This is wonderful news. Spiro splines are very cool, but I never considered them a real option for any projects I was working on because of the licensing issue. Hobby splines were the patent unencumbered next best choice as far as I could tell, but Spiro semantics always seemed incrementally preferable.

Raph's thesis on splines is a fun read: https://www.levien.com/phd/thesis.pdf

And the original paper on Hobby splines: https://link.springer.com/content/pdf/10.1007%2FBF02187690.p...