diff options
author | David Thompson <dthompson@member.fsf.org> | 2013-08-27 18:21:49 -0400 |
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committer | David Thompson <dthompson@member.fsf.org> | 2013-08-27 18:21:49 -0400 |
commit | e719d1e988617f623fac29c1bd347785833c5f71 (patch) | |
tree | 9a01f9cb00ba4a8f563b07d8bb59ad2cb6b2bbc8 /2d | |
parent | 79abec1b07129dbeea7eb11d203bb68f5571fe2b (diff) |
Create new 2D vector module.
Diffstat (limited to '2d')
-rw-r--r-- | 2d/vector2.scm | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/2d/vector2.scm b/2d/vector2.scm new file mode 100644 index 0000000..7720095 --- /dev/null +++ b/2d/vector2.scm @@ -0,0 +1,107 @@ +;;; guile-2d +;;; Copyright (C) 2013 David Thompson <dthompson2@worcester.edu> +;;; +;;; Guile-2d is free software: you can redistribute it and/or modify it +;;; under the terms of the GNU Lesser General Public License as +;;; published by the Free Software Foundation, either version 3 of the +;;; License, or (at your option) any later version. +;;; +;;; Guile-2d is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +;;; Lesser General Public License for more details. +;;; +;;; You should have received a copy of the GNU Lesser General Public +;;; License along with this program. If not, see +;;; <http://www.gnu.org/licenses/>. + +;;; Commentary: +;; +;; 2D vector math operations. +;; +;;; Code: + +(define-module (2d vector2) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-9) + #:export (<vector2> + vector2 + vector2? + vx + vy + null-vector2 + identity-vector2 + vector2-polar + v+ + v* + vscale + vmag + vnorm + vdot + vcross)) + +(define-record-type <vector2> + (vector2 x y) + vector2? + (x vx) + (y vy)) + +(define null-vector2 (vector2 0 0)) +(define identity-vector2 (vector2 1 1)) + +(define (vector2-polar r theta) + "Converts polar coordinates into a cartesian vector." + (vector2 (* r (cos theta)) + (* r (sin theta)))) + +(define (v+ . vectors) + "Adds vectors." + (define (add-vectors x y vectors) + (cond ((null? vectors) + (vector2 x y)) + (else + (add-vectors (+ x (vx (car vectors))) + (+ y (vy (car vectors))) + (cdr vectors))))) + (add-vectors 0 0 vectors)) + +(define (v* . vectors) + "Multiplies vectors." + (define (multiply-vectors x y vectors) + (cond ((null? vectors) + (vector2 x y)) + (else + (multiply-vectors (* x (vx (car vectors))) + (* y (vy (car vectors))) + (cdr vectors))))) + (multiply-vectors 1 1 vectors)) + +(define (vscale v scalar) + "Multiply vector by a scalar." + (vector2 (* (vx v) scalar) + (* (vy v) scalar))) + +(define (vmag v) + "Returns the magnitude of a vector" + (sqrt (+ (expt (vx v) 2) + (expt (vy v) 2)))) + +(define (vnorm v) + "Normalizes a vector." + (let ((m (vmag v))) + (if (zero? m) + null-vector2 + (vector2 (/ (vx v) m) + (/ (vy v) m))))) + +(define (vdot v1 v2) + "Returns the dot product of two vectors." + (+ (* (vx v1) (vx v2)) + (* (vy v1) (vy v2)))) + +(define (vcross v1 v2) + "Returns the cross product of two vectors. The cross product of a 2D +vector is not defined. This function instead returns the Z coordinate +of the cross product as if the vectors were in 3D space." + (- (* (vx v1) (vy v2)) + (* (vy v1) (vx v2)))) |