Here is a quick look at the Bezier Curve editor I made in XNA that uses the function from my prior blog . Note there are circular Paths each withe 3 segments. Each segment is a 4 point Bezier calculation.

The basic tricks in getting this to be a smooth curve across the whole path is to:

The basic tricks in getting this to be a smooth curve across the whole path is to:

- p3 of the each segment is in common to p0 of next each segment.
- To make the circular, p3 of last segment must be same as p0 of 1st segment.
- p2 and p3 of each segment must be on a strait line with p0 and p1 or the next segment. So this means

- If a path point was moved by user, you must also move left and right control handler points by same deltas
- If left handler moved, must also move corresponding path point so it intersects line to other handler at mid point
- If right handler moved, must also move corresponding path point so it intersects line to other handler at mid point