Midpoint snaps halfway along the length of an elliptical arc or open spline.
Perpendicular and Tangent from a base point find every foot point and
tangent point on ellipses, elliptical arcs and splines (the one nearest the
cursor wins, as for circles): tangents to an ellipse exactly through the unit
circle, the rest by sampling the parameter range and bisecting each sign
change, with fixed iteration bounds. Quadrant on an elliptical arc offers only
the quadrant points the arc passes through.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
