the outlines of the faces are drawn from the arrangement data itself …

…now (no KML needed)

Arrangement_on_surface_2/demo/earth/Aos.cpp

@@ -297,9 +297,6 @@ Aos::Approx_arc Aos::get_approx_identification_curve(double error)
 
 Aos::Approx_arcs Aos::get_approx_arcs(double error)
 {
-  //Geom_traits traits;
-  Arrangement arr(&s_traits);
-
   auto ctr_p = s_traits.construct_point_2_object();
   auto ctr_cv = s_traits.construct_curve_2_object();
 
@@ -310,36 +307,13 @@ Aos::Approx_arcs Aos::get_approx_arcs(double error)
   //xcvs.push_back(ctr_cv(ctr_p(1, 0, 0), ctr_p(0, 1, 0), Dir3(0, 0, -1)));
   //xcvs.push_back(ctr_cv(Dir3(0, 0, -1)));
 
-  auto approx = s_traits.approximate_2_object();
-
   auto approx_arcs = get_approx_curves(xcvs, error);
-  //std::vector<std::vector<QVector3D>>  arcs;
-  //for (const auto& xcv : xcvs)
-  //{
-  //  std::vector<Approximate_point_2> v;
-  //  auto oi2 = approx(xcv, error, std::back_insert_iterator(v));
-  //
-  //  std::vector<QVector3D> arc_points;
-  //  for (const auto& p : v)
-  //  {
-  //    const QVector3D arc_point(p.dx(), p.dy(), p.dz());
-  //    arc_points.push_back(arc_point);
-  //  }
-  //  arcs.push_back(std::move(arc_points));
-  //}
-  //std::cout << "offset count = " << m_arc_offsets.size() << std::endl;
-
   return approx_arcs;
 }
 Aos::Approx_arcs Aos::get_approx_arcs(const Kml::Placemark& placemark, double error)
 {
-  //Geom_traits traits;
-  auto ctr_p = s_traits.construct_point_2_object();
-  auto ctr_cv = s_traits.construct_curve_2_object();
-
   auto xcvs = get_arcs(placemark);
   auto arcs = ::get_approx_curves(xcvs, error);
-
   return arcs;
 }
 
@@ -1936,4 +1910,20 @@ std::string Aos::locate_country(Arr_handle arrh, const QVector3D& point)
   //else CGAL_error_msg("Invalid object.");
 
   return "";
-}
+}
+
+Aos::Approx_arcs Aos::get_approx_arcs_from_faces_edges(Arr_handle arrh, 
+                                                       float error)
+{
+  auto& arr = *reinterpret_cast<Countries_arr*>(arrh.get());
+  auto ctr_cv = s_traits.construct_curve_2_object();
+  Curves xcvs;
+  for (auto eit = arr.halfedges_begin(); eit != arr.halfedges_end(); ++eit)
+  {
+    auto& s = eit->curve();
+    xcvs.push_back( ctr_cv(s.source(), s.target()) );
+  }
+
+  auto arcs = ::get_approx_curves(xcvs, error);
+  return arcs;
+}

Arrangement_on_surface_2/demo/earth/Aos.h

@@ -76,6 +76,11 @@ class Aos
   static Country_color_map get_color_mapping(Arr_handle arrh);
 
   static std::string locate_country(Arr_handle arrh, const QVector3D& point);
+
+  // this will get the approximate arcs of face-edges from the arrangement
+  // NOTE: this is similar to "get_approx_arcs(KML::Placemarks&, float)" above!
+  static Approx_arcs get_approx_arcs_from_faces_edges(Arr_handle arrh, 
+                                                      float error);
 };
 
 

Arrangement_on_surface_2/demo/earth/Main_widget.cpp

@@ -277,9 +277,9 @@ void Main_widget::initializeGL()
   //Shapefile::read(shape_file_name);
 
   //const auto file_name = data_path + "world_countries.kml";
-  const auto file_name = data_path + "ne_110m_admin_0_countries.kml";
+  //const auto file_name = data_path + "ne_110m_admin_0_countries.kml";
   //const auto file_name = data_path + "ne_110m_admin_0_countries_africa.kml";
-  //const auto file_name = data_path + "ne_110m_admin_0_countries_equatorial_guinea.kml";
+  const auto file_name = data_path + "ne_110m_admin_0_countries_equatorial_guinea.kml";
   m_countries = Kml::read(file_name);
 
   // find the country with the least number of nodes
@@ -326,7 +326,7 @@ void Main_widget::initializeGL()
 
   // triangulation
   {
-    qDebug() << "constructiong arr..";
+    qDebug() << "loading arr..";
     //auto arrh = Aos::construct(m_countries);
     m_arrh = Aos::load_arr("C:/work/gsoc2023/ne_110m_admin_0_countries.json");
     if (m_arrh == nullptr)
@@ -456,6 +456,16 @@ void Main_widget::init_shader_programs()
 
 void Main_widget::init_country_borders(float error)
 {
+  // this part does the same as the code below but using arrangement!
+  // NOTE: the old code interferes with some logic (NEEDS REFACTORING!!!)
+  {
+    m_country_borders.clear();
+    qDebug() << "approximating the arcs of each edge of all faces..";
+    auto all_approx_arcs = Aos::get_approx_arcs_from_faces_edges(m_arrh, error);
+    m_gr_all_approx_arcs = std::make_unique<Line_strips>(all_approx_arcs);
+    return;
+  }
+
   // TO-DO: move this code to resizeGL (when viewport is initialized)
   // has to be defined after camera has been defined:
   // because we want to compute the error based on camera parameters!
@@ -637,8 +647,9 @@ void Main_widget::paintGL()
     // draw all countries 
     float a = 0.0;
     sp.set_uniform("u_color", QVector4D(a, a, a, 1));
-    for(auto& country_border : m_country_borders)
-      country_border->draw();
+    //for(auto& country_border : m_country_borders)
+    //  country_border->draw();
+    m_gr_all_approx_arcs->draw();
 
     //// draw the SELECTED COUNTRY in BLUE
     //auto& selected_country = m_country_borders[m_selected_country_index];

Arrangement_on_surface_2/demo/earth/Main_widget.h

@@ -88,6 +88,7 @@ class Main_widget : public QOpenGLWidget, protected OpenGLFunctionsBase
 private:
   // ARRANGEMENT
   Aos::Arr_handle   m_arrh;
+  std::unique_ptr<Line_strips>   m_gr_all_approx_arcs;
 
   // GUI: event handler for picking with right mouse button
   std::unique_ptr<GUI_event_handler> m_pick_handler;