From 2ee383241c08a1dadc0f22b6152b441a39775d45 Mon Sep 17 00:00:00 2001
From: denizdiktas <denizdiktas@gmail.com>
Date: Tue, 13 Jun 2023 12:06:20 +0300
Subject: [PATCH] Added: camera-zoom

---
 .../demo/earth/Camera.cpp                     |  7 ++++
 Arrangement_on_surface_2/demo/earth/Camera.h  |  3 ++
 .../demo/earth/mainwidget.cpp                 | 42 +++++++++++++++----
 .../demo/earth/mainwidget.h                   |  4 +-
 4 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/Arrangement_on_surface_2/demo/earth/Camera.cpp b/Arrangement_on_surface_2/demo/earth/Camera.cpp
index e6112160fd5..d6fe8b8c552 100644
--- a/Arrangement_on_surface_2/demo/earth/Camera.cpp
+++ b/Arrangement_on_surface_2/demo/earth/Camera.cpp
@@ -41,3 +41,10 @@ void Camera::rotate(float theta_around_x, float theta_around_y)
   m_ux = m_ux * rot;
   m_uz = m_uz * rot;
 }
+
+void Camera::move_forward(float distance)
+{
+  // recall that in OpenGL camera model, camera's z-axis points always
+  // out of the screen (towards the user).
+  m_pos -= distance * m_uz;
+}
diff --git a/Arrangement_on_surface_2/demo/earth/Camera.h b/Arrangement_on_surface_2/demo/earth/Camera.h
index 532d8b83a22..4deb0b9a64a 100644
--- a/Arrangement_on_surface_2/demo/earth/Camera.h
+++ b/Arrangement_on_surface_2/demo/earth/Camera.h
@@ -24,6 +24,9 @@ class Camera
   // rotate the camera around its own axes
   void rotate(float theta_around_x, float theta_around_y);
 
+  // move the camera forward around its own z-axis
+  void move_forward(float distance);
+
 private:
   QVector3D m_pos;
   QVector3D m_ux;
diff --git a/Arrangement_on_surface_2/demo/earth/mainwidget.cpp b/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
index 6da96304121..9b789e5f800 100644
--- a/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
+++ b/Arrangement_on_surface_2/demo/earth/mainwidget.cpp
@@ -19,29 +19,57 @@ MainWidget::~MainWidget()
 
 void MainWidget::mousePressEvent(QMouseEvent *e)
 {
-  m_mouse_pressed = true;
+  switch (e->button())
+  {
+  case Qt::LeftButton:
+    m_left_mouse_button_down = true;
+    break;
+
+  case Qt::MiddleButton:
+    m_middle_mouse_button_down = true;
+    break;
+  }
   m_last_mouse_pos = QVector2D(e->position());
 }
 void MainWidget::mouseMoveEvent(QMouseEvent* e)
 {
   auto current_mouse_pos = QVector2D(e->position());
+  const auto diff = current_mouse_pos - m_last_mouse_pos;
 
-  if (m_mouse_pressed)
+  if (m_left_mouse_button_down)
   {  
-    const auto diff = current_mouse_pos - m_last_mouse_pos;
-    const float scale_factor = 0.1f;
-    const float theta_around_x = scale_factor * diff.y();
-    const float theta_around_y = scale_factor * diff.x();
+    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);
   }
+  else
+  {
+    const float zoom_scale_factor = 0.01f;
+    const auto distance = zoom_scale_factor * diff.y();
+    m_camera.move_forward(distance);
+  }
 
   m_last_mouse_pos = current_mouse_pos;
 }
+void MainWidget::wheelEvent(QWheelEvent* e)
+{
+  auto distance = e->angleDelta();
+  m_camera.move_forward(distance.x());
+}
 void MainWidget::mouseReleaseEvent(QMouseEvent *e)
 {
-  m_mouse_pressed = false;
+  switch (e->button())
+  {
+  case Qt::LeftButton:
+    m_left_mouse_button_down = false;
+    break;
 
+  case Qt::MiddleButton:
+    m_middle_mouse_button_down = false;
+    break;
+  }
 }
 void MainWidget::timerEvent(QTimerEvent *)
 {
diff --git a/Arrangement_on_surface_2/demo/earth/mainwidget.h b/Arrangement_on_surface_2/demo/earth/mainwidget.h
index 6cb8b23d1c4..86c3d7334b3 100644
--- a/Arrangement_on_surface_2/demo/earth/mainwidget.h
+++ b/Arrangement_on_surface_2/demo/earth/mainwidget.h
@@ -31,6 +31,7 @@ class MainWidget : public QOpenGLWidget, protected OpenGLFunctionsBase
 protected:
     void mousePressEvent(QMouseEvent *e) override;
     void mouseMoveEvent(QMouseEvent* e) override;
+    void wheelEvent(QWheelEvent* event) override;
     void mouseReleaseEvent(QMouseEvent *e) override;
     void timerEvent(QTimerEvent *e) override;
 
@@ -54,7 +55,8 @@ class MainWidget : public QOpenGLWidget, protected OpenGLFunctionsBase
   
   // camera & controls
   Camera m_camera;
-  bool m_mouse_pressed = false;
+  bool m_left_mouse_button_down = false;
+  bool m_middle_mouse_button_down = false;
   QVector2D m_last_mouse_pos;