VolumeRendering

QGL Class Concept

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As opposed to overriding the paintEvent method inherited from QWidget, an OpenGL window needs to inherit from QGLWidget and override its paintGL method, which contains the OpenGL rendering calls for a particular 3D scene.

By starting a timer in the widget’s constructor that triggers a repaint event we get a consistent animation frame rate.

#ifndef QGLWINDOW_H
#define QGLWINDOW_H

#include <QtGui/QWidget>
#include <QtOpenGL/qgl.h>

class QGLWindow: public QGLWidget
{
public:

   static const double fps; // animated frames per second

   //! default ctor
   QGLWindow(QWidget *parent = 0)
      : QGLWidget(parent)
   {
      setFormat(QGLFormat(QGL::DoubleBuffer|QGL::DepthBuffer));

      startTimer((int)(1000.0/fps)); // ms=1000/fps
   }

   //! dtor
   ~QGLWindow()
   {}

protected:

   void initializeGL()
   {
      qglClearColor(Qt::black);
      glEnable(GL_DEPTH_TEST);
      glDisable(GL_CULL_FACE);
   }

   void resizeGL(int, int)
   {
      glViewport(0, 0, width(), height());
   }

   void paintGL();

   void timerEvent(QTimerEvent *)
   {
      repaint();
   }

};

#endif
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