Added: identification curve in the scene

Arrangement_on_surface_2/demo/earth/Aos.cpp

@@ -183,9 +183,32 @@ namespace {
 }
 
 
+Aos::Approx_arc Aos::get_approx_identification_curve(double error)
+{
+  Geom_traits traits;
+  auto ctr_p = traits.construct_point_2_object();
+  auto ctr_cv = traits.construct_curve_2_object();
+
+  // identification curve (meridian pierced by NEGATIVE Y-AXIS)
+  auto xcv = ctr_cv(ctr_p(0, 0, -1), ctr_p(0, 0, 1), Dir3(0,1,0));
+
+  auto approx = traits.approximate_2_object();
+  Approx_arc approx_arc;
+  {
+    std::vector<Approximate_point_2> v;
+    auto oi2 = approx(xcv, error, std::back_insert_iterator(v));
+    for (const auto& p : v)
+    {
+      const QVector3D arc_point(p.dx(), p.dy(), p.dz());
+      approx_arc.push_back(arc_point);
+    }
+  }
+
+  return approx_arc;
+}
+
 Aos::Approx_arcs Aos::get_approx_arcs(double error)
 {
-  // Construct the arrangement from 12 geodesic arcs.
   Geom_traits traits;
   Arrangement arr(&traits);
 
@@ -311,7 +334,10 @@ std::vector<QVector3D> Aos::ext_check(const Kml::Placemarks& placemarks)
 
       if (1 == vit->degree())
       {
-        std::cout << "1-deg vertex: " << std::boolalpha << vit->incident_halfedges()->target()->data().v << std::endl;
+        auto p = vit->point();
+        auto p2 = p.location();
+        std::cout << "deg-1 vertex = " << p << std::endl;
+        std::cout << "deg-1 vertex: " << std::boolalpha << vit->incident_halfedges()->target()->data().v << std::endl;
       }
 
 

Arrangement_on_surface_2/demo/earth/Aos.h

@@ -11,7 +11,11 @@
 class Aos
 {
 public:
-  using Approx_arcs = std::vector<std::vector<QVector3D>>;
+  using Approx_arc = std::vector<QVector3D>;
+  using Approx_arcs = std::vector<Approx_arc>;
+
+
+  static Approx_arc get_approx_identification_curve(double error);
 
   // this constructs some sample arcs manually (used to check the visual output)
   static Approx_arcs get_approx_arcs(double error);

Arrangement_on_surface_2/demo/earth/Main_widget.cpp

@@ -276,13 +276,18 @@ void Main_widget::init_camera()
 }
 void Main_widget::init_geometry()
 {
+  // SPHERE
   int num_slices, num_stacks;
   num_slices = num_stacks = 64;
   float r = 1;
   m_sphere = std::make_unique<Sphere>(num_slices, num_stacks, r);
   const float c = 0.8;
   m_sphere->set_color(c, c, c, 1);
 
+  // IDENTIFICATION CURVE
+  const double error = 0.001;
+  auto approx_ident_curve = Aos::get_approx_identification_curve(error);
+  m_identification_curve = std::make_unique<Line_strips>(approx_ident_curve);
 
   const float axes_length = 2;
   m_world_coord_axes = std::make_unique<World_coord_axes>(axes_length);
@@ -475,6 +480,10 @@ void Main_widget::paintGL()
     glLineWidth(5);
     sp.set_uniform("u_plane", plane);
 
+    // IDENTIFICATION CURVE
+    sp.set_uniform("u_color", QVector4D(0, 1, 1, 1));
+    m_identification_curve->draw(m_selected_arc_index);
+
     // draw all countries 
     float a = 0.0;
     sp.set_uniform("u_color", QVector4D(a, a, a, 1));

Arrangement_on_surface_2/demo/earth/Main_widget.h

@@ -61,6 +61,7 @@ class Main_widget : public QOpenGLWidget, protected OpenGLFunctionsBase
   std::unique_ptr<World_coord_axes> m_world_coord_axes;
   std::unique_ptr<Line_strips>      m_geodesic_arcs;
   std::unique_ptr<Vertices>         m_vertices;
+  std::unique_ptr<Line_strips>      m_identification_curve;
 
   // COUNTRY DATA
   Kml::Placemarks                             m_countries;