/* Este es el error que me da:

    X Error of failed request:  BadMatch (invalid parameter attributes)
      Major opcode of failed request:  153 (GLX)
      Minor opcode of failed request:  11 (X_GLXSwapBuffers)
      Serial number of failed request:  28
      Current serial number in output stream:  28

*/

#include <iostream>
#include <cstdlib>

#include <GL/glx.h>    /* this includes the necessary X headers */
#include <GL/gl.h>

#include <X11/X.h>    /* X11 constant (e.g. TrueColor) */
#include <X11/Xlib.h>    /* X11 constant (e.g. TrueColor) */
#include <X11/keysym.h>

using namespace std;

Display                 *dpy;   //La superficie sobre la que pintar
Window                  root;   //La ventana
GLint                   att[] = { GLX_RGBA, GLX_DEPTH_SIZE, 24, GLX_DOUBLEBUFFER, None }; //Atributos de la superficie
XVisualInfo             *vi;    //
Colormap                cmap;   //
XSetWindowAttributes    swa;    //
Window                  win;    //
GLXContext              glc;    //
XWindowAttributes       gwa;    //
XEvent                  xev;    //

int main(int argc, char **argv)
{
    //Inicializamos "dpy"
        dpy = XOpenDisplay(NULL);
        if(dpy == NULL)
        {
            cout<<"cannot connect to X server"<<endl;
            exit(0);
        }

    //Asignamos a la ventana raíz su superficie
        root = DefaultRootWindow(dpy);

        //Y la configuramos
            vi = glXChooseVisual(dpy, 0, att);
            if(vi == NULL)
            {
                cout<<"no appropriate visual found"<<endl;
                exit(0);
            }
            else
            {
                cout<<"visual "<<(void *)vi->visualid<<" selected"<<endl;
            }

            cmap = XCreateColormap(dpy, root, vi->visual, AllocNone);
            swa.colormap = cmap;
            swa.event_mask = ExposureMask | KeyPressMask;

    win = XCreateWindow(dpy, root, 0, 0, 600, 600, 0, vi->depth, InputOutput, vi->visual, CWColormap | CWEventMask, &swa);
    XMapWindow(dpy, win);
    XStoreName(dpy, win, "Hola mundo");
    glEnable(GL_DEPTH_TEST);

    while(1)
    {
        XNextEvent(dpy, &xev);

        if(xev.type == Expose)
        {
            XGetWindowAttributes(dpy, win, &gwa);
            glViewport(0, 0, gwa.width, gwa.height);

            glBegin(GL_QUADS);
                glColor3f(1., 0., 0.); glVertex3f(-.75, -.75, 0.);
                glColor3f(0., 1., 0.); glVertex3f( .75, -.75, 0.);
                glColor3f(0., 0., 1.); glVertex3f( .75,  .75, 0.);
                glColor3f(1., 1., 0.); glVertex3f(-.75,  .75, 0.);
            glEnd();

            glXSwapBuffers(dpy, win);
        }

        else if(xev.type == KeyPress)
        {
            glXMakeCurrent(dpy, None, NULL);
            glXDestroyContext(dpy, glc);
            XDestroyWindow(dpy, win);
            XCloseDisplay(dpy);
            exit(0);
        }
    }
    return 0;
}