#include <GL/glx.h>
#include <GL/gl.h>
#include <unistd.h>
#include <stdio.h>

static int attributeList[] = {
    GLX_RGBA,
    GLX_DOUBLEBUFFER,
    GLX_DEPTH_SIZE, 24,
    None
};

static Bool WaitForNotify(Display *d, XEvent *e, char *arg)
{
    return (e->type == MapNotify) && (e->xmap.window == (Window)arg);
}

int main(int argc, char **argv)
{
    Display *dpy;
    XVisualInfo *vi;
    Colormap cmap;
    XSetWindowAttributes swa;
    Window win;
    GLXContext cx;
    XEvent event;

    /* get a connection */
    dpy = XOpenDisplay(NULL);
    if (dpy == NULL)
    {
        fprintf(stderr, "XOpenDisplay() returned NULL\n");
        return 2;
    }

    /* get an appropriate visual */
    vi = glXChooseVisual(dpy, DefaultScreen(dpy), attributeList);
    if (vi == NULL)
    {
        fprintf(stderr, "glXChooseVisual() returned NULL\n");
        return 2;
    }

    /* create a GLX context */
    cx = glXCreateContext(dpy, vi, NULL, GL_TRUE);
    if (cx == NULL)
    {
        fprintf(stderr, "glXCreateContext() returned NULL\n");
        return 2;
    }

    /* create a color map */
    cmap = XCreateColormap(dpy, RootWindow(dpy, vi->screen),
            vi->visual, AllocNone);

    /* create a window */
    swa.colormap = cmap;
    swa.border_pixel = 0;
    swa.event_mask = StructureNotifyMask;
    win = XCreateWindow(dpy, RootWindow(dpy, vi->screen), 0, 0, 100, 100,
            0, vi->depth, InputOutput, vi->visual,
            CWBorderPixel | CWColormap | CWEventMask, &swa);
    XMapWindow(dpy, win);
    XIfEvent(dpy, &event, WaitForNotify, (char*)win);
    /* connect the context to the window */
    if (glXMakeCurrent(dpy, win, cx) == GL_FALSE)
    {
        fprintf(stderr, "glXMakeCurrent() returned false\n");
        return 2;
    }

    /* setup */
    glEnable(GL_DEPTH_TEST);

    /* clear the buffer */
    glClearColor(1, 1, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glXSwapBuffers(dpy, win);

    /* wait a while */
    sleep(5);

    /* teardown */
    XFree(vi);
    XCloseDisplay(dpy);
}