From b3d657d1dbb9ced4db3d3d408cefd1032f610dbd Mon Sep 17 00:00:00 2001
From: denizdiktas <denizdiktas@gmail.com>
Date: Fri, 16 Jun 2023 10:40:53 +0300
Subject: [PATCH] intermediate camera fix (initial axes are not correct, this
 needs to be fixed!)

---
 .../demo/earth/Camera.cpp                     | 25 ++++++++++++++++---
 Arrangement_on_surface_2/demo/earth/Camera.h  |  6 ++++-
 .../demo/earth/mainwidget.cpp                 | 14 +++++++----
 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/Arrangement_on_surface_2/demo/earth/Camera.cpp b/Arrangement_on_surface_2/demo/earth/Camera.cpp
index 10c93125209..467d85dd5cd 100644
--- a/Arrangement_on_surface_2/demo/earth/Camera.cpp
+++ b/Arrangement_on_surface_2/demo/earth/Camera.cpp
@@ -57,10 +57,29 @@ void Camera::rotate_around_y(float theta)
   m_ux = ux.toVector3D();
   m_uz = uz.toVector3D();
 }
-void Camera::rotate(float theta_around_x, float theta_around_y)
+//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::rotate(float theta, float phi)
 {
-  rotate_around_x(theta_around_x);
-  rotate_around_y(theta_around_y);
+  QMatrix4x4 r1;
+  QVector3D ey(0, 1, 0);
+  r1.rotate(theta, ey);
+
+  // rx = rotated x axis
+  auto rx = r1 * QVector3D(1,0,0);
+  QMatrix4x4 r2;
+  r2.rotate(phi, rx);
+
+  // total rotation:
+  auto r = r2 * r1;
+
+  m_pos = r * QVector3D(0, 0, 3);
+  m_ux = r * QVector3D(1, 0, 0); // should be the same as rx (sanity check?)
+  m_uy = r * QVector3D(0, 1, 0);
+  m_uz = r * QVector3D(0, 0, 1);
 }
 
 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 458798cde65..88f8a03480c 100644
--- a/Arrangement_on_surface_2/demo/earth/Camera.h
+++ b/Arrangement_on_surface_2/demo/earth/Camera.h
@@ -25,7 +25,11 @@ public:
   // 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);
+  //void rotate(float theta_around_x, float theta_around_y);
+  
+  // theta: angle around y-axis
+  // phi: angle from the xz-plane (= rotated x-axis after the above rotation)
+  void rotate(float theta, float phi);
 
   // move the camera forward around its own z-axis
   void move_forward(float distance);
diff --git a/Arrangement_on_surface_2/demo/earth/mainwidget.cpp b/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
index 81887630c61..0f4c7f00317 100644
--- a/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
+++ b/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
@@ -16,6 +16,8 @@ MainWidget::~MainWidget()
 }
 
 
+float theta = 0, phi = 0;
+
 void MainWidget::set_mouse_button_pressed_flag(QMouseEvent* e, bool flag)
 {
   switch (e->button())
@@ -42,9 +44,12 @@ void MainWidget::mouseMoveEvent(QMouseEvent* e)
   if (m_left_mouse_button_down)
   {  
     const float rotation_scale_factor = 0.1f;
-    const float theta_around_x = rotation_scale_factor * diff.y();
-    const float theta_around_y = rotation_scale_factor * diff.x();
-    m_camera.rotate(theta_around_x, theta_around_y);
+    //const float theta_around_x = rotation_scale_factor * diff.y();
+    //const float theta_around_y = rotation_scale_factor * diff.x();
+    //m_camera.rotate(theta_around_x, theta_around_y);
+    theta += rotation_scale_factor * diff.x();
+    phi += rotation_scale_factor * diff.y();
+    m_camera.rotate(-theta, -phi);
   }
   else if(m_middle_mouse_button_down)
   {
@@ -92,7 +97,7 @@ void MainWidget::initializeGL()
 void MainWidget::init_camera()
 {
   m_camera.set_pos(0, 0, 3);
-  m_camera.rotate_around_x(-90);
+  //m_camera.rotate_around_x(-90);
 }
 void MainWidget::init_geometry()
 {
@@ -118,7 +123,6 @@ void MainWidget::init_sp_smooth()
   const char* vs = "shaders/smooth_vs.glsl";
   const char* fs = "shaders/smooth_fs.glsl";
   m_sp_smooth.init(vs, "", fs);
-
 }
 void MainWidget::init_sp_per_vertex_color()
 {