ikarus/benchmarks/rnrs-benchmarks/ray.ss

181 lines
5.4 KiB
Scheme

;;; RAY -- Ray-trace a simple scene with spheres, generating a ".pgm" file.
;;; Translated to Scheme from Paul Graham's book ANSI Common Lisp, Example 9.8
(library (rnrs-benchmarks ray)
(export main)
(import (rnrs) (rnrs arithmetic flonums) (rnrs-benchmarks))
(define (make-point x y z)
(vector x y z))
(define (point-x p) (vector-ref p 0))
(define (point-y p) (vector-ref p 1))
(define (point-z p) (vector-ref p 2))
(define (sq x) (fl* x x))
(define (mag x y z)
(flsqrt (fl+ (sq x) (sq y) (sq z))))
(define (unit-vector x y z)
(let ((d (mag x y z)))
(make-point (fl/ x d) (fl/ y d) (fl/ z d))))
(define (distance p1 p2)
(mag (fl- (point-x p1) (point-x p2))
(fl- (point-y p1) (point-y p2))
(fl- (point-z p1) (point-z p2))))
(define (minroot a b c)
(if (flzero? a)
(fl/ (fl- c) b)
(let ((disc (fl- (sq b) (fl* 4.0 a c))))
(if (flnegative? disc)
#f
(let ((discrt (flsqrt disc))
(minus-b (fl- b))
(two-a (fl* 2.0 a)))
(flmin (fl/ (fl+ minus-b discrt) two-a)
(fl/ (fl- minus-b discrt) two-a)))))))
(define *world* '())
(define eye (make-point 0.0 0.0 200.0))
(define (tracer pathname res)
(call-with-output-file/truncate
pathname
(lambda (p)
(let ((extent (* res 100)))
(display "P2 " p)
(write extent p)
(display " " p)
(write extent p)
(display " 255" p)
(newline p)
(do ((y 0 (+ y 1)))
((= y extent))
(do ((x 0 (+ x 1)))
((= x extent))
(write (color-at
(fl+ -50.0
(fl/ (exact->inexact x) (exact->inexact res)))
(fl+ -50.0
(fl/ (exact->inexact y) (exact->inexact res))))
p)
(newline p)))))))
(define (color-at x y)
(let ((ray (unit-vector (fl- x (point-x eye))
(fl- y (point-y eye))
(fl- (point-z eye)))))
(inexact->exact (flround (fl* (sendray eye ray) 255.0)))))
(define (sendray pt ray)
(let* ((x (first-hit pt ray))
(s (vector-ref x 0))
(int (vector-ref x 1)))
(if s
(fl* (lambert s int ray)
(surface-color s))
0.0)))
(define (first-hit pt ray)
(let loop ((lst *world*) (surface #f) (hit #f) (dist 1e308))
(if (null? lst)
(vector surface hit)
(let ((s (car lst)))
(let ((h (intersect s pt ray)))
(if h
(let ((d (distance h pt)))
(if (fl<? d dist)
(loop (cdr lst) s h d)
(loop (cdr lst) surface hit dist)))
(loop (cdr lst) surface hit dist)))))))
(define (lambert s int ray)
(let ((n (normal s int)))
(flmax 0.0
(fl+ (fl* (point-x ray) (point-x n))
(fl* (point-y ray) (point-y n))
(fl* (point-z ray) (point-z n))))))
(define (make-sphere color radius center)
(vector color radius center))
(define (sphere-color s) (vector-ref s 0))
(define (sphere-radius s) (vector-ref s 1))
(define (sphere-center s) (vector-ref s 2))
(define (defsphere x y z r c)
(let ((s (make-sphere c r (make-point x y z))))
(set! *world* (cons s *world*))
s))
(define (surface-color s)
(sphere-color s))
(define (intersect s pt ray)
(sphere-intersect s pt ray))
(define (sphere-intersect s pt ray)
(let* ((xr (point-x ray))
(yr (point-y ray))
(zr (point-z ray))
(c (sphere-center s))
(n (minroot
(fl+ (sq xr) (sq yr) (sq zr))
(fl* 2.0
(fl+ (fl* (fl- (point-x pt) (point-x c)) xr)
(fl* (fl- (point-y pt) (point-y c)) yr)
(fl* (fl- (point-z pt) (point-z c)) zr)))
(fl+ (sq (fl- (point-x pt) (point-x c)))
(sq (fl- (point-y pt) (point-y c)))
(sq (fl- (point-z pt) (point-z c)))
(fl- (sq (sphere-radius s)))))))
(if n
(make-point (fl+ (point-x pt) (fl* n xr))
(fl+ (point-y pt) (fl* n yr))
(fl+ (point-z pt) (fl* n zr)))
#f)))
(define (normal s pt)
(sphere-normal s pt))
(define (sphere-normal s pt)
(let ((c (sphere-center s)))
(unit-vector (fl- (point-x c) (point-x pt))
(fl- (point-y c) (point-y pt))
(fl- (point-z c) (point-z pt)))))
(define (ray-test . opt)
(set! *world* '())
(defsphere 0.0 -300.0 -1200.0 200.0 0.8)
(defsphere -80.0 -150.0 -1200.0 200.0 0.7)
(defsphere 70.0 -100.0 -1200.0 200.0 0.9)
(do ((x -2 (+ x 1)))
((> x 2))
(do ((z 2 (+ z 1)))
((> z 7))
(defsphere
(fl* (exact->inexact x) 200.0)
300.0
(fl* (exact->inexact z) -400.0)
40.0
0.75)))
(tracer "spheres.pgm" (if (null? opt) 1 (car opt))))
(define (run)
(ray-test 1)
'ok)
(define (main . args)
(run-benchmark
"ray"
ray-iters
(lambda (result)
(equal? result 'ok))
(lambda () (lambda () (run))))))