Example: math_polygon_split

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2021, 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.h>
#include <mrpt/math/geometry.h>
#include <mrpt/system/datetime.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::system::now()));
    display();
    return 0;
}