Add idle rotation

Author: ChangLi27

src/Renderer/OpenGL/OpenGLRendererWidget.cpp

@@ -85,9 +85,27 @@ void OpenGLRendererWidget::paintGL()
 
     float aspect = (float)w / h;
 
+    // Idle Rotation
+    if (_rotating) {
+        // Increment yaw angle
+        _camAngle.y += 0.005f; // faster or slower
+
+        // Keep angle bounded to prevent float precision issues over time
+        if (_camAngle.y > 6.283185f) _camAngle.y -= 6.283185f;
+
+        // Recalculate camera position
+        _camPos.x = _camDist * sin(_camAngle.x) * cos(_camAngle.y);
+        _camPos.y = _camDist * cos(_camAngle.x);
+        _camPos.z = _camDist * sin(_camAngle.x) * sin(_camAngle.y);
+
+        // Repaint continuously
+        update();
+    }
+
     _volumeRenderer.render(defaultFramebufferObject(), _camPos, _camAngle, aspect);
 }
 
+
 void OpenGLRendererWidget::cleanup()
 {
     _isInitialized = false;
@@ -115,6 +133,7 @@ bool OpenGLRendererWidget::eventFilter(QObject* target, QEvent* event)
         _previousMousePos = mousePos;
 
         _mousePressed = true;
+        _rotating = false; // FIXME: improve interaction with roation
         break;
     }
     case QEvent::MouseMove:

src/Renderer/OpenGL/OpenGLRendererWidget.h

@@ -29,6 +29,7 @@ class OpenGLRendererWidget : public QOpenGLWidget, QOpenGLFunctions_4_2_Core
     void setColormap(const QImage& colormap);
     void setCursorPoint(mv::Vector3f cursorPoint);
 
+
 public:
     bool eventFilter(QObject* target, QEvent* event);
 
@@ -49,4 +50,7 @@ class OpenGLRendererWidget : public QOpenGLWidget, QOpenGLFunctions_4_2_Core
     bool _mousePressed = false;
 
     bool _isInitialized = false;
+
+    // for rotation
+    bool _rotating = true;
 };