xref: /dports/graphics/Coin/coin-Coin-4.0.0/src/glue/gl.cpp

/**************************************************************************\
 * Copyright (c) Kongsberg Oil & Gas Technologies AS
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * Neither the name of the copyright holder nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\**************************************************************************/

/*!
  How to use OpenGL / GLX|WGL|AGL|CGL inside Coin
  ===============================================

  Creating portable OpenGL applications can be a complicated matter
  since you have to have both compile-time and run-time tests for
  OpenGL version, and what extensions are available. In addition, you
  might not have an entry point to the (extension) function in
  question on your build system.  The cc_glglue abstraction is here
  to relieve the application programmer for that burden.

  To use the cc_glglue interface, include Inventor/C/glue/gl.h.

  The cc_glglue interface is part of the public API of Coin, but is
  not documented on the public documentation pages at
  https://coin3d.bitbucket.io/Coin/ yet. The status for client application
  usage is "unofficial, use at own risk, interface may change without
  warning for major version number upgrade releases".

  Coin programmer's responsibilities
  ----------------------------------

  o OpenGL calls that are part of OpenGL 1.0 can safely be used
    without any kind of checking.

  o Do _not_ use cc_glglue unless you are sure that you have a valid
    OpenGL context. cc_glglue implicitly assumes that this is the case
    for most of its functions. In short, only use OpenGL functions
    inside an SoGLRenderAction.

  o To get hold of a cc_glglue instance:
      const cc_glglue * cc_glglue_instance(int contextid);
    or
      const cc_glglue * cc_glglue_instance_from_context_ptr(void * ctx);

    See header file for more information about these.

  o Always check that the capability you want to use is supported.
    Queries for this is supported through the cc_glglue_has_*()
    functions.

  o cc_glglue has some functions for querying OpenGL/GLX version and
    extension availability. Usually you shouldn't need to use these
    unless you want to bypass cc_glglue or your function isn't
    supported by cc_glglue (in which case you should add it).

  o SoGLCacheContextElement also has some functions for querying
    OpenGL version and extension availability. These are public, so
    you can use them even in external code. However, use cc_glglue
    internally for consistency.

  What cc_glglue supplies
  -----------------------

  o cc_glglue supplies function pointer to OpenGL and GLX functions
    used in Coin that are _not_ part of OpenGL 1.0 and GLX 1.1.  Note
    that cc_glglue supplies OpenGL extension functions as if they were
    standard functions (i.e. without the EXT suffix).

  o In addition, the Inventor/system/gl.h file supplies OpenGL enums
    that might not otherwise be present in your system's GL headers.

  The following example accesses OpenGL 3D texturing. It works both on
  OpenGL >= 1.2 and on OpenGL drivers with the GL_EXT_texture3D
  extension.

  ------ 8< --------- [snip] --------------------- 8< --------- [snip] -----

  const cc_glglue * glw = cc_glglue_instance(SoGLCacheContextElement::get(state));
  if (cc_glglue_has_3d_textures(glw)) {
    cc_glglue_glTexImage3D(glw, GL_PROXY_TEXTURE_3D, 0, GL_RGBA,
                           64, 64, 64, 0,
                           GL_RGBA, GL_UNSIGNED_BYTE,
                           NULL);
  }
  else {
    // Implement a proper fallback or error handling.
  }

  ------ 8< --------- [snip] --------------------- 8< --------- [snip] -----
*/

/*!
  For the library/API doc, here's the environment variables
  influencing the OpenGL binding:

  - COIN_DEBUG_GLGLUE: set equal to "1" to make the wrapper
    initialization spit out lots of info about the underlying OpenGL
    implementation.

  - COIN_PREFER_GLPOLYGONOFFSET_EXT: when set to "1" and both
    glPolygonOffset() and glPolygonOffsetEXT() is available, the
    latter will be used. This can be useful to work around a
    problematic glPolygonOffset() implementation for certain SGI
    platforms.

  - COIN_FULL_INDIRECT_RENDERING: set to "1" to let Coin take
    advantage of OpenGL1.1+ and extensions even when doing
    remote/indirect rendering.

    We don't allow this by default now, for mainly two reasons: 1)
    we've seen NVidia GLX bugs when attempting this. 2) We generally
    prefer a "better safe than sorry" strategy.

    We might consider changing this strategy to allow it by default,
    and provide an envvar to turn it off instead -- if we can get
    confirmation that the assumed NVidia driver bug is indeed NVidia's
    problem.

  - COIN_FORCE_GL1_0_ONLY: set to "1" to disallow use of OpenGL1.1+
    and extensions under all circumstances.

  - COIN_FORCE_AGL: set to "1" to prefer using the old AGL bindings over CGL.
    Note that AGL is not available on 64-bit systems. The AGL code is not
    compiled into Coin by default, but must be enabled at configure-time using
    --enable-agl in addition to using the environment variable.
*/


/*
  Useful resources:

   - About OpenGL 1.2, 1.3, 1.4:
     <URL:http://www.opengl.org/developers/documentation/OpenGL12.html>
     <URL:http://www.opengl.org/developers/documentation/OpenGL13.html>
     <URL:http://www.opengl.org/developers/documentation/OpenGL14.html>
     (explains all new features in depth)

   - The OpenGL Extension Registry:
     <URL:http://oss.sgi.com/projects/ogl-sample/registry/>

   - A great overview of what OpenGL driver capabilities are available
     for different cards, check out "3D Hardware Info" on
     <URL:http://www.delphi3d.net/>.

   - Brian Paul presentation "Using OpenGL Extensions" from SIGGRAPH '97:
     <URL:http://www.mesa3d.org/brianp/sig97/exten.htm>

   - Sun's man pages:
     <URL:http://wwws.sun.com/software/graphics/OpenGL/manpages>

   - IBM AIX GL man pages (try to find a "more official looking" link):
     <URL:http://molt.zdv.uni-mainz.de/doc_link/en_US/a_doc_lib/libs/openglrf/OpenGLXEnv.htm>

   - HP GL man pages:
     <URL:http://www.hp.com/workstations/support/documentation/manuals/user_guides/graphics/opengl/RefTOC.html>

   - An Apple Technical Q&A on how to do dynamic binding to OpenGL symbols:
     <URL:http://developer.apple.com/qa/qa2001/qa1188.html>

     Full documentation on all "Object File Image" functions, see:
     <URL:http://developer.apple.com/techpubs/macosx/DeveloperTools/MachORuntime/5rt_api_reference/_Object_Fil_e_Functions.html>
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */

// *************************************************************************

/* The configure script should protect against more than one of
   HAVE_WGL, HAVE_GLX, HAVE_AGL|HAVE_CGL being defined at the same time, but
   we set up this little trip-wire in addition, just in case someone
   is either fiddling manually with config.h, or in case a change is
   made which breaks this protection in the configure script. */

#if defined(HAVE_WGL) && (defined(HAVE_GLX) || defined(HAVE_AGL) || defined(HAVE_CGL))
#error More than one of HAVE_WGL, HAVE_GLX and HAVE_AGL|HAVE_CGL set simultaneously!
#endif

#if defined(HAVE_GLX) && (defined(HAVE_AGL) || defined(HAVE_CGL))
#error More than one of HAVE_WGL, HAVE_GLX and HAVE_AGL|HAVE_CGL set simultaneously!
#endif

// Define HAVE_NOGL if no platform GL binding exists
#if !defined(HAVE_WGL) && !defined(HAVE_GLX) && !(defined(HAVE_AGL) || defined(HAVE_CGL))
#define HAVE_NOGL 1
#endif

// *************************************************************************

#include <cassert>
#include <cstdlib>
#include <cstring>
#include <climits> /* SHRT_MAX */

#ifdef HAVE_AGL
#include <AGL/agl.h>
#endif /* HAVE_AGL */

#ifdef HAVE_OPENGL_CGLCURRENT_H
#include <OpenGL/CGLCurrent.h>
#endif

#ifdef HAVE_CGL
#include <OpenGL/OpenGL.h>
#endif

#ifdef HAVE_GLX
#include <GL/glx.h>
#endif /* HAVE_GLX */

#include <Inventor/C/glue/gl.h>

#include <Inventor/C/errors/debugerror.h>
#include <Inventor/C/glue/dl.h>
#include <Inventor/C/tidbits.h>
#include <Inventor/C/base/list.h>

#include "coindefs.h"
#include "tidbitsp.h"
#include "base/dict.h"
#include "base/namemap.h"
#include "glue/glp.h"
#include "glue/dlp.h"
#include "glue/gl_agl.h"
#include "glue/gl_cgl.h"
#include "glue/gl_glx.h"
#include "glue/gl_wgl.h"
#include "threads/threadsutilp.h"

/* ********************************************************************** */

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

#if 0 /* emacs indentation fix */
}
#endif

static cc_list * gl_instance_created_cblist = NULL;
static int COIN_MAXIMUM_TEXTURE2_SIZE = -1;
static int COIN_MAXIMUM_TEXTURE3_SIZE = -1;
static cc_glglue_offscreen_cb_functions* offscreen_cb = NULL;
static int COIN_USE_AGL = -1;

/* ********************************************************************** */

/* Sanity checks for enum extension value assumed to be equal to the
 * final / "proper" / standard OpenGL enum values. (If not, we could
 * end up with hard-to-find bugs because of mismatches with the
 * compiled values versus the run-time values.)
 *
 * This doesn't really _fix_ anything, it is just meant as an aid to
 * smoke out platforms where we're getting unexpected enum values.
 */

#ifdef GL_CLAMP_TO_EDGE_EXT
#if GL_CLAMP_TO_EDGE != GL_CLAMP_TO_EDGE_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_CLAMP_TO_EDGE_EXT */

#ifdef GL_CLAMP_TO_EDGE_SGIS
#if GL_CLAMP_TO_EDGE != GL_CLAMP_TO_EDGE_SGIS
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_CLAMP_TO_EDGE_SGIS */

#ifdef GL_MAX_3D_TEXTURE_SIZE_EXT
#if GL_MAX_3D_TEXTURE_SIZE != GL_MAX_3D_TEXTURE_SIZE_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_MAX_3D_TEXTURE_SIZE_EXT */

#ifdef GL_PACK_IMAGE_HEIGHT_EXT
#if GL_PACK_IMAGE_HEIGHT != GL_PACK_IMAGE_HEIGHT_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_PACK_IMAGE_HEIGHT_EXT */

#ifdef GL_PACK_SKIP_IMAGES_EXT
#if GL_PACK_SKIP_IMAGES != GL_PACK_SKIP_IMAGES_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_PACK_SKIP_IMAGES_EXT */

#ifdef GL_PROXY_TEXTURE_2D_EXT
#if GL_PROXY_TEXTURE_2D != GL_PROXY_TEXTURE_2D_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_PROXY_TEXTURE_2D_EXT */

#ifdef GL_PROXY_TEXTURE_3D_EXT
#if GL_PROXY_TEXTURE_3D != GL_PROXY_TEXTURE_3D_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_PROXY_TEXTURE_3D_EXT */

#ifdef GL_TEXTURE_3D_EXT
#if GL_TEXTURE_3D != GL_TEXTURE_3D_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_TEXTURE_3D_EXT */

#ifdef GL_TEXTURE_DEPTH_EXT
#if GL_TEXTURE_DEPTH != GL_TEXTURE_DEPTH_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_TEXTURE_DEPTH_EXT */

#ifdef GL_TEXTURE_WRAP_R_EXT
#if GL_TEXTURE_WRAP_R != GL_TEXTURE_WRAP_R_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_TEXTURE_WRAP_R_EXT */

#ifdef GL_UNPACK_IMAGE_HEIGHT_EXT
#if GL_UNPACK_IMAGE_HEIGHT != GL_UNPACK_IMAGE_HEIGHT_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_UNPACK_IMAGE_HEIGHT_EXT */

#ifdef GL_UNPACK_SKIP_IMAGES_EXT
#if GL_UNPACK_SKIP_IMAGES != GL_UNPACK_SKIP_IMAGES_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_UNPACK_SKIP_IMAGES_EXT */

#ifdef GL_FUNC_ADD_EXT
#if GL_FUNC_ADD != GL_FUNC_ADD_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_FUNC_ADD_EXT */

#ifdef GL_MIN_EXT
#if GL_MIN != GL_MIN_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_MIN_EXT */

#ifdef GL_MAX_EXT
#if GL_MAX != GL_MAX_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_MAX_EXT */

#ifdef GL_COLOR_TABLE_WIDTH_EXT
#if GL_COLOR_TABLE_WIDTH != GL_COLOR_TABLE_WIDTH_EXT
#error dangerous enum mismatch
#endif /* cmp */
#endif /* GL_COLOR_TABLE_WIDTH_EXT */

/* ********************************************************************** */

/* Resolve and return the integer value of an environment variable. */
static int
glglue_resolve_envvar(const char * txt)
{
  const char * val = coin_getenv(txt);
  return val ? atoi(val) : 0;
}

/* Returns a flag which indicates whether or not to allow the use of
   OpenGL 1.1+ features and extensions.

   We default to *not* allowing this if rendering is indirect, as
   we've seen major problems with at least NVidia GLX when using
   OpenGL 1.1+ features. It can be forced on by an environment
   variable, though.

   (A better strategy *might* be to default to allow it, but to smoke
   out and warn if we detect NVidia GLX, and in addition to provide an
   environment variable that disables it.)
*/
static SbBool
glglue_allow_newer_opengl(const cc_glglue * w)
{
  static SbBool fullindirect = -1;
  static SbBool force1_0 = -1;
  static const char * COIN_FULL_INDIRECT_RENDERING = "COIN_FULL_INDIRECT_RENDERING";
  static const char * COIN_DONT_INFORM_INDIRECT_RENDERING = "COIN_DONT_INFORM_INDIRECT_RENDERING";

  if (fullindirect == -1) {
    fullindirect = (glglue_resolve_envvar(COIN_FULL_INDIRECT_RENDERING) > 0);
  }

  if (force1_0 == -1) {
    force1_0 = (glglue_resolve_envvar("COIN_FORCE_GL1_0_ONLY") > 0);
  }

  if (force1_0) return FALSE;

  if (!w->glx.isdirect && !fullindirect) {
    /* We give out a warning, once, when the full OpenGL feature set is not
       used, in case the end user uses an application with a remote display,
       and that was not expected by the application programmer. */
    static int inform = -1;
    if (inform == -1) { inform = glglue_resolve_envvar(COIN_DONT_INFORM_INDIRECT_RENDERING); }
    if (inform == 0) {
      cc_debugerror_postinfo("glglue_allow_newer_opengl",
                             "\n\nFeatures of OpenGL version > 1.0 has been\n"
                             "disabled, due to the use of a remote display.\n\n"
                             "This is so because many common OpenGL drivers\n"
                             "have problems in this regard.\n\n"
                             "To force full OpenGL use, set the environment\n"
                             "variable %s=1 and re-run the application.\n\n"
                             "If you don't want this message displayed again,\n"
                             "set the environment variable %s=1.\n",
                             COIN_FULL_INDIRECT_RENDERING,
                             COIN_DONT_INFORM_INDIRECT_RENDERING);
      inform = 1;
    }
    return FALSE;
  }

  return TRUE;
}


/* Returns whether or not COIN_GLGLUE_SILENCE_DRIVER_WARNINGS is set
   to a value > 0. If so, all known driver bugs will just be silently
   accepted and attempted worked around. */
static int
coin_glglue_silence_all_driver_warnings(void)
{
  static int d = -1;
  if (d == -1) { d = glglue_resolve_envvar("COIN_GLGLUE_SILENCE_DRIVER_WARNINGS"); }
  /* Note the inversion of the envvar value versus the return value. */
  return (d > 0) ? 0 : 1;
}

/* Return value of COIN_GLGLUE_NO_RADEON_WARNING environment variable. */
static int
coin_glglue_radeon_warning(void)
{
  static int d = -1;

  if (coin_glglue_silence_all_driver_warnings()) { return 0; }

  if (d == -1) { d = glglue_resolve_envvar("COIN_GLGLUE_NO_RADEON_WARNING"); }
  /* Note the inversion of the envvar value versus the return value. */
  return (d > 0) ? 0 : 1;
}

/* Return value of COIN_GLGLUE_NO_G400_WARNING environment variable. */
static int
coin_glglue_old_matrox_warning(void)
{
  static int d = -1;

  if (coin_glglue_silence_all_driver_warnings()) { return 0; }

  if (d == -1) { d = glglue_resolve_envvar("COIN_GLGLUE_NO_G400_WARNING"); }
  /* Note the inversion of the envvar value versus the return value. */
  return (d > 0) ? 0 : 1;
}

/* Return value of COIN_GLGLUE_NO_ELSA_WARNING environment variable. */
static int
coin_glglue_old_elsa_warning(void)
{
  static int d = -1;

  if (coin_glglue_silence_all_driver_warnings()) { return 0; }

  if (d == -1) { d = glglue_resolve_envvar("COIN_GLGLUE_NO_ELSA_WARNING"); }
  /* Note the inversion of the envvar value versus the return value. */
  return (d > 0) ? 0 : 1;
}

/* Return value of COIN_GLGLUE_NO_SUN_EXPERT3D_WARNING environment variable. */
static int
coin_glglue_sun_expert3d_warning(void)
{
  static int d = -1;

  if (coin_glglue_silence_all_driver_warnings()) { return 0; }

  if (d == -1) { d = glglue_resolve_envvar("COIN_GLGLUE_NO_SUN_EXPERT3D_WARNING"); }
  /* Note the inversion of the envvar value versus the return value. */
  return (d > 0) ? 0 : 1;
}

/* Return value of COIN_GLGLUE_NO_TRIDENT_WARNING environment variable. */
static int
coin_glglue_trident_warning(void)
{
  static int d = -1;

  if (coin_glglue_silence_all_driver_warnings()) { return 0; }

  if (d == -1) { d = glglue_resolve_envvar("COIN_GLGLUE_NO_TRIDENT_WARNING"); }
  /* Note the inversion of the envvar value versus the return value. */
  return (d > 0) ? 0 : 1;
}

/* Return value of COIN_DEBUG_GLGLUE environment variable. */
int
coin_glglue_debug(void)
{
  static int d = -1;
  if (d == -1) { d = glglue_resolve_envvar("COIN_DEBUG_GLGLUE"); }
  return (d > 0) ? 1 : 0;
}

/* Return value of COIN_PREFER_GLPOLYGONOFFSET_EXT environment variable. */
static int
glglue_prefer_glPolygonOffsetEXT(void)
{
  static int d = -1;
  if (d == -1) { d = glglue_resolve_envvar("COIN_PREFER_GLPOLYGONOFFSET_EXT"); }
  return (d > 0) ? 1 : 0;
}

/* FIXME: the following is a hack to get around a problem which really
   demands more effort to be solved properly.

   The problem is that there is no way in the API of the
   SoOffscreenRenderer class to specify what particular attributes to
   request. This most often manifests itself as a problem for app
   programmers in that they have made some kind of extension node
   which uses the OpenGL stencil buffer. If no stencil buffer happens
   to be part of the GL context format for the offscreen renderer,
   these will not work properly. At the same time, we don't want to
   default to requesting a stencil buffer, as that takes a non-trivial
   amount of extra memory resources on the gfx card.

   So until we have implemented the proper solution for making it
   possible to pass in a detailed specification of which attributes to
   request from offscreen GL contexts, we provide this temporary
   work-around: the app programmer can set an envvar with a value
   specifying the number of stencil buffer bits he/she wants.

   20060223 mortene.
*/
int
coin_glglue_stencil_bits_hack(void)
{
  const char * env = coin_getenv("COIN_OFFSCREEN_STENCIL_BITS");
  if (!env) { return -1; }
  return atoi(env);
}

cc_libhandle
coin_glglue_dl_handle(const cc_glglue * glue)
{
  if (!glue->dl_handle) {
    const_cast <cc_glglue *> (glue)->dl_handle = cc_dl_handle_with_gl_symbols();
  }
  return glue->dl_handle;
}

/* doc in header file */
void *
cc_glglue_getprocaddress(const cc_glglue * glue, const char * symname)
{
  void * ptr = NULL;

  // FIXME: also supply 'glue' to coin_[x]gl_getprocaddress()
  ptr = coin_wgl_getprocaddress(glue, symname);
  if (ptr) goto returnpoint;

  ptr = glxglue_getprocaddress(glue, symname);
  if (ptr) goto returnpoint;

  ptr = cc_dl_sym(coin_glglue_dl_handle(glue), symname);
  if (ptr) goto returnpoint;

returnpoint:
  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("cc_glglue_getprocaddress", "%s==%p", symname, ptr);
  }
  return ptr;
}

/* Global dictionary which stores the mappings from the context IDs to
   actual cc_glglue instances. */
static cc_dict * gldict = NULL;

static void
free_glglue_instance(uintptr_t COIN_UNUSED_ARG(key), void * value, void * COIN_UNUSED_ARG(closure))
{
  cc_glglue * glue = (cc_glglue*) value;
  cc_dict_destruct(glue->glextdict);
  free(value);
}

/* Cleans up at exit. */
static void
glglue_cleanup(void)
{
  if (gldict) {
    cc_dict_apply(gldict, free_glglue_instance, NULL);
    cc_dict_destruct(gldict);
    gldict = NULL;
  }
  offscreen_cb = NULL;

#ifdef HAVE_GLX
  glxglue_cleanup();
#elif defined(HAVE_WGL)
  wglglue_cleanup();
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) aglglue_cleanup(); else
#endif
#if defined(HAVE_CGL)
  cglglue_cleanup();
#else
  ;
#endif
#endif
}

static SbBool
glglue_has_nvidia_framebuffer_object_bug(int major, int minor, int release)
{
  return (major == 2) && (minor == 0) && (release == 0);
}

/*
  Set the OpenGL version variables in the given cc_glglue struct
  instance.

  Note: this code has been copied from GLUWrapper.c, so if any changes
  are made, make sure they are propagated over if necessary.
*/
static void
glglue_set_glVersion(cc_glglue * w)
{
  char buffer[256];
  char * dotptr;

  /* NB: if you are getting a crash here, it's because an attempt at
   * setting up a cc_glglue instance was made when there is no current
   * OpenGL context. */
  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("glglue_set_glVersion",
                           "glGetString(GL_VERSION)=='%s'", w->versionstr);
  }

  w->version.major = 0;
  w->version.minor = 0;
  w->version.release = 0;

  (void)strncpy(buffer, (const char *)w->versionstr, 255);
  buffer[255] = '\0'; /* strncpy() will not null-terminate if strlen > 255 */
  dotptr = strchr(buffer, '.');
  if (dotptr) {
    char * spaceptr;
    char * start = buffer;
    *dotptr = '\0';
    w->version.major = atoi(start);
    start = ++dotptr;

    dotptr = strchr(start, '.');
    spaceptr = strchr(start, ' ');
    if (!dotptr && spaceptr) dotptr = spaceptr;
    if (dotptr && spaceptr && spaceptr < dotptr) dotptr = spaceptr;
    if (dotptr) {
      int terminate = *dotptr == ' ';
      *dotptr = '\0';
      w->version.minor = atoi(start);
      if (!terminate) {
        start = ++dotptr;
        dotptr = strchr(start, ' ');
        if (dotptr) *dotptr = '\0';
        w->version.release = atoi(start);
      }
    }
    else {
      w->version.minor = atoi(start);
    }
  }

  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("glglue_set_glVersion",
                           "parsed to major=='%d', minor=='%d', micro=='%d'",
                           w->version.major,
                           w->version.minor,
                           w->version.release);
  }
}

void
cc_glglue_glversion(const cc_glglue * w,
                    unsigned int * major,
                    unsigned int * minor,
                    unsigned int * release)
{
  if (!glglue_allow_newer_opengl(w)) {
    *major = 1;
    *minor = 0;
    *release = 0;
  }
  else {
    *major = w->version.major;
    *minor = w->version.minor;
    *release = w->version.release;
  }
}


SbBool
cc_glglue_glversion_matches_at_least(const cc_glglue * w,
                                     unsigned int major,
                                     unsigned int minor,
                                     unsigned int revision)
{
  unsigned int glmajor, glminor, glrev;
  cc_glglue_glversion(w, &glmajor, &glminor, &glrev);

  if (glmajor < major) return FALSE;
  else if (glmajor > major) return TRUE;
  if (glminor < minor) return FALSE;
  else if (glminor > minor) return TRUE;
  if (glminor < revision) return FALSE;
  return TRUE;
}

SbBool
cc_glglue_glxversion_matches_at_least(const cc_glglue * w,
                                      int major,
                                      int minor)
{
  if (w->glx.version.major < major) return FALSE;
  else if (w->glx.version.major > major) return TRUE;
  if (w->glx.version.minor < minor) return FALSE;
  return TRUE;
}

int
coin_glglue_extension_available(const char * extensions, const char * ext)
{
  const char * start;
  size_t extlen;
  SbBool found = FALSE;

  assert(ext && "NULL string");
  assert((ext[0] != '\0') && "empty string");
  assert((strchr(ext, ' ') == NULL) && "extension name can't have spaces");

  start = extensions;
  extlen = strlen(ext);

  while (start) {
    const char * where = strstr(start, ext);
    if (!where) goto done;

    if (where == start || *(where - 1) == ' ') {
      const char * terminator = where + extlen;
      if (*terminator == ' ' || *terminator == '\0') {
        found = TRUE;
        goto done;
      }
    }

    start = where + extlen;
  }

done:
  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("coin_glglue_extension_available",
                           "extension '%s' is%s present",
                           ext, found ? "" : " NOT");
  }

  return found ? 1 : 0;
}

int
cc_glglue_glext_supported(const cc_glglue * wrapper, const char * extension)
{
  const uintptr_t key = (uintptr_t)cc_namemap_get_address(extension);

  void * result = NULL;
  if (cc_dict_get(wrapper->glextdict, key, &result)) {
    return result != NULL;
  }
  result = coin_glglue_extension_available(wrapper->extensionsstr, extension) ?
    (void*) 1 : NULL;
  cc_dict_put(wrapper->glextdict, key, result);

  return result != NULL;
}

#ifdef HAVE_DYNAMIC_LINKING

#define PROC(_glue_, _func_) cc_glglue_getprocaddress(_glue_, SO__QUOTE(_func_))

/* The OpenGL library which we dynamically pick up symbols from
   /could/ have all these defined. For the code below which tries to
   dynamically resolve the methods, we will assume that they are all
   defined. By doing this little "trick", can we use the same code
   below for resolving stuff dynamically as we need anyway to resolve
   in a static manner. */
#define GL_VERSION_1_1 1
#define GL_VERSION_1_2 1
#define GL_VERSION_1_3 1
#define GL_VERSION_1_4 1
#define GL_VERSION_1_5 1
#define GL_EXT_polygon_offset 1
#define GL_EXT_texture_object 1
#define GL_EXT_subtexture 1
#define GL_EXT_texture3D 1
#define GL_ARB_multitexture 1
#define GL_ARB_texture_compression 1
#define GL_EXT_paletted_texture 1
#define GL_ARB_imaging 1
#define GL_EXT_blend_minmax 1
#define GL_EXT_color_table 1
#define GL_EXT_color_subtable 1
#define GL_SGI_color_table 1
#define GL_SGI_texture_color_table 1
#define GL_ARB_vertex_buffer_object 1
#define GL_EXT_multi_draw_arrays 1
#define GL_NV_vertex_array_range 1
#define GL_NV_register_combiners 1
#define GL_NV_texture_rectangle 1
#define GL_NV_texture_shader 1
#define GL_ARB_depth_texture 1
#define GL_ARB_shadow 1
#define GL_EXT_texture_rectangle 1
#define GL_ARB_fragment_program 1
#define GL_ARB_vertex_program 1
#define GL_ARB_shader_objects 1
#define GL_ARB_vertex_shader 1
#define GL_ARB_occlusion_query 1

#else /* static binding */

#define PROC(_glue_, _func_) (&_func_)

#endif /* static binding */


static void
glglue_resolve_symbols(cc_glglue * w)
{
  /* Note that there's a good reason why we use version checking
     *along* with dynamic resolving (if the platform allows it): the
     OpenGL library could (prematurely) include function symbols
     without having an actual valid implementation behind them. */

  /* Appeared in OpenGL v1.1. We store both the "real" function
     pointer and the extension pointer, in case we need to work around
     an SGI bug (see comments in cc_glglue_glPolygonOffset(). */
  w->glPolygonOffset = NULL;
  w->glPolygonOffsetEXT = NULL;
#ifdef GL_VERSION_1_1
  if (cc_glglue_glversion_matches_at_least(w, 1, 1, 0)) {
    w->glPolygonOffset = (COIN_PFNGLPOLYGONOFFSETPROC)PROC(w, glPolygonOffset);
  }
#endif /* GL_VERSION_1_1 */
#ifdef GL_EXT_polygon_offset
  if (cc_glglue_glext_supported(w, "GL_EXT_polygon_offset")) {
    w->glPolygonOffsetEXT = (COIN_PFNGLPOLYGONOFFSETPROC)PROC(w, glPolygonOffsetEXT);
  }
#endif /* GL_EXT_polygon_offset */



  /* Appeared in OpenGL v1.1. */
  w->glGenTextures = NULL;
  w->glBindTexture = NULL;
  w->glDeleteTextures = NULL;
#ifdef GL_VERSION_1_1
  if (cc_glglue_glversion_matches_at_least(w, 1, 1, 0)) {
    w->glGenTextures = (COIN_PFNGLGENTEXTURESPROC)PROC(w, glGenTextures);
    w->glBindTexture = (COIN_PFNGLBINDTEXTUREPROC)PROC(w, glBindTexture);
    w->glDeleteTextures = (COIN_PFNGLDELETETEXTURESPROC)PROC(w, glDeleteTextures);
  }
#endif /* GL_VERSION_1_1 */
#ifdef GL_EXT_texture_object
  if (!w->glGenTextures && cc_glglue_glext_supported(w, "GL_EXT_texture_object")) {
    w->glGenTextures = (COIN_PFNGLGENTEXTURESPROC)PROC(w, glGenTexturesEXT);
    w->glBindTexture = (COIN_PFNGLBINDTEXTUREPROC)PROC(w, glBindTextureEXT);
    w->glDeleteTextures = (COIN_PFNGLDELETETEXTURESPROC)PROC(w, glDeleteTexturesEXT);
  }
#endif /* GL_EXT_texture_object */

  /* Appeared in OpenGL v1.1. */
  w->glTexSubImage2D = NULL;
#ifdef GL_VERSION_1_1
  if (cc_glglue_glversion_matches_at_least(w, 1, 1, 0)) {
    w->glTexSubImage2D = (COIN_PFNGLTEXSUBIMAGE2DPROC)PROC(w, glTexSubImage2D);
  }
#endif /* GL_VERSION_1_1 */
#ifdef GL_EXT_subtexture
  if (!w->glTexSubImage2D && cc_glglue_glext_supported(w, "GL_EXT_subtexture")) {
    w->glTexSubImage2D = (COIN_PFNGLTEXSUBIMAGE2DPROC)PROC(w, glTexSubImage2DEXT);
  }
#endif /* GL_EXT_subtexture */

  /* Appeared in OpenGL 1.1 */
  w->glPushClientAttrib = NULL;
  w->glPopClientAttrib = NULL;
#ifdef GL_VERSION_1_1
  if (cc_glglue_glversion_matches_at_least(w, 1, 1, 0)) {
    w->glPushClientAttrib = (COIN_PFNGLPUSHCLIENTATTRIBPROC) PROC(w, glPushClientAttrib);
    w->glPopClientAttrib = (COIN_PFNGLPOPCLIENTATTRIBPROC) PROC(w, glPopClientAttrib);
  }
#endif /* GL_VERSION_1_1 */

  /* These were introduced with OpenGL v1.2. */
  w->glTexImage3D = NULL;
  w->glCopyTexSubImage3D = NULL;
  w->glTexSubImage3D = NULL;
#ifdef GL_VERSION_1_2
  if (cc_glglue_glversion_matches_at_least(w, 1, 2, 0)) {
    w->glTexImage3D = (COIN_PFNGLTEXIMAGE3DPROC)PROC(w, glTexImage3D);
    w->glCopyTexSubImage3D = (COIN_PFNGLCOPYTEXSUBIMAGE3DPROC)PROC(w, glCopyTexSubImage3D);
    w->glTexSubImage3D = (COIN_PFNGLTEXSUBIMAGE3DPROC)PROC(w, glTexSubImage3D);
  }
#endif /* GL_VERSION_1_2 */
#ifdef GL_EXT_texture3D
  if (!w->glTexImage3D && cc_glglue_glext_supported(w, "GL_EXT_texture3D")) {
    w->glTexImage3D = (COIN_PFNGLTEXIMAGE3DPROC)PROC(w, glTexImage3DEXT);
    /* These are implicitly given if GL_EXT_texture3D is defined. */
    w->glCopyTexSubImage3D = (COIN_PFNGLCOPYTEXSUBIMAGE3DPROC)PROC(w, glCopyTexSubImage3DEXT);
    w->glTexSubImage3D = (COIN_PFNGLTEXSUBIMAGE3DPROC)PROC(w, glTexSubImage3DEXT);
  }
#endif /* GL_EXT_texture3D */

  /* Multi-texturing appeared in OpenGL v1.3, or with the
     GL_ARB_multitexture extension before that.
  */
  /*
     FIXME: we've found a bug prevalent in drivers for the "Intel
     Solano" graphcis chipset / driver. It manifests itself in the way
     that visual artifacts are seen when multi-textured polygons are
     partly outside the canvas view.

     The SoGuiExamples/nodes/textureunit example can be used to
     reproduce the error. The driver info from one confirmed affected
     system is as follows:

     GL_VERSION == 1.1.2 - Build 4.13.01.3196
     GL_VENDOR == Intel
     GL_RENDERER == Intel Solano
     GL_EXTENSIONS = GL_ARB_multitexture [...]

     This problem is not yet handled in any way by Coin. What we
     should do about this is to detect the above chipset / driver and
     issue an on-screen warning to the end user (in very
     "end-user-friendly" terms) when multi-texturing is first
     attempted used, *plus* make a wgl- or glut-based example which
     demonstrates the bug, for reporting to Intel.

     The bug was tested and confirmed with the latest Intel Solano
     driver as of today.

     20041108 mortene, based on information provided by handegar.
  */
  w->glActiveTexture = NULL;
  w->glClientActiveTexture = NULL;
  w->glMultiTexCoord2f = NULL;
  w->glMultiTexCoord2fv = NULL;
  w->glMultiTexCoord3fv = NULL;
  w->glMultiTexCoord4fv = NULL;
#ifdef GL_VERSION_1_3
  if (cc_glglue_glversion_matches_at_least(w, 1, 3, 0)) {
    w->glActiveTexture = (COIN_PFNGLACTIVETEXTUREPROC)PROC(w, glActiveTexture);
    w->glClientActiveTexture = (COIN_PFNGLCLIENTACTIVETEXTUREPROC)PROC(w, glClientActiveTexture);
    w->glMultiTexCoord2f = (COIN_PFNGLMULTITEXCOORD2FPROC)PROC(w, glMultiTexCoord2f);
    w->glMultiTexCoord2fv = (COIN_PFNGLMULTITEXCOORD2FVPROC)PROC(w, glMultiTexCoord2fv);
    w->glMultiTexCoord3fv = (COIN_PFNGLMULTITEXCOORD3FVPROC)PROC(w, glMultiTexCoord3fv);
    w->glMultiTexCoord4fv = (COIN_PFNGLMULTITEXCOORD4FVPROC)PROC(w, glMultiTexCoord4fv);
  }
#endif /* GL_VERSION_1_3 */
#ifdef GL_ARB_multitexture
  if (!w->glActiveTexture && cc_glglue_glext_supported(w, "GL_ARB_multitexture")) {
    w->glActiveTexture = (COIN_PFNGLACTIVETEXTUREPROC)PROC(w, glActiveTextureARB);
    w->glClientActiveTexture = (COIN_PFNGLACTIVETEXTUREPROC)PROC(w, glClientActiveTextureARB);
    w->glMultiTexCoord2f = (COIN_PFNGLMULTITEXCOORD2FPROC)PROC(w, glMultiTexCoord2fARB);
    w->glMultiTexCoord2fv = (COIN_PFNGLMULTITEXCOORD2FVPROC)PROC(w, glMultiTexCoord2fvARB);
    w->glMultiTexCoord3fv = (COIN_PFNGLMULTITEXCOORD3FVPROC)PROC(w, glMultiTexCoord3fvARB);
    w->glMultiTexCoord4fv = (COIN_PFNGLMULTITEXCOORD4FVPROC)PROC(w, glMultiTexCoord4fvARB);
  }
#endif /* GL_ARB_multitexture */

  if (w->glActiveTexture) {
    if (!w->glClientActiveTexture ||
        !w->glMultiTexCoord2f ||
        !w->glMultiTexCoord2fv ||
        !w->glMultiTexCoord3fv ||
        !w->glMultiTexCoord4fv) {
      w->glActiveTexture = NULL; /* cc_glglue_has_multitexture() will return FALSE */
      if (COIN_DEBUG || coin_glglue_debug()) {
        cc_debugerror_postwarning("glglue_init",
                                  "glActiveTexture found, but one or more of the other "
                                  "multitexture functions were not found");
      }
    }
  }
  w->maxtextureunits = 1; /* when multitexturing is not available */
  if (w->glActiveTexture) {
    GLint tmp;
    glGetIntegerv(GL_MAX_TEXTURE_COORDS_ARB, &tmp);
    w->maxtextureunits = (int) tmp;
  }

  w->glCompressedTexImage1D = NULL;
  w->glCompressedTexImage2D = NULL;
  w->glCompressedTexImage3D = NULL;
  w->glCompressedTexSubImage1D = NULL;
  w->glCompressedTexSubImage2D = NULL;
  w->glCompressedTexSubImage3D = NULL;
  w->glGetCompressedTexImage = NULL;

#ifdef GL_VERSION_1_3
  if (cc_glglue_glversion_matches_at_least(w, 1, 3, 0)) {
    w->glCompressedTexImage1D = (COIN_PFNGLCOMPRESSEDTEXIMAGE1DPROC)PROC(w, glCompressedTexImage1D);
    w->glCompressedTexImage2D = (COIN_PFNGLCOMPRESSEDTEXIMAGE2DPROC)PROC(w, glCompressedTexImage2D);
    w->glCompressedTexImage3D = (COIN_PFNGLCOMPRESSEDTEXIMAGE3DPROC)PROC(w, glCompressedTexImage3D);
    w->glCompressedTexSubImage1D = (COIN_PFNGLCOMPRESSEDTEXSUBIMAGE1DPROC)PROC(w, glCompressedTexSubImage1D);
    w->glCompressedTexSubImage2D = (COIN_PFNGLCOMPRESSEDTEXSUBIMAGE2DPROC)PROC(w, glCompressedTexSubImage2D);
    w->glCompressedTexSubImage3D = (COIN_PFNGLCOMPRESSEDTEXSUBIMAGE3DPROC)PROC(w, glCompressedTexSubImage3D);
    w->glGetCompressedTexImage = (COIN_PFNGLGETCOMPRESSEDTEXIMAGEPROC)PROC(w, glGetCompressedTexImage);
  }
#endif /* GL_VERSION_1_3 */

#ifdef GL_ARB_texture_compression
  if ((w->glCompressedTexImage1D == NULL) &&
      cc_glglue_glext_supported(w, "GL_ARB_texture_compression")) {
    w->glCompressedTexImage1D = (COIN_PFNGLCOMPRESSEDTEXIMAGE1DPROC)PROC(w, glCompressedTexImage1DARB);
    w->glCompressedTexImage2D = (COIN_PFNGLCOMPRESSEDTEXIMAGE2DPROC)PROC(w, glCompressedTexImage2DARB);
    w->glCompressedTexImage3D = (COIN_PFNGLCOMPRESSEDTEXIMAGE3DPROC)PROC(w, glCompressedTexImage3DARB);
    w->glCompressedTexSubImage1D = (COIN_PFNGLCOMPRESSEDTEXSUBIMAGE1DPROC)PROC(w, glCompressedTexSubImage1DARB);
    w->glCompressedTexSubImage2D = (COIN_PFNGLCOMPRESSEDTEXSUBIMAGE2DPROC)PROC(w, glCompressedTexSubImage2DARB);
    w->glCompressedTexSubImage3D = (COIN_PFNGLCOMPRESSEDTEXSUBIMAGE3DPROC)PROC(w, glCompressedTexSubImage3DARB);
    w->glGetCompressedTexImage = (COIN_PFNGLGETCOMPRESSEDTEXIMAGEPROC)PROC(w, glGetCompressedTexImageARB);
  }
#endif /* GL_ARB_texture_compression */

  w->glColorTable = NULL;
  w->glColorSubTable = NULL;
  w->glGetColorTable = NULL;
  w->glGetColorTableParameteriv = NULL;
  w->glGetColorTableParameterfv = NULL;

#if defined(GL_VERSION_1_2) && defined(GL_ARB_imaging)
  if (cc_glglue_glversion_matches_at_least(w, 1, 2, 0) &&
      cc_glglue_glext_supported(w, "GL_ARB_imaging")) {
    w->glColorTable = (COIN_PFNGLCOLORTABLEPROC)PROC(w, glColorTable);
    w->glColorSubTable = (COIN_PFNGLCOLORSUBTABLEPROC)PROC(w, glColorSubTable);
    w->glGetColorTable = (COIN_PFNGLGETCOLORTABLEPROC)PROC(w, glGetColorTable);
    w->glGetColorTableParameteriv = (COIN_PFNGLGETCOLORTABLEPARAMETERIVPROC)PROC(w, glGetColorTableParameteriv);
    w->glGetColorTableParameterfv = (COIN_PFNGLGETCOLORTABLEPARAMETERFVPROC)PROC(w, glGetColorTableParameterfv);
  }
#endif /* GL_VERSION_1_2 && GL_ARB_imaging */

#if defined(GL_EXT_color_table)
  if ((w->glColorTable == NULL) &&
      cc_glglue_glext_supported(w, "GL_EXT_color_table")) {
    w->glColorTable = (COIN_PFNGLCOLORTABLEPROC)PROC(w, glColorTableEXT);
    w->glGetColorTable = (COIN_PFNGLGETCOLORTABLEPROC)PROC(w, glGetColorTableEXT);
    w->glGetColorTableParameteriv = (COIN_PFNGLGETCOLORTABLEPARAMETERIVPROC)PROC(w, glGetColorTableParameterivEXT);
    w->glGetColorTableParameterfv = (COIN_PFNGLGETCOLORTABLEPARAMETERFVPROC)PROC(w, glGetColorTableParameterfvEXT);
  }
#endif /* GL_EXT_color_table */

#if defined(GL_SGI_color_table)
  if ((w->glColorTable == NULL) &&
      cc_glglue_glext_supported(w, "GL_SGI_color_table")) {
    w->glColorTable = (COIN_PFNGLCOLORTABLEPROC)PROC(w, glColorTableSGI);
    w->glGetColorTable = (COIN_PFNGLGETCOLORTABLEPROC)PROC(w, glGetColorTableSGI);
    w->glGetColorTableParameteriv = (COIN_PFNGLGETCOLORTABLEPARAMETERIVPROC)PROC(w, glGetColorTableParameterivSGI);
    w->glGetColorTableParameterfv = (COIN_PFNGLGETCOLORTABLEPARAMETERFVPROC)PROC(w, glGetColorTableParameterfvSGI);
  }
#endif /* GL_SGI_color_table */

#if defined(GL_EXT_color_subtable)
  if ((w->glColorSubTable == NULL) &&
      cc_glglue_glext_supported(w, "GL_EXT_color_subtable")) {
    w->glColorSubTable = (COIN_PFNGLCOLORSUBTABLEPROC)PROC(w, glColorSubTableEXT);
  }
#endif /* GL_EXT_color_subtable */

  w->supportsPalettedTextures =
    cc_glglue_glext_supported(w, "GL_EXT_paletted_texture");
  /* FIXME: is paletted textures _really_ not supported through any
     non-extension mechanism for the later OpenGL spec versions?
     Investigate. 20031027 mortene. */

#ifdef GL_EXT_paletted_texture
  /* Note that EXT_paletted_texture defines glColorTableEXT et al
     "on it's own", i.e. it doesn't need the presence of
     EXT_color_table / SGI_color_table / OGL1.2+ + ARB_imaging. It
     only defines a *subset* of what EXT_color_table etc defines,
     though. */
  if ((w->glColorTable == NULL) &&
      cc_glglue_glext_supported(w, "GL_EXT_paletted_texture")) {
    w->glColorTable = (COIN_PFNGLCOLORTABLEPROC)PROC(w, glColorTableEXT);
    w->glColorSubTable = (COIN_PFNGLCOLORSUBTABLEPROC)PROC(w, glColorSubTableEXT);
    w->glGetColorTable = (COIN_PFNGLGETCOLORTABLEPROC)PROC(w, glGetColorTableEXT);
    w->glGetColorTableParameteriv = (COIN_PFNGLGETCOLORTABLEPARAMETERIVPROC)PROC(w, glGetColorTableParameterivEXT);
    w->glGetColorTableParameterfv = (COIN_PFNGLGETCOLORTABLEPARAMETERFVPROC)PROC(w, glGetColorTableParameterfvEXT);
  }
#endif /* GL_EXT_paletted_texture */

  /*
    Using the SGI_texture_color_table extension has been temporarily
    disabled, as it uses a different enum value for
    glColorTable(<target>,...), and seems to only support 2D
    textures. Quoting from the extension spec document:

        Accepted by the <cap> parameter of Enable, Disable, and
        IsEnabled, [...] and by the <target> parameter of
        ColorTableSGI, CopyColorTableSGI, GetColorTableSGI,
        ColorTableParameterfvSGI, ColorTableParameterivSGI,
        GetColorTableParameterfvSGI, GetColorTableParameterivSGI:

        TEXTURE_COLOR_TABLE_SGI         0x80BC

        Accepted by the <target> parameter of ColorTableSGI,
        GetColorTableParameterivSGI, and GetColorTableParameterfvSGI:

        PROXY_TEXTURE_COLOR_TABLE_SGI   0x80BD

    As paletted textures can only be supported through extensions, we
    should probably implement support for using this one in addition
    to EXT_paletted_texture.

    Note: our O2 supports this extension, but not
    EXT_paletted_texture, so it can be used for development and
    testing of support for this extension.

    20030129 mortene.
   */
#if 0
  w->supportsPalettedTextures = w->supportsPalettedTextures ||
    cc_glglue_glext_supported(w, "GL_SGI_texture_color_table");

#ifdef GL_SGI_texture_color_table
  /* Note that SGI_texture_color_table defines glColorTableEXT et al
     "on it's own", i.e. it doesn't need the presence of
     EXT_color_table / SGI_color_table / OGL1.2+ + ARB_imaging. It
     only defines a *subset* of what EXT_color_table etc defines,
     though. */
  if ((w->glColorTable == NULL) &&
      cc_glglue_glext_supported(w, "GL_SGI_texture_color_table")) {
    w->glColorTable = (COIN_PFNGLCOLORTABLEPROC)PROC(w, glColorTableSGI);
    w->glGetColorTable = (COIN_PFNGLGETCOLORTABLEPROC)PROC(w, glGetColorTableSGI);
    w->glGetColorTableParameteriv = (COIN_PFNGLGETCOLORTABLEPARAMETERIVPROC)PROC(w, glGetColorTableParameterivSGI);
    w->glGetColorTableParameterfv = (COIN_PFNGLGETCOLORTABLEPARAMETERFVPROC)PROC(w, glGetColorTableParameterfvSGI);
  }
#endif /* GL_SGI_texture_color_table */
#endif /* disabled */


  w->glBlendEquation = NULL;
  w->glBlendEquationEXT = NULL;

#if defined(GL_VERSION_1_4)
  if (cc_glglue_glversion_matches_at_least(w, 1, 4, 0)) {
    w->glBlendEquation = (COIN_PFNGLBLENDEQUATIONPROC)PROC(w, glBlendEquation);
  }
#endif /* GL_VERSION_1_4 */

  if (w->glBlendEquation == NULL) {
#if defined(GL_VERSION_1_2) && defined(GL_ARB_imaging)
    if (cc_glglue_glversion_matches_at_least(w, 1, 2, 0) &&
        cc_glglue_glext_supported(w, "GL_ARB_imaging")) {
      w->glBlendEquation = (COIN_PFNGLBLENDEQUATIONPROC)PROC(w, glBlendEquation);
    }
#endif /* GL_VERSION_1_2 && GL_ARB_imaging */
  }

#ifdef GL_EXT_blend_minmax
  if (cc_glglue_glext_supported(w, "GL_EXT_blend_minmax")) {
    w->glBlendEquationEXT = (COIN_PFNGLBLENDEQUATIONPROC)PROC(w, glBlendEquationEXT);
  }
#endif /* GL_EXT_blend_minmax */

  w->glBlendFuncSeparate = NULL;
#if defined(GL_VERSION_1_4)
  if (cc_glglue_glversion_matches_at_least(w, 1, 4, 0)) {
    w->glBlendFuncSeparate = (COIN_PFNGLBLENDFUNCSEPARATEPROC)PROC(w, glBlendFuncSeparate);
  }
#endif /* GL_VERSION_1_4 */

  w->glVertexPointer = NULL; /* for cc_glglue_has_vertex_array() */
#if defined(GL_VERSION_1_1)
  if (cc_glglue_glversion_matches_at_least(w, 1, 1, 0)) {
    w->glVertexPointer = (COIN_PFNGLVERTEXPOINTERPROC) PROC(w, glVertexPointer);
    w->glTexCoordPointer = (COIN_PFNGLTEXCOORDPOINTERPROC) PROC(w, glTexCoordPointer);
    w->glNormalPointer = (COIN_PFNGLNORMALPOINTERPROC) PROC(w, glNormalPointer);
    w->glColorPointer = (COIN_PNFGLCOLORPOINTERPROC) PROC(w, glColorPointer);
    w->glIndexPointer = (COIN_PFNGLINDEXPOINTERPROC) PROC(w, glIndexPointer);
    w->glEnableClientState = (COIN_PFNGLENABLECLIENTSTATEPROC) PROC(w, glEnableClientState);
    w->glDisableClientState = (COIN_PFNGLDISABLECLIENTSTATEPROC) PROC(w, glDisableClientState);
    w->glInterleavedArrays = (COIN_PFNGLINTERLEAVEDARRAYSPROC) PROC(w, glInterleavedArrays);
    w->glDrawArrays = (COIN_PFNGLDRAWARRAYSPROC) PROC(w, glDrawArrays);
    w->glDrawElements = (COIN_PFNGLDRAWELEMENTSPROC) PROC(w, glDrawElements);
    w->glArrayElement = (COIN_PFNGLARRAYELEMENTPROC) PROC(w, glArrayElement);
  }
  if (w->glVertexPointer) {
    if (!w->glTexCoordPointer ||
        !w->glNormalPointer ||
        !w->glColorPointer ||
        !w->glIndexPointer ||
        !w->glEnableClientState ||
        !w->glDisableClientState ||
        !w->glInterleavedArrays ||
        !w->glDrawArrays ||
        !w->glDrawElements ||
        !w->glArrayElement) {
      w->glVertexPointer = NULL; /* cc_glglue_has_vertex_array() will return FALSE */
      if (COIN_DEBUG || coin_glglue_debug()) {
        cc_debugerror_postwarning("glglue_init",
                                  "glVertexPointer found, but one or more of the other "
                                  "vertex array functions were not found");
      }
    }
  }
#endif /* GL_VERSION_1_1 */


#if defined(GL_VERSION_1_2)
  w->glDrawRangeElements = NULL;
  if (cc_glglue_glversion_matches_at_least(w, 1, 2, 0))
    w->glDrawRangeElements = (COIN_PFNGLDRAWRANGEELEMENTSPROC) PROC(w, glDrawRangeElements);
#endif /* GL_VERSION_1_2 */


  /* Appeared in OpenGL v1.4 (but also in GL_EXT_multi_draw_array extension */
  w->glMultiDrawArrays = NULL;
  w->glMultiDrawElements = NULL;
#if defined(GL_VERSION_1_4)
  if (cc_glglue_glversion_matches_at_least(w, 1, 4, 0)) {
    w->glMultiDrawArrays = (COIN_PFNGLMULTIDRAWARRAYSPROC) PROC(w, glMultiDrawArrays);
    w->glMultiDrawElements = (COIN_PFNGLMULTIDRAWELEMENTSPROC) PROC(w, glMultiDrawElements);
  }
#endif /* GL_VERSION_1_4 */
#if defined(GL_EXT_multi_draw_arrays)
  if ((w->glMultiDrawArrays == NULL) && cc_glglue_glext_supported(w, "GL_EXT_multi_draw_arrays")) {
    w->glMultiDrawArrays = (COIN_PFNGLMULTIDRAWARRAYSPROC) PROC(w, glMultiDrawArraysEXT);
    w->glMultiDrawElements = (COIN_PFNGLMULTIDRAWELEMENTSPROC) PROC(w, glMultiDrawElementsEXT);
  }
#endif /* GL_EXT_multi_draw_arrays */

  w->glBindBuffer = NULL; /* so that cc_glglue_has_vertex_buffer_objects() works  */
#if defined(GL_VERSION_1_5)
  if (cc_glglue_glversion_matches_at_least(w, 1, 5, 0)) {
    w->glBindBuffer = (COIN_PFNGLBINDBUFFERPROC) PROC(w, glBindBuffer);
    w->glDeleteBuffers = (COIN_PFNGLDELETEBUFFERSPROC) PROC(w, glDeleteBuffers);
    w->glGenBuffers = (COIN_PFNGLGENBUFFERSPROC) PROC(w, glGenBuffers);
    w->glIsBuffer = (COIN_PFNGLISBUFFERPROC) PROC(w, glIsBuffer);
    w->glBufferData = (COIN_PFNGLBUFFERDATAPROC) PROC(w, glBufferData);
    w->glBufferSubData = (COIN_PFNGLBUFFERSUBDATAPROC) PROC(w, glBufferSubData);
    w->glGetBufferSubData = (COIN_PFNGLGETBUFFERSUBDATAPROC) PROC(w, glGetBufferSubData);
    w->glMapBuffer = (COIN_PNFGLMAPBUFFERPROC) PROC(w, glMapBuffer);
    w->glUnmapBuffer = (COIN_PFNGLUNMAPBUFFERPROC) PROC(w, glUnmapBuffer);
    w->glGetBufferParameteriv = (COIN_PFNGLGETBUFFERPARAMETERIVPROC) PROC(w, glGetBufferParameteriv);
    w->glGetBufferPointerv = (COIN_PFNGLGETBUFFERPOINTERVPROC) PROC(w, glGetBufferPointerv);
  }
#endif /* GL_VERSION_1_5 */

#if defined(GL_ARB_vertex_buffer_object)
  if ((w->glBindBuffer == NULL) && cc_glglue_glext_supported(w, "GL_ARB_vertex_buffer_object")) {
    w->glBindBuffer = (COIN_PFNGLBINDBUFFERPROC) PROC(w, glBindBufferARB);
    w->glDeleteBuffers = (COIN_PFNGLDELETEBUFFERSPROC) PROC(w, glDeleteBuffersARB);
    w->glGenBuffers = (COIN_PFNGLGENBUFFERSPROC) PROC(w, glGenBuffersARB);
    w->glIsBuffer = (COIN_PFNGLISBUFFERPROC) PROC(w, glIsBufferARB);
    w->glBufferData = (COIN_PFNGLBUFFERDATAPROC) PROC(w, glBufferDataARB);
    w->glBufferSubData = (COIN_PFNGLBUFFERSUBDATAPROC) PROC(w, glBufferSubDataARB);
    w->glGetBufferSubData = (COIN_PFNGLGETBUFFERSUBDATAPROC) PROC(w, glGetBufferSubDataARB);
    w->glMapBuffer = (COIN_PNFGLMAPBUFFERPROC) PROC(w, glMapBufferARB);
    w->glUnmapBuffer = (COIN_PFNGLUNMAPBUFFERPROC) PROC(w, glUnmapBufferARB);
    w->glGetBufferParameteriv = (COIN_PFNGLGETBUFFERPARAMETERIVPROC) PROC(w, glGetBufferParameterivARB);
    w->glGetBufferPointerv = (COIN_PFNGLGETBUFFERPOINTERVPROC) PROC(w, glGetBufferPointervARB);
  }

#if defined(HAVE_GLX)
  /* ARB_vertex_buffer_object does not work properly on Linux when
     using the Nvidia 44.96 driver (version 1.4.0). The VBO extension
     is therefore disabled for this driver. The issue was solved for
     the 53.28 driver (version 1.4.1). */
  if (!strcmp(w->vendorstr, "NVIDIA Corporation")) {
    if (!cc_glglue_glversion_matches_at_least(w, 1, 4, 1)) {
      w->glBindBuffer = NULL;
    }
    /* VBOs seems really slow on the GeForce4 Go GPUs, but this test
       is disabled for now until we know for sure that VBOs will
       always be slow for this GPU */
    /*     else if (strstr(w->rendererstr, "GeForce4 420 Go")) { */
    /*       w->glBindBuffer = NULL; */
    /*     } */
    /* FIXME: I guess the above has been made obsolete by the VBO
       performance testing we now do..? pederb should confirm.
       20061027 mortene. */
  }
#endif

  /* VBO support has been found to often trigger bugs in OpenGL
     drivers, so we make it possible to selectively disable that
     feature through an envvar.

     (Specifically, I've seen the following driver crash when using
     VBOs in an offscreen context: GL_RENDERER="GeForce 7950
     GX2/PCI/SSE2", GL_VERSION="2.0.2 NVIDIA 87.62", on an AMD64 with
     Linux. On-screen contexts with VBOs was ok on the exact same
     machine. -mortene.)
  */
  if (w->glBindBuffer) {
    const char * env = coin_getenv("COIN_GL_DISABLE_VBO");
    if (env && (atoi(env) > 0)) { w->glBindBuffer = NULL; }
  }


  /*
    All Intel drivers usually crash when we try to use VBO. This might be a bug in
    our VBO code, but we choose to disable VBO rendering for all Intel cards until
    we have time to look into this. pederb, 2007-08-16
  */

  if (w->glBindBuffer) {
    if (coin_runtime_os() != COIN_OS_X) { /* Apple has proper drivers */
      /* Enable users to override this workaround by setting COIN_VBO=1 */
      const char * env = coin_getenv("COIN_VBO");
      if (!env || (atoi(env) > 0)) {
        if (w->vendor_is_intel) {
          w->glBindBuffer = NULL;
        }
      }
    }
  }

  /*
    Sylvain Carette reported problems with some old 3DLabs drivers and VBO rendering.
    The drivers were from 2006, so we disable VBO rendering if 3DLabs and that driver
    version is detected (the driver version was 2.0)
   */
  if (w->glBindBuffer && w->vendor_is_3dlabs
      && !cc_glglue_glversion_matches_at_least(w, 2,0,1)) {
    /* Enable users to override this workaround by setting COIN_VBO=1 */
    const char * env = coin_getenv("COIN_VBO");
    if (!env || (atoi(env) > 0)) {
      w->glBindBuffer = NULL;
    }
  }

#endif /* GL_ARB_vertex_buffer_object */

  if (w->glBindBuffer) {
    if (!w->glDeleteBuffers ||
        !w->glGenBuffers ||
        !w->glIsBuffer ||
        !w->glBufferData ||
        !w->glBufferSubData ||
        !w->glGetBufferSubData ||
        !w->glMapBuffer ||
        !w->glUnmapBuffer ||
        !w->glGetBufferParameteriv ||
        !w->glGetBufferPointerv) {
      w->glBindBuffer = NULL; /* so that cc_glglue_has_vertex_buffer_object() will return FALSE */
      if (COIN_DEBUG || coin_glglue_debug()) {
        cc_debugerror_postwarning("glglue_init",
                                  "glBindBuffer found, but one or more of the other "
                                  "vertex buffer object functions were not found");
      }
    }
  }

  /* GL_NV_register_combiners */
  w->glCombinerParameterfvNV = NULL;
  w->glCombinerParameterivNV = NULL;
  w->glCombinerParameterfNV = NULL;
  w->glCombinerParameteriNV = NULL;
  w->glCombinerInputNV = NULL;
  w->glCombinerOutputNV = NULL;
  w->glFinalCombinerInputNV = NULL;
  w->glGetCombinerInputParameterfvNV = NULL;
  w->glGetCombinerInputParameterivNV = NULL;
  w->glGetCombinerOutputParameterfvNV = NULL;
  w->glGetCombinerOutputParameterivNV = NULL;
  w->glGetFinalCombinerInputParameterfvNV = NULL;
  w->glGetFinalCombinerInputParameterivNV = NULL;
  w->has_nv_register_combiners = FALSE;

#ifdef GL_NV_register_combiners

  if (cc_glglue_glext_supported(w, "GL_NV_register_combiners")) {

#define BIND_FUNCTION_WITH_WARN(_func_, _type_) \
   w->_func_ = (_type_)PROC(w, _func_); \
   do { \
     if (!w->_func_) { \
       w->has_nv_register_combiners = FALSE; \
       if (COIN_DEBUG || coin_glglue_debug()) { \
         static SbBool error_reported = FALSE; \
         if (!error_reported) { \
           cc_debugerror_postwarning("glglue_init", \
                                     "GL_NV_register_combiners found, but %s " \
                                     "function missing.", SO__QUOTE(_func_)); \
           error_reported = TRUE; \
         } \
       } \
     } \
   } while (0)

    w->has_nv_register_combiners = TRUE;
    BIND_FUNCTION_WITH_WARN(glCombinerParameterfvNV, COIN_PFNGLCOMBINERPARAMETERFVNVPROC);
    BIND_FUNCTION_WITH_WARN(glCombinerParameterivNV, COIN_PFNGLCOMBINERPARAMETERIVNVPROC);
    BIND_FUNCTION_WITH_WARN(glCombinerParameterfNV, COIN_PFNGLCOMBINERPARAMETERFNVPROC);
    BIND_FUNCTION_WITH_WARN(glCombinerParameteriNV, COIN_PFNGLCOMBINERPARAMETERINVPROC);
    BIND_FUNCTION_WITH_WARN(glCombinerInputNV, COIN_PFNGLCOMBINERINPUTNVPROC);
    BIND_FUNCTION_WITH_WARN(glCombinerOutputNV, COIN_PFNGLCOMBINEROUTPUTNVPROC);
    BIND_FUNCTION_WITH_WARN(glFinalCombinerInputNV, COIN_PFNGLFINALCOMBINERINPUTNVPROC);
    BIND_FUNCTION_WITH_WARN(glGetCombinerInputParameterfvNV, COIN_PFNGLGETCOMBINERINPUTPARAMETERFVNVPROC);
    BIND_FUNCTION_WITH_WARN(glGetCombinerInputParameterivNV, COIN_PFNGLGETCOMBINERINPUTPARAMETERIVNVPROC);
    BIND_FUNCTION_WITH_WARN(glGetCombinerOutputParameterfvNV, COIN_PFNGLGETCOMBINEROUTPUTPARAMETERFVNVPROC);
    BIND_FUNCTION_WITH_WARN(glGetCombinerOutputParameterivNV, COIN_PFNGLGETCOMBINEROUTPUTPARAMETERIVNVPROC);
    BIND_FUNCTION_WITH_WARN(glGetFinalCombinerInputParameterfvNV, COIN_PFNGLGETFINALCOMBINERINPUTPARAMETERFVNVPROC);
    BIND_FUNCTION_WITH_WARN(glGetFinalCombinerInputParameterivNV, COIN_PFNGLGETFINALCOMBINERINPUTPARAMETERIVNVPROC);

#undef BIND_FUNCTION_WITH_WARN
  }
#endif /* GL_NV_register_combiners */


  /* GL_[NV/EXT]_texture_rectangle */
  w->has_ext_texture_rectangle = (cc_glglue_glext_supported(w, "GL_EXT_texture_rectangle") ||
                                  cc_glglue_glext_supported(w, "GL_NV_texture_rectangle"));

  /* GL_NV_texture_shader */
  w->has_nv_texture_shader = cc_glglue_glext_supported(w, "GL_NV_texture_shader");

  /* GL_ARB_shadow */
  w->has_shadow = (cc_glglue_glext_supported(w, "GL_ARB_shadow") ||
                   cc_glglue_glversion_matches_at_least(w, 1, 4, 0));

  /* GL_ARB_depth_texture */
  w->has_depth_texture = (cc_glglue_glext_supported(w, "GL_ARB_depth_texture") ||
                          cc_glglue_glversion_matches_at_least(w, 1, 4, 0));

  /* GL_[ARB/EXT]_texture_env_combine */
  w->has_texture_env_combine = (cc_glglue_glext_supported(w, "GL_ARB_texture_env_combine") ||
                                cc_glglue_glext_supported(w, "GL_EXT_texture_env_combine") ||
                                cc_glglue_glversion_matches_at_least(w, 1, 3, 0));

  /* GL_ARB_fragment_program */
  w->glProgramStringARB = NULL;
  w->glBindProgramARB = NULL;
  w->glDeleteProgramsARB = NULL;
  w->glGenProgramsARB = NULL;
  w->glProgramEnvParameter4dARB = NULL;
  w->glProgramEnvParameter4dvARB = NULL;
  w->glProgramEnvParameter4fARB = NULL;
  w->glProgramEnvParameter4fvARB = NULL;
  w->glProgramLocalParameter4dARB = NULL;
  w->glProgramLocalParameter4dvARB = NULL;
  w->glProgramLocalParameter4fARB = NULL;
  w->glProgramLocalParameter4fvARB = NULL;
  w->glGetProgramEnvParameterdvARB = NULL;
  w->glGetProgramEnvParameterfvARB = NULL;
  w->glGetProgramLocalParameterdvARB = NULL;
  w->glGetProgramLocalParameterfvARB = NULL;
  w->glGetProgramivARB = NULL;
  w->glGetProgramStringARB = NULL;
  w->glIsProgramARB = NULL;
  w->has_arb_fragment_program = FALSE;

#ifdef GL_ARB_fragment_program
  if (cc_glglue_glext_supported(w, "GL_ARB_fragment_program")) {

#define BIND_FUNCTION_WITH_WARN(_func_, _type_) \
   w->_func_ = (_type_)PROC(w, _func_); \
   do { \
     if (!w->_func_) { \
       w->has_arb_fragment_program = FALSE; \
       if (COIN_DEBUG || coin_glglue_debug()) { \
         static SbBool error_reported = FALSE; \
         if (!error_reported) { \
           cc_debugerror_postwarning("glglue_init", \
                                     "GL_ARB_fragment_program found, but %s " \
                                     "function missing.", SO__QUOTE(_func_)); \
           error_reported = TRUE; \
         } \
       } \
     } \
   } while (0)

    w->has_arb_fragment_program = TRUE;
    BIND_FUNCTION_WITH_WARN(glProgramStringARB, COIN_PFNGLPROGRAMSTRINGARBPROC);
    BIND_FUNCTION_WITH_WARN(glBindProgramARB, COIN_PFNGLBINDPROGRAMARBPROC);
    BIND_FUNCTION_WITH_WARN(glDeleteProgramsARB, COIN_PFNGLDELETEPROGRAMSARBPROC);
    BIND_FUNCTION_WITH_WARN(glGenProgramsARB, COIN_PFNGLGENPROGRAMSARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4dARB, COIN_PFNGLPROGRAMENVPARAMETER4DARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4dvARB, COIN_PFNGLPROGRAMENVPARAMETER4DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4fARB, COIN_PFNGLPROGRAMENVPARAMETER4FARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4fvARB, COIN_PFNGLPROGRAMENVPARAMETER4FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4dARB, COIN_PFNGLPROGRAMLOCALPARAMETER4DARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4dvARB, COIN_PFNGLPROGRAMLOCALPARAMETER4DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4fARB, COIN_PFNGLPROGRAMLOCALPARAMETER4FARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4fvARB, COIN_PFNGLPROGRAMLOCALPARAMETER4FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramEnvParameterdvARB, COIN_PFNGLGETPROGRAMENVPARAMETERDVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramEnvParameterfvARB, COIN_PFNGLGETPROGRAMENVPARAMETERFVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramLocalParameterdvARB, COIN_PFNGLGETPROGRAMLOCALPARAMETERDVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramLocalParameterfvARB, COIN_PFNGLGETPROGRAMLOCALPARAMETERFVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramivARB, COIN_PFNGLGETPROGRAMIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramStringARB, COIN_PFNGLGETPROGRAMSTRINGARBPROC);
    BIND_FUNCTION_WITH_WARN(glIsProgramARB, COIN_PFNGLISPROGRAMARBPROC);

#undef BIND_FUNCTION_WITH_WARN
 }
#endif /* GL_ARB_fragment_program */

  w->has_arb_vertex_program = FALSE;
  w->glVertexAttrib1sARB = NULL;
  w->glVertexAttrib1fARB = NULL;
  w->glVertexAttrib1dARB = NULL;
  w->glVertexAttrib2sARB = NULL;
  w->glVertexAttrib2fARB = NULL;
  w->glVertexAttrib2dARB = NULL;
  w->glVertexAttrib3sARB = NULL;
  w->glVertexAttrib3fARB = NULL;
  w->glVertexAttrib3dARB = NULL;
  w->glVertexAttrib4sARB = NULL;
  w->glVertexAttrib4fARB = NULL;
  w->glVertexAttrib4dARB = NULL;
  w->glVertexAttrib4NubARB = NULL;
  w->glVertexAttrib1svARB = NULL;
  w->glVertexAttrib1fvARB = NULL;
  w->glVertexAttrib1dvARB = NULL;
  w->glVertexAttrib2svARB = NULL;
  w->glVertexAttrib2fvARB = NULL;
  w->glVertexAttrib2dvARB = NULL;
  w->glVertexAttrib3svARB = NULL;
  w->glVertexAttrib3fvARB = NULL;
  w->glVertexAttrib3dvARB = NULL;
  w->glVertexAttrib4bvARB = NULL;
  w->glVertexAttrib4svARB = NULL;
  w->glVertexAttrib4ivARB = NULL;
  w->glVertexAttrib4ubvARB = NULL;
  w->glVertexAttrib4usvARB = NULL;
  w->glVertexAttrib4uivARB = NULL;
  w->glVertexAttrib4fvARB = NULL;
  w->glVertexAttrib4dvARB = NULL;
  w->glVertexAttrib4NbvARB = NULL;
  w->glVertexAttrib4NsvARB = NULL;
  w->glVertexAttrib4NivARB = NULL;
  w->glVertexAttrib4NubvARB = NULL;
  w->glVertexAttrib4NusvARB = NULL;
  w->glVertexAttrib4NuivARB = NULL;
  w->glVertexAttribPointerARB = NULL;
  w->glEnableVertexAttribArrayARB = NULL;
  w->glDisableVertexAttribArrayARB = NULL;
  w->glProgramStringARB = NULL;
  w->glBindProgramARB = NULL;
  w->glDeleteProgramsARB = NULL;
  w->glGenProgramsARB = NULL;
  w->glProgramEnvParameter4dARB = NULL;
  w->glProgramEnvParameter4dvARB = NULL;
  w->glProgramEnvParameter4fARB = NULL;
  w->glProgramEnvParameter4fvARB = NULL;
  w->glProgramLocalParameter4dARB = NULL;
  w->glProgramLocalParameter4dvARB = NULL;
  w->glProgramLocalParameter4fARB = NULL;
  w->glProgramLocalParameter4fvARB = NULL;
  w->glGetProgramEnvParameterdvARB = NULL;
  w->glGetProgramEnvParameterfvARB = NULL;
  w->glGetProgramLocalParameterdvARB = NULL;
  w->glGetProgramLocalParameterfvARB = NULL;
  w->glGetProgramivARB = NULL;
  w->glGetProgramStringARB = NULL;
  w->glGetVertexAttribdvARB = NULL;
  w->glGetVertexAttribfvARB = NULL;
  w->glGetVertexAttribivARB = NULL;
  w->glGetVertexAttribPointervARB = NULL;
  w->glIsProgramARB = NULL;


#ifdef GL_ARB_vertex_program

  if (cc_glglue_glext_supported(w, "GL_ARB_vertex_program")) {

#define BIND_FUNCTION_WITH_WARN(_func_, _type_) \
   w->_func_ = (_type_)PROC(w, _func_); \
   do { \
     if (!w->_func_) { \
       w->has_arb_vertex_program = FALSE; \
       if (COIN_DEBUG || coin_glglue_debug()) { \
         static SbBool error_reported = FALSE; \
         if (!error_reported) { \
           cc_debugerror_postwarning("glglue_init", \
                                     "GL_ARB_vertex_program found, but %s " \
                                     "function missing.", SO__QUOTE(_func_)); \
           error_reported = TRUE; \
         } \
       } \
     } \
   } while (0)

    w->has_arb_vertex_program = TRUE;
    BIND_FUNCTION_WITH_WARN(glVertexAttrib1sARB, COIN_PFNGLVERTEXATTRIB1SARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib1fARB, COIN_PFNGLVERTEXATTRIB1FARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib1dARB, COIN_PFNGLVERTEXATTRIB1DARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib2sARB, COIN_PFNGLVERTEXATTRIB2SARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib2fARB, COIN_PFNGLVERTEXATTRIB2FARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib2dARB, COIN_PFNGLVERTEXATTRIB2DARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib3sARB, COIN_PFNGLVERTEXATTRIB3SARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib3fARB, COIN_PFNGLVERTEXATTRIB3FARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib3dARB, COIN_PFNGLVERTEXATTRIB3DARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4sARB, COIN_PFNGLVERTEXATTRIB4SARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4fARB, COIN_PFNGLVERTEXATTRIB4FARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4dARB, COIN_PFNGLVERTEXATTRIB4DARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NubARB, COIN_PFNGLVERTEXATTRIB4NUBARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib1svARB, COIN_PFNGLVERTEXATTRIB1SVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib1fvARB, COIN_PFNGLVERTEXATTRIB1FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib1dvARB, COIN_PFNGLVERTEXATTRIB1DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib2svARB, COIN_PFNGLVERTEXATTRIB2SVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib2fvARB, COIN_PFNGLVERTEXATTRIB2FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib2dvARB, COIN_PFNGLVERTEXATTRIB2DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib3svARB, COIN_PFNGLVERTEXATTRIB3SVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib3fvARB, COIN_PFNGLVERTEXATTRIB3FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib3dvARB, COIN_PFNGLVERTEXATTRIB3DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4bvARB, COIN_PFNGLVERTEXATTRIB4BVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4svARB, COIN_PFNGLVERTEXATTRIB4SVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4ivARB, COIN_PFNGLVERTEXATTRIB4IVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4ubvARB, COIN_PFNGLVERTEXATTRIB4UBVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4usvARB, COIN_PFNGLVERTEXATTRIB4USVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4uivARB, COIN_PFNGLVERTEXATTRIB4UIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4fvARB, COIN_PFNGLVERTEXATTRIB4FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4dvARB, COIN_PFNGLVERTEXATTRIB4DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NbvARB, COIN_PFNGLVERTEXATTRIB4NBVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NsvARB, COIN_PFNGLVERTEXATTRIB4NSVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NivARB, COIN_PFNGLVERTEXATTRIB4NIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NubvARB, COIN_PFNGLVERTEXATTRIB4NUBVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NusvARB, COIN_PFNGLVERTEXATTRIB4NUSVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttrib4NuivARB, COIN_PFNGLVERTEXATTRIB4NUIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glVertexAttribPointerARB, COIN_PFNGLVERTEXATTRIBPOINTERARBPROC);
    BIND_FUNCTION_WITH_WARN(glEnableVertexAttribArrayARB, COIN_PFNGLENABLEVERTEXATTRIBARRAYARBPROC);
    BIND_FUNCTION_WITH_WARN(glDisableVertexAttribArrayARB, COIN_PFNGLDISABLEVERTEXATTRIBARRAYARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramStringARB, COIN_PFNGLPROGRAMSTRINGARBPROC);
    BIND_FUNCTION_WITH_WARN(glBindProgramARB, COIN_PFNGLBINDPROGRAMARBPROC);
    BIND_FUNCTION_WITH_WARN(glDeleteProgramsARB, COIN_PFNGLDELETEPROGRAMSARBPROC);
    BIND_FUNCTION_WITH_WARN(glGenProgramsARB, COIN_PFNGLGENPROGRAMSARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4dARB, COIN_PFNGLPROGRAMENVPARAMETER4DARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4dvARB, COIN_PFNGLPROGRAMENVPARAMETER4DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4fARB, COIN_PFNGLPROGRAMENVPARAMETER4FARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramEnvParameter4fvARB, COIN_PFNGLPROGRAMENVPARAMETER4FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4dARB, COIN_PFNGLPROGRAMLOCALPARAMETER4DARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4dvARB, COIN_PFNGLPROGRAMLOCALPARAMETER4DVARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4fARB, COIN_PFNGLPROGRAMLOCALPARAMETER4FARBPROC);
    BIND_FUNCTION_WITH_WARN(glProgramLocalParameter4fvARB, COIN_PFNGLPROGRAMLOCALPARAMETER4FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramEnvParameterdvARB, COIN_PFNGLGETPROGRAMENVPARAMETERDVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramEnvParameterfvARB, COIN_PFNGLGETPROGRAMENVPARAMETERFVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramLocalParameterdvARB, COIN_PFNGLGETPROGRAMLOCALPARAMETERDVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramLocalParameterfvARB, COIN_PFNGLGETPROGRAMLOCALPARAMETERFVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramivARB, COIN_PFNGLGETPROGRAMIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetProgramStringARB, COIN_PFNGLGETPROGRAMSTRINGARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetVertexAttribdvARB, COIN_PFNGLGETVERTEXATTRIBDVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetVertexAttribfvARB, COIN_PFNGLGETVERTEXATTRIBFVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetVertexAttribivARB, COIN_PFNGLGETVERTEXATTRIBIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetVertexAttribPointervARB, COIN_PFNGLGETVERTEXATTRIBPOINTERVARBPROC);
    BIND_FUNCTION_WITH_WARN(glIsProgramARB, COIN_PFNGLISPROGRAMARBPROC);

#undef BIND_FUNCTION_WITH_WARN
  }
#endif /* GL_ARB_vertex_program */


#ifdef GL_ARB_vertex_shader

  w->glBindAttribLocationARB = NULL;
  w->glGetActiveAttribARB = NULL;
  w->glGetAttribLocationARB = NULL;

  if (cc_glglue_glext_supported(w, "GL_ARB_vertex_shader")) {

#define BIND_FUNCTION_WITH_WARN(_func_, _type_) \
   w->_func_ = (_type_)PROC(w, _func_); \
   do { \
     if (!w->_func_) { \
       w->has_arb_vertex_shader = FALSE; \
       if (COIN_DEBUG || coin_glglue_debug()) { \
         static SbBool error_reported = FALSE; \
         if (!error_reported) { \
           cc_debugerror_postwarning("glglue_init", \
                                     "GL_ARB_vertex_shader found, but %s " \
                                     "function missing.", SO__QUOTE(_func_)); \
           error_reported = TRUE; \
         } \
       } \
     } \
   } while (0)

    w->has_arb_vertex_shader = TRUE;
    BIND_FUNCTION_WITH_WARN(glBindAttribLocationARB, COIN_PFNGLBINDATTRIBLOCATIONARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetActiveAttribARB, COIN_PFNGLGETACTIVEATTRIBARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetAttribLocationARB, COIN_PFNGLGETATTRIBLOCATIONARBPROC);

#undef BIND_FUNCTION_WITH_WARN
  }
#endif /* GL_ARB_vertex_shader */


  w->glGetUniformLocationARB = NULL;
  w->glGetActiveUniformARB = NULL;
  w->glUniform1fARB = NULL;
  w->glUniform2fARB = NULL;
  w->glUniform3fARB = NULL;
  w->glUniform4fARB = NULL;
  w->glCreateShaderObjectARB = NULL;
  w->glShaderSourceARB = NULL;
  w->glCompileShaderARB = NULL;
  w->glGetObjectParameterivARB = NULL;
  w->glDeleteObjectARB = NULL;
  w->glAttachObjectARB = NULL;
  w->glDetachObjectARB = NULL;
  w->glGetInfoLogARB = NULL;
  w->glLinkProgramARB = NULL;
  w->glUseProgramObjectARB = NULL;
  w->glCreateProgramObjectARB = NULL;
  w->has_arb_shader_objects = FALSE;
  w->glUniform1fvARB = NULL;
  w->glUniform2fvARB = NULL;
  w->glUniform3fvARB = NULL;
  w->glUniform4fvARB = NULL;
  w->glUniform1iARB = NULL;
  w->glUniform2iARB = NULL;
  w->glUniform3iARB = NULL;
  w->glUniform4iARB = NULL;
  w->glUniform1ivARB = NULL;
  w->glUniform2ivARB = NULL;
  w->glUniform3ivARB = NULL;
  w->glUniform4ivARB = NULL;
  w->glUniformMatrix2fvARB = NULL;
  w->glUniformMatrix3fvARB = NULL;
  w->glUniformMatrix4fvARB = NULL;


#ifdef GL_ARB_shader_objects

  if (cc_glglue_glext_supported(w, "GL_ARB_shader_objects")) {

#define BIND_FUNCTION_WITH_WARN(_func_, _type_) \
   w->_func_ = (_type_)PROC(w, _func_); \
   do { \
     if (!w->_func_) { \
       w->has_arb_shader_objects = FALSE; \
       if (COIN_DEBUG || coin_glglue_debug()) { \
         static SbBool error_reported = FALSE; \
         if (!error_reported) { \
           cc_debugerror_postwarning("glglue_init", \
                                     "GL_ARB_shader_objects found, but %s " \
                                     "function missing.", SO__QUOTE(_func_)); \
           error_reported = TRUE; \
         } \
       } \
     } \
   } while (0)

    w->has_arb_shader_objects = TRUE;
    BIND_FUNCTION_WITH_WARN(glGetUniformLocationARB, COIN_PFNGLGETUNIFORMLOCATIONARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetActiveUniformARB, COIN_PFNGLGETACTIVEUNIFORMARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform1fARB, COIN_PFNGLUNIFORM1FARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform2fARB, COIN_PFNGLUNIFORM2FARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform3fARB, COIN_PFNGLUNIFORM3FARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform4fARB, COIN_PFNGLUNIFORM4FARBPROC);
    BIND_FUNCTION_WITH_WARN(glCreateShaderObjectARB, COIN_PFNGLCREATESHADEROBJECTARBPROC);
    BIND_FUNCTION_WITH_WARN(glShaderSourceARB, COIN_PFNGLSHADERSOURCEARBPROC);
    BIND_FUNCTION_WITH_WARN(glCompileShaderARB, COIN_PFNGLCOMPILESHADERARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetObjectParameterivARB, COIN_PFNGLGETOBJECTPARAMETERIVARBPROC);
    BIND_FUNCTION_WITH_WARN(glDeleteObjectARB, COIN_PFNGLDELETEOBJECTARBPROC);
    BIND_FUNCTION_WITH_WARN(glAttachObjectARB, COIN_PFNGLATTACHOBJECTARBPROC);
    BIND_FUNCTION_WITH_WARN(glDetachObjectARB, COIN_PFNGLDETACHOBJECTARBPROC);
    BIND_FUNCTION_WITH_WARN(glGetInfoLogARB, COIN_PFNGLGETINFOLOGARBPROC);
    BIND_FUNCTION_WITH_WARN(glLinkProgramARB, COIN_PFNGLLINKPROGRAMARBPROC);
    BIND_FUNCTION_WITH_WARN(glUseProgramObjectARB, COIN_PFNGLUSEPROGRAMOBJECTARBPROC);
    BIND_FUNCTION_WITH_WARN(glCreateProgramObjectARB, COIN_PFNGLCREATEPROGRAMOBJECTARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform1fvARB, COIN_PFNGLUNIFORM1FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform2fvARB, COIN_PFNGLUNIFORM2FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform3fvARB, COIN_PFNGLUNIFORM3FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform4fvARB, COIN_PFNGLUNIFORM4FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform1iARB, COIN_PFNGLUNIFORM1IARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform2iARB, COIN_PFNGLUNIFORM2IARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform3iARB, COIN_PFNGLUNIFORM3IARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform4iARB, COIN_PFNGLUNIFORM4IARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform1ivARB, COIN_PFNGLUNIFORM1IVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform2ivARB, COIN_PFNGLUNIFORM2IVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform3ivARB, COIN_PFNGLUNIFORM3IVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniform4ivARB, COIN_PFNGLUNIFORM4IVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniformMatrix2fvARB, COIN_PFNGLUNIFORMMATRIX2FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniformMatrix3fvARB, COIN_PFNGLUNIFORMMATRIX3FVARBPROC);
    BIND_FUNCTION_WITH_WARN(glUniformMatrix4fvARB, COIN_PFNGLUNIFORMMATRIX4FVARBPROC);


    w->glProgramParameteriEXT = NULL;
    if (cc_glglue_glext_supported(w, "GL_EXT_geometry_shader4")) {
      BIND_FUNCTION_WITH_WARN(glProgramParameteriEXT, COIN_PFNGLPROGRAMPARAMETERIEXT);
    }
#undef BIND_FUNCTION_WITH_WARN
  }
#endif /* GL_ARB_shader_objects */

  w->glGenQueries = NULL; /* so that cc_glglue_has_occlusion_query() works  */
#if defined(GL_VERSION_1_5)
  if (cc_glglue_glversion_matches_at_least(w, 1, 5, 0)) {
    w->glGenQueries = (COIN_PFNGLGENQUERIESPROC)PROC(w, glGenQueries);
    w->glDeleteQueries = (COIN_PFNGLDELETEQUERIESPROC)PROC(w, glDeleteQueries);
    w->glIsQuery = (COIN_PFNGLISQUERYPROC)PROC(w, glIsQuery);
    w->glBeginQuery = (COIN_PFNGLBEGINQUERYPROC)PROC(w, glBeginQuery);
    w->glEndQuery = (COIN_PFNGLENDQUERYPROC)PROC(w, glEndQuery);
    w->glGetQueryiv = (COIN_PFNGLGETQUERYIVPROC)PROC(w, glGetQueryiv);
    w->glGetQueryObjectiv = (COIN_PFNGLGETQUERYOBJECTIVPROC)PROC(w, glGetQueryObjectiv);
    w->glGetQueryObjectuiv = (COIN_PFNGLGETQUERYOBJECTUIVPROC)PROC(w, glGetQueryObjectuiv);
  }
#endif /* GL_VERSION_1_5 */

#if defined(GL_ARB_occlusion_query)
  if ((w->glGenQueries == NULL) && cc_glglue_glext_supported(w, "GL_ARB_occlusion_query")) {
    w->glGenQueries = (COIN_PFNGLGENQUERIESPROC)PROC(w, glGenQueriesARB);
    w->glDeleteQueries = (COIN_PFNGLDELETEQUERIESPROC)PROC(w, glDeleteQueriesARB);
    w->glIsQuery = (COIN_PFNGLISQUERYPROC)PROC(w, glIsQueryARB);
    w->glBeginQuery = (COIN_PFNGLBEGINQUERYPROC)PROC(w, glBeginQueryARB);
    w->glEndQuery = (COIN_PFNGLENDQUERYPROC)PROC(w, glEndQueryARB);
    w->glGetQueryiv = (COIN_PFNGLGETQUERYIVPROC)PROC(w, glGetQueryivARB);
    w->glGetQueryObjectiv = (COIN_PFNGLGETQUERYOBJECTIVPROC)PROC(w, glGetQueryObjectivARB);
    w->glGetQueryObjectuiv = (COIN_PFNGLGETQUERYOBJECTUIVPROC)PROC(w, glGetQueryObjectuivARB);
  }
#endif /* GL_ARB_occlusion_query */

  if (w->glGenQueries) {
    if (!w->glDeleteQueries ||
        !w->glIsQuery ||
        !w->glBeginQuery ||
        !w->glEndQuery ||
        !w->glGetQueryiv ||
        !w->glGetQueryObjectiv ||
        !w->glGetQueryObjectuiv) {
      w->glGenQueries = NULL; /* so that cc_glglue_has_occlusion_query() will return FALSE */
      if (COIN_DEBUG || coin_glglue_debug()) {
        cc_debugerror_postwarning("glglue_init",
                                  "glGenQueries found, but one or more of the other "
                                  "occlusion query functions were not found");
      }
    }
  }

  w->glVertexArrayRangeNV = NULL;
#if defined(GL_NV_vertex_array_range) && (defined(HAVE_GLX) || defined(HAVE_WGL))
  if (cc_glglue_glext_supported(w, "GL_NV_vertex_array_range")) {
    w->glVertexArrayRangeNV = (COIN_PFNGLVERTEXARRAYRANGENVPROC) PROC(w, glVertexArrayRangeNV);
    w->glFlushVertexArrayRangeNV = (COIN_PFNGLFLUSHVERTEXARRAYRANGENVPROC) PROC(w, glFlushVertexArrayRangeNV);
#ifdef HAVE_GLX
    w->glAllocateMemoryNV = (COIN_PFNGLALLOCATEMEMORYNVPROC) PROC(w, glXAllocateMemoryNV);
    w->glFreeMemoryNV = (COIN_PFNGLFREEMEMORYNVPROC) PROC(w, glXFreeMemoryNV);
#endif /* HAVE_GLX */
#ifdef HAVE_WGL
    w->glAllocateMemoryNV = (COIN_PFNGLALLOCATEMEMORYNVPROC) PROC(w, wglAllocateMemoryNV);
    w->glFreeMemoryNV = (COIN_PFNGLFREEMEMORYNVPROC) PROC(w, wglFreeMemoryNV);
#endif /* HAVE_WGL */
    if (w->glVertexArrayRangeNV) {
      if (!w->glFlushVertexArrayRangeNV ||
          !w->glAllocateMemoryNV ||
          !w->glFreeMemoryNV) {
        w->glVertexArrayRangeNV = NULL;
        if (COIN_DEBUG || coin_glglue_debug()) {
          cc_debugerror_postwarning("glglue_init",
                                    "glVertexArrayRangeNV found, but one or more of the other "
                                    "vertex array functions were not found");
        }
      }
    }
  }
#endif /* HAVE_GLX || HAVE_WGL */

  w->can_do_bumpmapping = FALSE;
  if (w->glActiveTexture &&
      (cc_glglue_glversion_matches_at_least(w, 1, 3, 0) ||
       (cc_glglue_glext_supported(w, "GL_ARB_texture_cube_map") &&
        w->has_texture_env_combine &&
        cc_glglue_glext_supported(w, "GL_ARB_texture_env_dot3")))) {
    w->can_do_bumpmapping = TRUE;
  }

  /* FIXME: We should be able to support more than one way to do order
     independent transparency (eg. by using fragment
     programming). This would demand a different combinations of
     extensions (and thus; a different codepath in
     SoGLRenderAction). (20031124 handegar) */
  w->can_do_sortedlayersblend =
    (w->has_nv_register_combiners &&
     w->has_ext_texture_rectangle &&
     w->has_nv_texture_shader &&
     w->has_depth_texture &&
     w->has_shadow) ||
    w->has_arb_fragment_program;

  if (cc_glglue_glext_supported(w, "GL_ARB_framebuffer_object") ||
      cc_glglue_glversion_matches_at_least(w, 3, 0, 0)) {
    w->glGenerateMipmap = (COIN_PFNGLGENERATEMIPMAPPROC)
      cc_glglue_getprocaddress(w, "glGenerateMipmap");
    if (!w->glGenerateMipmap) {
      w->glGenerateMipmap = (COIN_PFNGLGENERATEMIPMAPPROC)
        cc_glglue_getprocaddress(w, "glGenerateMipmapARB");
    }
  }
  if (!w->glGenerateMipmap) {
    if (cc_glglue_glext_supported(w, "GL_EXT_framebuffer_object")) {
      w->glGenerateMipmap = (COIN_PFNGLGENERATEMIPMAPPROC)
        cc_glglue_getprocaddress(w, "glGenerateMipmapEXT");
    }
  }

  if (cc_glglue_glext_supported(w, "GL_EXT_framebuffer_object")) {
    w->glIsRenderbuffer = (COIN_PFNGLISRENDERBUFFERPROC) cc_glglue_getprocaddress(w, "glIsRenderbufferEXT");
    w->glBindRenderbuffer = (COIN_PFNGLBINDRENDERBUFFERPROC) cc_glglue_getprocaddress(w, "glBindRenderbufferEXT");
    w->glDeleteRenderbuffers = (COIN_PFNGLDELETERENDERBUFFERSPROC)cc_glglue_getprocaddress(w, "glDeleteRenderbuffersEXT");
    w->glGenRenderbuffers = (COIN_PFNGLGENRENDERBUFFERSPROC)cc_glglue_getprocaddress(w, "glGenRenderbuffersEXT");
    w->glRenderbufferStorage = (COIN_PFNGLRENDERBUFFERSTORAGEPROC)cc_glglue_getprocaddress(w, "glRenderbufferStorageEXT");
    w->glGetRenderbufferParameteriv = (COIN_PFNGLGETRENDERBUFFERPARAMETERIVPROC)cc_glglue_getprocaddress(w, "glGetRenderbufferParameterivEXT");
    w->glIsFramebuffer = (COIN_PFNGLISFRAMEBUFFERPROC)cc_glglue_getprocaddress(w, "glIsFramebufferEXT");
    w->glBindFramebuffer = (COIN_PFNGLBINDFRAMEBUFFERPROC)cc_glglue_getprocaddress(w, "glBindFramebufferEXT");
    w->glDeleteFramebuffers = (COIN_PFNGLDELETEFRAMEBUFFERSPROC)cc_glglue_getprocaddress(w, "glDeleteFramebuffersEXT");
    w->glGenFramebuffers = (COIN_PFNGLGENFRAMEBUFFERSPROC)cc_glglue_getprocaddress(w, "glGenFramebuffersEXT");
    w->glCheckFramebufferStatus = (COIN_PFNGLCHECKFRAMEBUFFERSTATUSPROC)cc_glglue_getprocaddress(w, "glCheckFramebufferStatusEXT");
    w->glFramebufferTexture1D = (COIN_PFNGLFRAMEBUFFERTEXTURE1DPROC)cc_glglue_getprocaddress(w, "glFramebufferTexture1DEXT");
    w->glFramebufferTexture2D = (COIN_PFNGLFRAMEBUFFERTEXTURE2DPROC)cc_glglue_getprocaddress(w, "glFramebufferTexture2DEXT");
    w->glFramebufferTexture3D = (COIN_PFNGLFRAMEBUFFERTEXTURE3DPROC)cc_glglue_getprocaddress(w, "glFramebufferTexture3DEXT");
    w->glFramebufferRenderbuffer = (COIN_PFNGLFRAMEBUFFERRENDERBUFFERPROC)cc_glglue_getprocaddress(w, "glFramebufferRenderbufferEXT");
    w->glGetFramebufferAttachmentParameteriv = (COIN_PFNGLGETFRAMEBUFFERATTACHMENTPARAMETERIVPROC)
      cc_glglue_getprocaddress(w, "glGetFramebufferAttachmentParameterivEXT");

    if (!w->glIsRenderbuffer || !w->glBindRenderbuffer || !w->glDeleteRenderbuffers ||
        !w->glGenRenderbuffers || !w->glRenderbufferStorage || !w->glGetRenderbufferParameteriv ||
        !w->glIsFramebuffer || !w->glBindFramebuffer || !w->glDeleteFramebuffers ||
        !w->glGenFramebuffers || !w->glCheckFramebufferStatus || !w->glFramebufferTexture1D ||
        !w->glFramebufferTexture2D || !w->glFramebufferTexture3D || !w->glFramebufferRenderbuffer ||
        !w->glGetFramebufferAttachmentParameteriv || !w->glGenerateMipmap) {
      w->has_fbo = FALSE;
    }
    else {
      w->has_fbo = TRUE;
    }
  }

  /*
     Disable features based on known driver bugs  here.
     FIXME: move the driver workarounds to some other module. pederb, 2007-07-04
  */

  if (coin_runtime_os() == COIN_MSWINDOWS) {
    if (w->vendor_is_nvidia && w->has_fbo) {
      w->has_fbo = !glglue_has_nvidia_framebuffer_object_bug(w->version.major, w->version.minor, w->version.release);
    }
  }

  /*
     Option to disable FBO feature even if it's available.
     FIXME: FBO rendering fails in at least one application. To fix it properly
     we need to reproduce this bug in a minimal testcase. jkg, 2007-09-28
  */
  if ((glglue_resolve_envvar("COIN_DONT_USE_FBO") == 1) && w->has_fbo) {
    w->has_fbo = FALSE;
  }

}

#undef PROC

static SbBool
glglue_check_trident_clampedge_bug(const char * vendor,
                                   const char * renderer,
                                   const char * version)
{
  return
    (strcmp(vendor, "Trident") == 0) &&
    (strcmp(renderer, "Blade XP/AGP") == 0) &&
    (strcmp(version, "1.2.1") == 0);
}

static SbBool
glglue_check_ati_vbo_in_displaylist_bug(const char * vendor,
                                        const char * COIN_UNUSED_ARG(renderer),
                                        const char * COIN_UNUSED_ARG(version))
{
  /*
   * FIXME: is there a better way to test if we're on Mac OS X
   * pederb, 20051026
   */
#if !defined(HAVE_AGL) && !defined(HAVE_CGL) /* bug is not present on Mac OS X */
  /*
   * The ATI Windows/Linux driver has a nasty bug which causes a crash
   * in OpenGL whenever a VBO render call is added to a display
   * list. This has been confirmed on several ATI drivers.  (tested
   * drivers on Windows: 1.4.4145, 1.4.4054, and on Linux: 1.3.4641)
   *
   * FIXME: Check version string if ATI ever fixes this bug. The
   * scene graph below can be used to reproduce the bug:

   #Inventor V2.1 ascii

   MaterialBinding { value PER_VERTEX_INDEXED }
   LightModel { model BASE_COLOR }

   BaseColor {
     rgb [
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0,
      1 0 0, 0 1 0, 0 0 1, 1 1 0
      ]
   }
   Coordinate3 {
     point [
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0,
      0 0 0, 1 0 0, 1 1 0, 0 1 0
     ]
   }
   PointSet {
     numPoints 44
   }
   ShapeHints {
     vertexOrdering COUNTERCLOCKWISE
     faceType CONVEX
     shapeType UNKNOWN_SHAPE_TYPE
   }
   IndexedFaceSet {
     coordIndex [
       0,1,2,3,-1,
       4,5,6,7, -1,
       8,9,10,11, -1,
       12,13,14,15, -1,
       16,17,18,19,-1,
       20,21,22,23,-1,
       24,25,26,27,-1,
       28,29,30,31,-1,
       32,33,34,35,-1,
       36,37,38,39,-1,
       40,41,42,43,-1
     ]
   }
   IndexedLineSet {
     coordIndex [
       0,1,2,3,-1,
       4,5,6,7, -1,
       8,9,10,11, -1,
       12,13,14,15, -1,
       16,17,18,19,-1,
       20,21,22,23,-1,
       24,25,26,27,-1,
       28,29,30,31,-1,
       32,33,34,35,-1,
       36,37,38,39,-1,
       40,41,42,43,-1
     ]
   }
  *
  */
  return
    (strcmp(vendor, "ATI Technologies Inc.") == 0);
#else /* ATI driver bug */
  return FALSE;
#endif /* Mac OS X drivers are ok */
}

/* Give warnings on known faulty drivers. */
static void
glglue_check_driver(const char * vendor, const char * renderer,
                    const char * version)
{
#ifdef COIN_DEBUG
  /* Only spit out this in debug builds, as the bug was never properly
     confirmed. */
  if (coin_glglue_radeon_warning()) {
    if (strcmp(renderer, "Radeon 7500 DDR x86/SSE2") == 0) {
      cc_debugerror_postwarning("glglue_check_driver",
                                "We've had an unconfirmed bugreport that "
                                "this OpenGL driver ('%s') may crash upon "
                                "attempts to use 3D texturing. "
                                "We would like to get assistance to help "
                                "us debug the cause of this problem, so "
                                "please get in touch with us at "
                                "<coin-support@coin3d.org>. "
                                "This debug message can be turned off "
                                "permanently by setting the environment "
                                "variable COIN_GLGLUE_NO_RADEON_WARNING=1.",
                                renderer);

      /*
        Some additional information:

        The full driver information for the driver where this was
        reported is as follows:

        GL_VENDOR == 'ATI Technologies Inc.'
        GL_RENDERER == 'Radeon 7500 DDR x86/SSE2'
        GL_VERSION == '1.3.3302 Win2000 Release'

        The driver was reported to crash on MSWin with the
        SoGuiExamples/nodes/texture3 example. The reporter couldn't
        help us debug it, as he could a) not get a call-stack
        backtrace, and b) swapped his card for an NVidia card.

        Perhaps we should get hold of a Radeon card ourselves, to test
        and debug the problem.

        <mortene@sim.no>
      */
    }
  }
#endif /* COIN_DEBUG */

  if (coin_glglue_old_matrox_warning() &&
      (strcmp(renderer, "Matrox G400") == 0) &&
      (strcmp(version, "1.1.3 Aug 30 2001") == 0)) {
    cc_debugerror_postwarning("glglue_check_driver",
                              "This old OpenGL driver (\"%s\" \"%s\") has "
                              "known bugs, please upgrade.  "
                              "(This debug message can be turned off "
                              "permanently by setting the environment "
                              "variable COIN_GLGLUE_NO_G400_WARNING=1).",
                              renderer, version);
  }

  if (coin_glglue_old_elsa_warning() &&
      (strcmp(renderer, "ELSA TNT2 Vanta/PCI/SSE") == 0) &&
      (strcmp(version, "1.1.4 (4.06.00.266)") == 0)) {
    cc_debugerror_postwarning("glglue_check_driver",
                              "This old OpenGL driver (\"%s\" \"%s\") has "
                              "known bugs, please upgrade.  "
                              "(This debug message can be turned off "
                              "permanently by setting the environment "
                              "variable COIN_GLGLUE_NO_ELSA_WARNING=1).",
                              renderer, version);
  }

  /*
    The full driver information for the driver where this was reported
    is as follows:

    GL_VENDOR == 'Matrox Graphics Inc.'
    GL_RENDERER == 'Matrox G400'
    GL_VERSION == '1.1.3 Aug 30 2001'

    GL_VENDOR == 'ELSA AG (Aachen, Germany).'
    GL_RENDERER == 'ELSA TNT2 Vanta/PCI/SSE'
    GL_VERSION == '1.1.4 (4.06.00.266)'

    The driver was reported to crash on MSWin under following
    conditions, quoted verbatim from the problem report:

    ------8<---- [snip] -----------8<---- [snip] -----

    I observe a bit of strange behaviour on my NT4 systems. I have an
    appliction which uses the the following bit of code:

    // Define line width
    SoDrawStyle *drawStyle = new SoDrawStyle;
    drawStyle->lineWidth.setValue(3);
    drawStyle->linePattern.setValue(0x0F0F);
    root->addChild(drawStyle);

    // Define line connection
    SoCoordinate3 *coords = new SoCoordinate3;
    coords->point.setValues(0, 2, vert);
    root->addChild(coords);

    SoLineSet *lineSet = new SoLineSet ;
    lineSet->numVertices.set1Value(0, 2) ;
    root->addChild(lineSet);

    It defines a line with a dashed pattern. When the line is in a
    direction and the viewing direction is not parrallel to this line
    all works fine. In case the viewing direction is the same as the
    line direction one of my systems crashes [...]

    ------8<---- [snip] -----------8<---- [snip] -----

    <mortene@sim.no>

    UPDATE 20030116 mortene: as of this date, the most recent Matrox
    driver (version 5.86.032, from 2002-11-21) still exhibits the same
    problem, while the ELSA driver can be upgraded to a version that
    does not have the bug any more.
  */

  if (coin_glglue_sun_expert3d_warning() &&
      (strcmp(renderer, "Sun Expert3D, VIS") == 0) &&
      (strcmp(version, "1.2 Sun OpenGL 1.2.1 patch 109544-19 for Solaris") == 0)) {
    cc_debugerror_postwarning("glglue_check_driver",
                              "This OpenGL driver (\"%s\" \"%s\") has known "
                              "problems with dual screen configurations, "
                              "please upgrade.  "
                              "(This debug message can be turned off "
                              "permanently by setting the environment variable"
                              " COIN_GLGLUE_NO_SUN_EXPERT3D_WARNING=1).",
                              renderer, version);
  /*
    The full driver information for the driver where this was reported
    is as follows:

    GL_VENDOR == 'Sun Microsystems, Inc.'
    GL_RENDERER == 'Sun Expert3D, VIS'
    GL_VERSION == '1.2 Sun OpenGL 1.2.1 patch 109544-19 for Solaris'

    The driver was reported to fail when running on a Sun Solaris
    system with the XVR1000 graphics card. Quoted verbatim from the
    problem report:

    ------8<---- [snip] -----------8<---- [snip] -----

    [The client] works with two screens. One of the screen works as it
    should, while the otherone has erronious apperance (see uploaded
    image). The errors are the stripes on the texture (It should be
    one continious texture). The texture is wrapped on a rectangle
    (i.e. two large triangles). It is not only the OpenGl part of the
    window that is weired.  Some buttons are missing and other buttons
    have wrong colors++.

    ------8<---- [snip] -----------8<---- [snip] -----

    The error disappeared after a driver upgrade.

    <mortene@sim.no>
  */
  }

  if (coin_glglue_trident_warning() &&
      glglue_check_trident_clampedge_bug(vendor, renderer, version)) {
    cc_debugerror_postwarning("glglue_check_driver",
                              "This OpenGL driver (\"%s\" \"%s\" \"%s\") has "
                              "a known problem: it doesn't support the "
                              "GL_CLAMP_TO_EDGE texture wrapping mode. "
                              "(This debug message can be turned off "
                              "permanently by setting the environment variable"
                              " COIN_GLGLUE_NO_TRIDENT_WARNING=1).",
                              vendor, renderer, version);
    /*
      This problem manifests itself in the form of a glGetError()
      reporting GL_INVALID_ENUM if GL_TEXTURE_WRAP_[S|T] is attempted
      set to GL_CLAMP_TO_EDGE. GL_CLAMP_TO_EDGE was introduced with
      OpenGL v1.2.0, and the driver reports v1.2.1, so it is supposed
      to work.
    */
  }
}

static void check_force_agl()
{
#ifdef HAVE_AGL
  if (COIN_USE_AGL == -1) {
    const char * env = coin_getenv("COIN_FORCE_AGL");
    if (env) {
      COIN_USE_AGL = atoi(env);
    }
    else
#ifdef HAVE_CGL
    COIN_USE_AGL = 0;
#else
    COIN_USE_AGL = 1;
#endif
  }
#endif
}

/* We're basically using the Singleton pattern to instantiate and
   return OpenGL-glue "object structs". We're constructing one
   instance for each OpenGL context, though.  */
const cc_glglue *
cc_glglue_instance(int contextid)
{
  SbBool found;
  void * ptr;
  GLint gltmp;

  cc_glglue * gi = NULL;

  CC_SYNC_BEGIN(cc_glglue_instance);

  /* check environment variables */
  if (COIN_MAXIMUM_TEXTURE2_SIZE == 0) {
    const char * env = coin_getenv("COIN_MAXIMUM_TEXTURE2_SIZE");
    if (env) COIN_MAXIMUM_TEXTURE2_SIZE = atoi(env);
    else COIN_MAXIMUM_TEXTURE2_SIZE = -1;
  }
  if (COIN_MAXIMUM_TEXTURE3_SIZE == 0) {
    const char * env = coin_getenv("COIN_MAXIMUM_TEXTURE3_SIZE");
    if (env) COIN_MAXIMUM_TEXTURE3_SIZE = atoi(env);
    else COIN_MAXIMUM_TEXTURE3_SIZE = -1;
  }
  check_force_agl();

  if (!gldict) {  /* First invocation, do initializations. */
    gldict = cc_dict_construct(16, 0.75f);
    coin_atexit((coin_atexit_f *)glglue_cleanup, CC_ATEXIT_NORMAL);
  }

  found = cc_dict_get(gldict, (uintptr_t)contextid, &ptr);

  if (!found) {
    GLenum glerr;

    /* Internal consistency checking.

       Make it possible to disabled this assert because GLX in Mesa
       version 3.4.2 (GL_VENDOR "VA Linux Systems, Inc", GL_RENDERER
       "Mesa GLX Indirect", GL_VERSION "1.2 Mesa 3.4.2") returns NULL
       even though there really is a current context set up. (Reported
       by kintel.)
    */
    static int chk = -1;
    if (chk == -1) {
      /* Note: don't change envvar name without updating the assert
         text below. */
      chk = coin_getenv("COIN_GL_NO_CURRENT_CONTEXT_CHECK") ? 0 : 1;
    }
    if (chk) {
      const void * current_ctx = coin_gl_current_context();
      assert(current_ctx && "Must have a current GL context when instantiating cc_glglue!! (Note: if you are using an old Mesa GL version, set the environment variable COIN_GL_NO_CURRENT_CONTEXT_CHECK to get around what may be a Mesa bug.)");
    }

    /* FIXME: this is not free'd until app exit, which is bad because
       it opens a small window of possibility for errors; the value of
       id/key inputs could in principle be reused, so we'd get an old,
       invalid instance instead of creating a new one. Should rather
       hook into SoContextHandler and kill off an instance when a GL
       context is taken out. 20051104 mortene. */
    gi = (cc_glglue*)malloc(sizeof(cc_glglue));
    /* clear to set all pointers and variables to NULL or 0 */
    memset(gi, 0, sizeof(cc_glglue));
    /* FIXME: handle out-of-memory on malloc(). 20000928 mortene. */

    gi->contextid = (uint32_t) contextid;

    /* create dict that makes a quick lookup for GL extensions */
    gi->glextdict = cc_dict_construct(256, 0.75f);

    ptr = gi;
    cc_dict_put(gldict, (uintptr_t)contextid, ptr);

    /*
       Make sure all GL errors are cleared before we do our assert
       test below. The OpenGL context might be set up by the user, and
       it's better to print a warning than asserting here if the user
       did something wrong while creating it.
    */
    glerr = glGetError();
    while (glerr != GL_NO_ERROR) {
      cc_debugerror_postwarning("cc_glglue_instance",
                                "Error when setting up the GL context. This can happen if "
                                "there is no current context, or if the context has been set "
                                "up incorrectly.");
      glerr = glGetError();

      /* We might get this error if there is no current context.
         Break out and assert later in that case */
      if (glerr == GL_INVALID_OPERATION) break;
    }

    /* NB: if you are getting a crash here, it's because an attempt at
     * setting up a cc_glglue instance was made when there is no
     * current OpenGL context. */
    gi->versionstr = (const char *)glGetString(GL_VERSION);
    assert(gi->versionstr && "could not call glGetString() -- no current GL context?");
    assert(glGetError() == GL_NO_ERROR && "GL error when calling glGetString() -- no current GL context?");

    glglue_set_glVersion(gi);
    glxglue_init(gi);

    gi->vendorstr = (const char *)glGetString(GL_VENDOR);
    gi->vendor_is_SGI = strcmp((const char *)gi->vendorstr, "SGI") == 0;
    gi->vendor_is_nvidia = strcmp((const char*)gi->vendorstr, "NVIDIA Corporation") == 0;
    gi->vendor_is_intel =
      strstr((const char *)gi->vendorstr, "Tungsten") ||
      strstr((const char *)gi->vendorstr, "Intel");
    gi->vendor_is_ati = (strcmp((const char *) gi->vendorstr, "ATI Technologies Inc.") == 0);
    gi->vendor_is_3dlabs = strcmp((const char *) gi->vendorstr, "3Dlabs") == 0;

    /* FIXME: update when nVidia fixes their driver. pederb, 2004-09-01 */
    gi->nvidia_color_per_face_bug = gi->vendor_is_nvidia;
    if (gi->nvidia_color_per_face_bug) {
      const char * env = coin_getenv("COIN_NO_NVIDIA_COLOR_PER_FACE_BUG_WORKAROUND");
      if (env) gi->nvidia_color_per_face_bug = 0;
    }

    gi->rendererstr = (const char *)glGetString(GL_RENDERER);
    gi->extensionsstr = (const char *)glGetString(GL_EXTENSIONS);

    /* Randall O'Reilly reports that the above call is deprecated from OpenGL 3.0
       onwards and may, particularly on some Linux systems, return NULL.

       The recommended method is to use glGetStringi to get each string in turn.
       The following code, supplied by Randall, implements this to end up with the
       same result as the old method.
    */
    if (gi->extensionsstr == NULL) {
      COIN_PFNGLGETSTRINGIPROC glGetStringi = NULL;
      glGetStringi = (COIN_PFNGLGETSTRINGIPROC)cc_glglue_getprocaddress(gi, "glGetStringi");
      if (glGetStringi != NULL) {
        GLint num_strings = 0;
        glGetIntegerv(GL_NUM_EXTENSIONS, &num_strings);
        if (num_strings > 0) {
          int buffer_size = 1024;
          char *ext_strings_buffer = (char *)malloc(buffer_size * sizeof (char));
          int buffer_pos = 0;
          for (int i_string = 0 ; i_string < num_strings ; i_string++) {
            const char * extension_string = (char *)glGetStringi (GL_EXTENSIONS, i_string);
            int extension_string_length = (int)strlen(extension_string);
            if (buffer_pos + extension_string_length + 1 > buffer_size) {
              buffer_size += 1024;
              ext_strings_buffer = (char *)realloc(ext_strings_buffer, buffer_size * sizeof (char));
            }
            strcpy(ext_strings_buffer + buffer_pos, extension_string);
            buffer_pos += extension_string_length;
            ext_strings_buffer[buffer_pos++] = ' '; // Space separated, overwrites NULL.
          }
          ext_strings_buffer[++buffer_pos] = '\0';  // NULL terminate.
          gi->extensionsstr = ext_strings_buffer;   // Handing over ownership, don't free here.
        } else {
          cc_debugerror_postwarning ("cc_glglue_instance",
                                     "glGetIntegerv(GL_NUM_EXTENSIONS) did not return a value, "
                                     "so unable to get extensions for this GL driver, ",
                                     "version: %s, vendor: %s", gi->versionstr, gi->vendorstr);
        }
      } else {
        cc_debugerror_postwarning ("cc_glglue_instance",
                                   "glGetString(GL_EXTENSIONS) returned null, but glGetStringi "
                                   "procedure not found, so unable to get extensions for this GL driver, "
                                   "version: %s, vendor: %s", gi->versionstr, gi->vendorstr);
      }
    }

    /* read some limits */

    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &gltmp);
    gi->max_texture_size = gltmp;

    glGetIntegerv(GL_MAX_LIGHTS, &gltmp);
    gi->max_lights = (int) gltmp;

    {
      GLfloat vals[2];
      glGetFloatv(GL_POINT_SIZE_RANGE, vals);

      /* Matthias Koenig reported on coin-discuss that the OpenGL
         implementation on SGI Onyx 2 InfiniteReality returns 0 for the
         lowest pointsize, but it will still set the return value of
         glGetError() to GL_INVALID_VALUE if this size is attempted
         used. So the boundary range fix in the next line of code is a
         workaround for that OpenGL implementation bug.

         0.0f and lower values are explicitly disallowed, according to
         the OpenGL 1.3 specification, Chapter 3.3. */
      if (vals[0] <= 0.0f) {
        vals[0] = vals[1] < 1.0f ? vals[1] : 1.0f;
      }
      gi->point_size_range[0] = vals[0];
      gi->point_size_range[1] = vals[1];
    }
    {
      GLfloat vals[2];
      glGetFloatv(GL_LINE_WIDTH_RANGE, vals);

      /* Matthias Koenig reported on coin-discuss that the OpenGL
         implementation on SGI Onyx 2 InfiniteReality returns 0 for the
         lowest linewidth, but it will still set the return value of
         glGetError() to GL_INVALID_VALUE if this size is attempted
         used. This is a workaround for what looks like an OpenGL bug. */

      if (vals[0] <= 0.0f) {
        vals[0] = vals[1] < 1.0f ? vals[1] : 1.0f;
      }
      gi->line_width_range[0] = vals[0];
      gi->line_width_range[1] = vals[1];
    }

    if (coin_glglue_debug()) {
      cc_debugerror_postinfo("cc_glglue_instance",
                             "glGetString(GL_VENDOR)=='%s' (=> vendor_is_SGI==%s)",
                             gi->vendorstr,
                             gi->vendor_is_SGI ? "TRUE" : "FALSE");
      cc_debugerror_postinfo("cc_glglue_instance",
                             "glGetString(GL_RENDERER)=='%s'",
                             gi->rendererstr);
      cc_debugerror_postinfo("cc_glglue_instance",
                             "glGetString(GL_EXTENSIONS)=='%s'",
                             gi->extensionsstr);

      cc_debugerror_postinfo("cc_glglue_instance",
                             "Rendering is %sdirect.",
                             gi->glx.isdirect ? "" : "in");
    }

    /* anisotropic test */
    gi->can_do_anisotropic_filtering = FALSE;
    gi->max_anisotropy = 0.0f;
    if (cc_glglue_glext_supported(gi, "GL_EXT_texture_filter_anisotropic")) {
      gi->can_do_anisotropic_filtering = TRUE;
      glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &gi->max_anisotropy);
      if (coin_glglue_debug()) {
        cc_debugerror_postinfo("cc_glglue_instance",
                               "Anisotropic filtering: %s (%g)",
                               gi->can_do_anisotropic_filtering ? "TRUE" : "FALSE",
                               gi->max_anisotropy);
      }
    }

    /* check for ATI vbo in displaylist bug */
    gi->vbo_in_displaylist_ok = !glglue_check_ati_vbo_in_displaylist_bug(gi->vendorstr,
                                                                         gi->rendererstr,
                                                                         gi->versionstr);

    glglue_check_driver(gi->vendorstr, gi->rendererstr, gi->versionstr);

    gi->non_power_of_two_textures =
      (cc_glglue_glversion_matches_at_least(gi, 2, 1, 0) ||
       cc_glglue_glext_supported(gi, "GL_ARB_texture_non_power_of_two"));

    /* Resolve our function pointers. */
      glglue_resolve_symbols(gi);
  }
  else {
    gi = (cc_glglue *)ptr;
  }

  CC_SYNC_END(cc_glglue_instance);

  if (!found && gl_instance_created_cblist) {
    int i, n = cc_list_get_length(gl_instance_created_cblist) / 2;
    for (i = 0; i < n; i++) {
      coin_glglue_instance_created_cb * cb =
        (coin_glglue_instance_created_cb *) cc_list_get(gl_instance_created_cblist, i*2);
      cb(contextid, cc_list_get(gl_instance_created_cblist, i*2+1));
    }
  }
  return gi;
}

const cc_glglue *
cc_glglue_instance_from_context_ptr(void * ctx)
{
  /* The id can really be anything unique for the current context, but
     we should avoid a crash with the possible ids defined by
     SoGLCacheContextElement. It's a bit of a hack, this. */

  /* MSVC7 on 64-bit Windows wants this extra cast. */
  const uintptr_t cast_aid = (uintptr_t)ctx;
  /* FIXME: holy shit! This doesn't look sensible at all! (Could this
     e.g. be where the remote rendering bugs are coming from?)
     20050525 mortene.*/
  const int id = (int)cast_aid;

  return cc_glglue_instance(id);
}

void
coin_glglue_destruct(uint32_t contextid)
{
  SbBool found;
  void * ptr;
  CC_SYNC_BEGIN(cc_glglue_instance);
  if (gldict) { // might happen if a context is destructed without using the cc_glglue interface
    found = cc_dict_get(gldict, (uintptr_t)contextid, &ptr);
    if (found) {
      cc_glglue * glue = (cc_glglue*) ptr;
      if (glue->normalizationcubemap) {
        cc_glglue_glDeleteTextures(glue, 1, &glue->normalizationcubemap);
      }
      (void)cc_dict_remove(gldict, (uintptr_t)contextid);

      if (glue->dl_handle) {
        cc_dl_close(glue->dl_handle);
      }
    }
  }
  CC_SYNC_END(cc_glglue_instance);
}

SbBool
cc_glglue_isdirect(const cc_glglue * w)
{
  return w->glx.isdirect;
}


/*!
  Whether glPolygonOffset() is availble or not: either we're on OpenGL
  1.1 or the GL_EXT_polygon_offset extension is available.

  Method then available for use:
  \li cc_glglue_glPolygonOffset
*/
SbBool
cc_glglue_has_polygon_offset(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return FALSE;

  return (w->glPolygonOffset || w->glPolygonOffsetEXT) ? TRUE : FALSE;
}

/* Returns the glPolygonOffset() we're actually going to use. */
static COIN_PFNGLPOLYGONOFFSETPROC
glglue_glPolygonOffset(const cc_glglue * w)
{
  COIN_PFNGLPOLYGONOFFSETPROC poff = NULL;

  assert(w->glPolygonOffset ||  w->glPolygonOffsetEXT);

  poff = w->glPolygonOffset;

  /* Some SGI OpenGL 1.1 driver(s) seems to have a buggy
     implementation of glPolygonOffset(), according to pederb after
     some debugging he did for Fedem. These drivers'
     glPolygonOffsetEXT() actually seems to work better, so we prefer
     that if available. */
  if (w->vendor_is_SGI && w->glPolygonOffsetEXT &&
      cc_glglue_glversion_matches_at_least(w, 1, 1, 0) &&
      !cc_glglue_glversion_matches_at_least(w, 1, 2, 0)) {
    poff = w->glPolygonOffsetEXT;
  }

  /* Since we know glPolygonOffset() can be problematic, we also
     provide a way to prefer the EXT function instead through an
     environment variable "COIN_PREFER_GLPOLYGONOFFSET_EXT" (which
     could be handy for help debugging remote systems, at least). */
  if (w->glPolygonOffsetEXT && glglue_prefer_glPolygonOffsetEXT()) {
    poff = w->glPolygonOffsetEXT;
  }

  /* If glPolygonOffset() is not available (and the function pointer
     was not set by any of the bug workaround if-checks above), fall
     back on extension. */
  if (poff == NULL) { poff = w->glPolygonOffsetEXT; }

  return poff;
}

/*!
  Enable or disable z-buffer offsetting for the given primitive types.
*/
void
cc_glglue_glPolygonOffsetEnable(const cc_glglue * w,
                                SbBool enable, int m)
{
  COIN_PFNGLPOLYGONOFFSETPROC poff = glglue_glPolygonOffset(w);

  if (enable) {
    if (poff == w->glPolygonOffset) {
      if (m & cc_glglue_FILLED) glEnable(GL_POLYGON_OFFSET_FILL);
      else glDisable(GL_POLYGON_OFFSET_FILL);
      if (m & cc_glglue_LINES) glEnable(GL_POLYGON_OFFSET_LINE);
      else glDisable(GL_POLYGON_OFFSET_LINE);
      if (m & cc_glglue_POINTS) glEnable(GL_POLYGON_OFFSET_POINT);
      else glDisable(GL_POLYGON_OFFSET_POINT);
    }
    else { /* using glPolygonOffsetEXT() */
      /* The old pre-1.1 extension only supports filled polygon
         offsetting. */
      if (m & cc_glglue_FILLED) glEnable(GL_POLYGON_OFFSET_EXT);
      else glDisable(GL_POLYGON_OFFSET_EXT);

      if (coin_glglue_debug() && (m != cc_glglue_FILLED)) {
        static SbBool first = TRUE;
        if (first) {
          cc_debugerror_postwarning("cc_glglue_glPolygonOffsetEnable",
                                    "using EXT_polygon_offset, which only "
                                    "supports filled-polygon offsetting");
          first = FALSE;
        }
      }
    }
  }
  else { /* disable */
    if (poff == w->glPolygonOffset) {
      if (m & cc_glglue_FILLED) glDisable(GL_POLYGON_OFFSET_FILL);
      if (m & cc_glglue_LINES) glDisable(GL_POLYGON_OFFSET_LINE);
      if (m & cc_glglue_POINTS) glDisable(GL_POLYGON_OFFSET_POINT);
    }
    else { /* using glPolygonOffsetEXT() */
      if (m & cc_glglue_FILLED) glDisable(GL_POLYGON_OFFSET_EXT);
      /* Pre-1.1 glPolygonOffset extension only supported filled primitives.*/
    }
  }
}

void
cc_glglue_glPolygonOffset(const cc_glglue * w,
                          GLfloat factor,
                          GLfloat units)
{
  COIN_PFNGLPOLYGONOFFSETPROC poff = glglue_glPolygonOffset(w);

  if (poff == w->glPolygonOffsetEXT) {
    /* Try to detect if user actually attempted to specify a valid
       bias value, like the old glPolygonOffsetEXT() extension
       needs. If not, assume that the "units" argument was set up for
       the "real" glPolygonOffset() function, and use a default value
       that should work fairly ok under most circumstances. */
    SbBool isbias = (units > 0.0f) && (units < 0.01f);
    if (!isbias) units = 0.000001f;

    /* FIXME: shouldn't there be an attempt to convert the other way
       around too? Ie, if it *is* a "bias" value and we're using the
       "real" 1.1 glPolygonOffset() function, try to convert it into a
       valid "units" value? 20020919 mortene. */
  }

  poff(factor, units);
}

/*!
  Whether 3D texture objects are available or not: either we're on OpenGL
  1.1, or the GL_EXT_texture_object extension is available.

  Methods then available for use:

  \li cc_glglue_glGenTextures
  \li cc_glglue_glBindTexture
  \li cc_glglue_glDeleteTextures
*/
SbBool
cc_glglue_has_texture_objects(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return FALSE;

  return w->glGenTextures && w->glBindTexture && w->glDeleteTextures;
}

void
cc_glglue_glGenTextures(const cc_glglue * w, GLsizei n, GLuint * textures)
{
  assert(w->glGenTextures);
  w->glGenTextures(n, textures);

#if 0 /* debug */
  cc_debugerror_postinfo("cc_glglue_glGenTextures", "%p, size==%d, textures==%p", w, n, textures);
#endif /* debug */
}

void
cc_glglue_glBindTexture(const cc_glglue * w, GLenum target, GLuint texture)
{
  assert(w->glBindTexture);
  w->glBindTexture(target, texture);

#if 0 /* debug */
  cc_debugerror_postinfo("cc_glglue_glBindTexture", "%p, ..., %d", w, texture);
#endif /* debug */
}

void
cc_glglue_glDeleteTextures(const cc_glglue * w, GLsizei n, const GLuint * textures)
{
  assert(w->glDeleteTextures);
  w->glDeleteTextures(n, textures);

#if 0 /* debug */
  cc_debugerror_postinfo("cc_glglue_glDeleteTextures", "%p, size==%d, textures==%p", w, n, textures);
#endif /* debug */
}

/*!
  Whether sub-textures are supported: either we're on OpenGL 1.2, or
  the GL_EXT_texture3D extension is available.

  Methods then available for use:

  \li cc_glglue_glTexImage3D
  \li cc_glglue_glTexSubImage3D
  \li cc_glglue_glCopyTexSubImage3D
*/
SbBool
cc_glglue_has_texsubimage(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return FALSE;

  return w->glTexSubImage2D ? TRUE : FALSE;
}

void
cc_glglue_glTexSubImage2D(const cc_glglue * w,
                          GLenum target,
                          GLint level,
                          GLint xoffset,
                          GLint yoffset,
                          GLsizei width,
                          GLsizei height,
                          GLenum format,
                          GLenum type,
                          const GLvoid * pixels)
{
  assert(w->glTexSubImage2D);
  w->glTexSubImage2D(target, level, xoffset, yoffset,
                     width, height, format, type, pixels);
}

/*!
  Whether 3D textures are available or not: either we're on OpenGL
  1.2, or the GL_EXT_texture3D extension is available.

  Methods then available for use:

  \li cc_glglue_glTexImage3D
  \li cc_glglue_glTexSubImage3D
  \li cc_glglue_glCopyTexSubImage3D
*/
SbBool
cc_glglue_has_3d_textures(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return FALSE;

  return
    w->glTexImage3D &&
    w->glCopyTexSubImage3D &&
    w->glTexSubImage3D;
}

SbBool
cc_glglue_has_2d_proxy_textures(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return FALSE;

  // Our Proxy code seems to not be compatible with Intel drivers
  // FIXME: should be handled by SoGLDriverDatabase
  if (w->vendor_is_intel) return FALSE;

  /* FIXME: there are differences between the 1.1 proxy mechanisms and
     the GL_EXT_texture proxy extension; the 1.1 support considers
     mipmaps. I think. Check documentation in the GL spec. If that is
     correct, we can't really use them interchangeable versus each
     other like we now do in Coin code. 20030121 mortene. */
  return
    cc_glglue_glversion_matches_at_least(w, 1, 1, 0) ||
    cc_glglue_glext_supported(w, "GL_EXT_texture");
}

SbBool
cc_glglue_has_texture_edge_clamp(const cc_glglue * w)
{
  static int buggytrident = -1;

  if (!glglue_allow_newer_opengl(w)) return FALSE;

  if (buggytrident == -1) {
    buggytrident = glglue_check_trident_clampedge_bug(w->vendorstr,
                                                      w->rendererstr,
                                                      w->versionstr);
  }
  if (buggytrident) { return FALSE; }

  return
    cc_glglue_glversion_matches_at_least(w, 1, 2, 0) ||
    cc_glglue_glext_supported(w, "GL_EXT_texture_edge_clamp") ||
    cc_glglue_glext_supported(w, "GL_SGIS_texture_edge_clamp");
}

void
cc_glglue_glPushClientAttrib(const cc_glglue * w, GLbitfield mask)
{
  if (!glglue_allow_newer_opengl(w)) return;
  assert(w->glPushClientAttrib);
  w->glPushClientAttrib(mask);
}

void
cc_glglue_glPopClientAttrib(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return;
  assert(w->glPopClientAttrib);
  w->glPopClientAttrib();
}


SbBool
cc_glglue_has_multitexture(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return FALSE;
  return w->glActiveTexture != NULL;
}

int
cc_glglue_max_texture_units(const cc_glglue * w)
{
  if (!glglue_allow_newer_opengl(w)) return 1;
  return w->maxtextureunits; /* will be 1 when multitexturing is not available */
}


void
cc_glglue_glTexImage3D(const cc_glglue * w,
                       GLenum target,
                       GLint level,
                       GLenum internalformat,
                       GLsizei width,
                       GLsizei height,
                       GLsizei depth,
                       GLint border,
                       GLenum format,
                       GLenum type,
                       const GLvoid *pixels)
{
  assert(w->glTexImage3D);
  w->glTexImage3D(target, level, internalformat,
                  width, height, depth, border,
                  format, type, pixels);
}

void
cc_glglue_glTexSubImage3D(const cc_glglue * w,
                          GLenum target,
                          GLint level,
                          GLint xoffset,
                          GLint yoffset,
                          GLint zoffset,
                          GLsizei width,
                          GLsizei height,
                          GLsizei depth,
                          GLenum format,
                          GLenum type,
                          const GLvoid * pixels)
{
  assert(w->glTexSubImage3D);
  w->glTexSubImage3D(target, level, xoffset, yoffset,
                     zoffset, width, height, depth, format,
                     type, pixels);
}

void
cc_glglue_glCopyTexSubImage3D(const cc_glglue * w,
                              GLenum target,
                              GLint level,
                              GLint xoffset,
                              GLint yoffset,
                              GLint zoffset,
                              GLint x,
                              GLint y,
                              GLsizei width,
                              GLsizei height)
{
  assert(w->glCopyTexSubImage3D);
  w->glCopyTexSubImage3D(target,
                         level,
                         xoffset,
                         yoffset,
                         zoffset,
                         x,
                         y,
                         width,
                         height);
}

void
cc_glglue_glActiveTexture(const cc_glglue * w,
                          GLenum texture)
{
  assert(w->glActiveTexture);
  w->glActiveTexture(texture);
}

void
cc_glglue_glClientActiveTexture(const cc_glglue * w,
                                GLenum texture)
{
  if (!w->glClientActiveTexture && texture == GL_TEXTURE0)
    return;
  assert(w->glClientActiveTexture);
  w->glClientActiveTexture(texture);
}
void
cc_glglue_glMultiTexCoord2f(const cc_glglue * w,
                            GLenum target,
                            GLfloat s,
                            GLfloat t)
{
  assert(w->glMultiTexCoord2f);
  w->glMultiTexCoord2f(target, s, t);
}

void
cc_glglue_glMultiTexCoord2fv(const cc_glglue * w,
                             GLenum target,
                             const GLfloat * v)
{
  assert(w->glMultiTexCoord2fv);
  w->glMultiTexCoord2fv(target, v);
}

void
cc_glglue_glMultiTexCoord3fv(const cc_glglue * w,
                             GLenum target,
                             const GLfloat * v)
{
  assert(w->glMultiTexCoord3fv);
  w->glMultiTexCoord3fv(target, v);
}

void
cc_glglue_glMultiTexCoord4fv(const cc_glglue * w,
                             GLenum target,
                             const GLfloat * v)
{
  assert(w->glMultiTexCoord4fv);
  w->glMultiTexCoord4fv(target, v);
}

SbBool
cc_glue_has_texture_compression(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;

  return
    glue->glCompressedTexImage1D &&
    glue->glCompressedTexImage2D &&
    glue->glCompressedTexImage3D &&
    glue->glGetCompressedTexImage;
}

SbBool
cc_glue_has_texture_compression_2d(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glCompressedTexImage2D && glue->glGetCompressedTexImage;
}

SbBool
cc_glue_has_texture_compression_3d(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glCompressedTexImage3D && glue->glGetCompressedTexImage;
}

void
cc_glglue_glCompressedTexImage3D(const cc_glglue * glue,
                                 GLenum target,
                                 GLint level,
                                 GLenum internalformat,
                                 GLsizei width,
                                 GLsizei height,
                                 GLsizei depth,
                                 GLint border,
                                 GLsizei imageSize,
                                 const GLvoid * data)
{
  assert(glue->glCompressedTexImage3D);
  glue->glCompressedTexImage3D(target,
                               level,
                               internalformat,
                               width,
                               height,
                               depth,
                               border,
                               imageSize,
                               data);
}

void
cc_glglue_glCompressedTexImage2D(const cc_glglue * glue,
                                 GLenum target,
                                 GLint level,
                                 GLenum internalformat,
                                 GLsizei width,
                                 GLsizei height,
                                 GLint border,
                                 GLsizei imageSize,
                                 const GLvoid *data)
{
  assert(glue->glCompressedTexImage2D);
  glue->glCompressedTexImage2D(target,
                               level,
                               internalformat,
                               width,
                               height,
                               border,
                               imageSize,
                               data);
}

void
cc_glglue_glCompressedTexImage1D(const cc_glglue * glue,
                                 GLenum target,
                                 GLint level,
                                 GLenum internalformat,
                                 GLsizei width,
                                 GLint border,
                                 GLsizei imageSize,
                                 const GLvoid *data)
{
  assert(glue->glCompressedTexImage1D);
  glue->glCompressedTexImage1D(target,
                               level,
                               internalformat,
                               width,
                               border,
                               imageSize,
                               data);
}

void
cc_glglue_glCompressedTexSubImage3D(const cc_glglue * glue,
                                    GLenum target,
                                    GLint level,
                                    GLint xoffset,
                                    GLint yoffset,
                                    GLint zoffset,
                                    GLsizei width,
                                    GLsizei height,
                                    GLsizei depth,
                                    GLenum format,
                                    GLsizei imageSize,
                                    const GLvoid *data)
{
  assert(glue->glCompressedTexSubImage3D);
  glue->glCompressedTexSubImage3D(target,
                                  level,
                                  xoffset,
                                  yoffset,
                                  zoffset,
                                  width,
                                  height,
                                  depth,
                                  format,
                                  imageSize,
                                  data);
}

void
cc_glglue_glCompressedTexSubImage2D(const cc_glglue * glue,
                                    GLenum target,
                                    GLint level,
                                    GLint xoffset,
                                    GLint yoffset,
                                    GLsizei width,
                                    GLsizei height,
                                    GLenum format,
                                    GLsizei imageSize,
                                    const GLvoid *data)
{
  assert(glue->glCompressedTexSubImage2D);
  glue->glCompressedTexSubImage2D(target,
                                  level,
                                  xoffset,
                                  yoffset,
                                  width,
                                  height,
                                  format,
                                  imageSize,
                                  data);
}

void
cc_glglue_glCompressedTexSubImage1D(const cc_glglue * glue,
                                    GLenum target,
                                    GLint level,
                                    GLint xoffset,
                                    GLsizei width,
                                    GLenum format,
                                    GLsizei imageSize,
                                    const GLvoid *data)
{
  assert(glue->glCompressedTexSubImage1D);
  glue->glCompressedTexSubImage1D(target,
                                  level,
                                  xoffset,
                                  width,
                                  format,
                                  imageSize,
                                  data);
}

void
cc_glglue_glGetCompressedTexImage(const cc_glglue * glue,
                                  GLenum target,
                                  GLint level,
                                  void * img)
{
  assert(glue->glGetCompressedTexImage);
  glue->glGetCompressedTexImage(target,
                                level,
                                img);
}

SbBool
cc_glglue_has_paletted_textures(const cc_glglue * glue)
{
  static int disable = -1;
  if (disable == -1) {
    disable = glglue_resolve_envvar("COIN_GLGLUE_DISABLE_PALETTED_TEXTURE");
  }
  if (disable) { return FALSE; }

  if (!glglue_allow_newer_opengl(glue)) { return FALSE; }
  return glue->supportsPalettedTextures;
}

SbBool
cc_glglue_has_color_tables(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glColorTable != NULL;
}

SbBool
cc_glglue_has_color_subtables(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glColorSubTable != NULL;
}

void
cc_glglue_glColorTable(const cc_glglue * glue,
                       GLenum target,
                       GLenum internalFormat,
                       GLsizei width,
                       GLenum format,
                       GLenum type,
                       const GLvoid *table)
{
  assert(glue->glColorTable);
  glue->glColorTable(target,
                     internalFormat,
                     width,
                     format,
                     type,
                     table);
}

void
cc_glglue_glColorSubTable(const cc_glglue * glue,
                          GLenum target,
                          GLsizei start,
                          GLsizei count,
                          GLenum format,
                          GLenum type,
                          const GLvoid * data)
{
  assert(glue->glColorSubTable);
  glue->glColorSubTable(target,
                        start,
                        count,
                        format,
                        type,
                        data);
}

void
cc_glglue_glGetColorTable(const cc_glglue * glue,
                          GLenum target,
                          GLenum format,
                          GLenum type,
                          GLvoid *data)
{
  assert(glue->glGetColorTable);
  glue->glGetColorTable(target,
                        format,
                        type,
                        data);
}

void
cc_glglue_glGetColorTableParameteriv(const cc_glglue * glue,
                                     GLenum target,
                                     GLenum pname,
                                     GLint *params)
{
  assert(glue->glGetColorTableParameteriv);
  glue->glGetColorTableParameteriv(target,
                                   pname,
                                   params);
}

void
cc_glglue_glGetColorTableParameterfv(const cc_glglue * glue,
                                     GLenum target,
                                     GLenum pname,
                                     GLfloat *params)
{
  assert(glue->glGetColorTableParameterfv);
  glue->glGetColorTableParameterfv(target,
                                   pname,
                                   params);
}

SbBool
cc_glglue_has_blendequation(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;

  return glue->glBlendEquation || glue->glBlendEquationEXT;
}

void
cc_glglue_glBlendEquation(const cc_glglue * glue, GLenum mode)
{
  assert(glue->glBlendEquation || glue->glBlendEquationEXT);

  if (glue->glBlendEquation) glue->glBlendEquation(mode);
  else glue->glBlendEquationEXT(mode);
}

SbBool
cc_glglue_has_blendfuncseparate(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;

  return glue->glBlendFuncSeparate != NULL;
}

void
cc_glglue_glBlendFuncSeparate(const cc_glglue * glue,
                              GLenum rgbsrc, GLenum rgbdst,
                              GLenum alphasrc, GLenum alphadst)
{
  assert(glue->glBlendFuncSeparate);
  glue->glBlendFuncSeparate(rgbsrc, rgbdst, alphasrc, alphadst);
}

SbBool
cc_glglue_has_vertex_array(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glVertexPointer != NULL;
}

void
cc_glglue_glVertexPointer(const cc_glglue * glue,
                          GLint size, GLenum type, GLsizei stride, const GLvoid * pointer)
{
  assert(glue->glVertexPointer);
  glue->glVertexPointer(size, type, stride, pointer);
}

void
cc_glglue_glTexCoordPointer(const cc_glglue * glue,
                            GLint size, GLenum type,
                            GLsizei stride, const GLvoid * pointer)
{
  assert(glue->glTexCoordPointer);
  glue->glTexCoordPointer(size, type, stride, pointer);
}

void
cc_glglue_glNormalPointer(const cc_glglue * glue,
                          GLenum type, GLsizei stride, const GLvoid *pointer)
{
  assert(glue->glNormalPointer);
  glue->glNormalPointer(type, stride, pointer);
}

void
cc_glglue_glColorPointer(const cc_glglue * glue,
                         GLint size, GLenum type,
                         GLsizei stride, const GLvoid * pointer)
{
  assert(glue->glColorPointer);
  glue->glColorPointer(size, type, stride, pointer);
}

void
cc_glglue_glIndexPointer(const cc_glglue * glue,
                         GLenum type, GLsizei stride, const GLvoid * pointer)
{
  assert(glue->glIndexPointer);
  glue->glIndexPointer(type, stride, pointer);
}

void
cc_glglue_glEnableClientState(const cc_glglue * glue, GLenum array)
{
  assert(glue->glEnableClientState);
  glue->glEnableClientState(array);
}

void
cc_glglue_glDisableClientState(const cc_glglue * glue, GLenum array)
{
  assert(glue->glDisableClientState);
  glue->glDisableClientState(array);
}

void
cc_glglue_glInterleavedArrays(const cc_glglue * glue,
                              GLenum format, GLsizei stride, const GLvoid * pointer)
{
  assert(glue->glInterleavedArrays);
  glue->glInterleavedArrays(format, stride, pointer);
}

void
cc_glglue_glDrawArrays(const cc_glglue * glue,
                       GLenum mode, GLint first, GLsizei count)
{
  assert(glue->glDrawArrays);
  glue->glDrawArrays(mode, first, count);
}

void
cc_glglue_glDrawElements(const cc_glglue * glue,
                         GLenum mode, GLsizei count, GLenum type,
                         const GLvoid * indices)
{
  assert(glue->glDrawElements);
  glue->glDrawElements(mode, count, type, indices);
}

void
cc_glglue_glDrawRangeElements(const cc_glglue * glue,
                              GLenum mode, GLuint start, GLuint end, GLsizei count, GLenum type,
                              const GLvoid * indices)
{
  assert(glue->glDrawRangeElements);
  glue->glDrawRangeElements(mode, start, end, count, type, indices);
}

void
cc_glglue_glArrayElement(const cc_glglue * glue, GLint i)
{
  assert(glue->glArrayElement);
  glue->glArrayElement(i);
}

SbBool
cc_glglue_has_multidraw_vertex_arrays(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glMultiDrawArrays && glue->glMultiDrawElements;
}

void
cc_glglue_glMultiDrawArrays(const cc_glglue * glue, GLenum mode, const GLint * first,
                            const GLsizei * count, GLsizei primcount)
{
  assert(glue->glMultiDrawArrays);
  glue->glMultiDrawArrays(mode, first, count, primcount);
}

void
cc_glglue_glMultiDrawElements(const cc_glglue * glue, GLenum mode, const GLsizei * count,
                              GLenum type, const GLvoid ** indices, GLsizei primcount)
{
  assert(glue->glMultiDrawElements);
  glue->glMultiDrawElements(mode, count, type, indices, primcount);
}

SbBool
cc_glglue_has_nv_vertex_array_range(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->glVertexArrayRangeNV != NULL;
}

void
cc_glglue_glFlushVertexArrayRangeNV(const cc_glglue * glue)
{
  assert(glue->glFlushVertexArrayRangeNV);
  glue->glFlushVertexArrayRangeNV();
}

void
cc_glglue_glVertexArrayRangeNV(const cc_glglue * glue, GLsizei size, const GLvoid * pointer)
{
  assert(glue->glVertexArrayRangeNV);
  glue->glVertexArrayRangeNV(size, pointer);
}

void *
cc_glglue_glAllocateMemoryNV(const cc_glglue * glue,
                             GLsizei size, GLfloat readfreq,
                             GLfloat writefreq, GLfloat priority)
{
  assert(glue->glAllocateMemoryNV);
  return glue->glAllocateMemoryNV(size, readfreq, writefreq, priority);
}

void
cc_glglue_glFreeMemoryNV(const cc_glglue * glue, GLvoid * buffer)
{
  assert(glue->glFreeMemoryNV);
  glue->glFreeMemoryNV(buffer);
}

SbBool
cc_glglue_has_vertex_buffer_object(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;

  /* check only one function for speed. It's set to NULL when
     initializing if one of the other functions wasn't found */
  return glue->glBindBuffer != NULL;
}

void
cc_glglue_glBindBuffer(const cc_glglue * glue, GLenum target, GLuint buffer)
{
  assert(glue->glBindBuffer);
  glue->glBindBuffer(target, buffer);
}

void
cc_glglue_glDeleteBuffers(const cc_glglue * glue, GLsizei n, const GLuint *buffers)
{
  assert(glue->glDeleteBuffers);
  glue->glDeleteBuffers(n, buffers);
}

void
cc_glglue_glGenBuffers(const cc_glglue * glue, GLsizei n, GLuint *buffers)
{
  assert(glue->glGenBuffers);
  glue->glGenBuffers(n, buffers);
}

GLboolean
cc_glglue_glIsBuffer(const cc_glglue * glue, GLuint buffer)
{
  assert(glue->glIsBuffer);
  return glue->glIsBuffer(buffer);
}

void
cc_glglue_glBufferData(const cc_glglue * glue,
                       GLenum target,
                       intptr_t size, /* 64 bit on 64 bit systems */
                       const GLvoid *data,
                       GLenum usage)
{
  assert(glue->glBufferData);
  glue->glBufferData(target, size, data, usage);
}

void
cc_glglue_glBufferSubData(const cc_glglue * glue,
                          GLenum target,
                          intptr_t offset, /* 64 bit */
                          intptr_t size, /* 64 bit */
                          const GLvoid * data)
{
  assert(glue->glBufferSubData);
  glue->glBufferSubData(target, offset, size, data);
}

void
cc_glglue_glGetBufferSubData(const cc_glglue * glue,
                             GLenum target,
                             intptr_t offset, /* 64 bit */
                             intptr_t size, /* 64 bit */
                             GLvoid *data)
{
  assert(glue->glGetBufferSubData);
  glue->glGetBufferSubData(target, offset, size, data);
}

GLvoid *
cc_glglue_glMapBuffer(const cc_glglue * glue,
                      GLenum target, GLenum access)
{
  assert(glue->glMapBuffer);
  return glue->glMapBuffer(target, access);
}

GLboolean
cc_glglue_glUnmapBuffer(const cc_glglue * glue,
                        GLenum target)
{
  assert(glue->glUnmapBuffer);
  return glue->glUnmapBuffer(target);
}

void
cc_glglue_glGetBufferParameteriv(const cc_glglue * glue,
                                 GLenum target,
                                 GLenum pname,
                                 GLint * params)
{
  assert(glue->glGetBufferParameteriv);
  glue->glGetBufferParameteriv(target, pname, params);
}

void
cc_glglue_glGetBufferPointerv(const cc_glglue * glue,
                              GLenum target,
                              GLenum pname,
                              GLvoid ** params)
{
  assert(glue->glGetBufferPointerv);
  glue->glGetBufferPointerv(target, pname, params);
}


SbBool
cc_glglue_can_do_bumpmapping(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->can_do_bumpmapping;
}

SbBool
cc_glglue_can_do_sortedlayersblend(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->can_do_sortedlayersblend;
}

int
cc_glglue_get_max_lights(const cc_glglue * glue)
{
  return glue->max_lights;
}

const float *
cc_glglue_get_line_width_range(const cc_glglue * glue)
{
  return glue->line_width_range;
}

const float *
cc_glglue_get_point_size_range(const cc_glglue * glue)
{
  return glue->point_size_range;
}

/* GL_NV_register_combiners functions */
SbBool
cc_glglue_has_nv_register_combiners(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_nv_register_combiners;
}

void
cc_glglue_glCombinerParameterfvNV(const cc_glglue * glue,
                                  GLenum pname,
                                  const GLfloat *params)
{
  glue->glCombinerParameterfvNV(pname, params);
}

void
cc_glglue_glCombinerParameterivNV(const cc_glglue * glue,
                                  GLenum pname,
                                  const GLint *params)
{
  glue->glCombinerParameterivNV(pname, params);
}

void
cc_glglue_glCombinerParameterfNV(const cc_glglue * glue,
                                 GLenum pname,
                                 GLfloat param)
{
  glue->glCombinerParameterfNV(pname, param);
}

void
cc_glglue_glCombinerParameteriNV(const cc_glglue * glue,
                                 GLenum pname,
                                 GLint param)
{
  glue->glCombinerParameteriNV(pname, param);
}

void
cc_glglue_glCombinerInputNV(const cc_glglue * glue,
                            GLenum stage,
                            GLenum portion,
                            GLenum variable,
                            GLenum input,
                            GLenum mapping,
                            GLenum componentUsage)
{
  glue->glCombinerInputNV(stage, portion, variable, input, mapping, componentUsage);
}

void
cc_glglue_glCombinerOutputNV(const cc_glglue * glue,
                             GLenum stage,
                             GLenum portion,
                             GLenum abOutput,
                             GLenum cdOutput,
                             GLenum sumOutput,
                             GLenum scale,
                             GLenum bias,
                             GLboolean abDotProduct,
                             GLboolean cdDotProduct,
                             GLboolean muxSum)
{
  glue->glCombinerOutputNV(stage, portion, abOutput, cdOutput, sumOutput, scale, bias,
                           abDotProduct, cdDotProduct, muxSum);
}

void
cc_glglue_glFinalCombinerInputNV(const cc_glglue * glue,
                                 GLenum variable,
                                 GLenum input,
                                 GLenum mapping,
                                 GLenum componentUsage)
{
  glue->glFinalCombinerInputNV(variable, input, mapping, componentUsage);
}

void
cc_glglue_glGetCombinerInputParameterfvNV(const cc_glglue * glue,
                                          GLenum stage,
                                          GLenum portion,
                                          GLenum variable,
                                          GLenum pname,
                                          GLfloat *params)
{
  glue->glGetCombinerInputParameterfvNV(stage, portion, variable, pname, params);
}

void
cc_glglue_glGetCombinerInputParameterivNV(const cc_glglue * glue,
                                          GLenum stage,
                                          GLenum portion,
                                          GLenum variable,
                                          GLenum pname,
                                          GLint *params)
{
  glue->glGetCombinerInputParameterivNV(stage, portion, variable, pname, params);
}

void
cc_glglue_glGetCombinerOutputParameterfvNV(const cc_glglue * glue,
                                           GLenum stage,
                                           GLenum portion,
                                           GLenum pname,
                                           GLfloat *params)
{
  glue->glGetCombinerOutputParameterfvNV(stage, portion, pname, params);
}

void
cc_glglue_glGetCombinerOutputParameterivNV(const cc_glglue * glue,
                                           GLenum stage,
                                           GLenum portion,
                                           GLenum pname,
                                           GLint *params)
{
  glue->glGetCombinerOutputParameterivNV(stage, portion, pname, params);
}

void
cc_glglue_glGetFinalCombinerInputParameterfvNV(const cc_glglue * glue,
                                               GLenum variable,
                                               GLenum pname,
                                               GLfloat *params)
{
  glue->glGetFinalCombinerInputParameterfvNV(variable, pname, params);
}

void
cc_glglue_glGetFinalCombinerInputParameterivNV(const cc_glglue * glue,
                                               GLenum variable,
                                               GLenum pname,
                                               GLint *params)
{
  glue->glGetFinalCombinerInputParameterivNV(variable, pname, params);
}

/* ARB_shader_objects */
SbBool
cc_glglue_has_arb_shader_objects(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_arb_shader_objects;
}


/* ARB_fragment_program functions */
SbBool
cc_glglue_has_arb_fragment_program(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_arb_fragment_program;
}

void
cc_glglue_glProgramString(const cc_glglue * glue,
                          GLenum target,
                          GLenum format,
                          GLsizei len,
                          const GLvoid *string)
{
  glue->glProgramStringARB(target, format, len, string);
}

void
cc_glglue_glBindProgram(const cc_glglue * glue,
                        GLenum target,
                        GLuint program)
{
  glue->glBindProgramARB(target, program);
}

void
cc_glglue_glDeletePrograms(const cc_glglue * glue,
                           GLsizei n,
                           const GLuint *programs)
{
  glue->glDeleteProgramsARB(n, programs);
}

void
cc_glglue_glGenPrograms(const cc_glglue * glue,
                        GLsizei n,
                        GLuint *programs)
{
  glue->glGenProgramsARB(n, programs);
}

void
cc_glglue_glProgramEnvParameter4d(const cc_glglue * glue,
                                  GLenum target,
                                  GLuint index,
                                  GLdouble x,
                                  GLdouble y,
                                  GLdouble z,
                                  GLdouble w)
{
  glue->glProgramEnvParameter4dARB(target, index, x, y, z, w);
}

void
cc_glglue_glProgramEnvParameter4dv(const cc_glglue * glue,
                                   GLenum target,
                                   GLuint index,
                                   const GLdouble *params)
{
  glue->glProgramEnvParameter4dvARB(target, index, params);
}

void
cc_glglue_glProgramEnvParameter4f(const cc_glglue * glue,
                                  GLenum target,
                                  GLuint index,
                                  GLfloat x,
                                  GLfloat y,
                                  GLfloat z,
                                  GLfloat w)
{
  glue->glProgramEnvParameter4fARB(target, index, x, y, z, w);
}

void
cc_glglue_glProgramEnvParameter4fv(const cc_glglue * glue,
                                   GLenum target,
                                   GLuint index,
                                   const GLfloat *params)
{
  glue->glProgramEnvParameter4fvARB(target, index, params);
}

void
cc_glglue_glProgramLocalParameter4d(const cc_glglue * glue,
                                    GLenum target,
                                    GLuint index,
                                    GLdouble x,
                                    GLdouble y,
                                    GLdouble z,
                                    GLdouble w)
{
  glue->glProgramLocalParameter4dARB(target, index, x, y, z, w);
}

void
cc_glglue_glProgramLocalParameter4dv(const cc_glglue * glue,
                                     GLenum target,
                                     GLuint index,
                                     const GLdouble *params)
{
  glue->glProgramLocalParameter4dvARB(target, index, params);
}

void
cc_glglue_glProgramLocalParameter4f(const cc_glglue * glue,
                                    GLenum target,
                                    GLuint index,
                                    GLfloat x,
                                    GLfloat y,
                                    GLfloat z,
                                    GLfloat w)
{
  glue->glProgramLocalParameter4fARB(target, index, x, y, z, w);
}

void
cc_glglue_glProgramLocalParameter4fv(const cc_glglue * glue,
                                     GLenum target,
                                     GLuint index,
                                     const GLfloat *params)
{
  glue->glProgramLocalParameter4fvARB(target, index, params);
}

void
cc_glglue_glGetProgramEnvParameterdv(const cc_glglue * glue,
                                     GLenum target,
                                     GLuint index,
                                     GLdouble *params)
{
  glue->glGetProgramEnvParameterdvARB(target, index, params);
}

void
cc_glglue_glGetProgramEnvParameterfv(const cc_glglue * glue,
                                     GLenum target,
                                     GLuint index,
                                     GLfloat *params)
{
  glue->glGetProgramEnvParameterfvARB(target, index, params);
}

void
cc_glglue_glGetProgramLocalParameterdv(const cc_glglue * glue,
                                       GLenum target,
                                       GLuint index,
                                       GLdouble *params)
{
  glue->glGetProgramLocalParameterdvARB(target, index, params);
}

void
cc_glglue_glGetProgramLocalParameterfv(const cc_glglue * glue,
                                       GLenum target,
                                       GLuint index,
                                       GLfloat *params)
{
  glue->glGetProgramLocalParameterfvARB(target, index, params);
}

void
cc_glglue_glGetProgramiv(const cc_glglue * glue,
                         GLenum target,
                         GLenum pname,
                         GLint *params)
{
  glue->glGetProgramivARB(target, pname, params);
}

void
cc_glglue_glGetProgramString(const cc_glglue * glue,
                             GLenum target,
                             GLenum pname,
                             GLvoid *string)
{
  glue->glGetProgramStringARB(target, pname, string);
}

SbBool
cc_glglue_glIsProgram(const cc_glglue * glue,
                      GLuint program)
{
  return glue->glIsProgramARB(program);
}


/* ARB_vertex_program functions */
SbBool
cc_glglue_has_arb_vertex_program(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_arb_vertex_program;
}

/* ARB_vertex_shaders functions */
SbBool
cc_glglue_has_arb_vertex_shader(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_arb_vertex_shader;
}

void
cc_glglue_glVertexAttrib1s(const cc_glglue * glue,
                           GLuint index, GLshort x)
{
  glue->glVertexAttrib1sARB(index, x);
}

void
cc_glglue_glVertexAttrib1f(const cc_glglue * glue,
                           GLuint index, GLfloat x)
{
  glue->glVertexAttrib1fARB(index, x);
}

void
cc_glglue_glVertexAttrib1d(const cc_glglue * glue,
                           GLuint index, GLdouble x)
{
  glue->glVertexAttrib1dARB(index, x);
}

void
cc_glglue_glVertexAttrib2s(const cc_glglue * glue,
                           GLuint index, GLshort x, GLshort y)
{
  glue->glVertexAttrib2sARB(index, x, y);
}

void
cc_glglue_glVertexAttrib2f(const cc_glglue * glue,
                           GLuint index, GLfloat x, GLfloat y)
{
  glue->glVertexAttrib2fARB(index, x, y);
}

void
cc_glglue_glVertexAttrib2d(const cc_glglue * glue,
                           GLuint index, GLdouble x, GLdouble y)
{
  glue->glVertexAttrib2dARB(index, x, y);
}

void
cc_glglue_glVertexAttrib3s(const cc_glglue * glue,
                           GLuint index, GLshort x,
                           GLshort y, GLshort z)
{
  glue->glVertexAttrib3sARB(index, x, y, z);
}

void
cc_glglue_glVertexAttrib3f(const cc_glglue * glue,
                           GLuint index, GLfloat x,
                           GLfloat y, GLfloat z)
{
  glue->glVertexAttrib3fARB(index, x, y, z);
}

void
cc_glglue_glVertexAttrib3d(const cc_glglue * glue,
                           GLuint index, GLdouble x,
                           GLdouble y, GLdouble z)
{
  glue->glVertexAttrib3dARB(index, x, y, z);
}

void
cc_glglue_glVertexAttrib4s(const cc_glglue * glue,
                           GLuint index, GLshort x,
                           GLshort y, GLshort z, GLshort w)
{
  glue->glVertexAttrib4sARB(index, x, y, z, w);
}

void
cc_glglue_glVertexAttrib4f(const cc_glglue * glue,
                           GLuint index, GLfloat x,
                           GLfloat y, GLfloat z, GLfloat w)
{
  glue->glVertexAttrib4fARB(index, x, y, z, w);
}

void
cc_glglue_glVertexAttrib4d(const cc_glglue * glue,
                           GLuint index, GLdouble x,
                           GLdouble y, GLdouble z, GLdouble w)
{
  glue->glVertexAttrib4dARB(index, x, y, z, w);
}

void
cc_glglue_glVertexAttrib4Nub(const cc_glglue * glue,
                             GLuint index, GLubyte x,
                             GLubyte y, GLubyte z, GLubyte w)
{
  glue->glVertexAttrib4NubARB(index, x, y, z, w);
}

void
cc_glglue_glVertexAttrib1sv(const cc_glglue * glue,
                            GLuint index, const GLshort *v)
{
  glue->glVertexAttrib1svARB(index, v);
}

void
cc_glglue_glVertexAttrib1fv(const cc_glglue * glue,
                            GLuint index, const GLfloat *v)
{
  glue->glVertexAttrib1fvARB(index, v);
}

void
cc_glglue_glVertexAttrib1dv(const cc_glglue * glue,
                            GLuint index, const GLdouble *v)
{
  glue->glVertexAttrib1dvARB(index, v);
}

void
cc_glglue_glVertexAttrib2sv(const cc_glglue * glue,
                            GLuint index, const GLshort *v)
{
  glue->glVertexAttrib2svARB(index, v);
}

void
cc_glglue_glVertexAttrib2fv(const cc_glglue * glue,
                            GLuint index, const GLfloat *v)
{
  glue->glVertexAttrib2fvARB(index, v);
}

void
cc_glglue_glVertexAttrib2dv(const cc_glglue * glue,
                            GLuint index, const GLdouble *v)
{
  glue->glVertexAttrib2dvARB(index, v);
}

void
cc_glglue_glVertexAttrib3sv(const cc_glglue * glue,
                            GLuint index, const GLshort *v)
{
  glue->glVertexAttrib3svARB(index, v);
}

void
cc_glglue_glVertexAttrib3fv(const cc_glglue * glue,
                            GLuint index, const GLfloat *v)
{
  glue->glVertexAttrib3fvARB(index, v);
}

void
cc_glglue_glVertexAttrib3dv(const cc_glglue * glue,
                            GLuint index, const GLdouble *v)
{
  glue->glVertexAttrib3dvARB(index, v);
}

void
cc_glglue_glVertexAttrib4bv(const cc_glglue * glue,
                            GLuint index, const GLbyte *v)
{
  glue->glVertexAttrib4bvARB(index, v);
}

void
cc_glglue_glVertexAttrib4sv(const cc_glglue * glue,
                            GLuint index, const GLshort *v)
{
  glue->glVertexAttrib4svARB(index, v);
}

void
cc_glglue_glVertexAttrib4iv(const cc_glglue * glue,
                            GLuint index, const GLint *v)
{
  glue->glVertexAttrib4ivARB(index, v);
}

void
cc_glglue_glVertexAttrib4ubv(const cc_glglue * glue,
                             GLuint index, const GLubyte *v)
{
  glue->glVertexAttrib4ubvARB(index, v);
}

void
cc_glglue_glVertexAttrib4usv(const cc_glglue * glue,
                             GLuint index, const GLushort *v)
{
  glue->glVertexAttrib4usvARB(index, v);
}

void
cc_glglue_glVertexAttrib4uiv(const cc_glglue * glue,
                             GLuint index, const GLuint *v)
{
  glue->glVertexAttrib4uivARB(index, v);
}

void
cc_glglue_glVertexAttrib4fv(const cc_glglue * glue,
                            GLuint index, const GLfloat *v)
{
  glue->glVertexAttrib4fvARB(index, v);
}

void
cc_glglue_glVertexAttrib4dv(const cc_glglue * glue,
                            GLuint index, const GLdouble *v)
{
  glue->glVertexAttrib4dvARB(index, v);
}

void
cc_glglue_glVertexAttrib4Nbv(const cc_glglue * glue,
                             GLuint index, const GLbyte *v)
{
  glue->glVertexAttrib4NbvARB(index, v);
}

void
cc_glglue_glVertexAttrib4Nsv(const cc_glglue * glue,
                             GLuint index, const GLshort *v)
{
  glue->glVertexAttrib4NsvARB(index, v);
}

void
cc_glglue_glVertexAttrib4Niv(const cc_glglue * glue,
                             GLuint index, const GLint *v)
{
  glue->glVertexAttrib4NivARB(index, v);
}

void
cc_glglue_glVertexAttrib4Nubv(const cc_glglue * glue,
                              GLuint index, const GLubyte *v)
{
  glue->glVertexAttrib4NubvARB(index, v);
}

void
cc_glglue_glVertexAttrib4Nusv(const cc_glglue * glue,
                              GLuint index, const GLushort *v)
{
  glue->glVertexAttrib4NusvARB(index, v);
}

void
cc_glglue_glVertexAttrib4Nuiv(const cc_glglue * glue,
                              GLuint index, const GLuint *v)
{
  glue->glVertexAttrib4NuivARB(index, v);
}

void
cc_glglue_glVertexAttribPointer(const cc_glglue * glue,
                                GLuint index, GLint size,
                                GLenum type, GLboolean normalized,
                                GLsizei stride,
                                const GLvoid *pointer)
{
  glue->glVertexAttribPointerARB(index, size, type, normalized, stride, pointer);
}

void
cc_glglue_glEnableVertexAttribArray(const cc_glglue * glue,
                                    GLuint index)
{
  glue->glEnableVertexAttribArrayARB(index);
}

void
cc_glglue_glDisableVertexAttribArray(const cc_glglue * glue,
                                     GLuint index)
{
  glue->glDisableVertexAttribArrayARB(index);
}

void
cc_glglue_glGetVertexAttribdv(const cc_glglue * glue,
                              GLuint index, GLenum pname,
                              GLdouble *params)
{
  glue->glGetVertexAttribdvARB(index, pname, params);
}

void
cc_glglue_glGetVertexAttribfv(const cc_glglue * glue,
                              GLuint index, GLenum pname,
                              GLfloat *params)
{
  glue->glGetVertexAttribfvARB(index, pname, params);
}

void
cc_glglue_glGetVertexAttribiv(const cc_glglue * glue,
                              GLuint index, GLenum pname,
                              GLint *params)
{
  glue->glGetVertexAttribivARB(index, pname, params);
}

void
cc_glglue_glGetVertexAttribPointerv(const cc_glglue * glue,
                                    GLuint index, GLenum pname,
                                    GLvoid **pointer)
{
  glue->glGetVertexAttribPointervARB(index, pname, pointer);
}

/* GL_ARB_occlusion_query */

SbBool
cc_glglue_has_occlusion_query(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;

  /* check only one function for speed. It's set to NULL when
     initializing if one of the other functions wasn't found */
  return glue->glGenQueries != NULL;
}

void
cc_glglue_glGenQueries(const cc_glglue * glue,
                       GLsizei n, GLuint * ids)
{
  glue->glGenQueries(n, ids);
}

void
cc_glglue_glDeleteQueries(const cc_glglue * glue,
                          GLsizei n, const GLuint *ids)
{
  glue->glDeleteQueries(n, ids);
}

GLboolean
cc_glglue_glIsQuery(const cc_glglue * glue,
                    GLuint id)
{
  return glue->glIsQuery(id);
}

void
cc_glglue_glBeginQuery(const cc_glglue * glue,
                       GLenum target, GLuint id)
{
  glue->glBeginQuery(target, id);
}

void
cc_glglue_glEndQuery(const cc_glglue * glue,
                     GLenum target)
{
  glue->glEndQuery(target);
}

void
cc_glglue_glGetQueryiv(const cc_glglue * glue,
                       GLenum target, GLenum pname,
                       GLint * params)
{
  glue->glGetQueryiv(target, pname, params);
}

void
cc_glglue_glGetQueryObjectiv(const cc_glglue * glue,
                             GLuint id, GLenum pname,
                             GLint * params)
{
  glue->glGetQueryObjectiv(id, pname, params);
}

void
cc_glglue_glGetQueryObjectuiv(const cc_glglue * glue,
                              GLuint id, GLenum pname,
                              GLuint * params)
{
  glue->glGetQueryObjectuiv(id, pname, params);
}

/* GL_NV_texture_rectangle (identical to GL_EXT_texture_rectangle) */
SbBool
cc_glglue_has_nv_texture_rectangle(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_ext_texture_rectangle;
}

/* GL_EXT_texture_rectangle */
SbBool
cc_glglue_has_ext_texture_rectangle(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_ext_texture_rectangle;
}

/* GL_NV_texture_shader */
SbBool
cc_glglue_has_nv_texture_shader(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_nv_texture_shader;
}

/* GL_ARB_shadow */
SbBool
cc_glglue_has_arb_shadow(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_shadow;
}

/* GL_ARB_depth_texture */
SbBool
cc_glglue_has_arb_depth_texture(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_depth_texture;
}

/* GL_EXT_texture_env_combine || GL_ARB_texture_env_combine || OGL 1.4 */
SbBool
cc_glglue_has_texture_env_combine(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_texture_env_combine;
}

/*!
  Returns current X11 display the OpenGL context is in. If none, or if
  the glXGetCurrentDisplay() method is not available (it was
  introduced with GLX 1.3), returns \c NULL.
*/
void *
cc_glglue_glXGetCurrentDisplay(const cc_glglue * w)
{
  return w->glx.glXGetCurrentDisplay ? w->glx.glXGetCurrentDisplay() : NULL;
}

/*** Offscreen buffer handling. *********************************************/

/*
  Below is a stand-alone example that can be compiled and linked with
  the Coin library for testing that the context handling interface
  works:
 */
/*
  #include <Inventor/C/glue/gl.h>
  #include <Inventor/elements/SoGLCacheContextElement.h>
  #include <Inventor/SoDB.h>
  #include <cassert>
  #include <cstdio>

  int
  main(void)
  {
    SoDB::init();
    void * ctx = cc_glglue_context_create_offscreen(128, 128);
    assert(ctx);
    SbBool ok = cc_glglue_context_make_current(ctx);
    assert(ok);

    const GLubyte * str = glGetString(GL_VERSION);
    assert(str && "could not call glGetString() -- no current GL context?");
    assert(glGetError() == GL_NO_ERROR && "GL error when calling glGetString() -- no current GL context?");

    (void)fprintf(stdout, "glGetString(GL_VERSION)=='%s'\n", str);
    (void)fprintf(stdout, "glGetString(GL_VENDOR)=='%s'\n", glGetString(GL_VENDOR));
    (void)fprintf(stdout, "glGetString(GL_RENDERER)=='%s'\n", glGetString(GL_RENDERER));

    uint32_t contextid = SoGLCacheContextElement::getUniqueCacheContext();
    const cc_glglue * glue = cc_glglue_instance(contextid);
    (void)fprintf(stdout, "glGenTextures=='%p'\n",
                  cc_glglue_getprocaddress(glue, "glGenTextures"));

    (void)fprintf(stdout, "glGenTexturesEXT=='%p'\n",
                  cc_glglue_getprocaddress(glue, "glGenTexturesEXT"));

    cc_glglue_context_reinstate_previous(ctx);
    cc_glglue_context_destruct(ctx);
    return 0;
  }
*/

/* offscreen rendering callback handling */

void
cc_glglue_context_set_offscreen_cb_functions(cc_glglue_offscreen_cb_functions* p)
{
  offscreen_cb = p;
}

void *
cc_glglue_context_create_offscreen(unsigned int width, unsigned int height)
{
  if (offscreen_cb && offscreen_cb->create_offscreen) {
    return (*offscreen_cb->create_offscreen)(width, height);
  } else {
#ifdef HAVE_NOGL
  assert(FALSE && "unimplemented");
  return NULL;
#elif defined(HAVE_GLX)
  return glxglue_context_create_offscreen(width, height);
#elif defined(HAVE_WGL)
  return wglglue_context_create_offscreen(width, height);
#else
#if defined(HAVE_AGL)
  check_force_agl();
  if (COIN_USE_AGL > 0) return aglglue_context_create_offscreen(width, height); else
#endif
#if defined(HAVE_CGL)
  return cglglue_context_create_offscreen(width, height);
#else
#endif
#endif
  }
  assert(FALSE && "unimplemented");
  return NULL;
}

SbBool
cc_glglue_context_make_current(void * ctx)
{
  if (offscreen_cb && offscreen_cb->make_current) {
    return (*offscreen_cb->make_current)(ctx);
  } else {
#ifdef HAVE_NOGL
  assert(FALSE && "unimplemented");
  return FALSE;
#elif defined(HAVE_GLX)
  return glxglue_context_make_current(ctx);
#elif defined(HAVE_WGL)
  return wglglue_context_make_current(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) return aglglue_context_make_current(ctx); else
#endif
#if defined(HAVE_CGL)
  return cglglue_context_make_current(ctx);
#else
  ;
#endif
#endif
  }
  assert(FALSE && "unimplemented");
  return FALSE;
}

void
cc_glglue_context_reinstate_previous(void * ctx)
{
  /* FIXME: I believe two cc_glglue_context_make_current() invocations
     before invoking this function would make this function behave
     erroneously, as previous contexts are not stacked (at least not
     in the GLX implementation, which I have checked), but only the
     last context is kept track of.

     Probably needs to be fixed. Or at least we should detect and
     assert, if this is not allowed for some reason.

     20040621 mortene. */

  if (offscreen_cb && offscreen_cb->reinstate_previous) {
    (*offscreen_cb->reinstate_previous)(ctx);
  } else {
#ifdef HAVE_NOGL
  assert(FALSE && "unimplemented");
#elif defined(HAVE_GLX)
  glxglue_context_reinstate_previous(ctx);
#elif defined(HAVE_WGL)
  wglglue_context_reinstate_previous(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) aglglue_context_reinstate_previous(ctx); else
#endif
#if defined(HAVE_CGL)
  cglglue_context_reinstate_previous(ctx);
#else
  ;
#endif
#endif
  }
}

void
cc_glglue_context_destruct(void * ctx)
{
  if (offscreen_cb && offscreen_cb->destruct) {
    (*offscreen_cb->destruct)(ctx);
  } else {
#ifdef HAVE_NOGL
  assert(FALSE && "unimplemented");
#elif defined(HAVE_GLX)
  glxglue_context_destruct(ctx);
#elif defined(HAVE_WGL)
  wglglue_context_destruct(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) aglglue_context_destruct(ctx); else
#endif
#if defined(HAVE_CGL)
  cglglue_context_destruct(ctx);
#else
  ;
#endif
#endif
  }
}

/*!
  Returns the \e theoretical maximum dimensions for an offscreen
  buffer.

  Note that we're still not guaranteed that allocation of this size
  will succeed, as that is also subject to e.g. memory constraints,
  which is something that will dynamically change during the running
  time of an application.

  So the values returned from this function should be taken as hints,
  and client code of cc_glglue_context_create_offscreen() and
  cc_glglue_context_make_current() should re-request offscreen
  contexts with lower dimensions if any of those fails.
*/
void
cc_glglue_context_max_dimensions(unsigned int * width, unsigned int * height)
{
  void * ctx;
  SbBool ok;
  const char * vendor;
  GLint size[2];
  static SbBool cached = FALSE;
  static unsigned int dim[2] = { 0, 0 };

    *width = dim[0];
    *height = dim[1];

  if (cached) { /* value cached */ return; }

  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("cc_glglue_context_max_dimensions",
                           "query by making a dummy offscreen context");
  }

  cached = TRUE; /* Flip flag on first run. Note: it doesn't matter
                    that the detection below might fail -- as we
                    should report <0,0> on consecutive runs. */

  /* The below calls *can* fail, due to e.g. lack of resources, or no
     usable visual for the GL context. We try to handle gracefully.
     This is straightforward to do here, simply returning dimensions
     of <0,0>, but note that we also need to handle the exception in
     the callers. */

  ctx = cc_glglue_context_create_offscreen(32, 32);
  if (!ctx) { return; }
  ok = cc_glglue_context_make_current(ctx);
  if (!ok) { cc_glglue_context_destruct(ctx); return; }

  glGetIntegerv(GL_MAX_VIEWPORT_DIMS, size);
  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("cc_glglue_context_max_dimensions",
                           "GL_MAX_VIEWPORT_DIMS==<%d, %d>",
                           size[0], size[1]);
  }

  vendor = (const char *)glGetString(GL_VENDOR);
  if (strcmp(vendor, "NVIDIA Corporation") == 0) {

    /* NVIDIA seems to have a bug where max render size is limited
       by desktop resolution (at least for their Linux X11
       drivers), not the texture maxsize returned by OpenGL. So we
       use a workaround by limiting max size to the lowend
       resolution for desktop monitors.

       According to pederb, there are versions of the NVidia
       drivers where the offscreen buffer also has to have
       dimensions that are 2^x, so we limit further down to these
       dimension settings to be sure.
    */

    /* FIXME: should make a stand-alone test-case (not dependent
       on Coin, only GL, GLX & X11) that demonstrates this problem
       for a) submitting to <linux-bugs@nvidia.com>, and b) to
       test which versions of the NVidia drivers are affected --
       as it is now, we shrink the max to <512,512> on all
       versions (even if we're under MSWin). 20030812 mortene.
    */

    /* UPDATE 20050712 mortene: this clamping should no longer be
       necessary, as we now re-request a new, lower size for offscreen
       buffers from SoOffscreenRenderer (i.e. the values returned from
       this function is considered just a hint).

       I'm keeping the code comments and the commented out code below,
       in case there have been issues with NVidia drivers hidden by
       this clamping, which will surface now...

       Eventually, this special case check should be removed, though.
    */
/*     size[0] = cc_min(size[0], 512); */
/*     size[1] = cc_min(size[1], 512); */
  }

  *width = (unsigned int) size[0];
  *height = (unsigned int) size[1];

  /* Check additional limits from pbuffer capabilities: */
  {
    /* will be filled with max-width, max-height and max-pixels: */
    unsigned int pbufmax[3];
    /* query functions below should return TRUE if implemented, and
       the current offscreen buffer is a pbuffer: */
    SbBool ok = FALSE;
#if defined(HAVE_WGL)
    ok = wglglue_context_pbuffer_max(ctx, pbufmax);
#elif defined(HAVE_GLX)
    ok = glxglue_context_pbuffer_max(ctx, pbufmax);
#elif defined(HAVE_AGL) || defined(HAVE_CGL)
    /* FIXME: implement check on max pbuffer width, height and number
       of pixels for AGL/CGL, if any such limits are imposed there.
       20040713 mortene. */
#endif
    if (ok) {
      int modulo = 0;

      if (coin_glglue_debug()) {
        cc_debugerror_postinfo("cc_glglue_context_max_dimensions",
                               "pbuffer max dimensions, "
                               "width==%u, height==%u, pixels==%u",
                               pbufmax[0], pbufmax[1], pbufmax[2]);
      }

      *width = cc_min(*width, pbufmax[0]);
      *height = cc_min(*height, pbufmax[1]);

      while ((*width * *height) > pbufmax[2]) {
        if (modulo % 2) { *width /= 2; }
        else { *height /= 2; }
        modulo++;
      }
    }
  }

  cc_glglue_context_reinstate_previous(ctx);
  cc_glglue_context_destruct(ctx);

  /* Force an additional limit to the maximum tilesize to 4096x4096
     pixels.

     This is done to work around a problem with some OpenGL drivers: a
     huge value is returned for the maximum offscreen OpenGL canvas,
     where the driver obviously does not take into account the amount
     of memory needed to actually allocate such a large buffer.

     This problem has at least been observed with the MS Windows XP
     software OpenGL renderer, which reports a maximum viewport size
     of 16k x 16k pixels.

     FIXME: we really shouldn't f*ck around with this here, but rather
     make the client code of this more robust. That means
     SoOffscreenRenderer should try with successively smaller buffers
     of allocation if the maximum (or wanted) buffer size fails. For
     further discussion, see the FIXME at the top of the
     SoOffscreenRendererP::renderFromBase() method. 20040714 mortene.

     UPDATE 20050712 mortene: this has now been fixed in
     SoOffscreenRenderer -- it will try with sucessively smaller
     sizes. I'm still keeping the max clamping below, though, to avoid
     unexpected problems with external applications, as we're
     currently between patch-level releases with Coin-2, and I have
     only limited time right now for testing that removing this would
     not cause badness.
  */
  *width = cc_min(*width, 4096);
  *height = cc_min(*height, 4096);

  if (coin_glglue_debug()) {
    cc_debugerror_postinfo("cc_glglue_context_max_dimensions",
                           "clamped max dimensions==<%u, %u>",
                           *width, *height);
  }

  /* cache values for next invocation */

  dim[0] = *width;
  dim[1] = *height;
}

SbBool
cc_glglue_context_can_render_to_texture(void * COIN_UNUSED_ARG(ctx))
{
  /* No render-to-texture support in external offscreen rendering. */
  if (offscreen_cb) return FALSE;

#if defined(HAVE_GLX) || defined(HAVE_NOGL)
  return FALSE;
#elif defined(HAVE_WGL)
  return wglglue_context_can_render_to_texture(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) return aglglue_context_can_render_to_texture(ctx); else
#endif
#if defined(HAVE_CGL)
  return cglglue_context_can_render_to_texture(ctx);
#else
  ;
#endif
#endif
}


void
cc_glglue_context_bind_pbuffer(void * COIN_UNUSED_ARG(ctx))
{
  /* No render-to-texture support in external offscreen rendering. */
  if (offscreen_cb) return;

#if defined(HAVE_GLX) || defined(HAVE_NOGL)
  /* FIXME: Implement for GLX.  The problem is that in GLX, there is
     no way to bind a PBuffer as a texture (i.e. there is no
     equivalent to the aglTexImagePBuffer() and wglBindTexImageARB()
     calls).  kyrah 20031123. */
  assert(FALSE && "unimplemented");
#elif defined(HAVE_WGL)
  wglglue_context_bind_pbuffer(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) aglglue_context_bind_pbuffer(ctx); else
#endif
#if defined(HAVE_CGL)
  cglglue_context_bind_pbuffer(ctx);
#else
  ;
#endif
#endif
}

void
cc_glglue_context_release_pbuffer(void * COIN_UNUSED_ARG(ctx))
{
  /* No render-to-texture support in external offscreen rendering. */
  if (offscreen_cb) return;

#if defined(HAVE_GLX) || defined(HAVE_NOGL)
  /* FIXME: Implement for GLX. kyrah 20031123. */
  assert(FALSE && "unimplemented");
#elif defined(HAVE_WGL)
  wglglue_context_release_pbuffer(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) aglglue_context_release_pbuffer(ctx); else
#endif
#if defined(HAVE_CGL)
  cglglue_context_release_pbuffer(ctx);
#else
  ;
#endif
#endif
}

SbBool
cc_glglue_context_pbuffer_is_bound(void * COIN_UNUSED_ARG(ctx))
{
  /* No render-to-texture support in external offscreen rendering. */
  if (offscreen_cb) return FALSE;

#if defined(HAVE_GLX) || defined(HAVE_NOGL)
  /* FIXME: Implement for GLX. kyrah 20031123. */
  assert(FALSE && "unimplemented");
  return FALSE;
#elif defined(HAVE_WGL)
  return wglglue_context_pbuffer_is_bound(ctx);
#else
#if defined(HAVE_AGL)
  if (COIN_USE_AGL > 0) return aglglue_context_pbuffer_is_bound(ctx); else
#endif
#if defined(HAVE_CGL)
  return cglglue_context_pbuffer_is_bound(ctx);
#else
  return false;
#endif
#endif
}

/* This abomination is needed to support SoOffscreenRenderer::getDC(). */
const void *
cc_glglue_win32_HDC(void * COIN_UNUSED_ARG(ctx))
{
#if defined(HAVE_WGL)
  return wglglue_context_win32_HDC(ctx);
#else /* not WGL */
  return NULL;
#endif /* not WGL */
}
void cc_glglue_win32_updateHDCBitmap(void * COIN_UNUSED_ARG(ctx))
{
#if defined(HAVE_WGL)
  wglglue_copy_to_bitmap_win32_HDC(ctx);
#endif /* not WGL */
}

/*** </Offscreen buffer handling.> ******************************************/

/*** <PROXY texture handling> ***********************************************/

static int
compute_log(int value)
{
  int i = 0;
  while (value > 1) { value>>=1; i++; }
  return i;
}

/*  proxy mipmap creation */
static SbBool
proxy_mipmap_2d(int width, int height,
                GLenum internalFormat,
                GLenum format,
                GLenum type,
                SbBool mipmap)
{
  GLint w;
  int level;
  int levels = compute_log(cc_max(width, height));

  glTexImage2D(GL_PROXY_TEXTURE_2D, 0, internalFormat, width, height, 0,
               format, type, NULL);
  glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0,
                           GL_TEXTURE_WIDTH, &w);

  if (w == 0) return FALSE;
  if (!mipmap) return TRUE;

  for (level = 1; level <= levels; level++) {
    if (width > 1) width >>= 1;
    if (height > 1) height >>= 1;
    glTexImage2D(GL_PROXY_TEXTURE_2D, level, internalFormat, width,
                 height, 0, format, type,
                 NULL);
    glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0,
                             GL_TEXTURE_WIDTH, &w);
    if (w == 0) return FALSE;
  }
  return TRUE;
}

/* proxy mipmap creation. 3D version. */
static SbBool
proxy_mipmap_3d(const cc_glglue * glw, int width, int height, int depth,
                GLenum internalFormat,
                GLenum format,
                GLenum type,
                SbBool mipmap)
{
  GLint w;
  int level;
  int levels = compute_log(cc_max(cc_max(width, height), depth));

  cc_glglue_glTexImage3D(glw, GL_PROXY_TEXTURE_3D, 0, internalFormat,
                         width, height, depth, 0, format, type,
                         NULL);
  glGetTexLevelParameteriv(GL_PROXY_TEXTURE_3D, 0,
                           GL_TEXTURE_WIDTH, &w);
  if (w == 0) return FALSE;
  if (!mipmap) return TRUE;

  for (level = 1; level <= levels; level++) {
    if (width > 1) width >>= 1;
    if (height > 1) height >>= 1;
    if (depth > 1) depth >>= 1;
    cc_glglue_glTexImage3D(glw, GL_PROXY_TEXTURE_3D, level, internalFormat,
                           width, height, depth, 0, format, type,
                           NULL);
    glGetTexLevelParameteriv(GL_PROXY_TEXTURE_3D, 0,
                             GL_TEXTURE_WIDTH, &w);
    if (w == 0) return FALSE;
  }
  return TRUE;
}

SbBool
cc_glglue_is_texture_size_legal(const cc_glglue * glw,
                                int xsize, int ysize, int zsize,
                                int bytespertexel, SbBool mipmap)
{
  GLenum internalformat;
  GLenum format;
  GLenum type = GL_UNSIGNED_BYTE;

  switch (bytespertexel) {
  default:
  case 1:
    format = internalformat = GL_LUMINANCE;
    break;
  case 2:
    format = internalformat = GL_LUMINANCE_ALPHA;
    break;
  case 3:
    format = internalformat = GL_RGB8;
    break;
  case 4:
    format = internalformat = GL_RGBA8;
    break;
  }

  return coin_glglue_is_texture_size_legal(glw, xsize, ysize, zsize,
                                           internalformat, format, type, mipmap);
}

/*!
  Note that the \e internalformat parameter corresponds to the \e
  internalFormat parameter to glTexImage2D; either the number of
  components per texel or a constant specifying the internal texture format.
 */
SbBool
coin_glglue_is_texture_size_legal(const cc_glglue * glw,
                                  int xsize, int ysize, int zsize,
                                  GLenum internalformat,
                                  GLenum format,
                                  GLenum type,
                                  SbBool mipmap)
 {
  if (zsize == 0) { /* 2D textures */
    if (COIN_MAXIMUM_TEXTURE2_SIZE > 0) {
      if (xsize > COIN_MAXIMUM_TEXTURE2_SIZE) return FALSE;
      if (ysize > COIN_MAXIMUM_TEXTURE2_SIZE) return FALSE;
      return TRUE;
    }
    if (cc_glglue_has_2d_proxy_textures(glw)) {
      return proxy_mipmap_2d(xsize, ysize, internalformat, format, type, mipmap);
    }
    else {
      if (xsize > glw->max_texture_size) return FALSE;
      if (ysize > glw->max_texture_size) return FALSE;
      return TRUE;
    }
  }
  else { /*  3D textures */
    if (cc_glglue_has_3d_textures(glw)) {
      if (COIN_MAXIMUM_TEXTURE3_SIZE > 0) {
        if (xsize > COIN_MAXIMUM_TEXTURE3_SIZE) return FALSE;
        if (ysize > COIN_MAXIMUM_TEXTURE3_SIZE) return FALSE;
        if (zsize > COIN_MAXIMUM_TEXTURE3_SIZE) return FALSE;
        return TRUE;
      }
      return proxy_mipmap_3d(glw, xsize, ysize, zsize, internalformat, format, type, mipmap);
    }
    else {
#if COIN_DEBUG
      static SbBool first = TRUE;
      if (first) {
        cc_debugerror_post("glglue_is_texture_size_legal",
                           "3D not supported with this OpenGL driver");
        first = FALSE;
      }
#endif /*  COIN_DEBUG */
      return FALSE;
    }
  }
}

/*
  Convert from num components to internal texture format for use
  in glTexImage*D's internalFormat parameter.
*/
GLint coin_glglue_get_internal_texture_format(const cc_glglue * glw,
                                              int numcomponents,
                                              SbBool compress)
{
  GLenum format;
  if (compress) {
    switch (numcomponents) {
    case 1:
      format = GL_COMPRESSED_LUMINANCE_ARB;
      break;
    case 2:
      format = GL_COMPRESSED_LUMINANCE_ALPHA_ARB;
      break;
    case 3:
      format = GL_COMPRESSED_RGB_ARB;
      break;
    case 4:
    default:
      format = GL_COMPRESSED_RGBA_ARB;
      break;
    }
  }
  else {
    SbBool usenewenums = glglue_allow_newer_opengl(glw) && cc_glglue_glversion_matches_at_least(glw,1,1,0);
    switch (numcomponents) {
    case 1:
      format = usenewenums ? GL_LUMINANCE8 : GL_LUMINANCE;
      break;
    case 2:
      format = usenewenums ? GL_LUMINANCE8_ALPHA8 : GL_LUMINANCE_ALPHA;
      break;
    case 3:
      format = usenewenums ? GL_RGB8 : GL_RGB;
      break;
    case 4:
    default:
      format = usenewenums ? GL_RGBA8 : GL_RGBA;
      break;
    }
  }
  return format;
}

/*
  Convert from num components to client texture format for use
  in glTexImage*D's format parameter.
*/
GLenum coin_glglue_get_texture_format(const cc_glglue * COIN_UNUSED_ARG(glw), int numcomponents)
{
  GLenum format;
  switch (numcomponents) {
  case 1:
    format = GL_LUMINANCE;
    break;
  case 2:
    format = GL_LUMINANCE_ALPHA;
    break;
  case 3:
    format = GL_RGB;
    break;
  case 4:
  default:
    format = GL_RGBA;
    break;
  }
  return format;
}

/*** </PROXY texture handling> ***********************************************/

/*** <Anisotropic filtering> *************************************************/

float cc_glglue_get_max_anisotropy(const cc_glglue * glue)
{
  return glue->max_anisotropy;
}

SbBool
cc_glglue_can_do_anisotropic_filtering(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->can_do_anisotropic_filtering;
}

/*** </Anisotropic filtering> *************************************************/

/* Convert an OpenGL enum error code to a textual representation. */
const char *
coin_glerror_string(GLenum errorcode)
{
  static const char INVALID_VALUE[] = "GL_INVALID_VALUE";
  static const char INVALID_ENUM[] = "GL_INVALID_ENUM";
  static const char INVALID_OPERATION[] = "GL_INVALID_OPERATION";
  static const char STACK_OVERFLOW[] = "GL_STACK_OVERFLOW";
  static const char STACK_UNDERFLOW[] = "GL_STACK_UNDERFLOW";
  static const char OUT_OF_MEMORY[] = "GL_OUT_OF_MEMORY";
  static const char unknown[] = "Unknown OpenGL error";

  switch (errorcode) {
  case GL_INVALID_VALUE:
    return INVALID_VALUE;
  case GL_INVALID_ENUM:
    return INVALID_ENUM;
  case GL_INVALID_OPERATION:
    return INVALID_OPERATION;
  case GL_STACK_OVERFLOW:
    return STACK_OVERFLOW;
  case GL_STACK_UNDERFLOW:
    return STACK_UNDERFLOW;
  case GL_OUT_OF_MEMORY:
    return OUT_OF_MEMORY;
  default:
    return unknown;
  }
  return NULL; /* avoid compiler warning */
}

/* Simple utility function for dumping the current set of error codes
   returned from glGetError(). Returns number of errors reported by
   OpenGL. */

unsigned int
coin_catch_gl_errors(cc_string * str)
{
  unsigned int errs = 0;
  GLenum glerr = glGetError();
  while (glerr != GL_NO_ERROR) {
    if (errs < 10) {
      if (errs > 0) {
        cc_string_append_char(str, ' ');
      }
      cc_string_append_text(str, coin_glerror_string(glerr));
    }
    /* ignore > 10, so we don't run into a situation were we end up
       practically locking up the app due to vast amounts of errors */
    else if (errs == 10) {
      cc_string_append_text(str, "... and more");
    }

    errs++;
    glerr = glGetError();
  }
  return errs;
}

/* ********************************************************************** */

void *
coin_gl_current_context(void)
{
  void * ctx = NULL;

#ifdef HAVE_GLX
  ctx = glXGetCurrentContext();
#endif /* HAVE_GLX */

#ifdef HAVE_WGL
  ctx = wglGetCurrentContext();
#endif /* HAVE_WGL */

#if defined(HAVE_AGL) || defined(HAVE_CGL)
  /* Note: We cannot use aglGetCurrentContext() here, since that only
     returns a value != NULL if the context has been set using
     aglSetCurrentContext(). */
  ctx = CGLGetCurrentContext();
#endif

  return ctx;
}

/* ********************************************************************** */

SbBool
coin_glglue_vbo_in_displaylist_supported(const cc_glglue * glw)
{
  return glw->vbo_in_displaylist_ok;
}

/* ********************************************************************** */

SbBool
coin_glglue_non_power_of_two_textures(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;

  // ATi and Intel both seem to have problems with this feature,
  // especially on old drivers. Disable for everything except nVidia
  // until we can build a better driver database
  if (!glue->vendor_is_nvidia) return FALSE;
  return glue->non_power_of_two_textures;
}

/* ********************************************************************** */

uint32_t
coin_glglue_get_contextid(const cc_glglue * glue)
{
  return glue->contextid;
}

/* ********************************************************************** */

static void cleanup_instance_created_list(void)
{
  cc_list_destruct(gl_instance_created_cblist);
  gl_instance_created_cblist = NULL;
}

void
coin_glglue_add_instance_created_callback(coin_glglue_instance_created_cb * cb,
                                          void * closure)
{
  if (gl_instance_created_cblist == NULL) {
    gl_instance_created_cblist = cc_list_construct();
    coin_atexit((coin_atexit_f *)cleanup_instance_created_list, CC_ATEXIT_NORMAL);
  }
  cc_list_append(gl_instance_created_cblist, (void*)cb);
  cc_list_append(gl_instance_created_cblist, (void*)closure);
}

/* ********************************************************************** */

void
cc_glglue_glIsRenderbuffer(const cc_glglue * glue, GLuint renderbuffer)
{
  assert(glue->has_fbo);
  glue->glIsRenderbuffer(renderbuffer);
}

void
cc_glglue_glBindRenderbuffer(const cc_glglue * glue, GLenum target, GLuint renderbuffer)
{
  assert(glue->has_fbo);
  glue->glBindRenderbuffer(target, renderbuffer);
}

void
cc_glglue_glDeleteRenderbuffers(const cc_glglue * glue, GLsizei n, const GLuint *renderbuffers)
{
  assert(glue->has_fbo);
  glue->glDeleteRenderbuffers(n, renderbuffers);
}

void
cc_glglue_glGenRenderbuffers(const cc_glglue * glue, GLsizei n, GLuint *renderbuffers)
{
  assert(glue->has_fbo);
  glue->glGenRenderbuffers(n, renderbuffers);
}

void
cc_glglue_glRenderbufferStorage(const cc_glglue * glue, GLenum target, GLenum internalformat, GLsizei width, GLsizei height)
{
  assert(glue->has_fbo);
  glue->glRenderbufferStorage(target, internalformat, width, height);
}

void
cc_glglue_glGetRenderbufferParameteriv(const cc_glglue * glue, GLenum target, GLenum pname, GLint * params)
{
  assert(glue->has_fbo);
  glue->glGetRenderbufferParameteriv(target, pname, params);
}

GLboolean
cc_glglue_glIsFramebuffer(const cc_glglue * glue, GLuint framebuffer)
{
  assert(glue->has_fbo);
  return glue->glIsFramebuffer(framebuffer);
}

void
cc_glglue_glBindFramebuffer(const cc_glglue * glue, GLenum target, GLuint framebuffer)
{
  assert(glue->has_fbo);
  glue->glBindFramebuffer(target, framebuffer);
}

void
cc_glglue_glDeleteFramebuffers(const cc_glglue * glue, GLsizei n, const GLuint * framebuffers)
{
  assert(glue->has_fbo);
  glue->glDeleteFramebuffers(n, framebuffers);
}

void
cc_glglue_glGenFramebuffers(const cc_glglue * glue, GLsizei n, GLuint * framebuffers)
{
  assert(glue->has_fbo);
  glue->glGenFramebuffers(n, framebuffers);
}

GLenum
cc_glglue_glCheckFramebufferStatus(const cc_glglue * glue, GLenum target)
{
  assert(glue->has_fbo);
  return glue->glCheckFramebufferStatus(target);
}

void
cc_glglue_glFramebufferTexture1D(const cc_glglue * glue, GLenum target, GLenum attachment, GLenum textarget, GLuint texture, GLint level)
{
  assert(glue->has_fbo);
  glue->glFramebufferTexture1D(target, attachment, textarget, texture, level);
}

void
cc_glglue_glFramebufferTexture2D(const cc_glglue * glue, GLenum target, GLenum attachment, GLenum textarget, GLuint texture, GLint level)
{
  assert(glue->has_fbo);
  glue->glFramebufferTexture2D(target, attachment, textarget, texture, level);
}

void
cc_glglue_glFramebufferTexture3D(const cc_glglue * glue, GLenum target, GLenum attachment, GLenum textarget, GLuint texture, GLint level, GLint zoffset)
{
  assert(glue->has_fbo);
  glue->glFramebufferTexture3D(target, attachment, textarget, texture, level,zoffset);
}

void
cc_glglue_glFramebufferRenderbuffer(const cc_glglue * glue, GLenum target, GLenum attachment, GLenum renderbuffertarget, GLuint renderbuffer)
{
  assert(glue->has_fbo);
  glue->glFramebufferRenderbuffer(target, attachment, renderbuffertarget, renderbuffer);
}

void
cc_glglue_glGetFramebufferAttachmentParameteriv(const cc_glglue * glue, GLenum target, GLenum attachment, GLenum pname, GLint * params)
{
  assert(glue->has_fbo);
  glue->glGetFramebufferAttachmentParameteriv(target, attachment, pname, params);
}

SbBool
coin_glglue_has_generate_mipmap(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  // ATi's handling of this function is very buggy. It's possible to
  // work around these quirks, but we just disable it for now since we
  // have other ways to generate mipmaps. Only disable on Windows. The
  // OS X and Linux drivers are probably ok.
  if ((coin_runtime_os() == COIN_MSWINDOWS) && glue->vendor_is_ati) {
    return FALSE;
  }
  return (glue->glGenerateMipmap != NULL);
}

void
cc_glglue_glGenerateMipmap(const cc_glglue * glue, GLenum target)
{
  glue->glGenerateMipmap(target);
}

SbBool
cc_glglue_has_framebuffer_objects(const cc_glglue * glue)
{
  if (!glglue_allow_newer_opengl(glue)) return FALSE;
  return glue->has_fbo;
}

/* ********************************************************************** */

#ifdef __cplusplus
} /* extern "C" */
#endif /* __cplusplus */