(defun make-structure ()
  (labels ((doit ()
             (case (random 2)
               (0 (case (random 3)
                    (0 (gl:scale 1 9 2))
                    (1 (gl:translate -2 -3 -1.5))
                    (2 (gl:rotate 119 997 27)))
                  (doit structure))
               (1 (case (pop structure)
                    (0 (glut:solid-sphere 11.529d0 13 3))
                    (1 (glut:solid-cube 19.d0)))))))
    (let ((state (make-random-state *random-state*)))
      (lambda ()
        (setf *random-state* state)
        (doit)))))