Delivered-To: garrigue at math.nagoya-u.ac.jp
Delivered-To: lablgtk at yquem.inria.fr
From: Florent Monnier <fmonnier at linux-nantes.fr.eu.org>
To: lablgtk at yquem.inria.fr
Subject: Re: [Lablgtk] lablGL and GLX extentions?
Date: Mon, 26 Jan 2009 20:07:39 +0100
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Cc: Erik de Castro Lopo <erikd at mega-nerd.com>


> > I am under the impression that I need glXBindTexImageEXT,
> > glXReleaseTexImageEXT and maybe some others.
>
> Ha I see, these functions don't appear in the base manual (I only read the
> manual until now), it is an extension :
> http://people.freedesktop.org/~davidr/GLX_EXT_texture_from_pixmap.txt

in fact the right url is this one:
http://www.opengl.org/registry/specs/EXT/texture_from_pixmap.txt
(but there aren't real differences)

> I guess it provides an optimisation or usefull additional options, because
> the script "pixmap_to_gl.ml" already works, but doing real-time this way
> would perhaps be too slow.

this thread continued off-list, but maybe other people could be interested,
That's it I have wrapped the GLX extension "GLX_EXT_texture_from_pixmap"
it is a very ALPHA / experimental version which will have to be polished
and tested.
it's there: http://www.linux-nantes.org/~fmonnier/OCaml/Xlib/

I have noticed differences between running Mesa or the NV-drivers,
for example these 2 demos (in the tarball):

./texture_from_pixmap.sh  # uses the extension "GLX_EXT_texture_from_pixmap"
# this one works fine with Mesa but not with the NV-drivers
(this one is the C version rewritten in ocaml, from here:
http://cgit.freedesktop.org/mesa/mesa/tree/progs/xdemos/texture_from_pixmap.c
and in ocaml:
http://www.linux-nantes.org/~fmonnier/OCaml/Xlib/tmp/texture_from_pixmap.ml.html
)

./glxdemo.sh
# this one works with my NV-drivers but not with Mesa

I switch between NV-drivers and Mesa this way:
export LD_LIBRARY_PATH=/tmp/Mesa-7.3/lib  # where mesa lib is available
export LD_LIBRARY_PATH=""
______________

My 3D desktop under KDE for changing in 3D the desktop and for moving soft 
windows works just fine (and needs hardware acceleration) so as I do not have 
the extension 'GLX_EXT_texture_from_pixmap' I think that it is not absolutly 
needed. The classic method that you can see in the other demo 
./pixmap_to_gl.sh works fine with both Mesa and the closed-drivers. So I 
guess if you wish to use the extension you will still have to put the 2 
methods and test if the extension is there to know which method to use.

Also the GLX module is opengl-bindings agnostic, the examples I have done use 
glMLite, but it should work the same with the 2 other ocaml opengl-bindings.
(And the sed script glMLite_to_LablGL.sed.sh may help a little to convert.)

have fun!
Florent

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