From 9a5bfa00bef5ea0149ef3e5456114e6e1b40de61 Mon Sep 17 00:00:00 2001
From: denizdiktas <denizdiktas@gmail.com>
Date: Wed, 14 Jun 2023 10:24:08 +0300
Subject: [PATCH] Corrected initial camera position such that z-axis points to
 up, x-axis to right, y-axis into the screen

---
 .../demo/earth/Camera.cpp                     | 19 ++++++++++++-------
 Arrangement_on_surface_2/demo/earth/Camera.h  |  2 ++
 .../demo/earth/mainwidget.cpp                 | 12 ++++--------
 .../demo/earth/mainwidget.h                   | 10 +++++++---
 4 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/Arrangement_on_surface_2/demo/earth/Camera.cpp b/Arrangement_on_surface_2/demo/earth/Camera.cpp
index d6fe8b8c552..e52004a3577 100644
--- a/Arrangement_on_surface_2/demo/earth/Camera.cpp
+++ b/Arrangement_on_surface_2/demo/earth/Camera.cpp
@@ -25,22 +25,27 @@ QMatrix4x4 Camera::get_view_matrix() const
 }
 
 
-void Camera::rotate(float theta_around_x, float theta_around_y)
+void Camera::rotate_around_x(float theta)
 {
-  // rotate the camera around its x-axis
   QMatrix4x4 rot;
-  rot.rotate(theta_around_x, m_ux);
+  rot.rotate(theta, m_ux);
   m_pos = m_pos * rot;
   m_uy = m_uy * rot;
   m_uz = m_uz * rot;
-
-  // rotate the camera around its y-axis
-  rot.setToIdentity();
-  rot.rotate(theta_around_y, m_uy);
+}
+void Camera::rotate_around_y(float theta)
+{
+  QMatrix4x4 rot;
+  rot.rotate(theta, m_uy);
   m_pos = m_pos * rot;
   m_ux = m_ux * rot;
   m_uz = m_uz * rot;
 }
+void Camera::rotate(float theta_around_x, float theta_around_y)
+{
+  rotate_around_x(theta_around_x);
+  rotate_around_y(theta_around_y);
+}
 
 void Camera::move_forward(float distance)
 {
diff --git a/Arrangement_on_surface_2/demo/earth/Camera.h b/Arrangement_on_surface_2/demo/earth/Camera.h
index 4deb0b9a64a..1daedcea3ba 100644
--- a/Arrangement_on_surface_2/demo/earth/Camera.h
+++ b/Arrangement_on_surface_2/demo/earth/Camera.h
@@ -22,6 +22,8 @@ public:
   QMatrix4x4 get_projection_matrix() const { return m_projection; }
 
   // rotate the camera around its own axes
+  void rotate_around_x(float theta);
+  void rotate_around_y(float theta);
   void rotate(float theta_around_x, float theta_around_y);
 
   // move the camera forward around its own z-axis
diff --git a/Arrangement_on_surface_2/demo/earth/mainwidget.cpp b/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
index d2a15a0605e..7b0fb64fbb9 100644
--- a/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
+++ b/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
@@ -84,26 +84,22 @@ void MainWidget::initializeGL()
 
 
 
-
-#include "World_coordinate_axes.h"
-std::unique_ptr<World_coord_axes> m_world_coord_axes;
-
-
 void MainWidget::init_camera()
 {
-  m_camera.set_pos(0, 0, 10);
+  m_camera.set_pos(0, 0, 3);
+  m_camera.rotate_around_x(-90);
 }
 void MainWidget::init_geometry()
 {
   int num_slices, num_stacks;
   num_slices = num_stacks = 64;
-  float r = 3;
+  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);
 
 
-  m_world_coord_axes = std::make_unique<World_coord_axes>(5);
+  m_world_coord_axes = std::make_unique<World_coord_axes>(2);
 }
 void MainWidget::init_shader_programs()
 {
diff --git a/Arrangement_on_surface_2/demo/earth/mainwidget.h b/Arrangement_on_surface_2/demo/earth/mainwidget.h
index 98c57db7a27..0354a34365a 100644
--- a/Arrangement_on_surface_2/demo/earth/mainwidget.h
+++ b/Arrangement_on_surface_2/demo/earth/mainwidget.h
@@ -18,6 +18,7 @@
 #include "Common_defs.h"
 #include "Shader_program.h"
 #include "Sphere.h"
+#include "World_coordinate_axes.h"
 
 
 class MainWidget : public QOpenGLWidget, protected OpenGLFunctionsBase
@@ -50,18 +51,21 @@ protected:
   void init_shader_programs();
 
 private:
-  std::unique_ptr<Sphere>  m_sphere;
+  // Objects in the scene
+  std::unique_ptr<Sphere>           m_sphere;
+  std::unique_ptr<World_coord_axes> m_world_coord_axes;
 
+  // Shaders
   Shader_program  m_sp_smooth;
   Shader_program  m_sp_color_only;
   
-  // camera & controls
+  // Camera & controls
   Camera m_camera;
   bool m_left_mouse_button_down = false;
   bool m_middle_mouse_button_down = false;
   QVector2D m_last_mouse_pos;
 
-
+  // Timer for continuous screen-updates
   QBasicTimer m_timer;
 };