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;;; guile-2d
;;; Copyright (C) 2013 David Thompson <dthompson2@worcester.edu>
;;;
;;; Guile-2d is free software: you can redistribute it and/or modify it
;;; under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; Guile-2d 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
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Tilesets encapsulate a group of uniformly sized texture regions
;; that come from a single texture.
;;
;;; Code:
(define-module (2d tileset)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-42)
#:use-module (2d texture)
#:export (<tileset>
make-tileset
load-tileset
tileset?
tileset-tiles
tileset-width
tileset-height
tileset-margin
tileset-spacing
tileset-ref))
(define-record-type <tileset>
(%make-tileset tiles width height margin spacing)
tileset?
(tiles tileset-tiles)
(width tileset-width)
(height tileset-height)
(margin tileset-margin)
(spacing tileset-spacing))
(define (split-texture texture width height margin spacing)
"Splits a texture into a vector of texture regions of width x height
size."
(define (build-tile tx ty)
(let* ((x (+ (* tx (+ width spacing)) margin))
(y (+ (* ty (+ height spacing)) margin)))
(make-texture-region texture x y width height)))
(let* ((tw (texture-width texture))
(th (texture-height texture))
(rows (/ (- tw margin) (+ width spacing)))
(columns (/ (- tw margin) (+ height spacing))))
(vector-ec (: y rows) (: x columns) (build-tile x y))))
(define* (make-tileset texture width height
#:optional #:key (margin 0) (spacing 0))
"Returns a new tileset that is built by splitting the given texture
into tiles."
(let ((tiles (split-texture texture
width
height
margin
spacing)))
(%make-tileset tiles width height margin spacing)))
(define* (load-tileset filename width height
#:optional #:key (margin 0) (spacing 0))
"Returns a new tileset that is built by loading the given texture
file and splitting the texture into tiles."
(let* ((tiles (split-texture (load-texture filename)
width
height
margin
spacing)))
(%make-tileset tiles width height margin spacing)))
(define (tileset-ref tileset i)
"Returns the tile at index i."
(vector-ref (tileset-tiles tileset) i))
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