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;;; guile-2d
;;; Copyright (C) 2013, 2014 David Thompson <dthompson2@worcester.edu>
;;;
;;; This program is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; This program 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
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU 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 (gl)
#:use-module (gl contrib packed-struct)
#:use-module (2d color)
#:use-module (2d helpers)
#:use-module (2d vector)
#:use-module (2d wrappers gl)
#:use-module (2d wrappers freeimage)
#: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
anchor-texture
texture-vertex
pack-texture-vertices
draw-texture-vertices))
;;;
;;; 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)
"Return #t if TEXTURE has a parent texture."
(texture? (texture-parent texture)))
(define (make-texture id parent width height s1 t1 s2 t2)
"Create a new texture object. ID is the OpenGL texture id. PARENT is
a texture object (if this texture only represents a region of another
texture) or #f. WIDTH and HEIGHT are the texture dimensions in
pixels. S1, T1, S2, and T2 are the OpenGL texture coordinates
representing the area of the texture that will be rendered."
(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 new texture region object. TEXTURE is the region's parent
texture. X, Y, WIDTH, and HEIGHT represent the region of the texture
that will be rendered, in pixels."
(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-guardian texture-guardian
(lambda (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.
(false-if-exception (gl-delete-texture (texture-id texture))))))
(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)
"Load a texture from an image file at FILENAME."
(let* ((bitmap (load-bitmap filename))
(texture (bitmap->texture bitmap)))
(freeimage-unload bitmap)
texture))
(define (anchor-texture texture anchor)
"Return a vector of the coordinates for the center point of a
texture."
(let ((w (texture-width texture))
(h (texture-height texture)))
(cond
((vector2? anchor)
anchor)
((eq? anchor 'center)
(vector (/ w 2)
(/ h 2)))
((eq? anchor 'top-left)
#(0 0))
((eq? anchor 'top-right)
(vector w 0))
((eq? anchor 'bottom-left)
(vector 0 h))
((eq? anchor 'bottom-right)
(vector w h))
((eq? anchor 'top-center)
(vector (/ w 2) 0))
((eq? anchor 'bottom-center)
(vector (/ w 2) h))
(else
(error "Invalid anchor type!" anchor)))))
;;;
;;; Texture Vertices
;;;
(define-packed-struct texture-vertex
;; Position
(x float)
(y float)
;; Texture Coordinates
(s float)
(t float))
(define texture-vertex-size (packed-struct-size texture-vertex))
(define x-offset (packed-struct-offset texture-vertex x))
(define s-offset (packed-struct-offset texture-vertex s))
(define (pack-texture-vertices vertices offset width height s1 t1 s2 t2)
;; Vertices go counter clockwise, starting from the top-left
;; corner.
(pack vertices offset texture-vertex 0 0 s1 t1)
(pack vertices (+ offset 1) texture-vertex 0 height s1 t2)
(pack vertices (+ offset 2) texture-vertex width height s2 t2)
(pack vertices (+ offset 3) texture-vertex width 0 s2 t1))
(define (draw-texture-vertices texture vertices size)
(let ((pointer-type (tex-coord-pointer-type float)))
(gl-enable-client-state (enable-cap vertex-array))
(gl-enable-client-state (enable-cap texture-coord-array))
(with-gl-bind-texture (texture-target texture-2d) (texture-id texture)
(set-gl-vertex-array pointer-type
vertices
2
#:stride texture-vertex-size
#:offset x-offset)
(set-gl-texture-coordinates-array pointer-type
vertices
#:stride texture-vertex-size
#:offset s-offset)
(gl-draw-arrays (begin-mode quads) 0 (* size 4)))
(gl-disable-client-state (enable-cap texture-coord-array))
(gl-disable-client-state (enable-cap vertex-array))))
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