Can DRI and compositing desktop coexist? (FreeNode: #xorg)

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<justin_lee> when DRI is enabled, can we also see the compositing desktop effect?
 i've heard that DRI will cause the X clients to draw directly into the frambuffer
 which means the drawings will appear immediatly on the screen
 <http://hoegsberg.blogspot.com/2007/08/redirected-direct-rendering.html>
<jcristau> that's fixed with dri2.
<justin_lee> jcristau: but DRI2 is not widely supported, isn't it
 jcristau: i mean so far
<jcristau> well yeah. it's pretty new code.
<justin_lee> jcristau: not really understand why we should define the DRI standard
 jcristau: I suspect that Mac OS X and Vista don't need DRI
 jcristau: but why we need it in Xorg... hmmm... strange....
<jcristau> you don't make any sense.
<justin_lee> jcristau: sorry just a newbie here
 jcristau: i don't
 jcristau: just want to know more...
 because use of DRI2 needs hardware support
 that would be a difficulty to make it popular
<jcristau> not more so than dri
 what it needs is driver support.
<justin_lee> jcristau: only driver?
 jcristau: not hardware change needed?
<jcristau> no
<justin_lee> that sounds a good point
 jcristau: thanks for the education

How to implement so called 'network transparency' when DRI is enabled? (FreeNode: #freedesktop)

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<justin_lee> ...just a DRI newbie here
 according to http://en.wikipedia.org/wiki/Direct_Rendering_Infrastructure
 Direct Rendering Infrastructure (DRI) is an interface and a free software implementation used in the X Window System 
 to securely allow user applications to access the video hardware without requiring data to be passed (slowly) through the X server
 notice that "without requiring data to be passed (slowly) through the X server"
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<justin_lee> just curious...
 how to implement so called 'network transparency' when DRI is enabled
<Robot101> you can't use direct rendering over the network
 you have to use indirect GLX
<justin_lee> but...
<Robot101> GLX is an X protocol extension for sending 3D instructions to the server
<justin_lee> so... GLX can pass data without X server...?
<Robot101> no, it goes through the X server
 it's much much slower than DRI
<justin_lee> and can i use AIGLX?
<Robot101> if you have AIGLX (accelerated, indirect GLX) then your X server itself can use DRI to draw the 3D stuff, but the fact it has to go from the client to the server before it goes to the hardware kills the performance
 indirect means the X server does it, direct means the client does it
 you can only do direct rendering when the client is running on the same machine as the hardware, and has access to the kernel's drm devices in /dev/drm
 sorry, /dev/dri
<justin_lee> so AIGLX over nework should faster than GLX over network?
 will that sound good....
<Robot101> AIGLX is the only way to make GLX work on the server in Xorg - if you don't have it then mesa (the glx library) will fall back to software rendering, and the client will do it all and send pixmaps to the server, which will be hella slow...
 at least, I think
 I might be wrong, the server might do software rendering if there's no AIGLX, but it'll still be slow
<justin_lee> it sounds good at least the network transparency is preserved
 so that i can use XDMCP to connect the remote desktop
<Robot101> yes, network tranparency will continue to work, it'll just be really slow (if it's doing software rendering) or pretty slow (if it's doing AIGLX)
<justin_lee> and... network tranparency work under DRI2?
 because DRI seems not to support compositing desktop
 such as Compiz fusion etc...
<Robot101> doesn't matter, the network transparency is done at the X level, not the DRI level
 I think if you use a compositor and don't have DRI, it will be unusably slow
 if it works at all, in fact
 Robot101 robtaylor
 Robot101 robtaylor
<justin_lee> Robot101: excuse me, are you really a bot?
<Robot101> what do you think?
<justin_lee> well not likely, a bot should not be able to give such a excellent answer
 Robot101: thank you very much
<Robot101> correct! :)
 you've passed today's turing test
<justin_lee> Robot101: it's very helpful in order to give me a clear concept :)
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 Robot101 robtaylor
<Robot101> just got some info from a friend: in the case of GLX and there's no DRI support on the server, then the server will usually use Mesa to do software rendering
<justin_lee> Robot101: well, that will be painfully slow
 Robot101: have a good day and thanks again :-)
<Robot101> the difference between DRI and GLX will already cause you a lot of pain
<justin_lee> yep, and it gets me headache