+;;; Dungeon Master --- RPG Adventure Generator
+;;; Copyright © 2019 Javier Sancho <jsf@jsancho.org>
+;;;
+;;; Dungeon Master 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.
+;;;
+;;; Dungeon Master 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 Dungeon Master. If not, see <http://www.gnu.org/licenses/>.
+
+
(define-module (dungeon-master geom point)
#:use-module (srfi srfi-9)
#:export (make-point
point?
point-x
point-y
- points-distance))
+ points-distance
+ sum-points
+ scale-point))
(define-record-type <point>
(make-point x y)
(abs
(sqrt (+ (expt (- (point-x p1) (point-x p2)) 2)
(expt (- (point-y p1) (point-y p2)) 2)))))
+
+(define (sum-points . points-to-sum)
+ (let loop ((points points-to-sum)
+ (x 0)
+ (y 0))
+ (cond ((null? points)
+ (make-point x y))
+ (else
+ (loop (cdr points)
+ (+ x (point-x (car points)))
+ (+ y (point-y (car points))))))))
+
+(define (scale-point point scale)
+ (make-point
+ (* (point-x point) scale)
+ (* (point-y point) scale)))