49 lines
2.1 KiB
Scheme
49 lines
2.1 KiB
Scheme
;;; PNPOLY - Test if a point is contained in a 2D polygon.
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(define (pt-in-poly2 xp yp x y)
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(let loop ((c #f) (i (- (FLOATvector-length xp) 1)) (j 0))
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(if (< i 0)
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c
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(if (or (and (or (FLOAT> (FLOATvector-ref yp i) y)
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(FLOAT>= y (FLOATvector-ref yp j)))
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(or (FLOAT> (FLOATvector-ref yp j) y)
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(FLOAT>= y (FLOATvector-ref yp i))))
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(FLOAT>= x
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(FLOAT+ (FLOATvector-ref xp i)
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(FLOAT/ (FLOAT*
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(FLOAT- (FLOATvector-ref xp j)
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(FLOATvector-ref xp i))
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(FLOAT- y (FLOATvector-ref yp i)))
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(FLOAT- (FLOATvector-ref yp j)
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(FLOATvector-ref yp i))))))
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(loop c (- i 1) i)
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(loop (not c) (- i 1) i)))))
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(define (run)
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(let ((count 0)
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(xp (FLOATvector-const 0. 1. 1. 0. 0. 1. -.5 -1. -1. -2. -2.5
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-2. -1.5 -.5 1. 1. 0. -.5 -1. -.5))
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(yp (FLOATvector-const 0. 0. 1. 1. 2. 3. 2. 3. 0. -.5 -1.
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-1.5 -2. -2. -1.5 -1. -.5 -1. -1. -.5)))
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(if (pt-in-poly2 xp yp .5 .5) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp .5 1.5) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp -.5 1.5) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp .75 2.25) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp 0. 2.01) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp -.5 2.5) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp -1. -.5) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp -1.5 .5) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp -2.25 -1.) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp .5 -.25) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp .5 -1.25) (set! count (+ count 1)))
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(if (pt-in-poly2 xp yp -.5 -2.5) (set! count (+ count 1)))
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count))
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(define (main . args)
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(run-benchmark
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"pnpoly"
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pnpoly-iters
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(lambda (result)
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(and (number? result) (= result 6)))
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(lambda () (lambda () (run)))))
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