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/*
* Copyright (C) 2018 Tomasz Kramkowski <tk@the-tk.com>
* SPDX-License-Identifier: MIT
*/
#include <assert.h>
#include <png.h>
#include <stdlib.h>
#include "eprintf.h"
#include "tex.h"
// png2tex: read a PNG and produce an OpenGL texture out of it
GLuint png2tex(FILE *f)
{
png_image pi = { .version = PNG_IMAGE_VERSION };
unsigned char *data;
size_t stride, size;
GLuint id;
assert(f != NULL);
png_image_begin_read_from_stdio(&pi, f);
pi.format = PNG_FORMAT_RGB;
stride = sizeof *data * PNG_IMAGE_SAMPLE_CHANNELS(pi.format) * pi.width;
// OpenGL alignment requirement
stride = (stride + 3) & ~(size_t)3;
size = stride * pi.height;
data = emalloc(size);
png_image_finish_read(&pi, NULL, data, stride, NULL);
gl_tex_gen(1, &id);
gl_tex_bind(GL_TEXTURE_2D, id);
gl_tex_parami(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
gl_tex_parami(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
gl_tex_parami(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
gl_tex_parami(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
gl_tex_img2d(GL_TEXTURE_2D, 0, GL_SRGB, pi.width, pi.height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
gl_tex_genmip(GL_TEXTURE_2D);
free(data);
png_image_free(&pi);
return id;
}
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