Dance Game (StepMania) Step Generator
Mainly developed with 4-panel play in mind,
but it should work for any dance stage layout
(incl. PIU and SMX).
And mainly developed for use with dancetracker-related projects,
but it should work as a general-purpose library.
Huge thanks to this blog post https://mjvotaw.github.io/posts/step-annotation/step-annotations
and everyone who's worked on the ITGmania/SMeditor implementation.