README correctly indicates that Spiro's Left and Right constraints were confusing to use and removed them in this implementation.
In code I find this confusion is because they're named according to the order of the array which is easily confused with left and right as screen coordinates. I suggest calling them CurveToLine and LineToCurve and re-adding them to spline-research as they continue to be a useful way to weld lines to curves. The implementation is easy by translating them to a corner with an explicit tangent early in solve. This terminology may help in Spiro too.
To solve the confusion in a GUI, you may need to show this as a new type of explicit tangent.
(context: i'm translating this library to F# to here: https://github.com/terryspitz/dactyl-font/tree/spline-research/spline-research)
README correctly indicates that Spiro's Left and Right constraints were confusing to use and removed them in this implementation.
In code I find this confusion is because they're named according to the order of the array which is easily confused with left and right as screen coordinates. I suggest calling them CurveToLine and LineToCurve and re-adding them to spline-research as they continue to be a useful way to weld lines to curves. The implementation is easy by translating them to a corner with an explicit tangent early in solve. This terminology may help in Spiro too.
To solve the confusion in a GUI, you may need to show this as a new type of explicit tangent.
(context: i'm translating this library to F# to here: https://github.com/terryspitz/dactyl-font/tree/spline-research/spline-research)