src/texture.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright 2024 Mike Becker. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "ascension/texture.h"
#include "ascension/error.h"

#include <assert.h>
#include <GL/glew.h>

void asc_texture_bind(AscTexture const *tex, int uniform_location, int unit) {
    glActiveTexture(GL_TEXTURE0 + unit);
    GLenum error = glGetError();
    if (error == GL_INVALID_ENUM) {
        asc_error("Tried to use more texture units than available.");
    }
    glBindTexture(tex->target, tex->tex_id);
    glUniform1i(uniform_location, unit);
}

void asc_texture_from_surface(AscTexture *tex, SDL_Surface const *surface) {
    glBindTexture(tex->target,tex->tex_id);
    glPixelStorei(GL_UNPACK_ROW_LENGTH,
                  surface->pitch / surface->format->BytesPerPixel);
    glTexImage2D(tex->target, 0, GL_RGBA,
                 surface->w, surface->h,
                 0, GL_BGRA,
                 GL_UNSIGNED_BYTE, surface->pixels);
}

void asc_texture_init(
        AscTexture *tex,
        enum asc_texture_target target,
        enum asc_texture_min_filter min_filter,
        enum asc_texture_mag_filter mag_filter
) {
    static const GLenum texture_targets[] = {
            GL_TEXTURE_RECTANGLE
    };
    static const GLint texture_filters[] = {
            GL_NEAREST,
            GL_LINEAR,
            GL_NEAREST_MIPMAP_NEAREST,
            GL_LINEAR_MIPMAP_NEAREST,
            GL_NEAREST_MIPMAP_LINEAR,
            GL_LINEAR_MIPMAP_LINEAR
    };
    assert(target < sizeof(texture_targets) / sizeof(GLenum));
    assert(min_filter < sizeof(texture_filters) / sizeof(GLint));
    assert(mag_filter < 2); // mag filter only supports nearest/linear
    tex->target = texture_targets[target];
    glGenTextures(1, &tex->tex_id);
    glBindTexture(tex->target, tex->tex_id);
    glTexParameteri(tex->target, GL_TEXTURE_MIN_FILTER,
                    texture_filters[min_filter]);
    glTexParameteri(tex->target, GL_TEXTURE_MAG_FILTER,
                    texture_filters[mag_filter]);
    asc_dprintf("Generated new texture for text node: %u", tex->tex_id);
}

void asc_texture_destroy(AscTexture *tex) {
    asc_dprintf("Release text node texture: %u", tex->tex_id);
    glDeleteTextures(1, &tex->tex_id);
}