costmap_math.cpp

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/*
 * Copyright (c) 2013, Willow Garage, Inc.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
 *
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 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include <costmap_2d/costmap_math.h>

double distanceToLine(double pX, double pY, double x0, double y0, double x1, double y1)
{
  double A = pX - x0;
  double B = pY - y0;
  double C = x1 - x0;
  double D = y1 - y0;

  double dot = A * C + B * D;
  double len_sq = C * C + D * D;
  double param = dot / len_sq;

  double xx, yy;

  if (param < 0)
  {
    xx = x0;
    yy = y0;
  }
  else if (param > 1)
  {
    xx = x1;
    yy = y1;
  }
  else
  {
    xx = x0 + param * C;
    yy = y0 + param * D;
  }

  return distance(pX, pY, xx, yy);
}

bool intersects(std::vector<geometry_msgs::Point>& polygon, float testx, float testy)
{
  bool c = false;
  int i, j, nvert = polygon.size();
  for (i = 0, j = nvert - 1; i < nvert; j = i++)
  {
    float yi = polygon[i].y, yj = polygon[j].y, xi = polygon[i].x, xj = polygon[j].x;

    if (((yi > testy) != (yj > testy)) && (testx < (xj - xi) * (testy - yi) / (yj - yi) + xi))
      c = !c;
  }
  return c;
}

bool intersects_helper(std::vector<geometry_msgs::Point>& polygon1, std::vector<geometry_msgs::Point>& polygon2)
{
  for (unsigned int i = 0; i < polygon1.size(); i++)
    if (intersects(polygon2, polygon1[i].x, polygon1[i].y))
      return true;
  return false;
}

bool intersects(std::vector<geometry_msgs::Point>& polygon1, std::vector<geometry_msgs::Point>& polygon2)
{
  return intersects_helper(polygon1, polygon2) || intersects_helper(polygon2, polygon1);
}