(define gl-loop
(lambda (time delta-t)
(arrows_clockspin_heads (* (cos (* .0000053 time)) .3) (* time 0.0000074))
(gl_draw_arrows)
;; (println 'time: time)
(callback (+ time (* *second* delta-t) 0.5)
'gl-loop
(+ time (* *second* delta-t))
delta-t)))