/*
 $ gcc -g glxcontext-xlib.c -o glxcontext-xlib $(pkg-config --cflags --libs  x11) -lGL -lGLU
 */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<X11/Xlib.h>
#include<GL/gl.h>
#include<GL/glx.h>
#include<GL/glu.h>

static int
handleXError (Display * dpy, XErrorEvent * err)
{
    return 0;
}


int main(int argc, char *argv[])
{
    Display             *dpy;
    Window               root;
    GLint                att[] = { GLX_RGBA, GLX_DEPTH_SIZE, 24 };
    XVisualInfo         *vi;
    XSetWindowAttributes swa;
    Window               win;
    GLXContext           glc;
    XEvent               xev;

    dpy = XOpenDisplay(NULL);
    if (!dpy)
    {
        fprintf(stderr, "Cannot open display\n");
        exit(0); 
    }

    root = DefaultRootWindow(dpy);
    vi = glXChooseVisual(dpy, 0, att);
    if (!vi)
    {
        fprintf(stderr, "No visual found\n");
        exit(0);
    }

    swa.colormap   = XCreateColormap(dpy, root, vi->visual, AllocNone);
    win = XCreateWindow(dpy, root, 0, 0, 600, 600, 0, vi->depth, InputOutput, vi->visual, CWColormap, &swa);
    XMapWindow(dpy, win);

    XSetErrorHandler (handleXError);
    glc = glXCreateContext(dpy, vi, NULL, GL_FALSE);
    if (!glc)
    {
        printf("\n\tcannot create gl context\n\n");
        exit(0);
    }

    glXIsDirect(dpy, glc);
    glXDestroyContext(dpy, glc);

    while(1) {
        XNextEvent(dpy, &xev);
    } /* while(1) */

    XSync (dpy, 0);

    XCloseDisplay(dpy);
    exit(0);
}