63 lines
1.6 KiB
Racket
63 lines
1.6 KiB
Racket
#lang racket
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(require graphics/value-turtles)
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(require file/convertible)
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(define forward 3)
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(define theta 20)
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(define generations 6)
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(define (tend sym)
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(cond
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[(eq? sym 'F) '(F F)]
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[(eq? sym 'X) '(F m l l X r p X r p F l p F X r m X)]
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[else `(,sym)]))
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(define (season plant)
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(foldr append '()
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(map tend plant)))
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(define (grow seed years)
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(if (<= years 0)
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seed
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(grow (season seed) (- years 1))))
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(define init-turtle
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(set-pen-width (turtles 600 800 300 400 (/ pi -2))
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1))
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(define state '())
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(define (step-turtle op turtle)
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(cond
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[(eq? op 'F) (draw forward turtle)]
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[(eq? op 'm) (turn theta turtle)]
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[(eq? op 'p) (turn (* -1 theta) turtle)]
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[(eq? op 'l) (begin (set! state
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(cons (turtle-state turtle)
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state))
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turtle)]
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[(eq? op 'r) (restore-turtle-state turtle
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(begin (let ([s (car state)])
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(set! state (cdr state))
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s)))]
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[else turtle]))
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(define (run-turtle plant turtle)
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(if (null? plant)
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turtle
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(run-turtle (cdr plant)
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(step-turtle (car plant) turtle))))
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(define (write-plant turtle filename)
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(let ([file (open-output-file filename #:exists 'replace)]
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[pict (convert (turtles-pict turtle) 'png-bytes)])
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(write-bytes pict file)))
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(define (test-plant)
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(let ([plant (grow '(X) generations)])
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(begin (set! state '())
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(write-plant (run-turtle plant init-turtle)
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"test-plant.png"))))
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(test-plant)
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