Curve subdivision schemes:
To edit the blue Contol Polygon:
Click and drag control vertices (large black dots) to move them
Drag them out of the window to delete them
Click and drag mid-edge points (smaller dots) to insert new vertices
Press "o" to square the polygon edges if nearly axis-aligned
Press "c" to center (and scale/skew) the polygon
Press "w" to print the coordinates of all control vertices
Press "i" to save a tiff image of the window

To modify the subdivision scheme (filled red curve, spans marked by small dots):
Press "b" for cubic B-spline subdivision
Press "f" for four-piont subdivision
Press "j" for Jarek's subdivision curve
Press "z" for non-unifoem subdivisoin
Press "z" for non-unifoem subdivisoin
Press "-" and "=" adjust the subdivision level up and down
Press "[" and "]" adjust jarek's parameter for that level
Press "," and "." adjust parameters for all levels

Built by Jarek Rossignac with Processing. Source code: subdivide.pde