+++ /dev/null
-;;; 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 triangle)
- #:use-module (ice-9 receive)
- #:use-module (srfi srfi-9)
- #:use-module (dungeon-master geom point)
- #:export (make-triangle
- triangle?
- triangle-points
- triangle-center
- triangle-radius
- triangle-has-edge))
-
-(define-record-type <triangle>
- (make-raw-triangle points center radius)
- triangle?
- (points triangle-points)
- (center triangle-center)
- (radius triangle-radius))
-
-(define (make-triangle p1 p2 p3)
- (let ((center (circumcenter p1 p2 p3)))
- (make-raw-triangle
- (list p1 p2 p3)
- center
- (points-distance center p1))))
-
-(define (circumcenter p1 p2 p3)
- (receive (a b c)
- (perpendicular-line-from-points p1 p2)
- (receive (e f g)
- (perpendicular-line-from-points p2 p3)
- (let ((determinant (- (* a f) (* e b))))
- (make-point
- (/ (- (* f c) (* b g)) determinant)
- (/ (- (* a g) (* e c)) determinant))))))
-
-(define (perpendicular-line-from-points p1 p2)
- (let ((x1 (point-x p1))
- (y1 (point-y p1))
- (x2 (point-x p2))
- (y2 (point-y p2)))
- (let* ((a (- y2 y1))
- (b (- x1 x2))
- (c (+ (* a x1) (* b y2))))
- (let ((mid-x (/ (+ x1 x2) 2))
- (mid-y (/ (+ y1 y2) 2)))
- (values (- b)
- a
- (+ (* (- b) mid-x) (* a mid-y)))))))
-
-(define (triangle-has-edge triangle a b)
- (let ((points (triangle-points triangle)))
- (let ((p1 (car points))
- (p2 (cadr points))
- (p3 (caddr points)))
- (or (and (equal? p1 a) (equal? p2 b))
- (and (equal? p1 b) (equal? p2 a))
- (and (equal? p2 a) (equal? p3 b))
- (and (equal? p2 b) (equal? p3 a))
- (and (equal? p3 a) (equal? p1 b))
- (and (equal? p3 b) (equal? p1 a))))))