X-Git-Url: https://git.jsancho.org/?a=blobdiff_plain;f=src%2Fmath.scm;fp=src%2Fmath.scm;h=64317dd757e0a929899d7d49411209102c0016d8;hb=a3bf97e36510439b714ac53543491f7955497f3d;hp=0000000000000000000000000000000000000000;hpb=905abebe9a3b80a9ae2723024c6df8a728076157;p=gacela.git

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+;;; Gacela, a GNU Guile extension for fast games development
+;;; Copyright (C) 2009 by Javier Sancho Fernandez <jsf at jsancho dot org>
+;;;
+;;; This program is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; This program 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 General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+(define-module (gacela math)
+  #:export (*pi*
+	    degrees-to-radians
+	    radians-to-degrees
+	    distance-between-points
+	    nearest-power-of-two))
+
+
+;;; Constants
+
+(define *pi* (* (asin 1) 2))
+
+
+;;; Geometry
+
+(define (degrees-to-radians angle)
+  (/ (* angle *pi*) 180))
+
+(define (radians-to-degrees angle)
+  (/ (* angle 180) *pi*))
+
+(define (distance-between-points p1 p2)
+  (define (add-power-of-two p1 p2)
+    (cond ((null? p1)
+	   0)
+	  (else
+	   (+ (expt (- (car p1) (car p2)) 2)
+	      (add-power-of-two (cdr p1) (cdr p2))))))
+
+  (cond ((not (= (length p1) (length p2)))
+	 #f)
+	(else
+	 (sqrt (add-power-of-two p1 p2)))))
+
+
+;;; Functions
+
+(define (nearest-power-of-two n)
+  (define (power p n)
+    (cond ((> (* p 2) n) p)
+	  (else (power (* p 2) n))))
+  (power 1 n))