[Mesa3d-dev] Re: recent changes to Xgl

Matthias Hopf mhopf at suse.de
Tue Jun 14 10:27:49 PDT 2005

Just a sidenote:

> > The Xgl displatch table needs to default to passing these calls onto
> > libGL unless it is a remote call and the table has been overwritten
> > with the GLX versions. I don't think you initially filled the dispatch
> > table with the libGL version of the calls so you are just getting the
> > default table of noop implementations. You have to dlopen(libGL) and
> > get the symbols explicitly otherwise you'll get the Xgl versions.
> > 
> We shouldn't have to dlopen libGL. However, we could do that if we found
> it useful.

We definitively will have to use dlopen for libGL in the future, if Xglx
should work with older libGLs. I guess it is not needed if this is not
a requirement.

Short explanation: in former times you had to look up function pointers
with glProcAddressARB(), while in newer standards (1.4 AFAIR) the
function pointer is called glProcAddress(), and the ARB variant is no
longer allowed to exist! At least the prototypes have vanished, I doubt
the function entry in the libraries will vanish soon (to remain
backwards compatible), but that could change...

I don't exactly understand what the ARB drove to nuke the ARB function
prototype. It really made portable programming a lot more difficult.


Matthias Hopf <mhopf at suse.de>       __        __   __
Maxfeldstr. 5 / 90409 Nuernberg    (_   | |  (_   |__         mat at mshopf.de
Phone +49-911-74053-715            __)  |_|  __)  |__  labs   www.mshopf.de

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