I might suggest that you search the forums for some code related to bezier curves. These are a class of cubic spline curves that were adopted because they are simple to implement and lead to some very smooth curves that are easy to deflect and control. You now find them in most drawing packages. They were initially developed to aid in finding the most visually satisfying curve functions for shaping automobile parts. I already found two programs out there, and once you understand the principles of the code, I believe you can come with some excellent results that will fit your needs.