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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:
;;
;; Textures and texture regions are high level wrappers over OpenGL
;; textures.
;;
;;; Code:
(define-module (2d texture)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-42)
#:use-module ((sdl sdl) #:prefix SDL:)
#:use-module (figl gl)
#:use-module (2d gl))
;;;
;;; Textures
;;;
;; 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))
;; Use a guardian and an after GC hook that ensures that OpenGL
;; textures are deleted when texture objects are GC'd.
(define texture-guardian (make-guardian))
(define (reap-textures)
(let loop ((texture (texture-guardian)))
(when texture
;; When attempting to reap structures upon guile exit, the
;; dynamic pointer to gl-delete-textures becomes invalid. So, we
;; ignore the error and move on.
(catch 'misc-error
(lambda () (gl-delete-texture (texture-id texture)))
(lambda (key . args) #f))
(loop (texture-guardian)))))
(add-hook! after-gc-hook reap-textures)
(define (surface-pixel-format surface)
"Returns the OpenGL pixel format for a surface. RGB and RGBA formats
are supported."
(case (SDL:surface:depth surface)
((24) (pixel-format* rgb))
((32) (pixel-format* rgba))
(else (throw 'unsupported-pixel-format (SDL:surface:depth surface)))))
(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))
(pixel-format (surface-pixel-format surface)))
(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
(SDL:surface:w surface)
(SDL:surface:h surface)
0
pixel-format
(color-pointer-type unsigned-byte)
(SDL:surface-pixels surface)))
(let ((texture (make-texture texture-id
(SDL:surface:w surface)
(SDL:surface:h surface))))
(texture-guardian texture)
texture)))
(define (load-texture filename)
"Loads a texture from a file."
(surface->texture (SDL:load-image filename)))
(define* (texture-quad texture x y w h #:optional (color '(1 1 1))
(u 0) (v 0) (u2 1) (v2 1))
"Renders a textured quad."
(let ((x2 (+ x w))
(y2 (+ y h)))
(with-gl-bind-texture (texture-target texture-2d) (texture-id texture)
(gl-begin (primitive-type quads)
(apply gl-color color)
(gl-texture-coordinates u v)
(gl-vertex x y)
(gl-texture-coordinates u2 v)
(gl-vertex x2 y)
(gl-texture-coordinates u2 v2)
(gl-vertex x2 y2)
(gl-texture-coordinates u v2)
(gl-vertex x y2)))))
(export make-texture
load-texture
texture?
texture-id
texture-width
texture-height
surface->texture
texture-quad)
;;;
;;; Texture Regions
;;;
;; Texture regions represent a segment of a texture.
(define-record-type <texture-region>
(%make-texture-region texture width height u v u2 v2)
texture-region?
(texture texture-region-texture)
(width texture-region-width)
(height texture-region-height)
(u texture-region-u)
(v texture-region-v)
(u2 texture-region-u2)
(v2 texture-region-v2))
(define (make-texture-region texture x y width height)
"Creates a new texture region given a texture and a pixel region."
(let* ((w (texture-width texture))
(h (texture-height texture))
(u (/ x w))
(v (/ y h))
(u2 (/ (+ x width) w))
(v2 (/ (+ y height) h)))
(%make-texture-region texture width height u v u2 v2)))
(define* (split-texture texture width height
#:optional #:key (margin 0) (spacing 0))
"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))))
(export make-texture-region
texture-region?
texture-region-texture
texture-region-width
texture-region-height
texture-region-u
texture-region-v
texture-region-u2
texture-region-v2
split-texture)
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