Re: X11Drv: move WGL extension code

[Lionel Ulmer]

On Fri, Sep 01, 2006 at 01:57:24PM +0200, Roderick Colenbrander wrote:
> The way WGL extensions are loaded is different. The old code correctly
> advertised the names of available WGL extensions but the wglGetProcAddress
> code didn't work correctly. Even if an extension wasn't advertised you could
> get a function pointer to the functions. On Windows wglGetProcAddress would
> return NULL.

Note that (as far as I know), 'wglGetProcAddress' returns NULL on
non-existant extensions for all extensions, whether they are GL or WGL ones.

This means that our implementation of it is broken (at least on DRI / Mesa)
as 'glXGetProcAddress' may return a non-NULL value when querying a
non-supported extension.

So if we really want to be windows-like, we would need to add a 'function
name / extension name' database and check if the extension corresponding to
the function is present before actually calling 'glXGetProcAddress'.

But as I ever only once got a bug report linked to that, I never took the
pain to fix it :-)

  Lionel (catching up his old mails)

PS: I guess that this 'database' may be automatically build by the
'make_opengl' script though so it should not be that hard to do :-)

-- 
 Lionel Ulmer - http://www.bbrox.org/

Re: X11Drv: move WGL extension code

[Alexandre Julliard]

"Roderick Colenbrander" <[EMAIL PROTECTED]> writes:

> The patch adds new WGL extension loading code based on code written
> by an old opengl32 -> x11drv patch written by Tomas Carnacky. The
> code properly advertises WGL extensions and only returns function
> pointers when the extension is really available.

It would be nicer to declare the extensions as constant variables
instead of building everything at run time. Something like:

static const struct wglextension swap_control =
{
  "WGL_EXT_swap_control",
  {
{ "wglSwapIntervalEXT", X11DRV_wglSwapIntervalEXT },
{ "wglGetSwapIntervalEXT", X11DRV_wglGetSwapIntervalEXT },
  }
};

static void load_extensions(void)
{
if (glxRequireExtension("GLX_SGI_swap_control"))
register_extension( &swap_control );
... etc.
}

Then the extension list can simply store a pointer instead of copying
the whole thing once more, and you avoid a lot of nasty macros.

-- 
Alexandre Julliard
[EMAIL PROTECTED]