;;; Your entry for the Scheme contest
;;;
;;; Title: 
;;;   Ammonite
;;;
;;; Description:
;;;   Within a spiral
;;;   There is another spiral
;;;   Containing spirals

;;; be advised that this particular routine takes a long time to run
;;; it is a bit faster but worse looking if minlen is greater than 1


(showturtle)
(clear)
(penup)

(goto (- 350) 350)
(color 'black)
(begin_fill)
(goto (- 350) (- 350))
(goto 350 (- 350))
(goto 350 350)
(goto (- 350) 350)
(end_fill)

(goto 308 (- 170))
(setheading 0)
(speed 1000)
 (hideturtle)

(define minlen 1)
(define ang 32)
(define offspringang 1)
(define lenfactor .95)
(define offspringfactor .23)

(define (spiral len ang heading lenfactor offspringang offspringfactor col)
    ;heading is 1 for CCW, -1 for CW
    ;use cooler colors
;    (define (nextcolor col) (case col
;        (('|#000000|) '|#080000|)
;        (('|#080000|) '|#100000|)
;        (('|#100000|) '|#180000|)
;        (('|#180000|) '|#200000|)
;        (('|#200000|) '|#280000|)
;        (('|#280000|) '|#300000|)
;        (('|#300000|) '|#380000|)
;        (('|#380000|) '|#400000|)
;        (('|#400000|) '|#480000|)
;        (('|#480000|) '|#500000|)
;        (('|#500000|) '|#580000|)
;        (('|#580000|) '|#600000|)
;        (('|#600000|) '|#680000|)
;        (('|#680000|) '|#700000|)
;        (('|#700000|) '|#780000|)
;        (('|#780000|) '|#800000|)
;        (('|#800000|) '|#880000|)
;        (('|#880000|) '|#900000|)
;        (('|#900000|) '|#980000|)
;        (('|#980000|) '|#A00000|)
;        (('|#A00000|) '|#A80000|)
;        (('|#A80000|) '|#B00000|)
;        (('|#B00000|) '|#B80000|)
;        (('|#B80000|) '|#C00000|)
;        (('|#C00000|) '|#C80000|)
;        (('|#C80000|) '|#D00000|)
;        (('|#D00000|) '|#D80000|)
;        (('|#D80000|) '|#E00000|)
;        (('|#E00000|) '|#E80000|)
;        (('|#E80000|) '|#F00000|)
;        (('|#F00000|) '|#F80000|)
;        (('|#F80000|) '|#000000|)
;    ))
    (define (oldnextcolor col) (case col
        ((red) 'orange)
        ((orange) 'yellow)
        ((yellow) 'green)
        ((green) 'blue)
        ((blue) 'purple)
        ((purple) 'red)
    ))
    ;base case: if length < 1, then abort recursion
    (if (< len minlen)
        #t ; return value indicating completion
        (begin ; the rest of the function - draw self, and then offspring into 2 spirals
            ;everything needs to be done kind of recursively - move forward, branch, move back
            (color col)
            (pendown)
            (forward len)
            (penup)
            ;we'll try one branch for now
            (left (* ang heading))
            (spiral (* len lenfactor) ang heading lenfactor offspringang offspringfactor col)
            ;now for the other branch
            (spiral (* len offspringfactor) (* ang offspringang) heading lenfactor offspringang offspringfactor (oldnextcolor col))
            (right (* ang heading))
            (backward len)
        )
    )
    #t
)
;(spiral 170 ang 1 lenfactor offspringang offspringfactor '|#000000|)
(spiral 205 ang 1 lenfactor offspringang offspringfactor 'blue)
;(exitonclick)