IRCSS

//Moebius transformations in 3d, by reverse stereographic projection to the 3-sphere,
//rotation in 4d space, and projection back.
//by Daniel Piker 09/08/20
//Feel free to use, adapt and reshare. I'd appreciate a mention if you post something using this.
//You can also now find this transformation as a component in Grasshopper/Rhino
//I first wrote about these transformations here:
//https://spacesymmetrystructure.wordpress.com/2008/12/11/4-dimensional-rotations/

//If you want to transform about a given circle. Points on the circle and its axis stay on those curves.
//You can skip these 2 lines if you want to always use the origin centred unit circle.