;;; Scheme Recursive Art Contest Entry
;;;
;;; Please do not include your name or personal info in this file.
;;;
;;; Title: Fun with Fractals
;;;
;;; Description: Sierpiński triangles and binary trees
;;;
(define (draw)

  (define pen '(
    "#F50000"
    "#F50029"
    "#F40051"
    "#F4007A"
    "#F300A2"
    "#F300CA"
    "#F300F3"
    "#CA00F2"
    "#A100F2"
    "#7900F1"
    "#5000F1"
    "#2800F0"
    "#0000F0"
    "#2800F0"
    "#5000F1"
    "#7900F1"
    "#A100F2"
    "#CA00F2"
    "#F300F3"
    "#F300CA"
    "#F300A2"
    "#F4007A"
    "#F40051"
    "#F50029"
  ))

  (define (h c d a p)
    (color (car p))
    (if (= c 0)
    (begin (forward d) (backward d))
    (begin
      (forward d)
      (left a)
      (h (- c 1) (* d (/ 4 5)) a (cdr p))
      (right (* a 2))
      (h (- c 1) (* d (/ 4 5)) a (cdr p))
      (left a)
      (color (car p))
      (backward d)))
  )
  
  (define (f r p)
    (cond
      ((> r (+ (/ (screen_width) 2) 100)) nil)
      ((null? p) (f r pen))
      (else (begin
        (color (car p))
        (setheading 90)
        (penup)
        (forward 15)
        (setheading 0)
        (pendown)
        (circle r)
        (f (+ r 15) (cdr p)))))
  )

  (define (t c d p)
    (color (car p))
    (if (> c 0)
      (begin
        (forward d)
        (left 120)
        (t (- c 1) (/ d 2) (cdr (cdr p)))
        (forward d)
        (left 120)
        (forward d)
        (left 120)
        (t (- c 1) (/ d 2) (cdr (cdr p)))
        (forward d)
        (left 120)
        (forward d)
        (left 120)
        (t (- c 1) (/ d 2) (cdr (cdr p)))
        (forward d)
        (left 120)
        (t 0 d p))

      (begin 
        (forward (* d 1))
        (left 120)
        (forward (* d 1))
        (left 120)
        (forward (* d 1))
        (left 120))
    )
  )
  
  (f 15 pen)
  (penup)
  (setposition 150 0)
  (pendown)

  (left 90)
  (t 5 300 pen)
  (left 180)
  (backward 300)
  (t 5 300 pen)
  (forward 100)
  (left 180)
  (h 10 100 30 pen)
  (left 180)
  (forward 100)
  (h 10 100 30 pen)
  (exitonclick))

(hideturtle)
(speed 0)

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