BTW you may also use delta-t as the parameter to make sure the animation runs with the same overall speed on machines with diffrent power/framerate. Something like:
old_t=t
t=millisecs()
delta#=float(t-old_t)/16.67
updateworld(delta)
You may have to initialize old_t before you start the main loop, eg: old_t=millisecs()-17
old_t=t
t=millisecs()
delta#=float(t-old_t)/16.67
updateworld(delta)
You may have to initialize old_t before you start the main loop, eg: old_t=millisecs()-17