[Xcb] Re: XCB/AIGLX Matchbox/GTK

Jeremy A. Kolb jkolb at brandeis.edu
Thu Nov 2 15:08:23 PST 2006

Hi Guillaume,

Yes I saw your question on the xcb list.

Basically all of the GLX proto stuff has been done and the transport 
mechanism the vendor and render requests is taken care of using XCB.  If 
you have a look at indirect.c (I think it's in Mesa/src/x11/glx or 
something like that, I don't have the source in front of me) you'll see a 
bunch of #define USE_XCB blocks (Just grep through the Mesa code and 
you'll find these).  This file is autogenerated by some python scripts 
(glX_proto.py).  This takes care of all of most of the indirect rendering 
stubs.  There are a lot of mesa calls that don't use XCB yet.  If you grep 
for USE_XCB again you'll be able to see which files have stuff in them... 
look at what's there and use that as a guide.

The general strategy here is to fill in like so:

#ifdef USE_XCB
Use XCB's glx code.
Use the default Xlib code.

There are two things to note:

1.  There is no plan for a pure XCB backend.  This was discussed and the 
decision was that it was a waste of time since libX11 now uses XCB 
internally and it would be a difficult job to do.  (Though if you want to 
do it then go for it!  Look at the Xlib software renderer for details).

2.  It is possible to use Mesa with XCB now.  Simply set up your program 
using XCB's version of GLX (create your context, find your visual etc.) 
and then simple use OpenGL calls like you normally would and this should 
work fine.

If you have any questions let me know.


 On Thu, 2 Nov 2006, Guillaume FORTAINE wrote:

> Hello Mr Kolb,
>  Let me introduce myself : Guillaume FORTAINE, French Engineer in 
> Informatics .I would want to build a start up to sell mobile phones ( OEM 
> level ). I am currently in discussion with investors.
> I had a discussion with Josh Triplett who told me this :
> Adding OpenGL functionality to Matchbox would depend on what kinds of things
> you want to add.  This task would require finishing up the Mesa port to XCB
> (unless you want to port some other software implementation of GL to XCB), and
> for a time estimate on that, I'd suggest asking Jeremy Kolb, who actively
> develops and maintains that port.  Meanwhile, adding various OpenGL effects to
> Matchbox would require minimal time for anyone experienced in the use of
> OpenGL.
> Any idea ?
> We look forward to your answer,
> Best Regards,
> 		Guillaume

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