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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 (figl gl)
#:use-module (2d wrappers gl)
#:use-module (2d wrappers freeimage)
#:use-module (2d helpers)
#:export (make-texture
make-texture-region
load-texture
texture?
texture-region?
texture-id
texture-width
texture-height
texture-s1
texture-t1
texture-s2
texture-t2
surface->texture
draw-texture))
;;;
;;; Textures
;;;
;; The <texture> object is a simple wrapper around an OpenGL texture
;; id.
(define-record-type <texture>
(%make-texture id parent width height s1 t1 s2 t2)
texture?
(id texture-id)
(parent texture-parent)
(width texture-width)
(height texture-height)
(s1 texture-s1)
(t1 texture-t1)
(s2 texture-s2)
(t2 texture-t2))
(define (texture-region? texture)
(texture? (texture-parent texture)))
(define (make-texture id parent width height s1 t1 s2 t2)
(let ((texture (%make-texture id parent width height s1 t1 s2 t2)))
(texture-guardian texture)
texture))
(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)))
(make-texture (texture-id texture)
texture
width
height
(/ x w)
(/ y h)
(/ (+ x width) w)
(/ (+ y height) h))))
;; 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
;; Do not reap texture regions
(unless (texture-region? 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 (bitmap->texture bitmap)
"Translates a freeimage bitmap into an OpenGL texture."
(let ((texture-id (gl-generate-texture))
(pixels (freeimage-get-bits bitmap)))
(with-gl-bind-texture (texture-target texture-2d) texture-id
;; Use "nearest" scaling method so that pixel art doesn't become
;; blurry when scaled.
(gl-texture-parameter (texture-target texture-2d)
(texture-parameter-name texture-min-filter)
(texture-min-filter nearest))
(gl-texture-parameter (texture-target texture-2d)
(texture-parameter-name texture-mag-filter)
(texture-mag-filter nearest))
(gl-texture-image-2d (texture-target texture-2d)
0
(pixel-format rgba)
(freeimage-get-width bitmap)
(freeimage-get-height bitmap)
0
(version-1-2 bgra)
(color-pointer-type unsigned-byte)
pixels))
(make-texture texture-id
#f
(freeimage-get-width bitmap)
(freeimage-get-height bitmap)
0 0 1 1)))
(define (load-bitmap filename)
;; Throw an error if image file does not exist or else we will
;; segfault later.
(unless (file-exists? filename)
(throw 'image-not-found filename))
;; Load image and convert it to 32 bit color.
(let* ((image-type (freeimage-get-file-type filename))
(bitmap (freeimage-load image-type filename))
(32bit-bitmap (freeimage-convert-to-32-bits bitmap)))
(freeimage-unload bitmap)
;; Need to flip because y-axis is reversed.
(freeimage-flip-vertical 32bit-bitmap)
32bit-bitmap))
(define (load-texture filename)
"Loads a texture from a file."
(let* ((bitmap (load-bitmap filename))
(texture (bitmap->texture bitmap)))
(freeimage-unload bitmap)
texture))
(define* (draw-texture texture x y #:optional (color #xffffffff))
"Renders a textured quad in GL immediate mode."
(let* ((x2 (+ x (texture-width texture)))
(y2 (+ y (texture-height texture)))
(color (rgba->gl-color color))
(r (vector-ref color 0))
(g (vector-ref color 1))
(b (vector-ref color 2))
(a (vector-ref color 3))
(s1 (texture-s1 texture))
(t1 (texture-t1 texture))
(s2 (texture-s2 texture))
(t2 (texture-t2 texture)))
(with-gl-bind-texture (texture-target texture-2d) (texture-id texture)
(gl-begin (begin-mode quads)
(gl-color r g b a)
(gl-texture-coordinates s1 t1)
(gl-vertex x y)
(gl-texture-coordinates s1 t2)
(gl-vertex x y2)
(gl-texture-coordinates s2 t2)
(gl-vertex x2 y2)
(gl-texture-coordinates s2 t1)
(gl-vertex x2 y)))))
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