;;; Scheme Recursive Art Contest Entry
;;;
;;; Please do not include your name or personal info in this file.
;;;
;;; Inspiration & Thx: https://www.zhihu.com/question/271643290/
;;;
;;; Title: A Random Tree and Blossom
;;;
;;; Description:
;;;   Plum blossoms from the bitter cold. 
;;;   梅花香自苦寒来。
;;;   Does pseudorandom == random?
(define (rand_seq s) (modulo (+ (* s 69069) 1) (expt 2 32)))
(define (rand s) (cons-stream (/ (rand_seq s) (expt 2 32)) (rand (rand_seq s))))
(define a (rand 5201314))
(define (random)
  (set-car! a (car (cdr-stream a)))
  (set-cdr! a (cdr (cdr-stream a)))
  (car a)
)

(define (tree n l hd)
  (pd)
  (define t (+ 0.25 (/ (cos (radians (+ hd 45))) 8)))
  (color (rgb t t t))
  (branch (/ n 3) l)
  (cond ((> n 0)
      (define lb (+ 10 (* 15 (random))))
      (define rb (+ 10 (* 15 (random))))
      (define nl (* l (+ 0.7 (* (random) 0.25))))
      (rt rb)
      (tree (- n 1) nl (+ hd rb))
      (lt (+ lb rb))
      (tree (- n 1) nl (- hd lb))
      (rt lb)
    )
    (else 
      (rt 90)
      (define n (+ 0.5 (/ (cos (radians (- hd 45))) 4)))
      (color (rgb n (* n 0.4) (* n 0.4)))
      (circle 3)
      (lt 90)
    )
  )
  (cond ((> (random) 0.8)
    (pu)
    (define t (- hd 90))
    (define angle (+ 90 (* (random) 40)))
    (seth angle)
    (define dis (+ 80 (* (random) 400)))
    (fd dis)
    (seth t)
    (pd)
    (rt 90)
    (define n (+ 0.5 (/ (cos (radians (- hd 135))) 4)))
    (color (rgb (+ 0.5 (* n 0.5)) (+ 0.2 (* n 0.2)) (+ 0.2 (* n 0.2))))
    (circle 2)
    (lt 90)
    (pu)
    (define t (- hd 90))
    (seth angle)
    (bk dis)
    (seth t)
  ))
  (pu)
  (bk l)
)

(define (draw)
  (bgcolor (rgb 0.5 0.5 0.5))
  (hideturtle)
  (tracer)
  ; (speed 0)
  (seth 0)
  (pu)
  (bk 330)
  (tree 12 100 90)
)

(define (branch w l)
  (begin_fill)
  (fd l)
  (rt 90)
  (fd w)
  (rt 90)
  (fd l)
  (rt 90)
  (end_fill)
  (fd w)
  (rt 90)
  (fd l)
)

(draw)

; Please leave this last line alone.  You may add additional procedures above
; this line.