http://www.opengl.org/wiki/Tutorial:_OpenGL_3.0_Context_Creation_(GLX)

gl3.cpp

// g++ gl3.cpp -o gl3 -lX11 -lGL

#include <GL/glx.h>
#include <GL/gl.h>
#include <iostream>

#define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091
#define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092
typedef GLXContext (glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);


int main(int argc, char **argv)
{
    glXCreateContextAttribsARBProc *glx_createContextAttribs = (glXCreateContextAttribsARBProc*)glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");
    if (glx_createContextAttribs == NULL) {
        std::cout << "glXCreateContextAttribsARB entry point not found. Aborting." << std::endl;
        return false;
    }

    Display *display = XOpenDisplay(0);
    const char *extensions = glXQueryExtensionsString(display, DefaultScreen(display));
    std::cout << extensions << std::endl;

    std::cout << "Getting framebuffer config" << std::endl;
    static int visual_attribs[] = {
        GLX_RENDER_TYPE, GLX_RGBA_BIT,
        GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
        GLX_DOUBLEBUFFER, true,
        GLX_RED_SIZE, 1,
        GLX_GREEN_SIZE, 1,
        GLX_BLUE_SIZE, 1,
        None};
    int fbcount;
    GLXFBConfig *fbc = glXChooseFBConfig(display, DefaultScreen(display), visual_attribs, &fbcount);
    if (!fbc) {
        std::cout << "Failed to retrieve a framebuffer config" << std::endl;
        return 1;
    }

    std::cout << "Getting XVisualInfo" << std::endl;
    XVisualInfo *vi = glXGetVisualFromFBConfig(display, fbc[0]);

    std::cout << "Creating colormap" << std::endl;
    XSetWindowAttributes swa;
    swa.colormap = XCreateColormap(display, RootWindow(display, vi->screen), vi->visual, AllocNone);
    swa.border_pixel = 0;
    swa.event_mask = StructureNotifyMask;

    std::cout << "Creating window" << std::endl;
    Window win = XCreateWindow(display, RootWindow(display, vi->screen), 0, 0, 100, 100, 0, vi->depth, InputOutput, vi->visual, CWBorderPixel|CWColormap|CWEventMask, &swa);
    if (!win) {
        std::cout << "Failed to create window." << std::endl;
        return 1;
    }

    std::cout << "Mapping window" << std::endl;
    XMapWindow(display, win);

    std::cout << "Creating context" << std::endl;
    static int context_attribs[] = {
        GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
        GLX_CONTEXT_MINOR_VERSION_ARB, 2,
        None};
    GLXContext ctx = glx_createContextAttribs(display, fbc[0], NULL, true, context_attribs);
    if (!ctx) {
        std::cout << "Failed to create GL3 context." << std::endl;
        return 1;
    }

    std::cout << "Making context current" << std::endl;
    glXMakeCurrent(display, win, ctx);

    // testing
    {
        glClearColor (0, 0.5, 1, 1);
        glClear (GL_COLOR_BUFFER_BIT);
        glXSwapBuffers(display, win);
        sleep(1);

        glClearColor(1, 0.5, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT);
        glXSwapBuffers(display, win);
        sleep(1);
    }

    std::cout << "Destroying context" << std::endl;
    ctx = glXGetCurrentContext();
    glXMakeCurrent(display, 0, 0);
    glXDestroyContext(display, ctx);
}