;;; Sly ;;; Copyright (C) 2013, 2014 David Thompson ;;; ;;; 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 ;;; . ;;; Commentary: ;; ;; Textures and texture regions are high level wrappers over OpenGL ;; textures. ;; ;;; Code: (define-module (sly texture) #:use-module (ice-9 match) #:use-module (srfi srfi-9) #:use-module (gl) #:use-module (gl low-level) #:use-module (gl contrib packed-struct) #:use-module (sly color) #:use-module (sly helpers) #:use-module (sly math vector) #:use-module (sly wrappers gl) #:use-module (sly 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 with-texture)) ;;; ;;; Textures ;;; ;; The object is a simple wrapper around an OpenGL texture ;; id. (define-record-type (%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 min-filter mag-filter) "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) (match min-filter ('nearest (texture-min-filter nearest)) ('linear (texture-min-filter linear)))) (gl-texture-parameter (texture-target texture-2d) (texture-parameter-name texture-mag-filter) (match mag-filter ('nearest (texture-mag-filter nearest)) ('linear (texture-mag-filter linear)))) (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 file-name #:optional #:key (min-filter 'nearest) (mag-filter 'nearest)) "Load a texture from an image file at FILENAME. MIN-FILTER and MAG-FILTER describe the method that should be used for minification and magnification. Valid values are 'nearest and 'linear. By default, 'nearest is used." (let* ((bitmap (load-bitmap file-name)) (texture (bitmap->texture bitmap min-filter mag-filter))) (freeimage-unload bitmap) texture)) (define (anchor-texture texture anchor) "Translate ANCHOR into a vector that represents the desired centtral point for TEXTURE. Valid values for ANCHOR are: 'center, 'top-left, 'top-right, 'bottom-left, 'bottom-right, 'top-center, 'bottom-center, or any 2D vector. Passing a 2D vector will simply cause the same vector to be returned." (let ((w (texture-width texture)) (h (texture-height texture))) (match anchor ((? vector2? anchor) anchor) ('center (vector2 (/ w 2) (/ h 2))) ('top-left (vector2 0 0)) ('top-right (vector2 w 0)) ('bottom-left (vector2 0 h)) ('bottom-right (vector2 w h)) ('top-center (vector2 (/ w 2) 0)) ('bottom-center (vector2 (/ w 2) h)) (_ (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-syntax-rule (with-texture texture body ...) (begin (glBindTexture (texture-target texture-2d) (texture-id texture)) body ... (glBindTexture (texture-target texture-2d) 0))) (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))))