Check out Raph Levien's thesis: http://levien.com/phd/phd.html http://levien.com/phd/phd.html It doesn't talk about dynamically varying stiffness along the cur

Check out Raph Levien's thesis: http://levien.com/phd/phd.html http://levien.com/phd/phd.html It doesn't talk about dynamically varying stiffness along the curve, but is otherwise a very detailed dive into splines.