void displayFunc()
{
      static double previousTickCount = (double)cvGetTickCount();
      static int frameCount = 0;

///………
      glutSwapBuffers();

      frameCount++;
      if (frameCount == FPS_STATS_NB_FRAMES)
      {
            frameCount = 0;
            double newTickCount = (double)cvGetTickCount();
            double fps = (cvGetTickFrequency()*1000000.0*FPS_STATS_NB_FRAMES)/(newTickCount-previousTickCount);
            previousTickCount = newTickCount;
            char title[100];
            sprintf(title, "VisualWall - %d fps", (int)(0.5+fps));
            glutSetWindowTitle(title);
      }
}