57 lines
1.1 KiB
Scheme
57 lines
1.1 KiB
Scheme
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(define pi (* 2 (acos 0)))
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(define res 200)
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(define data
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(letrec
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((delta (/ (* 2 pi) res))
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(vect (make-vector res))
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(iter
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(lambda (q)
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(if (< q res)
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(begin
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(vector-set!
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vect q
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(cons (cos (* q delta))
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(sin (* q delta))))
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(let ((ev (eval '(iter (+ 1 q)))))
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ev))))))
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(iter 0)
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vect))
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(define draw-circle
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(lambda (radius)
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(letrec
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((iter
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(lambda (q)
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(if (< q res)
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(begin
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(draw-line
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(* radius (car (vector-ref data q)))
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(* radius (cdr (vector-ref data q))))
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(iter (+ 1 q)))))))
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(draw-move radius 0)
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(iter 0)
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(draw-line radius 0))))
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(define steps 8)
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(define circles
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(lambda (maxrad)
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(letrec
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((iter
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(lambda (q)
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(if (< q maxrad)
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(begin
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(draw-color 0 (/ (* 255.0 q) maxrad) 0)
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(draw-circle q)
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(iter (+ q steps)))))))
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(iter 1))))
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(circles 100)
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