vpMbHiddenFaces.h

/*
 * 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:
 * Generic model based tracker. This class declares the methods to implement
 * in order to have a model based tracker.
 */
 
#ifndef VP_MB_HIDDEN_FACES_H
#define VP_MB_HIDDEN_FACES_H
 
#include <visp3/core/vpConfig.h>
#include <visp3/core/vpDebug.h>
#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/core/vpMeterPixelConversion.h>
#include <visp3/core/vpPixelMeterConversion.h>
#include <visp3/mbt/vpMbScanLine.h>
#include <visp3/mbt/vpMbtPolygon.h>
 
#ifdef VISP_HAVE_OGRE
#include <visp3/ar/vpAROgre.h>
#endif
 
#include <limits>
#include <vector>
 
BEGIN_VISP_NAMESPACE
template <class PolygonType> class vpMbHiddenFaces;
 
// Forward declaration to have the operator in the global namespace
template <class PolygonType> void swap(vpMbHiddenFaces<PolygonType> &first, vpMbHiddenFaces<PolygonType> &second);
END_VISP_NAMESPACE
 
BEGIN_VISP_NAMESPACE
template <class PolygonType = vpMbtPolygon> class vpMbHiddenFaces
{
private:
  std::vector<PolygonType *> Lpol;
  unsigned int nbVisiblePolygon;
  vpMbScanLine scanlineRender;
 
#ifdef VISP_HAVE_OGRE
  vpImage<unsigned char> ogreBackground;
  bool ogreInitialised;
  unsigned int nbRayAttempts;
  double ratioVisibleRay;
  vpAROgre *ogre;
  std::vector<Ogre::ManualObject *> lOgrePolygons;
  bool ogreShowConfigDialog;
#endif
 
  unsigned int setVisiblePrivate(const vpHomogeneousMatrix &cMo, const double &angleAppears,
                                 const double &angleDisappears, bool &changed, bool useOgre = false,
                                 bool not_used = false, unsigned int width = 0, unsigned int height = 0,
                                 const vpCameraParameters &cam = vpCameraParameters());
 
public:
  vpMbHiddenFaces();
  virtual ~vpMbHiddenFaces();
  vpMbHiddenFaces(const vpMbHiddenFaces &copy);
  vpMbHiddenFaces &operator=(vpMbHiddenFaces other);
  friend void swap<PolygonType>(vpMbHiddenFaces &first, vpMbHiddenFaces &second);
 
  void addPolygon(PolygonType *p);
 
  bool computeVisibility(const vpHomogeneousMatrix &cMo, const double &angleAppears, const double &angleDisappears,
                         bool &changed, bool useOgre, bool not_used, unsigned int width, unsigned int height,
                         const vpCameraParameters &cam, const vpTranslationVector &cameraPos, unsigned int index);
 
  void computeClippedPolygons(const vpHomogeneousMatrix &cMo, const vpCameraParameters &cam);
 
  void computeScanLineRender(const vpCameraParameters &cam, const unsigned int &w, const unsigned int &h);
 
  void computeScanLineQuery(const vpPoint &a, const vpPoint &b, std::vector<std::pair<vpPoint, vpPoint> > &lines,
                            const bool &displayResults = false);
 
  vpMbScanLine &getMbScanLineRenderer() { return scanlineRender; }
 
#ifdef VISP_HAVE_OGRE
  void displayOgre(const vpHomogeneousMatrix &cMo);
#endif

  std::vector<PolygonType *> &getPolygon() { return Lpol; }
 
#ifdef VISP_HAVE_OGRE
  void initOgre(const vpCameraParameters &cam = vpCameraParameters());
#endif

  unsigned int getNbVisiblePolygon() const { return nbVisiblePolygon; }
 
#ifdef VISP_HAVE_OGRE
  unsigned int getNbRayCastingAttemptsForVisibility() { return nbRayAttempts; }

  vpAROgre *getOgreContext() { return ogre; }

  double getGoodNbRayCastingAttemptsRatio() { return ratioVisibleRay; }
#endif
 
  bool isAppearing(unsigned int i) { return Lpol[i]->isAppearing(); }
 
#ifdef VISP_HAVE_OGRE
  bool isOgreInitialised() { return ogreInitialised; }
#endif

  bool isVisible(unsigned int i) { return Lpol[i]->isVisible(); }
 
#ifdef VISP_HAVE_OGRE
  bool isVisibleOgre(const vpTranslationVector &cameraPos, const unsigned int &index);
#endif

  inline PolygonType *operator[](unsigned int i) { return Lpol[i]; }
  inline const PolygonType *operator[](unsigned int i) const { return Lpol[i]; }
 
  void reset();
 
#ifdef VISP_HAVE_OGRE
  void setBackgroundSizeOgre(const unsigned int &h, const unsigned int &w)
  {
    ogreBackground = vpImage<unsigned char>(h, w, 0);
  }

  void setNbRayCastingAttemptsForVisibility(const unsigned int &attempts) { nbRayAttempts = attempts; }

  void setGoodNbRayCastingAttemptsRatio(const double &ratio)
  {
    ratioVisibleRay = ratio;
    if (ratioVisibleRay > 1.0)
      ratioVisibleRay = 1.0;
    if (ratioVisibleRay < 0.0)
      ratioVisibleRay = 0.0;
  }

  inline void setOgreShowConfigDialog(bool showConfigDialog) { ogreShowConfigDialog = showConfigDialog; }
#endif
 
  unsigned int setVisible(unsigned int width, unsigned int height, const vpCameraParameters &cam,
                          const vpHomogeneousMatrix &cMo, const double &angle, bool &changed);
  unsigned int setVisible(unsigned int width, unsigned int height, const vpCameraParameters &cam,
                          const vpHomogeneousMatrix &cMo, const double &angleAppears, const double &angleDisappears,
                          bool &changed);
  unsigned int setVisible(const vpHomogeneousMatrix &cMo, const double &angleAppears, const double &angleDisappears,
                          bool &changed);
 
#ifdef VISP_HAVE_OGRE
  unsigned int setVisibleOgre(unsigned int width, unsigned int height, const vpCameraParameters &cam,
                              const vpHomogeneousMatrix &cMo, const double &angleAppears, const double &angleDisappears,
                              bool &changed);
  unsigned int setVisibleOgre(const vpHomogeneousMatrix &cMo, const double &angleAppears, const double &angleDisappears,
                              bool &changed);
#endif
  inline unsigned int size() const { return static_cast<unsigned int>(Lpol.size()); }
};

template <class PolygonType>
vpMbHiddenFaces<PolygonType>::vpMbHiddenFaces() : Lpol(), nbVisiblePolygon(0), scanlineRender()
{
#ifdef VISP_HAVE_OGRE
  ogreInitialised = false;
  nbRayAttempts = 1;
  ratioVisibleRay = 1.0;
  ogreShowConfigDialog = false;
  ogre = new vpAROgre();
  ogreBackground = vpImage<unsigned char>(480, 640, 0);
#endif
}

template <class PolygonType> vpMbHiddenFaces<PolygonType>::~vpMbHiddenFaces()
{
  for (unsigned int i = 0; i < Lpol.size(); i++) {
    if (Lpol[i] != nullptr) {
      delete Lpol[i];
    }
    Lpol[i] = nullptr;
  }
  Lpol.resize(0);
 
#ifdef VISP_HAVE_OGRE
  if (ogre != nullptr) {
    delete ogre;
    ogre = nullptr;
  }
 
  // This is already done by calling "delete ogre"
  //  for(unsigned int i = 0 ; i < lOgrePolygons.size() ; i++){
  //    if (lOgrePolygons[i]!=nullptr){
  //      delete lOgrePolygons[i];
  //    }
  //    lOgrePolygons[i] = nullptr;
  //  }
 
  lOgrePolygons.resize(0);
#endif
}

template <class PolygonType>
vpMbHiddenFaces<PolygonType>::vpMbHiddenFaces(const vpMbHiddenFaces<PolygonType> &copy)
  : Lpol(), nbVisiblePolygon(copy.nbVisiblePolygon), scanlineRender(copy.scanlineRender)
#ifdef VISP_HAVE_OGRE
  ,
  ogreBackground(copy.ogreBackground), ogreInitialised(copy.ogreInitialised), nbRayAttempts(copy.nbRayAttempts),
  ratioVisibleRay(copy.ratioVisibleRay), ogre(nullptr), lOgrePolygons(), ogreShowConfigDialog(copy.ogreShowConfigDialog)
#endif
{
  // Copy the list of polygons
  for (unsigned int i = 0; i < copy.Lpol.size(); i++) {
    PolygonType *poly = new PolygonType(*copy.Lpol[i]);
    Lpol.push_back(poly);
  }
}
 
template <class PolygonType> void swap(vpMbHiddenFaces<PolygonType> &first, vpMbHiddenFaces<PolygonType> &second)
{
  using std::swap;
  swap(first.Lpol, second.Lpol);
  swap(first.nbVisiblePolygon, second.nbVisiblePolygon);
  swap(first.scanlineRender, second.scanlineRender);
#ifdef VISP_HAVE_OGRE
  swap(first.ogreInitialised, second.ogreInitialised);
  swap(first.nbRayAttempts, second.nbRayAttempts);
  swap(first.ratioVisibleRay, second.ratioVisibleRay);
  swap(first.ogreShowConfigDialog, second.ogreShowConfigDialog);
  swap(first.ogre, second.ogre);
  swap(first.ogreBackground, second.ogreBackground);
#endif
}

template <class PolygonType>
vpMbHiddenFaces<PolygonType> &vpMbHiddenFaces<PolygonType>::operator=(vpMbHiddenFaces<PolygonType> other)
{
  swap(*this, other);
 
  return *this;
}

template <class PolygonType> void vpMbHiddenFaces<PolygonType>::addPolygon(PolygonType *p)
{
  PolygonType *p_new = new PolygonType;
  p_new->index = p->index;
  p_new->setNbPoint(p->nbpt);
  p_new->isvisible = p->isvisible;
  p_new->useLod = p->useLod;
  p_new->minLineLengthThresh = p->minLineLengthThresh;
  p_new->minPolygonAreaThresh = p->minPolygonAreaThresh;
  p_new->setName(p->name);
  p_new->hasOrientation = p->hasOrientation;
 
  for (unsigned int i = 0; i < p->nbpt; i++)
    p_new->p[i] = p->p[i];
  Lpol.push_back(p_new);
}

template <class PolygonType> void vpMbHiddenFaces<PolygonType>::reset()
{
  nbVisiblePolygon = 0;
  for (unsigned int i = 0; i < Lpol.size(); i++) {
    if (Lpol[i] != nullptr) {
      delete Lpol[i];
    }
    Lpol[i] = nullptr;
  }
  Lpol.resize(0);
 
#ifdef VISP_HAVE_OGRE
  if (ogre != nullptr) {
    delete ogre;
    ogre = nullptr;
  }
 
  // This is already done by calling "delete ogre"
  //  for(unsigned int i = 0 ; i < lOgrePolygons.size() ; i++){
  //    if (lOgrePolygons[i]!=nullptr){
  //      delete lOgrePolygons[i];
  //    }
  //    lOgrePolygons[i] = nullptr;
  //  }
 
  lOgrePolygons.resize(0);
 
  ogreInitialised = false;
  nbRayAttempts = 1;
  ratioVisibleRay = 1.0;
  ogre = new vpAROgre();
  ogreBackground = vpImage<unsigned char>(480, 640);
#endif
}

template <class PolygonType>
void vpMbHiddenFaces<PolygonType>::computeClippedPolygons(const vpHomogeneousMatrix &cMo, const vpCameraParameters &cam)
{
  for (unsigned int i = 0; i < Lpol.size(); i++) {
    // For fast result we could just clip visible polygons.
    // However clipping all of them gives us the possibility to return more
    // information in the scanline visibility results
    //    if(Lpol[i]->isVisible())
    {
      Lpol[i]->changeFrame(cMo);
      Lpol[i]->computePolygonClipped(cam);
    }
  }
}

template <class PolygonType>
void vpMbHiddenFaces<PolygonType>::computeScanLineRender(const vpCameraParameters &cam, const unsigned int &w,
                                                         const unsigned int &h)
{
  std::vector<std::vector<std::pair<vpPoint, unsigned int> > > polyClipped(Lpol.size());
  std::vector<std::vector<std::pair<vpPoint, unsigned int> > *> listPolyClipped;
  std::vector<int> listPolyIndices;
 
  for (unsigned int i = 0; i < Lpol.size(); i++) {
    // For fast result we could just use visible polygons.
    // However using all of them gives us the possibility to return more
    // information in the scanline visibility results
    //    if(Lpol[i]->isVisible())
    {
      polyClipped[i].clear();
      Lpol[i]->getPolygonClipped(polyClipped[i]);
      if (polyClipped[i].size() != 0) {
        listPolyClipped.push_back(&polyClipped[i]);
        listPolyIndices.push_back(Lpol[i]->getIndex());
      }
    }
  }
 
  scanlineRender.drawScene(listPolyClipped, listPolyIndices, cam, w, h);
}

template <class PolygonType>
void vpMbHiddenFaces<PolygonType>::computeScanLineQuery(const vpPoint &a, const vpPoint &b,
                                                        std::vector<std::pair<vpPoint, vpPoint> > &lines,
                                                        const bool &displayResults)
{
  scanlineRender.queryLineVisibility(a, b, lines, displayResults);
}

template <class PolygonType>
unsigned int vpMbHiddenFaces<PolygonType>::setVisiblePrivate(const vpHomogeneousMatrix &cMo, const double &angleAppears,
                                                             const double &angleDisappears, bool &changed, bool useOgre,
                                                             bool not_used, unsigned int width, unsigned int height,
                                                             const vpCameraParameters &cam)
{
  nbVisiblePolygon = 0;
  changed = false;
 
  vpTranslationVector cameraPos;
 
  if (useOgre) {
#ifdef VISP_HAVE_OGRE
    cMo.inverse().extract(cameraPos);
    ogre->renderOneFrame(ogreBackground, cMo);
#else
    vpTRACE("ViSP doesn't have Ogre3D, simple visibility test used");
#endif
  }
 
  for (unsigned int i = 0; i < Lpol.size(); i++) {
    // std::cout << "Calling poly: " << i << std::endl;
    if (computeVisibility(cMo, angleAppears, angleDisappears, changed, useOgre, not_used, width, height, cam, cameraPos,
                          i))
      nbVisiblePolygon++;
  }
  return nbVisiblePolygon;
}

template <class PolygonType>
bool vpMbHiddenFaces<PolygonType>::computeVisibility(const vpHomogeneousMatrix &cMo, const double &angleAppears,
                                                     const double &angleDisappears, bool &changed, bool useOgre,
                                                     bool not_used, unsigned int width, unsigned int height,
                                                     const vpCameraParameters &cam,
                                                     const vpTranslationVector &cameraPos, unsigned int index)
{
  (void)not_used;
  unsigned int i = index;
  Lpol[i]->changeFrame(cMo);
  Lpol[i]->isappearing = false;
 
  // Commented because we need to compute visibility
  // even when dealing with line in level of detail case
  /*if(Lpol[i]->getNbPoint() <= 2)
  {
      Lpol[i]->isvisible = true;
  }
  else*/
  {
    if (Lpol[i]->isVisible()) {
      bool testDisappear = false;
      // unsigned int nbCornerInsidePrev = 0;
 
      if (!testDisappear) {
        if (useOgre)
#ifdef VISP_HAVE_OGRE
          testDisappear =
          ((!Lpol[i]->isVisible(cMo, angleDisappears, true, cam, width, height)) || !isVisibleOgre(cameraPos, i));
#else
        {
          (void)cameraPos; // Avoid warning
          testDisappear = (!Lpol[i]->isVisible(cMo, angleDisappears, false, cam, width, height));
        }
#endif
        else
          testDisappear = (!Lpol[i]->isVisible(cMo, angleDisappears, false, cam, width, height));
      }
 
      // test if the face is still visible
      if (testDisappear) {
        //               std::cout << "Face " << i << " disappears" <<
        //               std::endl;
        changed = true;
        Lpol[i]->isvisible = false;
      }
      else {
     // nbVisiblePolygon++;
        Lpol[i]->isvisible = true;
 
        // if(nbCornerInsidePrev > Lpol[i]->getNbCornerInsidePrevImage())
        //  changed = true;
      }
    }
    else {
      bool testAppear = true;
 
      if (testAppear) {
        if (useOgre)
#ifdef VISP_HAVE_OGRE
          testAppear =
          ((Lpol[i]->isVisible(cMo, angleAppears, true, cam, width, height)) && isVisibleOgre(cameraPos, i));
#else
          testAppear = (Lpol[i]->isVisible(cMo, angleAppears, false, cam, width, height));
#endif
        else
          testAppear = (Lpol[i]->isVisible(cMo, angleAppears, false, cam, width, height));
      }
 
      if (testAppear) {
        //      std::cout << "Face " << i << " appears" << std::endl;
        Lpol[i]->isvisible = true;
        changed = true;
        // nbVisiblePolygon++;
      }
      else {
     //      std::cout << "Problem" << std::endl;
        Lpol[i]->isvisible = false;
      }
    }
  }
  //   std::cout << "Nombre de polygones visibles: " << nbVisiblePolygon <<
  //   std::endl;
  return Lpol[i]->isvisible;
}

template <class PolygonType>
unsigned int vpMbHiddenFaces<PolygonType>::setVisible(unsigned int width, unsigned int height,
                                                      const vpCameraParameters &cam, const vpHomogeneousMatrix &cMo,
                                                      const double &angle, bool &changed)
{
  return setVisible(width, height, cam, cMo, angle, angle, changed);
}

template <class PolygonType>
unsigned int vpMbHiddenFaces<PolygonType>::setVisible(unsigned int width, unsigned int height,
                                                      const vpCameraParameters &cam, const vpHomogeneousMatrix &cMo,
                                                      const double &angleAppears, const double &angleDisappears,
                                                      bool &changed)
{
  return setVisiblePrivate(cMo, angleAppears, angleDisappears, changed, false, true, width, height, cam);
}

template <class PolygonType>
unsigned int vpMbHiddenFaces<PolygonType>::setVisible(const vpHomogeneousMatrix &cMo, const double &angleAppears,
                                                      const double &angleDisappears, bool &changed)
{
  return setVisiblePrivate(cMo, angleAppears, angleDisappears, changed, false);
}
 
#ifdef VISP_HAVE_OGRE
template <class PolygonType> void vpMbHiddenFaces<PolygonType>::initOgre(const vpCameraParameters &cam)
{
  ogreInitialised = true;
  ogre->setCameraParameters(cam);
  ogre->setShowConfigDialog(ogreShowConfigDialog);
  ogre->init(ogreBackground, false, true);
 
  for (unsigned int n = 0; n < Lpol.size(); n++) {
    Ogre::ManualObject *manual = ogre->getSceneManager()->createManualObject(Ogre::StringConverter::toString(n));
 
    manual->begin("BaseWhiteNoLighting", Ogre::RenderOperation::OT_LINE_STRIP);
    for (unsigned int i = 0; i < Lpol[n]->nbpt; i++) {
      manual->position((Ogre::Real)Lpol[n]->p[i].get_oX(), (Ogre::Real)Lpol[n]->p[i].get_oY(),
                       (Ogre::Real)Lpol[n]->p[i].get_oZ());
      manual->colour(1.0, 1.0, 1.0);
      manual->index(i);
    }
 
    manual->index(0);
    manual->end();
 
    ogre->getSceneManager()->getRootSceneNode()->createChildSceneNode()->attachObject(manual);
 
    lOgrePolygons.push_back(manual);
  }
}

template <class PolygonType> void vpMbHiddenFaces<PolygonType>::displayOgre(const vpHomogeneousMatrix &cMo)
{
  if (ogreInitialised && !ogre->isWindowHidden()) {
    for (unsigned int i = 0; i < Lpol.size(); i++) {
      if (Lpol[i]->isVisible()) {
        lOgrePolygons[i]->setVisible(true);
      }
      else
        lOgrePolygons[i]->setVisible(false);
    }
    ogre->display(ogreBackground, cMo);
  }
}

template <class PolygonType>
unsigned int vpMbHiddenFaces<PolygonType>::setVisibleOgre(unsigned int width, unsigned int height,
                                                          const vpCameraParameters &cam, const vpHomogeneousMatrix &cMo,
                                                          const double &angleAppears, const double &angleDisappears,
                                                          bool &changed)
{
  return setVisiblePrivate(cMo, angleAppears, angleDisappears, changed, true, true, width, height, cam);
}

template <class PolygonType>
unsigned int vpMbHiddenFaces<PolygonType>::setVisibleOgre(const vpHomogeneousMatrix &cMo, const double &angleAppears,
                                                          const double &angleDisappears, bool &changed)
{
  return setVisiblePrivate(cMo, angleAppears, angleDisappears, changed, true);
}

template <class PolygonType>
bool vpMbHiddenFaces<PolygonType>::isVisibleOgre(const vpTranslationVector &cameraPos, const unsigned int &index)
{
  Ogre::Vector3 camera((Ogre::Real)cameraPos[0], (Ogre::Real)cameraPos[1], (Ogre::Real)cameraPos[2]);
  if (!ogre->getCamera()->isVisible(lOgrePolygons[index]->getBoundingBox())) {
    lOgrePolygons[index]->setVisible(false);
    Lpol[index]->isvisible = false;
    return false;
  }
 
  // Get the center of gravity
  bool visible = false;
  unsigned int nbVisible = 0;
 
  for (unsigned int i = 0; i < nbRayAttempts; i++) {
    Ogre::Vector3 origin(0, 0, 0);
    Ogre::Real totalFactor = 0.0f;
 
    for (unsigned int j = 0; j < Lpol[index]->getNbPoint(); j++) {
      Ogre::Real factor = 1.0f;
 
      if (nbRayAttempts > 1) {
        int r = rand() % 101;
 
        if (r != 0)
          factor = ((Ogre::Real)r) / 100.0f;
      }
 
      Ogre::Vector3 tmp((Ogre::Real)Lpol[index]->getPoint(j).get_oX(), (Ogre::Real)Lpol[index]->getPoint(j).get_oY(),
                        (Ogre::Real)Lpol[index]->getPoint(j).get_oZ());
      tmp *= factor;
      origin += tmp;
      totalFactor += factor;
    }
 
    origin /= totalFactor;
 
    Ogre::Vector3 direction = origin - camera;
    Ogre::Real distanceCollision = direction.length();
 
    direction.normalise();
    Ogre::RaySceneQuery *mRaySceneQuery = ogre->getSceneManager()->createRayQuery(Ogre::Ray(camera, direction));
    mRaySceneQuery->setSortByDistance(true);
 
    Ogre::RaySceneQueryResult &result = mRaySceneQuery->execute();
    Ogre::RaySceneQueryResult::iterator it = result.begin();
 
    //    while(it != result.end()){
    //      std::cout << it->movable->getName() << "(" << it->distance<< ") :
    //      " << std::flush; it++;
    //    }
    //    std::cout << std::endl;
    //    it = result.begin();
 
    if (it != result.end())
      if (it->movable->getName().find("SimpleRenderable") != Ogre::String::npos) // Test if the ogreBackground is
                                                                                 // intersect in first
        ++it;
 
    double distance;
    // In a case of a two-axis aligned segment, ray collision is not always
    // working.
    if (Lpol[index]->getNbPoint() == 2 &&
        (((std::fabs(Lpol[index]->getPoint(0).get_oX() - Lpol[index]->getPoint(1).get_oX()) <
           std::numeric_limits<double>::epsilon()) +
          (std::fabs(Lpol[index]->getPoint(0).get_oY() - Lpol[index]->getPoint(1).get_oY()) <
           std::numeric_limits<double>::epsilon()) +
          (std::fabs(Lpol[index]->getPoint(0).get_oZ() - Lpol[index]->getPoint(1).get_oZ()) <
           std::numeric_limits<double>::epsilon())) >= 2)) {
      if (it != result.end()) {
        if (it->movable->getName() == Ogre::StringConverter::toString(index)) {
          nbVisible++;
        }
        else {
          distance = it->distance;
          // Cannot use epsilon for comparison as ray length is slightly
          // different from the collision distance returned by
          // Ogre::RaySceneQueryResult.
          if (distance > distanceCollision || std::fabs(distance - distanceCollision) <
                                                  1e-6 /*std::fabs(distance) * std::numeric_limits<double>::epsilon()*/)
            nbVisible++;
        }
      }
      else
        nbVisible++; // Collision not detected but present.
    }
    else {
      if (it != result.end()) {
        distance = it->distance;
        double distancePrev = distance;
 
        // std::cout << "For " << Ogre::StringConverter::toString(index) << ":
        // " << it->movable->getName() << " / " << std::flush;
 
        if (it->movable->getName() == Ogre::StringConverter::toString(index)) {
          nbVisible++;
        }
        else {
          ++it;
          while (it != result.end()) {
            distance = it->distance;
 
            if (std::fabs(distance - distancePrev) <
                1e-6 /*std::fabs(distance) * std::numeric_limits<double>::epsilon()*/) {
              // std::cout << it->movable->getName() << " / " << std::flush;
              if (it->movable->getName() == Ogre::StringConverter::toString(index)) {
                nbVisible++;
                break;
              }
              ++it;
              distancePrev = distance;
            }
            else
              break;
          }
        }
      }
    }
 
    ogre->getSceneManager()->destroyQuery(mRaySceneQuery);
  }
 
  if ((static_cast<double>(nbVisible)) / (static_cast<double>(nbRayAttempts)) > ratioVisibleRay ||
      std::fabs((static_cast<double>(nbVisible)) / (static_cast<double>(nbRayAttempts)) - ratioVisibleRay) <
          ratioVisibleRay * std::numeric_limits<double>::epsilon())
    visible = true;
  else
    visible = false;
 
  if (visible) {
    lOgrePolygons[index]->setVisible(true);
    Lpol[index]->isvisible = true;
  }
  else {
    lOgrePolygons[index]->setVisible(false);
    Lpol[index]->isvisible = false;
  }
 
  return Lpol[index]->isvisible;
}
 
#endif // VISP_HAVE_OGRE
END_VISP_NAMESPACE
#endif // vpMbHiddenFaces