72 lines
4.0 KiB
Racket
72 lines
4.0 KiB
Racket
#lang racket/base
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(require racket/match racket/list
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"../common/math.rkt"
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"../common/vector.rkt"
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"../common/sample.rkt"
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"renderer.rkt")
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(provide renderer3d-bounds-fixpoint
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surface3d-bounds-fun)
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;; ===================================================================================================
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;; Fixpoint computation of bounds for multiple renderers
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;; Attempts to comptute a fixpoint of, roughly, the bounds functions for the given renderers.
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;; More precisely, starting with the given plot bounds, it attempts to compute a fixpoint of
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;; apply-bounds*, overridden at every iteration by the plot bounds (if given).
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;; Because a fixpoint doesn't always exist, or only exists in the limit, it stops after max-iters.
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(define (renderer3d-bounds-fixpoint renderers plot-x-min plot-x-max plot-y-min plot-y-max
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plot-z-min plot-z-max [max-iters 4])
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(let/ec break
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;; Shortcut eval: if the plot bounds are all specified, the code below just returns them
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(when (and plot-x-min plot-x-max plot-y-min plot-y-max plot-z-min plot-z-max)
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(break plot-x-min plot-x-max plot-y-min plot-y-max plot-z-min plot-z-max))
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;; Iterate joint bounds to (hopefully) a fixed point
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(for/fold ([x-min plot-x-min]
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[x-max plot-x-max]
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[y-min plot-y-min]
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[y-max plot-y-max]
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[z-min plot-z-min]
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[z-max plot-z-max]) ([n (in-range max-iters)])
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;(printf "bounds = ~v ~v ~v ~v ~v ~v~n" x-min x-max y-min y-max z-min z-max)
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;; Get new bounds from the renderers' bounds functions
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(define-values (new-x-min new-x-max new-y-min new-y-max new-z-min new-z-max)
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(let-values ([(new-x-min new-x-max new-y-min new-y-max new-z-min new-z-max)
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(apply-bounds* renderers x-min x-max y-min y-max z-min z-max)])
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;; Override by plot bounds
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(values (if plot-x-min plot-x-min new-x-min) (if plot-x-max plot-x-max new-x-max)
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(if plot-y-min plot-y-min new-y-min) (if plot-y-max plot-y-max new-y-max)
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(if plot-z-min plot-z-min new-z-min) (if plot-z-max plot-z-max new-z-max))))
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;; Shortcut eval: if the bounds haven't changed, another iteration won't change them
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(cond [(and (equal? new-x-min x-min) (equal? new-x-max x-max)
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(equal? new-y-min y-min) (equal? new-y-max y-max)
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(equal? new-z-min z-min) (equal? new-z-max z-max))
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(break new-x-min new-x-max new-y-min new-y-max new-z-min new-z-max)]
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[else (values new-x-min new-x-max new-y-min new-y-max new-z-min new-z-max)]))))
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;; Applies the bounds functions of multiple renderers, in parallel. Returns the smallest rectangle
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;; that contains all the new bounds.
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;; This function is monotone because renderer2d-apply-bounds is monotone. If iterating it is bounded,
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;; a fixed point exists.
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(define (apply-bounds* renderers x-min x-max y-min y-max z-min z-max)
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(define-values (x-mins x-maxs y-mins y-maxs z-mins z-maxs)
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(for/lists (x-mins x-maxs y-mins y-maxs z-mins z-maxs) ([renderer (in-list renderers)])
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(renderer3d-apply-bounds renderer x-min x-max y-min y-max z-min z-max)))
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(values (apply maybe-min x-mins) (apply maybe-max x-maxs)
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(apply maybe-min y-mins) (apply maybe-max y-maxs)
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(apply maybe-min z-mins) (apply maybe-max z-maxs)))
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;; ===================================================================================================
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;; Bounds functions
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(define ((surface3d-bounds-fun f samples) x-min x-max y-min y-max z-min z-max)
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(cond [(and x-min x-max y-min y-max)
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(match-define (list xs ys zss) (f x-min x-max samples y-min y-max samples))
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(define zs (filter regular? (2d-sample->list zss)))
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(cond [(empty? zs) (values x-min x-max y-min y-max z-min z-max)]
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[else (values x-min x-max y-min y-max
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(if z-min z-min (apply min* zs))
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(if z-max z-max (apply max* zs)))])]
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[else (values x-min x-max y-min y-max z-min z-max)]))
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