-(define-module (dungeon-master geom voronoi)
- #:use-module (ice-9 receive)
- #:use-module (srfi srfi-1)
- #:use-module (srfi srfi-9)
- #:use-module (dungeon-master geom point)
- #:use-module (dungeon-master geom triangle)
- #:export (make-voronoi-mesh
- voronoi-mesh?
- voronoi-mesh-triangles
- voronoi-mesh-points
- voronoi-mesh-frame))
-
-"https://github.com/watabou/TownGeneratorOS/blob/master/Source/com/watabou/geom/Voronoi.hx"
-
-(define-record-type <voronoi-mesh>
- (make-raw-voronoi-mesh triangles points frame)
- voronoi-mesh?
- (triangles voronoi-mesh-triangles set-voronoi-mesh-triangles!)
- (points voronoi-mesh-points set-voronoi-mesh-points!)
- (frame voronoi-mesh-frame set-voronoi-mesh-frame!))
-
-(define (make-voronoi-mesh vertices)
- (receive (minx miny maxx maxy)
- (calculate-mesh-limits vertices)
- (let ((c1 (make-point minx miny))
- (c2 (make-point minx maxy))
- (c3 (make-point maxx miny))
- (c4 (make-point maxx maxy)))
- (let ((frame (list c1 c2 c3 c4))
- (points (list c1 c2 c3 c4))
- (triangles (list (make-triangle c1 c2 c3)
- (make-triangle c2 c3 c4))))
- '()))))
-
-(define (calculate-mesh-limits vertices)
- (let ((xs (map (lambda (p) (point-x p)) vertices))
- (ys (map (lambda (p) (point-y p)) vertices)))
- (let ((minx (apply min (cons (expt 10 10) xs)))
- (miny (apply min (cons (expt 10 10) ys)))
- (maxx (apply max (cons (- (expt 10 9)) xs)))
- (maxy (apply max (cons (- (expt 10 9)) ys))))
- (let ((dx (* (- maxx minx) 0.5))
- (dy (* (- maxy miny) 0.5)))
- (values (- minx (/ dx 2))
- (- miny (/ dy 2))
- (+ maxx (/ dx 2))
- (+ maxy (/ dy 2)))))))
-
-(define (calculate-mesh points triangles vertices)
- (cond ((null? vertices)
- (values points triangles))
- (else
- (let ((vertice (car vertices)))
- (receive (to-split to-keep)
- (triangles-contains-point triangles vertice)
- (cond ((null? to-split)
- (calculate-mesh points triangles (cdr vertices)))
- (else
- (calculate-mesh (cons vertice points)
- (concatenate (calculate-new-triangles to-split vertice)
- to-keep)
- (cdr vertices)))))))))
-
-(define (calculate-new-triangles to-split p1)
- (let ((vertices (calculate-new-vertices to-split)))
- (let* ((a (car vertices))
- (b (cadr vertices))
- (len (length a)))
- (let loop ((sublist-a a)
- (triangles '()))
- (cond (sublist-a
- (let ((p2 (car sublist-a))
- (p3 (list-ref b (- len (length sublist-a)))))
- (loop (member p3 a)
- (cons (make-triangle p1 p2 p3) triangles))))
- (else
- triangles))))))
-
-(define* (calculate-new-vertices triangles #:optional (original-t triangles) (a '()) (b '()))
- (cond ((null? triangles)
- (list a b))
- (else
- (let* ((triangle (car triangles))
- (common-edge (triangles-has-common-edge triangle original-t)))
- (let ((points (triangle-points triangle)))
- (let ((p1 (car points))
- (p2 (cadr points))
- (p3 (caddr points))
- (e1 (car common-edge))
- (e2 (cadr common-edge))
- (e3 (caddr common-edge)))
- (cond (e1
- (set! a (cons p1 a))
- (set! b (cons p2 b))))
- (cond (e2
- (set! a (cons p2 a))
- (set! b (cons p3 b))))
- (cond (e3
- (set! a (cons p3 a))
- (set! b (cons p1 b))))
- (calculate-new-vertices (cdr triangles) original-t a b)))))))
-
-(define* (triangles-has-common-edge triangle triangles #:optional (e1 #t) (e2 #t) (e3 #t))
- (cond ((not (or e1 e2 e3))
- (list e1 e2 e3))
- ((null? triangles)
- (list e1 e2 e3))
- (else
- (let ((t (car triangles)))
- (cond ((equal? t triangle)
- (triangles-has-common-edge triangle (cdr triangles) e1 e2 e3))
- (else
- (let ((points (triangle-points triangle)))
- (let ((p1 (car points))
- (p2 (cadr points))
- (p3 (caddr points)))
- (when (and e1 (triangle-has-edge t p2 p1))
- (set! e1 #f))
- (when (and e2 (triangle-has-edge t p3 p2))
- (set! e2 #f))
- (when (and e3 (triangle-has-edge t p1 p3))
- (set! e3 #f))))
- (triangles-has-common-edge triangle (cdr triangles) e1 e2 e3)))))))
-
-(define (triangles-contains-point triangles point)
- (partition
- (lambda (triangle)
- (< (points-distance point (triangle-center triangle))
- (triangle-radius triangle)))
- triangles))