star.md

star.rkt

#lang racket

(require racket/draw)

(define target (make-bitmap 500 500))
(define dc (new bitmap-dc% [bitmap target]))

(define (square-star dc)
  ;; background
  (send dc set-alpha 1.0)
  (send dc set-brush "black" 'solid)
  (send dc draw-rectangle 0 0 500 500)

  (send dc translate 250 250)

  (send dc set-pen "white" 1 'transparent)

  (for-each (lambda (color)
              (send dc rotate (/ pi 3.5))
              (send dc set-brush color 'solid)
              (send dc set-alpha .25)
              (send dc draw-rectangle 0 0 100 100))
            '("red" "orange" "yellow" "green" "blue" "purple"))

  (for-each (lambda (color)
              (send dc rotate (/ pi -2.5))
              (send dc set-brush color 'solid)
              (send dc set-alpha .25)
              (send dc draw-rectangle 0 0 140 140))
            '("red" "orange" "yellow" "green" "blue" "purple")))