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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:
;;
;; OpenGL texture wrapper.
;;
;;; Code:
(define-module (2d texture)
#:use-module (srfi srfi-9)
#:use-module ((sdl sdl) #:prefix SDL:)
#:use-module (figl gl)
#:export (make-texture
texture?
texture-id
texture-width
texture-height
surface->texture
load-texture
texture-quad))
;; The <texture> object is a simple wrapper around an OpenGL texture
;; id.
(define-record-type <texture>
(make-texture id width height)
texture?
(id texture-id)
(width texture-width)
(height texture-height))
(define (surface->texture surface)
"Translates an SDL surface into an OpenGL texture.
Currently only works with RGBA format surfaces."
(let* ((texture-id (gl-generate-texture)))
(with-gl-bind-texture (texture-target texture-2d) texture-id
(gl-texture-parameter (texture-target texture-2d)
(texture-parameter-name texture-min-filter)
(texture-min-filter linear))
(gl-texture-parameter (texture-target texture-2d)
(texture-parameter-name texture-mag-filter)
(texture-mag-filter linear))
(gl-texture-image-2d (texture-target texture-2d)
0
(pixel-format rgba)
(SDL:surface:w surface)
(SDL:surface:h surface)
0
(pixel-format rgba)
(color-pointer-type unsigned-byte)
(SDL:surface-pixels surface)))
(make-texture texture-id
(SDL:surface:w surface)
(SDL:surface:h surface))))
(define (load-texture filename)
"Loads a texture from a file."
(surface->texture (SDL:load-image filename)))
(define* (texture-quad texture x y w h)
"Renders a textured quad."
(let ((x2 (+ x w))
(y2 (+ y h)))
(with-gl-bind-texture (texture-target texture-2d) (texture-id texture)
(gl-begin (begin-mode quads)
(gl-texture-coordinates 0 0)
(gl-vertex x y)
(gl-texture-coordinates 1 0)
(gl-vertex x2 y)
(gl-texture-coordinates 1 1)
(gl-vertex x2 y2)
(gl-texture-coordinates 0 1)
(gl-vertex x y2)))))
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