vpPolygon.cpp

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2025 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See https://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Defines a generic 2D polygon.
 */
 
// System
#include <limits>
#include <set>
 
// Core
#include <visp3/core/vpDisplay.h>
#include <visp3/core/vpException.h>
#include <visp3/core/vpMeterPixelConversion.h>
#include <visp3/core/vpPolygon.h>
#include <visp3/core/vpUniRand.h>
 
// Local helper
#if defined(VISP_HAVE_OPENCV) && defined(HAVE_OPENCV_IMGPROC)
 
#include <opencv2/imgproc/imgproc.hpp>
 

template <typename IpContainer> std::vector<VISP_NAMESPACE_ADDRESSING vpImagePoint> convexHull(const IpContainer &ips)
{
#ifdef ENABLE_VISP_NAMESPACE
  using namespace VISP_NAMESPACE_NAME;
#endif
  if (ips.size() == 0) {
    throw vpException(vpException::badValue,
                      "Convex Hull can not be computed as the input does not contain any image point.");
  }
 
  // Visp -> CV
  std::vector<cv::Point> cv_pts;
#if ((__cplusplus >= 201402L) || (defined(_MSVC_LANG) && (_MSVC_LANG >= 201402L)))  // Check if cxx14 or higher
  std::transform(cbegin(ips), cend(ips), std::back_inserter(cv_pts), [](const vpImagePoint &ip) {
    return cv::Point(static_cast<int>(ip.get_u()), static_cast<int>(ip.get_v()));
                 });
#elif ((__cplusplus >= 201103L) || (defined(_MSVC_LANG) && (_MSVC_LANG >= 201103L))) // Check if cxx11 or higher
  std::transform(begin(ips), end(ips), std::back_inserter(cv_pts), [](const vpImagePoint &ip) {
    return cv::Point(static_cast<int>(ip.get_u()), static_cast<int>(ip.get_v()));
                 });
#else // cxx98
  for (typename IpContainer::const_iterator it = ips.begin(); it != ips.end(); ++it) {
    cv_pts.push_back(cv::Point(static_cast<int>(it->get_u()), static_cast<int>(it->get_v())));
  }
#endif
 
  // Get convex hull from OpenCV
  std::vector<cv::Point> cv_conv_hull_corners;
  cv::convexHull(cv_pts, cv_conv_hull_corners);
 
  // CV -> Visp
  std::vector<vpImagePoint> conv_hull_corners;
#if ((__cplusplus >= 201402L) || (defined(_MSVC_LANG) && (_MSVC_LANG >= 201402L))) // Check if cxx14 or higher
  std::transform(cbegin(cv_conv_hull_corners), cend(cv_conv_hull_corners), std::back_inserter(conv_hull_corners),
                 [](const cv::Point &pt) {
                   return vpImagePoint { static_cast<double>(pt.y), static_cast<double>(pt.x) };
                 });
#elif ((__cplusplus >= 201103L) || (defined(_MSVC_LANG) && (_MSVC_LANG >= 201103L))) // Check if cxx11 or higher
  std::transform(begin(cv_conv_hull_corners), end(cv_conv_hull_corners), std::back_inserter(conv_hull_corners),
                 [](const cv::Point &pt) {
                   return vpImagePoint { static_cast<double>(pt.y), static_cast<double>(pt.x) };
                 });
#else // cxx98
  for (std::vector<cv::Point>::const_iterator it = cv_conv_hull_corners.begin(); it != cv_conv_hull_corners.end();
       ++it) {
    conv_hull_corners.push_back(vpImagePoint(static_cast<double>(it->y), static_cast<double>(it->x)));
  }
#endif
 
  return conv_hull_corners;
}
 
#endif
 
BEGIN_VISP_NAMESPACE
vpPolygon::vpPolygon()
  : _corners(), _center(), _area(0.), _goodPoly(true), _bbox(), m_PnPolyConstants(), m_PnPolyMultiples()
{ }

vpPolygon::vpPolygon(const std::vector<vpImagePoint> &corners)
  : _corners(), _center(), _area(0.), _goodPoly(true), _bbox(), m_PnPolyConstants(), m_PnPolyMultiples()
{
  const unsigned int val_3 = 3;
  if (corners.size() < val_3) {
    _goodPoly = false;
  }
  init(corners);
}

vpPolygon::vpPolygon(const std::list<vpImagePoint> &corners)
  : _corners(), _center(), _area(0.), _goodPoly(true), _bbox(), m_PnPolyConstants(), m_PnPolyMultiples()
{
  const unsigned int val_3 = 3;
  if (corners.size() < val_3) {
    _goodPoly = false;
  }
  init(corners);
}

vpPolygon::vpPolygon(const vpPolygon &poly)
  : _corners(poly._corners), _center(poly._center), _area(poly._area), _goodPoly(poly._goodPoly), _bbox(poly._bbox),
  m_PnPolyConstants(poly.m_PnPolyConstants), m_PnPolyMultiples(poly.m_PnPolyMultiples)
{ }

vpPolygon::~vpPolygon() { }

vpPolygon &vpPolygon::operator=(const vpPolygon &poly)
{
  _corners = poly._corners;
  _center = poly._center;
  _area = poly._area;
  _goodPoly = poly._goodPoly;
  _bbox = poly._bbox;
  m_PnPolyConstants = poly.m_PnPolyConstants;
  m_PnPolyMultiples = poly.m_PnPolyMultiples;
  return *this;
}

vpPolygon &vpPolygon::buildFrom(const std::vector<vpImagePoint> &corners, const bool &create_convex_hull)
{
  if (create_convex_hull) {
#if defined(VISP_HAVE_OPENCV) && defined(HAVE_OPENCV_IMGPROC)
    init(convexHull(corners));
#else
    vpException(vpException::notImplementedError, "Cannot build a convex hull without OpenCV imgproc module");
#endif
  }
  else {
    init(corners);
  }
  return *this;
}

vpPolygon &vpPolygon::buildFrom(const std::list<vpImagePoint> &corners, const bool &create_convex_hull)
{
  if (create_convex_hull) {
#if defined(VISP_HAVE_OPENCV) && defined(HAVE_OPENCV_IMGPROC)
    init(convexHull(corners));
#else
    vpException(vpException::notImplementedError, "Cannot build a convex hull without OpenCV imgproc module");
#endif
  }
  else {
    init(corners);
  }
  return *this;
}

vpPolygon &vpPolygon::buildFrom(const std::vector<vpPoint> &corners, const vpCameraParameters &cam,
                                const bool &create_convex_hull)
{
  std::vector<vpImagePoint> ipCorners(corners.size());
  size_t corners_size = corners.size();
  for (size_t i = 0; i < corners_size; ++i) {
    vpMeterPixelConversion::convertPoint(cam, corners[i].get_x(), corners[i].get_y(), ipCorners[i]);
  }
  buildFrom(ipCorners, create_convex_hull);
  return *this;
}

void vpPolygon::initClick(const vpImage<unsigned char> &I, unsigned int size, const vpColor &color,
                          unsigned int thickness)
{
  vpMouseButton::vpMouseButtonType button = vpMouseButton::button1;
  vpImagePoint ip;
 
  std::vector<vpImagePoint> cornersClick;
 
  while (button == vpMouseButton::button1) {
    bool ret = vpDisplay::getClick(I, ip, button, true);
    if (ret && (button == vpMouseButton::button1)) {
      vpDisplay::displayCross(I, ip, size, color, thickness);
      cornersClick.push_back(ip);
      vpDisplay::flush(I);
    }
  }
 
  buildFrom(cornersClick);
}

void vpPolygon::initClick(const vpImage<vpRGBa> &I, unsigned int size, const vpColor &color, unsigned int thickness)
{
  vpMouseButton::vpMouseButtonType button = vpMouseButton::button1;
  vpImagePoint ip;
 
  std::vector<vpImagePoint> cornersClick;
 
  while (button == vpMouseButton::button1) {
    bool ret = vpDisplay::getClick(I, ip, button, true);
    if (ret && (button == vpMouseButton::button1)) {
      vpDisplay::displayCross(I, ip, size, color, thickness);
      cornersClick.push_back(ip);
      vpDisplay::flush(I);
    }
  }
 
  buildFrom(cornersClick);
}

void vpPolygon::init(const std::vector<vpImagePoint> &corners)
{
  _corners = corners;
 
  updateBoundingBox();
  updateArea();
  updateCenter();
 
  precalcValuesPnPoly();
}

void vpPolygon::init(const std::list<vpImagePoint> &corners)
{
  _corners.insert(_corners.begin(), corners.begin(), corners.end());
 
  updateBoundingBox();
  updateArea();
  updateCenter();
 
  precalcValuesPnPoly();
}

bool vpPolygon::testIntersectionSegments(const vpImagePoint &ip1, const vpImagePoint &ip2, const vpImagePoint &ip3,
                                         const vpImagePoint &ip4) const
{
  double di1 = ip2.get_i() - ip1.get_i();
  double dj1 = ip2.get_j() - ip1.get_j();
 
  double di2 = ip4.get_i() - ip3.get_i();
  double dj2 = ip4.get_j() - ip3.get_j();
 
  double denominator = (di1 * dj2) - (dj1 * di2);
 
  if (fabs(denominator) < std::numeric_limits<double>::epsilon()) {
    throw vpException(vpException::divideByZeroError, "Denominator is null, lines are parallels");
  }
 
  double alpha = -(((ip1.get_i() - ip3.get_i()) * dj2) + (di2 * (ip3.get_j() - ip1.get_j()))) / denominator;
  if ((alpha < 0) || (alpha >= 1)) {
    return false;
  }
 
  double beta = -((di1 * (ip3.get_j() - ip1.get_j())) + (dj1 * (ip1.get_i() - ip3.get_i()))) / denominator;
  if ((beta < 0) || (beta >= 1)) {
    return false;
  }
 
  return true;
}

bool vpPolygon::isInside(const vpImagePoint &ip, const PointInPolygonMethod &method) const
{
  const int val_1000 = 1000;
  const unsigned int val_3 = 3;
  if (_corners.size() < val_3) {
    return false;
  }
 
  bool test = false;
  // comment: previous implementation: switch method
  // case PnPolySegmentIntersection:
  if (method == PnPolySegmentIntersection) {
    vpImagePoint infPoint(100000, 100000); // take a point at 'infinity'
    // we add random since it appears that sometimes infPoint may cause a degenerated case (so relaunch and
    // hope that result will be different).
    vpUniRand generator;
    infPoint.set_i(infPoint.get_i() + (val_1000 * generator()));
    infPoint.set_j(infPoint.get_j() + (val_1000 * generator()));
 
    bool oddNbIntersections = false;
    size_t v_corners_size = _corners.size();
    for (size_t i = 0; i < v_corners_size; ++i) {
      vpImagePoint ip1 = _corners[i];
      vpImagePoint ip2 = _corners[(i + 1) % _corners.size()];
      bool intersection = false;
 
      // If the points are the same we continue without trying to found
      // an intersection
      if (ip1 == ip2) {
        // continue
      }
      else {
        try {
          intersection = testIntersectionSegments(ip1, ip2, ip, infPoint);
        }
        catch (...) {
          return isInside(ip);
        }
 
        if (intersection) {
          oddNbIntersections = !oddNbIntersections;
        }
      }
    }
 
    test = oddNbIntersections;
  }
  else {
    // Reference: http://alienryderflex.com/polygon/
    // comment: case PnPolyRayCasting
    // comment: default
    bool oddNodes = false;
    size_t v_corners_size = _corners.size();
    size_t j = v_corners_size - 1;
    for (size_t i = 0; i < v_corners_size; ++i) {
      if (((_corners[i].get_v() < ip.get_v()) && (_corners[j].get_v() >= ip.get_v())) ||
          ((_corners[j].get_v() < ip.get_v()) && (_corners[i].get_v() >= ip.get_v()))) {
        oddNodes ^= (((ip.get_v() * m_PnPolyMultiples[i]) + m_PnPolyConstants[i]) < ip.get_u());
      }
 
      j = i;
    }
 
    test = oddNodes;
    // comment: }
    // comment: break
  }
 
  return test;
}
 
void vpPolygon::precalcValuesPnPoly()
{
  const std::size_t val_3 = 3;
  if (_corners.size() < val_3) {
    return;
  }
 
  m_PnPolyConstants.resize(_corners.size());
  m_PnPolyMultiples.resize(_corners.size());
 
  size_t v_corners_size = _corners.size();
  size_t j = v_corners_size - 1;
  for (size_t i = 0; i < v_corners_size; ++i) {
    if (vpMath::equal(_corners[j].get_v(), _corners[i].get_v(), std::numeric_limits<double>::epsilon())) {
      m_PnPolyConstants[i] = _corners[i].get_u();
      m_PnPolyMultiples[i] = 0.0;
    }
    else {
      m_PnPolyConstants[i] = (_corners[i].get_u() -
        ((_corners[i].get_v() * _corners[j].get_u()) / (_corners[j].get_v() - _corners[i].get_v()))) +
        ((_corners[i].get_v() * _corners[i].get_u()) / (_corners[j].get_v() - _corners[i].get_v()));
      m_PnPolyMultiples[i] = (_corners[j].get_u() - _corners[i].get_u()) / (_corners[j].get_v() - _corners[i].get_v());
    }
 
    j = i;
  }
}

void vpPolygon::updateArea()
{
  if (_corners.size() == 0) {
    _area = 0;
    _goodPoly = false;
    return;
  }
  _area = 0;
 
  size_t v_corners_size = _corners.size();
  for (size_t i = 0; i < v_corners_size; ++i) {
    size_t i_p_1 = (i + 1) % _corners.size();
    _area += (_corners[i].get_j() * _corners[i_p_1].get_i()) - (_corners[i_p_1].get_j() * _corners[i].get_i());
  }
 
  const int val_2 = 2;
  _area /= val_2;
  if (_area < 0) {
    _area = -_area;
  }
}

void vpPolygon::updateCenter()
{
  if (_corners.size() == 0) {
    _center = vpImagePoint(0, 0);
    _goodPoly = false;
    return;
  }
  double i_tmp = 0;
  double j_tmp = 0;
 
  size_t v_corners_size = _corners.size();
  for (size_t i = 0; i < v_corners_size; ++i) {
    size_t i_p_1 = (i + 1) % _corners.size();
    i_tmp += (_corners[i].get_i() + _corners[i_p_1].get_i()) *
      ((_corners[i_p_1].get_i() * _corners[i].get_j()) - (_corners[i_p_1].get_j() * _corners[i].get_i()));
 
    j_tmp += (_corners[i].get_j() + _corners[i_p_1].get_j()) *
      ((_corners[i_p_1].get_i() * _corners[i].get_j()) - (_corners[i_p_1].get_j() * _corners[i].get_i()));
  }
 
  const int val_6 = 6;
  if (_area > 0) {
    _center.set_i(fabs(i_tmp / (val_6 * _area)));
    _center.set_j(fabs(j_tmp / (val_6 * _area)));
  }
  else {
    _center = _corners[0];
    _goodPoly = false;
  }
}

void vpPolygon::updateBoundingBox()
{
  if (_corners.size() == 0) {
    _bbox.setBottomRight(vpImagePoint(0, 0));
    _bbox.setTopLeft(vpImagePoint(0, 0));
    _goodPoly = false;
    return;
  }
 
  std::set<double> setI;
  std::set<double> setJ;
  unsigned int v_corners_size = static_cast<unsigned int>(_corners.size());
  for (unsigned int i = 0; i < v_corners_size; ++i) {
    setI.insert(_corners[i].get_i());
    setJ.insert(_corners[i].get_j());
  }
  vpImagePoint tl(*(setI.begin()), *(setJ.begin()));
  std::set<double>::const_iterator iterI = setI.end();
  std::set<double>::const_iterator iterJ = setJ.end();
  --iterI;
  --iterJ;
  vpImagePoint br(*iterI, *iterJ);
 
  if (tl == br) {
    _goodPoly = false;
  }
  _bbox.setTopLeft(tl);
  _bbox.setBottomRight(br);
}

void vpPolygon::display(const vpImage<unsigned char> &I, const vpColor &color, unsigned int thickness) const
{
  const size_t N = _corners.size();
  for (size_t i = 0; i < N; ++i) {
    vpDisplay::displayLine(I, _corners[i], _corners[(i + 1) % N], color, thickness);
  }
}

bool vpPolygon::isInside(const std::vector<vpImagePoint> &roi, const double &i, const double &j,
                         const PointInPolygonMethod &method)
{
  vpPolygon poly(roi);
  return poly.isInside(vpImagePoint(i, j), method);
}

unsigned int vpPolygon::getSize() const
{
  return (static_cast<unsigned int>(_corners.size()));
}
END_VISP_NAMESPACE