(require (lib "fungraph.ss" "concabs"))
(set-default-image-size! 200)

(define c-curve
  (lambda (x0 y0 x1 y1 level)
    (if (= level 0)
        (line x0 y0 x1 y1)
        (let ((xmid (+ x0 (/ (- x1 x0) 2)))
              (ymid (+ y0 (/ (- y1 y0) 2)))
              (dx (- x1 x0))
              (dy (- y1 y0)))
          (let ((xa (- xmid (/ dy 2)))
                (ya (+ ymid (/ dx 2))))
            (overlay (c-curve x0 y0 xa ya (- level 1))
                     (c-curve xa ya x1 y1 (- level 1))))))))