examples/ex-129.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (let* ((T (unknown-transform))
         (u '1cm)
         (z0 (point 0 0))
         (z1 (point (op* 2 u) 0))
         (z3 (rotate 90 z1))
         (z2 (op+ z1 z3))
         (p (op-- z0 z1 z2 z3 'cycle)))
    (for ((a (in-list (list z0 z1 z2)))
          (b (in-list (list z1 z2 z3))))
         (eqn= (transform T a) (mediation 0.1 a b)))
    (fill p #:withcolor (op* 0.8 'white))
    (fill (transform T p) #:withcolor 'white)
    ))