X-Git-Url: https://git.jsancho.org/?p=dungeon-master.git;a=blobdiff_plain;f=dungeon-master%2Fgeom%2Fpoint.scm;h=72ca1bbe00ae662ae9d97ba448c721424bb745c9;hp=64faaac44a4c7b8e3272a463071418ce6bebea50;hb=602500ffe32004dc0437ed55ac2d25ec69fc9e25;hpb=695ecf94f5bb10ced4e66b0b4d036de9965c02ca

diff --git a/dungeon-master/geom/point.scm b/dungeon-master/geom/point.scm
index 64faaac..72ca1bb 100644
--- a/dungeon-master/geom/point.scm
+++ b/dungeon-master/geom/point.scm
@@ -1,10 +1,29 @@
+;;; 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)
@@ -16,3 +35,19 @@
   (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)))