Editor: With this program you can select a point light-source with the mouse (just left-click where you want when the mouse cross-hairs appear), and you will see the curve created by the envelope of Reflected Light rays from the surface of the chosen curve.
I achieve this by accurately estimating the derivative of the curve at each point the light hits it, from which I calculate the Unit Normal vector to the curve at that point, from which I can work out the correct reflected ray.
