src/primitives.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright 2023 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/primitives.h"
#include "ascension/error.h"
#include "ascension/context.h"

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

static void asc_primitives_init_plane(AscMesh *mesh) {
    asc_dprintf("Create primitive plane in VBO %u and VAO %u", mesh->vbo, mesh->vao);
    mesh->vertices = 4;
    float data[8] = {
            0.0f, 0.0f, // bottom left
            0.0f, 1.0f,    // top left
            1.0f, 0.0f, // bottom right
            1.0f, 1.0f    // top right
    };
    glBindBuffer(GL_ARRAY_BUFFER, mesh->vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
    glBindVertexArray(mesh->vao);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, NULL);
    glEnableVertexAttribArray(0);
}

bool asc_primitives_init(AscPrimitives *primitives) {
    asc_dprintf("Create primitives for the GL context of active window.");
    // TODO: more primitives

    GLuint buffers[1];
    GLuint arrays[1];
    glGenBuffers(1, buffers);
    glGenVertexArrays(1, arrays);

    AscMesh *plane = &(primitives->plane);
    plane->vbo = buffers[0];
    plane->vao = arrays[0];
    asc_primitives_init_plane(plane);

    GLenum error = glGetError();
    if (error == GL_NO_ERROR) {
        return true;
    } else {
        asc_error_gl(error, CX_STR("Initialization of primitive meshes failed."));
        return false;
    }
}

void asc_primitives_destroy(AscPrimitives *primitives) {
    asc_dprintf("Destroy primitives in GL context of active window.");

    GLuint buffers[1];
    GLuint arrays[1];

    buffers[0] = primitives->plane.vbo;
    arrays[0] = primitives->plane.vao;

    glDeleteBuffers(1, buffers);
    glDeleteVertexArrays(1, arrays);

    memset(primitives, 0, sizeof(AscPrimitives));
}

void asc_primitives_draw_plane(void) {
    AscMesh const *mesh = &(asc_context.active_window->primitives.plane);
    glBindVertexArray(mesh->vao);
    glDrawArrays(GL_TRIANGLE_STRIP, 0, mesh->vertices);
}