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Clipping lines now uses exact arithmetic. Fixes visual issues with plotting inexact functions at very small scales. Every plot should render correctly at every scale now.

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This commit is contained in:
Neil Toronto 2012-01-27 10:39:39 -07:00
parent e4b1ef1b6e
commit 713772959f
2 changed files with 29 additions and 17 deletions
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19
collects/plot/plot2d/clip.rkt
View File

@ -2,7 +2,8 @@
;; Small library for clipping points, rectangles, lines and polygons against axial planes. ;; Small library for clipping points, rectangles, lines and polygons against axial planes.
(require racket/match racket/list) (require racket/match racket/list
"../common/utils.rkt")
(provide point-in-bounds? clip-line clip-lines clip-polygon) (provide point-in-bounds? clip-line clip-lines clip-polygon)
@ -17,14 +18,18 @@
;; Line clipping ;; Line clipping
(define (clip-line-x start-in-bounds? x x1 y1 x2 y2) (define (clip-line-x start-in-bounds? x x1 y1 x2 y2)
(define t (/ (- x x1) (- x2 x1))) (let-map
(cond [start-in-bounds? (values x1 y1 x (+ y1 (* t (- y2 y1))))] (x x1 y1 x2 y2) inexact->exact
[else (values x (+ y1 (* t (- y2 y1))) x2 y2)])) (define t (/ (- x x1) (- x2 x1)))
(cond [start-in-bounds? (values x1 y1 x (+ y1 (* t (- y2 y1))))]
[else (values x (+ y1 (* t (- y2 y1))) x2 y2)])))
(define (clip-line-y start-in-bounds? y x1 y1 x2 y2) (define (clip-line-y start-in-bounds? y x1 y1 x2 y2)
(define t (/ (- y y1) (- y2 y1))) (let-map
(cond [start-in-bounds? (values x1 y1 (+ x1 (* t (- x2 x1))) y)] (y x1 y1 x2 y2) inexact->exact
[else (values (+ x1 (* t (- x2 x1))) y x2 y2)])) (define t (/ (- y y1) (- y2 y1)))
(cond [start-in-bounds? (values x1 y1 (+ x1 (* t (- x2 x1))) y)]
[else (values (+ x1 (* t (- x2 x1))) y x2 y2)])))
(define (clip-line-x-min x-min x1 y1 x2 y2) (define (clip-line-x-min x-min x1 y1 x2 y2)
(cond [(and (x1 . >= . x-min) (x2 . < . x-min)) (clip-line-x #t x-min x1 y1 x2 y2)] (cond [(and (x1 . >= . x-min) (x2 . < . x-min)) (clip-line-x #t x-min x1 y1 x2 y2)]

27
collects/plot/plot3d/clip.rkt
View File

@ -2,7 +2,8 @@
;; Small library for clipping points, lines and polygons against axial planes. ;; Small library for clipping points, lines and polygons against axial planes.
(require racket/match racket/list racket/unsafe/ops) (require racket/match racket/list racket/unsafe/ops
"../common/utils.rkt")
(provide point-in-bounds? clip-line clip-polygon (provide point-in-bounds? clip-line clip-polygon
clip-polygon-x-min clip-polygon-x-max clip-polygon-x-min clip-polygon-x-max
@ -20,19 +21,25 @@
;; Lines ;; Lines
(define (clip-line-x start-in-bounds? x x1 y1 z1 x2 y2 z2) (define (clip-line-x start-in-bounds? x x1 y1 z1 x2 y2 z2)
(define t (/ (- x x1) (- x2 x1))) (let-map
(cond [start-in-bounds? (values x1 y1 z1 x (+ y1 (* t (- y2 y1))) (+ z1 (* t (- z2 z1))))] (x x1 y1 z1 x2 y2 z2) inexact->exact
[else (values x (+ y1 (* t (- y2 y1))) (+ z1 (* t (- z2 z1))) x2 y2 z2)])) (define t (/ (- x x1) (- x2 x1)))
(cond [start-in-bounds? (values x1 y1 z1 x (+ y1 (* t (- y2 y1))) (+ z1 (* t (- z2 z1))))]
[else (values x (+ y1 (* t (- y2 y1))) (+ z1 (* t (- z2 z1))) x2 y2 z2)])))
(define (clip-line-y start-in-bounds? y x1 y1 z1 x2 y2 z2) (define (clip-line-y start-in-bounds? y x1 y1 z1 x2 y2 z2)
(define t (/ (- y y1) (- y2 y1))) (let-map
(cond [start-in-bounds? (values x1 y1 z1 (+ x1 (* t (- x2 x1))) y (+ z1 (* t (- z2 z1))))] (y x1 y1 z1 x2 y2 z2) inexact->exact
[else (values (+ x1 (* t (- x2 x1))) y (+ z1 (* t (- z2 z1))) x2 y2 z2)])) (define t (/ (- y y1) (- y2 y1)))
(cond [start-in-bounds? (values x1 y1 z1 (+ x1 (* t (- x2 x1))) y (+ z1 (* t (- z2 z1))))]
[else (values (+ x1 (* t (- x2 x1))) y (+ z1 (* t (- z2 z1))) x2 y2 z2)])))
(define (clip-line-z start-in-bounds? z x1 y1 z1 x2 y2 z2) (define (clip-line-z start-in-bounds? z x1 y1 z1 x2 y2 z2)
(define t (/ (- z z1) (- z2 z1))) (let-map
(cond [start-in-bounds? (values x1 y1 z1 (+ x1 (* t (- x2 x1))) (+ y1 (* t (- y2 y1))) z)] (z x1 y1 z1 x2 y2 z2) inexact->exact
[else (values (+ x1 (* t (- x2 x1))) (+ y1 (* t (- y2 y1))) z x2 y2 z2)])) (define t (/ (- z z1) (- z2 z1)))
(cond [start-in-bounds? (values x1 y1 z1 (+ x1 (* t (- x2 x1))) (+ y1 (* t (- y2 y1))) z)]
[else (values (+ x1 (* t (- x2 x1))) (+ y1 (* t (- y2 y1))) z x2 y2 z2)])))
(define (clip-line-x-min x-min x1 y1 z1 x2 y2 z2) (define (clip-line-x-min x-min x1 y1 z1 x2 y2 z2)
(cond [(and (x1 . >= . x-min) (x2 . < . x-min)) (clip-line-x #t x-min x1 y1 z1 x2 y2 z2)] (cond [(and (x1 . >= . x-min) (x2 . < . x-min)) (clip-line-x #t x-min x1 y1 z1 x2 y2 z2)]