Bezier curves. Rappture

For one application I am planning, it will be useful and convenient to be able to input an arbitrary curve, without a particular functional form. These can be achieved producing a table using Bezier curves. In this way, using a few control points, you could ‘draw’ an input curve with nice mathematical properties such as continuity of 1st, 2nd (etc) derivative. This curve could be a potential that holds a quantum particle, for example.

So the wish is to implement such a possibility as one of the input options for rappture.