest_point_on_line_segment_2d(position, vertices_.back(), vertices_.front());
      double new_dist = (new_pt - position).norm();
      if (new_dist < dist) {
        return new_pt;
      }
      return closest_pt;
    }
    return new_pt;  // closest point on line segment
  }

  ROS_ERROR("PolygonObstacle::getClosestPoint() cannot find any closest point. Polygon ill-defined?");
  return Eigen::Vector2d::Zero();  // todo: maybe boost::optional?
}

bool PolygonObstacle::checkLineIntersection(const Eigen::Vector2d& line_start, const Eigen::Vector2d& line_end, double min_dist) const {
  // Simple strategy, check all edge-line intersections until an intersection is found...
  // check each polygon edge
  for (int i = 0; i < noVertices() - 1; ++i) {
    if (check_line_segments_intersection_2d(line_start, line_end, vertices_.at(i), vertices_.at(i + 1))) {
      return true;
    }
  }
  if (noVertices() == 2)  // if polygon is a line
  {
    return false;
  }

  return check_line_segments_intersection_2d(line_start, line_end, vertices_.back(), vertices_.front());  // otherwise close polygon
}

// implements toPolygonMsg() of the base class
void PolygonObstacle::toPolygonMsg(geometry_msgs::Polygon& polygon) {
  polygon.points.resize(vertices_.size());
  for (std::size_t i = 0; i < vertices_.size(); ++i) {
    polygon.points[i].x = vertices_[i].x();
    polygon.points[i].y = vertices_[i].y();
    polygon.points[i].z = 0;
  }
}

}  // namespace hateb_local_planner