Some clarification for episode 12

[Warbo]

Hi, I like the podcast, but I found a few of the points raised in episode 12 were a bit misleading. I'll try to add the limited knowledge I have garnered from the Internet here, and I hope it's useful.

Firstly, XGL and AIGLX are OpenGL accelerated X servers. They don't offer any fancy eyecandy, and you can run your regular GNOME or KDE in them and you won't notice any difference (although I have found video playback is terrible on XGL with the proprietary nvidia driver, even in regular GNOME/KDE). The fancy eyecandy (like the wobbly windows) is done by the window/compositing manager Compiz. Compiz is used to replace the current window manager (Metacity is the default for GNOME and Kwin is the default for KDE), but as well as managing the windows, it also manages the Composite functions of the X server (in AIGLX these need to be enabled like on a normal Xorg, but they are built into XGL with no explicit enabling needed). Composite has obviously been around for about a year (I originally switched to Ubuntu from Debian since the Breezy preview had beta packages available for KDE 3.5 [which comes with kcompmgr]) and offers translucency and shadows. Compiz manages these functions as well as the windows, since moving (and wobbling) windows and switching desktops (on a cube) obviously needs control over the window manager. Compiz requires an OpenGL accelerated X server, but it doesn't care if that is XGL or AIGLX. Since Compiz works on both, and it is Compiz which deals with the effects, AIGLX and XGL have exactly the same eyecandy effects.

I think the main confusion about them offering different features is out-dated, since XGL and Compiz were developed heavily behind closed doors (which is fine, since Novell don't have to release the source if they don't give anyone the software) and work well together. AIGLX was (is?) RedHat's effort, and they did it in a more communal way. Since AIGLX needs a compositing window manager as well, and Compiz hadn't been released yet, they made an unstable branch of Metacity called Luminocity. Luminocity implemented the basic translucency/shadows that xcompmgr et al already had, but also used wobbly windows and other effects like Compiz has. When XGL and Compiz were released Luminocity was abandoned because Compiz could just be ported to AIGLX instead (and it has been). Therefore the feature differences are actually differences between Luminocity and Compiz (there is obviously a difference because Luminocity was discontinued and all work has been on Compiz, since that is what both "sides" use)

Secondly, to me there is not a divide between Free Software graphics drivers and 3D graphics card drivers. My Radeon 9200 works perfectly out of the box with the Free Software 3D driver and I have never had to jump through the same hoops that I had to with my Nvidia card. The big problem with ATI cards is the lack of knowledge about the DRI drivers, because in the past everyone tried to use the proprietary driver. Since ATI have broken support for their older cards (which are the only ones with Free Software 3D drivers) many people are left without 3D. Most seem to be trying older versions of the driver, but I have managed to steer a few to DRI (I hang out in #ubuntu a lot). The tools which do not support this driver are currently the dpkg-reconfigure xserver-xorg system, and the automagic xorg.conf regeneration when switching a hard drive between ATI/Nvidia systems (I assume this also works for changing graphics card in a single system). It would be great to let more people know that Free 3D drivers exist for cards like the Radeon 9200, and there is a page with a how-to at help.ubuntu.com/community/RadeonDriver (which I wrote). [Note: When I say 3D driver, that is all I mean. Alpha/translucency is still handled by Mesa for the 9200 at least. This makes Compiz really slow, and even xcompmgr can get annoying with too many fades occuring at once]

Finally I would like to say that I have tried Compiz (in AIGLX and XGL, on ATI and Nvidia) and I don't think it is configurable enough for me to use day to day. Exactly as was mentioned, the wow-factor wears off quickly, and I just find myself with what is essentially a version of Metacity which is stuck with a Clearlooks theme. Even Metacity allows basic theming support (if only for the graphics) and I find myself craving E16 again. The first time I tried Compiz I was put off by the rotating cube, since it only allowed 4 desktops, and when I tried it recently I could use more than 4, but they all had to be in a horizontal line. I think Compiz is a nice experiment, but I don't see it as a sensible window manager until it gets the basics of window managing right. Developers and code contributors are obviously more interested in adding new 3D effects, but there is a band of users who think that running feature-lacking, unstable (very, in my experience), experimental software on their desktop is perfectly normal. This is obviously OK as it is their choice, but they clog support channels (a specialist #ubuntu-xgl IRC channel exists, but nobody seems to use it) and try to encourage others into their fold. Since edge-flipping the desktop "cube" (actually a prism these days) doesn't work very well with brightside I would have to say that the only useful feature Compiz offers is zoom, but X has a basic version of this no matter what window manager is being used.

Don't take these clarifications in the wrong way, I just feel that with such a large audience some unintended rumours and myths may start to spread (like AIGLX not offering the same eyecandy as XGL, or that 2D drivers can run a 3D desktop at anything approaching usable speed)

[curuxz]

Don't take these clarifications in the wrong way, I just feel that with such a large audience some unintended rumours and myths may start to spread (like AIGLX not offering the same eyecandy as XGL, or that 2D drivers can run a 3D desktop at anything approaching usable speed)


Hi, thanks as always go to listeners to who take time to feedback on the show its always welcome. Hoever I cant really see the need for your clarification since you pretty much agree with what I said, my point about AIGLX being in Edgy was that the Nvidia or FireGL drivers would not and as you quite rightly point out without the 3d drives you wont be able to run it at a usable speed.

This is why I was questioning the diffrence between the 2 systems because if AIGLX is anything like comp/XGL then it will need a deal from ATI and Nvidia over drives if ubuntu wants it to work out the box.

Thanks

Btw if anyone wishes to direct comments to me about the Kubuntu show, please feel free to email james@ubuntuos.com or im on Skype under the name Curuxz.

James - Kubuntu Podcast

[Warbo]

I think the problem with including XGL/AIGLX is that they need some special feature of the video drivers, which means XGL works on the Free and non-Free ones but AIGLX only works on the Free ones (I think it is to do with applying high-resolution textures to 3D objects, which is used to make the windows 3D). AIGLX seems to be the better imlementation, since it is just extra modules for Xorg, but without Nvidia and ATI building the features it needs into their drivers anyone using fglrx or nvidia drivers is forced to use XGL (the less elegant one). The problem with the Free drivers is that there are only a few accelerated 3D ones (like for the Radeon 9200) and pretty much none for recent cards.

Personally I will stick to Enlightenment 0.16.8 with Xorg's regular Composite extensions for the time being. It would be really great to create a kind of invisible 3D window manager which lets other window managers run inside it, so then Compiz-type 3D effects can be applied to any window manager (I know Novell got a bit of flak for combining XGL's features into a window manager, since Composite is window manager independent, but they said that it was the only feasable way of doing it)

Just to clarify a little more, my main points were: 1) XGL and AIGLX both offer exactly the same eyecandy, because both run Compiz, 2) There are Free Software drivers out there which offer 3D support, they just aren't widely known and 3) I don't find Compiz stable enough or usable enough to run regularly (especially not by default), since it's cube restricts the virtual desktops which can be used, and edge flipping desktops (like with Brightside) makes it screw up.

[sal]

thanks for writing in to help out with the clarifactations. i should have stated about compiz, i already knew about it being needed but failed to mention it because when speeking of aiglx/xgl most people overlook compiz as the window manager and just label it aiglx or xgl as a whole.

but you are right i should have made referance to it none the less. my mistake and on the next cast i will be sure to point out my error becasue you are right, it could be misleading to the beginer.

thansk for the comment,
sal c.

[3rdalbum]

Warby, you raise some very good points.

I still haven't outgrown the Compiz effects, but what I *have* outgrown is its instability.

It crashes, it frigs up, it hides windows without being told to; yet every time I download a new CVS version I find that they've added a new effect!

For instance, the right-hand corner now moves your windows up past the top of the screen or down past the bottom, so you can see the desktop. Moving your mouse back to the bottom-right corner moves the windows back. But if you open a window while your current windows are retracted, then the new window will retract when the others un-retract!

Compiz needs stability and compatibility; not silly new effects that don't work properly.

[sharperguy]

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