Example: math_polygon_split

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2024, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include <mrpt/gui/CDisplayWindowPlots.h>
#include <mrpt/math/geometry.h>
#include <mrpt/system/datetime.h>
#include <mrpt/system/os.h>

#include <iostream>

using namespace std;
using namespace mrpt;
using namespace mrpt::gui;
using namespace mrpt::math;

const unsigned int NUMBER_OF_EDGES = 20;
const double MIN_RADIUS = 5;
const double MAX_RADIUS = 40;

const double DIFF_RADIUS = MAX_RADIUS - MIN_RADIUS;

inline double randomDouble(size_t precision = 1000)
{
  return MIN_RADIUS + DIFF_RADIUS * (static_cast<double>(rand() % precision) /
                                     static_cast<double>(precision - 1));
}

void display()
{
  CDisplayWindowPlots win1("Unsplitted polygon", 400, 300);
  win1.enableMousePanZoom(true);
  TPolygon2D randomPoly(NUMBER_OF_EDGES);
  for (size_t i = 0; i < NUMBER_OF_EDGES; i++)
  {
    double ang = 2 * M_PI * i / NUMBER_OF_EDGES;
    double radius = randomDouble();
    randomPoly[i].x = radius * cos(ang);
    randomPoly[i].y = radius * sin(ang);
  }
  randomPoly.removeRedundantVertices();
  std::vector<double> x, y;
  randomPoly.getPlotData(x, y);
  win1.plot(x, y, "b-5", "Polygon");
  win1.axis_fit();
  std::vector<TPolygon2D> convexPolys;
  if (!splitInConvexComponents(randomPoly, convexPolys)) convexPolys.push_back(randomPoly);
  CDisplayWindowPlots win2("Splitted polygon", 400, 300);
  win2.enableMousePanZoom(true);
  std::string plotName = "Polygon0";
  for (std::vector<TPolygon2D>::const_iterator it = convexPolys.begin(); it != convexPolys.end();
       ++it)
  {
    plotName[7]++;
    it->getPlotData(x, y);
    win2.plot(x, y, "r-3", plotName);
    if (!it->isConvex()) cout << "FAIL.\n";
  }
  win2.axis_fit();
  while (!mrpt::system::os::kbhit() && win1.isOpen() && win2.isOpen())
    ;
}

int main(int argc, char** argv)
{
  srand((unsigned int)mrpt::system::extractDayTimeFromTimestamp(mrpt::Clock::now()));
  display();
  return 0;
}