SDL2 + OpenGL + ES3 - Triangle

SDL2_OpenGL_ES3_Triangle

#include <GLES3/gl3.h>
#include <SDL2/SDL.h>

struct window_data {
    const unsigned int width = 800, height = 600, x = SDL_WINDOWPOS_CENTERED,
                       y = SDL_WINDOWPOS_CENTERED;
    SDL_Color fill_color;
} window_data;

SDL_Window *window;
SDL_Event event;
SDL_GLContext gl_context;

void init_GL() {
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);

    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

    gl_context = SDL_GL_CreateContext(window);

    SDL_GL_SetSwapInterval(SDL_FALSE);
}

int main() {
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Error",
                                 "Failed to initialize video!", NULL);

        return EXIT_FAILURE;
    }

    window = SDL_CreateWindow("window", window_data.x, window_data.y,
                              window_data.width, window_data.height,
                              SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);

    init_GL();

    GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);

    static const GLfloat vertex_buffer_data[] = {
        -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
    };

    GLuint vertex_buffer;
    glGenBuffers(1, &vertex_buffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertex_buffer_data),
                 vertex_buffer_data, GL_STATIC_DRAW);

    while (window != NULL) {
        if (SDL_WaitEvent(&event)) {
            if (event.type == SDL_QUIT)
                window = NULL;
        }

        glClearColor(window_data.fill_color.r, window_data.fill_color.g,
                     window_data.fill_color.b, window_data.fill_color.a);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void *)0);

        glDrawArrays(GL_TRIANGLES, 0, 3);
        glDisableVertexAttribArray(0);

        SDL_GL_SwapWindow(window);
    }
}