added separate shader for drawing arcs

Arrangement_on_surface_2/demo/earth/mainwidget.cpp

@@ -115,7 +115,7 @@ void MainWidget::init_geometry()
 void MainWidget::init_shader_programs()
 {
   init_sp_smooth();
-  init_sp_color_only();
+  init_sp_per_vertex_color();
 }
 void MainWidget::init_sp_smooth()
 {
@@ -124,11 +124,11 @@ void MainWidget::init_sp_smooth()
   m_sp_smooth.init(vs, "", fs);
 
 }
-void MainWidget::init_sp_color_only()
+void MainWidget::init_sp_per_vertex_color()
 {
   const char* vs = "shaders/color_only_vs.glsl";
   const char* fs = "shaders/color_only_fs.glsl";
-  m_sp_color_only.init(vs, "", fs);
+  m_sp_per_vertex_color.init(vs, "", fs);
 }
 
 
@@ -170,12 +170,23 @@ void MainWidget::paintGL()
 
   // WORLD COORDINATE AXES &  GEODESIC ARCS
   {
-    glDisable(GL_DEPTH_TEST);
-
-    auto& sp = m_sp_color_only;
+    auto& sp = m_sp_per_vertex_color;
     sp.use();
     sp.set_uniform("u_mvp", mvp);
-   
+
+    m_world_coord_axes->draw();
+
+    sp.unuse();
+  }
+
+  // GEODESIC ARCS
+  {
+    glDisable(GL_DEPTH_TEST);
+
+    auto& sp = m_sp_per_vertex_color;
+    sp.use();
+    sp.set_uniform("u_mvp", mvp);
+
     // compute the cutting plane
     auto c = m_camera.get_pos();
     const auto d = c.length();
@@ -184,16 +195,10 @@ void MainWidget::paintGL()
     const auto n = (c / d); // plane unit normal vector
     const auto cos_beta = sin_alpha;
     const auto p = (r * cos_beta) * n;
-    QVector4D plane(n.x(), n.y(), n.z(), -QVector3D::dotProduct(p,n));
-    std::cout << plane << std::endl;
+    QVector4D plane(n.x(), n.y(), n.z(), -QVector3D::dotProduct(p, n));
     sp.set_uniform("u_plane", plane);
-    glEnable(GL_DEPTH_TEST);
     m_geodesic_arcs->draw();
 
-    glEnable(GL_DEPTH_TEST);
-    sp.set_uniform("u_plane", QVector4D(0,0,0,0));// ad-hoc
-    m_world_coord_axes->draw();
-
     sp.unuse();
   }
 }

Arrangement_on_surface_2/demo/earth/mainwidget.h

@@ -46,7 +46,7 @@ protected:
   
   void init_shader_programs();
   void init_sp_smooth();
-  void init_sp_color_only();
+  void init_sp_per_vertex_color();
 
 private:
   // Objects in the scene
@@ -55,7 +55,8 @@ private:
 
   // Shaders
   Shader_program  m_sp_smooth;
-  Shader_program  m_sp_color_only;
+  Shader_program  m_sp_per_vertex_color;
+  Shader_program  m_sp_arc;
   
   // Camera & controls
   Camera m_camera;

Arrangement_on_surface_2/demo/earth/shaders/arc_fs.glsl

@@ -1,9 +1,10 @@
 
 #version 330
 
+uniform vec3 u_color;
 uniform vec4 u_plane;
 
-in vec3 v_color;
+
 in vec3 v_pos;
 out vec4 out_color;
 
@@ -13,5 +14,5 @@ void main()
 	if( dot(u_plane, vec4(v_pos, 1)) < 0 )
 		discard;
 
-	out_color = vec4(v_color, 1);
+	out_color = vec4(u_color, 1);
 }

Arrangement_on_surface_2/demo/earth/shaders/arc_vs.glsl

@@ -0,0 +1,15 @@
+
+#version 330
+
+layout (location = 0) in vec3 a_pos;
+
+uniform mat4 u_mvp; 
+
+out vec3 v_pos;
+
+
+void main()
+{
+	v_pos = a_pos;
+	gl_Position = u_mvp * vec4(a_pos.xyz, 1);
+}

Arrangement_on_surface_2/demo/earth/shaders/per_vertex_color_fs.glsl

@@ -0,0 +1,13 @@
+
+#version 330
+
+uniform vec4 u_plane;
+
+in vec3 v_color;
+out vec4 out_color;
+
+
+void main()
+{
+	out_color = vec4(v_color, 1);
+}

Arrangement_on_surface_2/demo/earth/shaders/per_vertex_color_vs.glsl

@@ -7,12 +7,10 @@ layout (location = 1) in vec3 a_color;
 uniform mat4 u_mvp; 
 
 out vec3 v_color;
-out vec3 v_pos;
 
 
 void main()
 {
 	v_color = a_color;
-	v_pos = a_pos;
 	gl_Position = u_mvp * vec4(a_pos.xyz, 1);
 }