Refactor: separated Geodesic arcs and their representation into diffe…

…rent classes

Arrangement_on_surface_2/demo/earth/CMakeLists.txt

@@ -43,6 +43,7 @@ qt_add_executable(earth
     Camera.h                  Camera.cpp
     Common_defs.h
     Geodesic_arcs.h           Geodesic_arcs.cpp
+    Line_strips.h             Line_strips.cpp
     Shader_program.h          Shader_program.cpp
     Sphere.h                  Sphere.cpp
     Tools.h                   Tools.cpp

Arrangement_on_surface_2/demo/earth/Common_defs.h

@@ -2,11 +2,21 @@
 #ifndef COMMON_DEFS_H
 #define COMMON_DEFS_H
 
+#include <vector>
+
 #include <qopenglfunctions_3_3_core.h>
 //#include <qopenglfunctions_4_5_core.h>
+#include <qvector3d.h>
 
 
 using OpenGLFunctionsBase = QOpenGLFunctions_3_3_Core;
 
 
+struct Line_strip_approx
+{
+  std::vector<QVector3D>  points;
+  std::vector<GLuint>     offsets;
+};
+
+
 #endif

Arrangement_on_surface_2/demo/earth/Geodesic_arcs.cpp

@@ -53,19 +53,16 @@ std::ostream& operator << (std::ostream& os, const Approximate_Vector_3& v)
 }
 
 
-Geodesic_arcs::Geodesic_arcs()
+Line_strip_approx Geodesic_arcs::get_approximate_arcs(double error)
 {
-  initializeOpenGLFunctions();
-
   // Construct the arrangement from 12 geodesic arcs.
   Geom_traits traits;
   Arrangement arr(&traits);
 
-
   auto ctr_p = traits.construct_point_2_object();
   auto ctr_cv = traits.construct_curve_2_object();
 
-  
+
   std::vector<Curve>  xcvs;
   xcvs.push_back(ctr_cv(ctr_p(1, 0, 0), ctr_p(0, 1, 0)));
   xcvs.push_back(ctr_cv(ctr_p(1, 0, 0), ctr_p(0, 0, 1)));
@@ -75,12 +72,9 @@ Geodesic_arcs::Geodesic_arcs()
 
   auto approx = traits.approximate_2_object();
 
-  const double error = 0.001;
-
-  std::vector<QVector3D> vertex_data;
 
-  m_arc_offsets.clear();
-  m_arc_offsets.push_back(0);
+  Line_strip_approx  lsa;
+  lsa.offsets.push_back(0);
   for (const auto& xcv : xcvs)
   {
     std::vector<Approximate_point_2> v;
@@ -89,54 +83,12 @@ Geodesic_arcs::Geodesic_arcs()
     for (const auto& p : v)
     {
       const QVector3D arc_point(p.dx(), p.dy(), p.dz());
-      vertex_data.push_back(arc_point);
+      lsa.points.push_back(arc_point);
     }
-    const auto current_vertex_data_size = vertex_data.size();
-    m_arc_offsets.push_back(current_vertex_data_size);
+    const auto current_vertex_data_size = lsa.points.size();
+    lsa.offsets.push_back(current_vertex_data_size);
   }
   //std::cout << "offset count = " << m_arc_offsets.size() << std::endl;
-
-
-  // DEFINE OPENGL BUFFERS
-  glGenVertexArrays(1, &m_vao);
-  glBindVertexArray(m_vao);
-
-
-  // Vertex Buffer
-  glGenBuffers(1, &m_vbo);
-  glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
-  auto vertex_buffer_size = sizeof(QVector3D) * vertex_data.size();
-  auto vertex_buffer_data = reinterpret_cast<const void*>(vertex_data.data());
-  glBufferData(GL_ARRAY_BUFFER,
-    vertex_buffer_size,
-    vertex_buffer_data,
-    GL_STATIC_DRAW);
-
-  // Position Vertex-Attribute
-  GLint position_attrib_index = 0;
-  const void* position_offset = 0;
-  GLsizei stride = 0;
-  glVertexAttribPointer(position_attrib_index,
-                        3,
-                        GL_FLOAT, GL_FALSE,
-                        stride,
-                        position_offset);
-  glEnableVertexAttribArray(position_attrib_index);
-
-  glBindBuffer(GL_ARRAY_BUFFER, 0);
-  glBindVertexArray(0);
-}
-
-void Geodesic_arcs::draw()
-{
-  glBindVertexArray(m_vao);
-  {
-    for (int i = 1; i < m_arc_offsets.size(); i++)
-    {
-      const auto first = m_arc_offsets[i - 1];
-      const auto count = m_arc_offsets[i] - first;
-      glDrawArrays(GL_LINE_STRIP, first, count);
-    }
-  }
-  glBindVertexArray(0);
+
+  return lsa;
 }

Arrangement_on_surface_2/demo/earth/Geodesic_arcs.h

@@ -3,18 +3,13 @@
 #define GEODESIC_ARCS_H
 
 #include "Common_defs.h"
-#include <vector>
 
-class Geodesic_arcs : protected OpenGLFunctionsBase
+
+class Geodesic_arcs
 {
 public:
-  Geodesic_arcs();
-
-  void draw();
-
-private:
-  GLuint    m_vao, m_vbo, m_num_arc_points;
-  std::vector<GLuint>   m_arc_offsets;
+
+  Line_strip_approx  get_approximate_arcs(double error);
 };
 
 

Arrangement_on_surface_2/demo/earth/Line_strips.cpp

@@ -0,0 +1,54 @@
+
+#include "Line_strips.h"
+
+
+Line_strips::Line_strips(Line_strip_approx& lsa)
+{
+  initializeOpenGLFunctions();
+
+  const auto& vertex_data = lsa.points;
+  m_offsets = lsa.offsets;
+
+  // DEFINE OPENGL BUFFERS
+  glGenVertexArrays(1, &m_vao);
+  glBindVertexArray(m_vao);
+
+
+  // Vertex Buffer
+  glGenBuffers(1, &m_vbo);
+  glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
+  auto vertex_buffer_size = sizeof(QVector3D) * vertex_data.size();
+  auto vertex_buffer_data = reinterpret_cast<const void*>(vertex_data.data());
+  glBufferData(GL_ARRAY_BUFFER,
+    vertex_buffer_size,
+    vertex_buffer_data,
+    GL_STATIC_DRAW);
+
+  // Position Vertex-Attribute
+  GLint position_attrib_index = 0;
+  const void* position_offset = 0;
+  GLsizei stride = 0;
+  glVertexAttribPointer(position_attrib_index,
+                        3,
+                        GL_FLOAT, GL_FALSE,
+                        stride,
+                        position_offset);
+  glEnableVertexAttribArray(position_attrib_index);
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+}
+
+void Line_strips::draw()
+{
+  glBindVertexArray(m_vao);
+  {
+    for (int i = 1; i < m_offsets.size(); i++)
+    {
+      const auto first = m_offsets[i - 1];
+      const auto count = m_offsets[i] - first;
+      glDrawArrays(GL_LINE_STRIP, first, count);
+    }
+  }
+  glBindVertexArray(0);
+}

Arrangement_on_surface_2/demo/earth/Line_strips.h

@@ -0,0 +1,22 @@
+
+#ifndef LINE_STRIPS_H
+#define LINE_STRIPS_H
+
+#include <vector>
+#include "Common_defs.h"
+
+
+class Line_strips : protected OpenGLFunctionsBase
+{
+public:
+  Line_strips(Line_strip_approx& lsa);
+
+  void draw();
+
+private:
+  GLuint                m_vao, m_vbo;
+  std::vector<GLuint>   m_offsets;
+};
+
+
+#endif

Arrangement_on_surface_2/demo/earth/Main_widget.cpp

@@ -7,6 +7,7 @@
 
 #include <QMouseEvent>
 
+#include "Geodesic_arcs.h"
 #include "Tools.h"
 
 
@@ -109,7 +110,10 @@ void Main_widget::initializeGL()
   {
     // has to be defined after camera has been defined:
     // because we want to compute the error based on camera parameters!
-    m_geodesic_arcs = std::make_unique<Geodesic_arcs>();
+    Geodesic_arcs ga;
+    const double error = 0.001; // calculate this from cam parameters!
+    auto lsa = ga.get_approximate_arcs(error);
+    m_geodesic_arcs = std::make_unique<Line_strips>(lsa);
   }
 
   glClearColor(0, 0, 0, 1);
@@ -195,7 +199,7 @@ void Main_widget::paintGL()
 
   // GEODESIC ARCS
   {
-    glDisable(GL_DEPTH_TEST);
+    //glDisable(GL_DEPTH_TEST);
 
     auto& sp = m_sp_arc;
     sp.use();

Arrangement_on_surface_2/demo/earth/Main_widget.h

@@ -16,7 +16,7 @@
 
 #include "Camera.h"
 #include "Common_defs.h"
-#include "Geodesic_arcs.h"
+#include "Line_strips.h"
 #include "Shader_program.h"
 #include "Sphere.h"
 #include "World_coordinate_axes.h"
@@ -51,7 +51,7 @@ class Main_widget : public QOpenGLWidget, protected OpenGLFunctionsBase
   // Objects in the scene
   std::unique_ptr<Sphere>           m_sphere;
   std::unique_ptr<World_coord_axes> m_world_coord_axes;
-  std::unique_ptr<Geodesic_arcs>    m_geodesic_arcs;
+  std::unique_ptr<Line_strips>      m_geodesic_arcs;
 
   // Shaders
   Shader_program  m_sp_smooth;