Hi,
Ideally I would only need the following:
two points and tangents ( a simple bezier curve), and as points and tangents are moved, the curve actually keeps as much as it can the actual original lengths. so the tangent direction and magnitude would needs adjusting.
If you can do that at runtime with no performance impact ( I mean here not more than simple maths), then you are in. If you think you can do it, pm me, I'll pay for it.
bye,
Jean