Please always attach as scene file, it takes time to replicate what is written and members usually do not want to invest effort to do that so questions go unanswered. Here is a little example, not sure if that is what you have in mind 🙂
Direction.c4d
Hi and to the Cafe
Good luck and happy learning, but, I will have to ask you to chose another display name, so please send me a message with desired one - thanks!
As far as I can see, formula uses parametric equations. t is a form of time (not scene time), basically a range from 0 to 2 * Pi. Try this in formula spline 🙂