93 lines
2.5 KiB
Scheme
93 lines
2.5 KiB
Scheme
;;; 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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;;; Vectors, in the linear algebra sense.
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;;;
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;;; Code:
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(library (math vector)
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(export vec2
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vec2?
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vec2-x
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vec2-y
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set-vec2-x!
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set-vec2-y!
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vec2-add!
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vec2-sub!
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vec2-mul-scalar!
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vec2-magnitude
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vec2-normalize!
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vec2-clamp!)
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(import (scheme base)
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(scheme inexact)
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(only (hoot bytevectors)
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bytevector-ieee-double-native-ref
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bytevector-ieee-double-native-set!)
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(math))
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;; For speed, a vec2 is a wrapper around a bytevector so that we can
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;; use unboxed floats.
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(define-record-type <vec2>
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(make-vec2 bv)
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vec2?
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(bv vec2-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 (vec2 x y)
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(let ((v (make-vec2 (make-bytevector 16))))
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(set-vec2-x! v x)
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(set-vec2-y! v y)
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v))
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(define (vec2-x v)
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(f64-ref (vec2-bv v) 0))
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(define (vec2-y v)
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(f64-ref (vec2-bv v) 8))
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(define (set-vec2-x! v x)
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(f64-set! (vec2-bv v) 0 x))
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(define (set-vec2-y! v y)
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(f64-set! (vec2-bv v) 8 y))
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(define (vec2-add! v w)
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(set-vec2-x! v (+ (vec2-x v) (vec2-x w)))
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(set-vec2-y! v (+ (vec2-y v) (vec2-y w))))
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(define (vec2-sub! v w)
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(set-vec2-x! v (- (vec2-x v) (vec2-x w)))
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(set-vec2-y! v (- (vec2-y v) (vec2-y w))))
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(define (vec2-mul-scalar! v x)
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(set-vec2-x! v (* (vec2-x v) x))
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(set-vec2-y! v (* (vec2-y v) x)))
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(define (vec2-magnitude v)
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(sqrt (+ (* (vec2-x v) (vec2-x v)) (* (vec2-y v) (vec2-y v)))))
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(define (vec2-normalize! v)
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(unless (and (= (vec2-x v) 0.0) (= (vec2-y v) 0.0))
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(let ((m (vec2-magnitude v)))
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(set-vec2-x! v (/ (vec2-x v) m))
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(set-vec2-y! v (/ (vec2-y v) m)))))
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(define (vec2-clamp! v xmin ymin xmax ymax)
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(set-vec2-x! v (clamp (vec2-x v) xmin xmax))
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(set-vec2-y! v (clamp (vec2-y v) ymin ymax))))
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