93 lines
2.5 KiB
Scheme
93 lines
2.5 KiB
Scheme
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;;; Copyright (C) 2024 David Thompson <dave@spritely.institute>
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;;;
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;;; Licensed under the Apache License, Version 2.0 (the "License");
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;;; you may not use this file except in compliance with the License.
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;;; You may obtain a copy of the License at
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;;;
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;;; http://www.apache.org/licenses/LICENSE-2.0
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;;;
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;;; Unless required by applicable law or agreed to in writing, software
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;;; distributed under the License is distributed on an "AS IS" BASIS,
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;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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;;; See the License for the specific language governing permissions and
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;;; limitations under the License.
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;;; Commentary:
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;;;
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;;; Rectangle data type.
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;;;
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;;; Code:
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(define-module (math rect)
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#:use-module (rnrs bytevectors)
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#:use-module (srfi srfi-9)
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#:export (make-rect
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rect?
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rect-x
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rect-y
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rect-width
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rect-height
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set-rect-x!
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set-rect-y!
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set-rect-width!
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set-rect-height!
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rect-intersects?
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rect-clip))
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;; For speed, a rect is a wrapper around a bytevector so that we can
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;; use unboxed floats.
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(define-record-type <rect>
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(%make-rect bv)
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rect?
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(bv rect-bv))
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(define f64-ref bytevector-ieee-double-native-ref)
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(define f64-set! bytevector-ieee-double-native-set!)
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(define (make-rect x y w h)
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(let ((bv (make-bytevector (* 8 4))))
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(f64-set! bv 0 x)
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(f64-set! bv 8 y)
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(f64-set! bv 16 w)
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(f64-set! bv 24 h)
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(%make-rect bv)))
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(define (rect-x r)
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(f64-ref (rect-bv r) 0))
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(define (rect-y r)
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(f64-ref (rect-bv r) 8))
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(define (rect-width r)
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(f64-ref (rect-bv r) 16))
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(define (rect-height r)
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(f64-ref (rect-bv r) 24))
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(define (set-rect-x! r x)
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(f64-set! (rect-bv r) 0 x))
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(define (set-rect-y! r y)
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(f64-set! (rect-bv r) 8 y))
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(define (set-rect-width! r width)
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(f64-set! (rect-bv r) 16 width))
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(define (set-rect-height! r height)
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(f64-set! (rect-bv r) 24 height))
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(define (rect-intersects? a b)
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(and (< (rect-x a) (+ (rect-x b) (rect-width b)))
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(< (rect-y a) (+ (rect-y b) (rect-height b)))
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(> (+ (rect-x a) (rect-width a)) (rect-x b))
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(> (+ (rect-y a) (rect-height a)) (rect-y b))))
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(define (rect-clip a b)
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(let* ((x1 (max (rect-x a) (rect-x b)))
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(x2 (min (+ (rect-x a) (rect-width a))
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(+ (rect-x b) (rect-width b))))
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(y1 (max (rect-y a) (rect-y b)))
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(y2 (min (+ (rect-y a) (rect-height a))
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(+ (rect-y b) (rect-height b)))))
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(make-rect x1 y1 (- x2 x1) (- y2 y1))))
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