RosettaCodeData/Task/Langtons-ant/EchoLisp/langtons-ant.echolisp
2016-12-05 23:44:36 +01:00

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1.6 KiB
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(lib 'plot)
(lib 'types)
(define (move iter x dir constant: plane turns cmax width xmax (cidx 0))
(while (> iter 0)
;; get color index of current square
(set! cidx (vector-ref plane x))
;; turn
(if (vector-ref turns cidx)
(set! dir (if (= dir 3) 0 (1+ dir))) ;; right is #t
(set! dir (if (= dir 0) 3 (1- dir))))
;; rotate colors
(set! cidx (if (= cidx cmax) 0 (1+ cidx)))
(vector-set! plane x cidx)
;; move
;; x = v + h*width for a pixel at (h,v)
(set! x
(cond
((= dir 0) (1+ x))
((= dir 1) (+ x width))
((= dir 2) (1- x))
((= dir 3) (- x width))))
(when (or (< x 0) (>= x xmax)) (set! iter -666)) ;; out of bounds
(set! iter (1- iter)))
iter)
;; a color table of 16 colors
(define colors
(list 0 (rgb 1 1 1) (rgb 1 0 0) (rgb 0 1 0) (rgb 0 0 1) (rgb 1 1 0) (rgb 1 0 1) (rgb 0 1 1)))
(define colors (list->vector (append colors colors)))
;; transform color index into rgb color, using colors table.
(define (colorize plane xmax)
(for ((x xmax))
(vector-set! plane x (vector-ref colors (vector-ref plane x))))
(vector->pixels plane)
xmax )
;; ant's patterns
(define turns #(#t #t #f #f #f #t #f #f #f #t #t #t)) ;; RRLLLRLLLRRR
;;(define turns #(#t #t #f #f #f #t #t #f)) ; RRLLLRRL
;;(define turns #(#t #f)) ; RL : basic ant
(define (ant (iter 100000))
(plot-clear)
(define width (first (pixels-dim))) ;; plane dimensions
(define height (rest (pixels-dim)))
(define plane (pixels->uint32-vector))
(define x (+ (quotient width 2) (* width (quotient height 2)))) ;; middle of plane
(define xmax (* width height))
(move iter x 0 plane turns (1- (vector-length turns)) width xmax)
(colorize plane xmax))
(ant) ;; run