void barChart (void)
   {
      GLint month, k;

      glClear (GL_COLOR_BUFFER_BIT);       //  Clear display window.

      glColor3f (1.0, 0.0, 0.0);           //  Set bar color to red.
      for (k = 0; k < 12; k++)
         glRecti (20 + k*50, 165, 40 + k*50, dataValue [k]);

      glColor3f (0.0, 0.0, 0.0);          //  Set text color to black.
      xRaster = 20;                       //  Display chart labels.
      for (month = 0; month < 12; month++) {
         glRasterPos2i (xRaster, yRaster);
         for (k = 3*month; k < 3*month + 3; k++)
            glutBitmapCharacter (GLUT_BITMAP_HELVETICA_12, label [k]);
         xRaster += 50;
      }
      glFlush ( );
   }