examples/ex-142.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (let* ((z0 (point 50 50))
         (z1 (rotate 90 z0))
         (z2 (rotate 90 z1))
         (z3 (rotate 90 z2))
         (carre (op-- z0 z1 z2 z3 'cycle))
         (s 0.01)
         (z4 (mediation s z2 z3))
         (z5 (mediation s z1 z0))
         (rect (op-- z1 z2 z3 z4 z5 'cycle)))
    (for ((i (in-range 0.0 1.0 s )))
         (fill (shift (op* i (op- z0 z1)) rect)
               #:withcolor (op* i 'white)))
    (draw carre
          #:withpen (scale '2bp 'pencircle))))