Stefan Röttger

#include <QtGui/QApplication>
#include <QtGui/QWidget>

#include <QtOpenGL/qgl.h>

#include <GL/gl.h>
#include <GL/glu.h>

static const double fps=30.0; // animated frames per second

class MyQGLWidget: public QGLWidget
{
public:

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

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

   //! dtor
   ~MyQGLWidget()
   {}

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()
   {
      // clear frame buffer
      glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

      // ... opengl rendering commands go here ...

      // setup perspective matrix
      glMatrixMode(GL_PROJECTION);
      glLoadIdentity();
      gluPerspective(90.0,1.0,0.1,10.0);

      // setup model-view matrix
      glMatrixMode(GL_MODELVIEW);
      glLoadIdentity();

      // define local rotated coordinate system
      static double angle=0.0; // rotation angle in degrees
      static const double omega=180.0; // rotation speed in degrees/s
      glTranslated(0.0,0.0,-2.0);
      glRotated(angle,0.0,1.0,0.0);

      // render triangles
      glBegin(GL_TRIANGLES);
         glColor3f(0.0f,0.75f,0.0f);
         glVertex3d(-0.5,-0.5,0.0);
         glVertex3d(0.5,-0.5,0.0);
         glVertex3d(0.0,0.5,0.0);
         glColor3f(1.0f,0.75f,1.0f);
         glVertex3d(0.0,-0.5,-0.5);
         glVertex3d(0.0,-0.5,0.5);
         glVertex3d(0.0,0.5,0.0);
      glEnd();

      // angle delta equals time delta times omega
      double dt=1.0/fps;
      angle+=dt*omega;
   }

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

};

int main(int argc, char *argv[])
{
   QApplication app(argc, argv);

   if (!QGLFormat::hasOpenGL()) return(1);

   MyQGLWidget main;
   main.show();

   return(app.exec());
}