src/test/faces.c

    int main()
    {
      origin (-0.5, -0.5);
      init_grid(4);
      refine (level == 2 && x*x + y*y < sq(0.25));
      foreach_face(x)
        fprintf (stderr, "%g %g\n", x, y);
      foreach_face(y)
        fprintf (stderr, "%g %g\n", x, y);
      foreach_face()
        fprintf (stderr, "%g %g\n", x, y);
      output_cells (stdout);
    }