void draw_triangles ()
{
    glBegin ( GL_TRIANGLES );
    glVertex2f ( 0.0f, 0.0f );
    glVertex2f ( 25.0f, 25.0f );
    glVertex2f ( 50.0f, 0.0f );

    glVertex2f ( -50.0f, 0.0f );
    glVertex2f ( -75.0f, 50.0f );
    glVertex2f ( -25.0f, 0.0f );
    glEnd ();
    glFlush ();
}

gboolean render ( GtkGLArea *area, GdkGLContext *context, gpointer user_data )
{
    glClearColor ( 0.44, 0.44, 0.44, 1.0 );
    glColor3f ( 1.0f, 1.0f, 1.0f );
    glClear ( GL_COLOR_BUFFER_BIT );

    draw_triangles ();

    return TRUE;
}