Since I already had the binary search and interpolation code, it was just a matter of writing different samplers for ellipses and Bézier curves.
;; make a sampler function for a bezier curve
(defun make-bezier-sampler (p0 p1 p2 p3)
(lambda (k)
(decasteljau p0 p1 p2 p3 k)))
;; make a sampler function for an ellipse
(defun make-ellipse-sampler (center xradius yradius)
(lambda (k)
(let ((x (* xradius (cos k)))
(y (* yradius (sin k))))
(make-point (+ x (xcoord center)) (+ y (ycoord center))))))
Equal angle increments:
Equal circumferential distances:
