With the eventual release of Windows Vista and its rumored new 3D graphical desktop capabilities putting it beyond what is presently available for Macintoshes and GNU/Linux, I was left wondering whether any such thing was planned for Linux and when such capabilities would be released.

After a bit of searching I came across Xgl, it is an X server which is layered on top of OpenGL and because of this, it can accelerate drawing operations on the desktop. Xgl takes advantage of the processing power available in modern graphics cards by using their OpenGL drivers to hardware accelerate X, OpenGL and Xvideo applications. In general terms, think of the processing which is put into rendering frames in 3D games and then using that capability to render the humble desktop. What this means is that you get noticeably fast rendering anti-aliased fonts and can perform intricate graphical calculations far faster than other X servers without OpenGL.

What this means for day to day usage is that when a window is moved around, you can set it up so that the window animates while moving. You can also change window transparencies on the fly, say for example I was writing a report in OO and wanted to briefly check the score for a football match, I can just increase the transparency of the present window allowing me to view the window beneath. Note that this transparency is not application specific, it is due to Xgl's graphic rendering capabilities that this is possible.

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High Resolution Video

A handy feature which will be a boon to those with poor eyesight or those who visit sites which display content using different font sizes is the zoom function. Presently, you either have to increase the font sizes using your browser's control or downgrade to a lower resolution or worst case install larger fonts. With an Xgl enabled desktop one has the ability to zoom into a particular section while leaving the rest of the X session at the normal resolution and zoom.

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Perhaps the most talked about feature of an Xgl enabled desktop is the desktop cube. Most people can visualize the virtual desktop available in most OS's (yes even Windows XP has this), the cube is just an extension of this. Instead of having a row of icons from which you select which desktop you want to go to, with a Xgl enabled X-Sever, you can "drag" the next desktop onto the screen. This dragging action is not just restricted to one direction, but in all directions. I know it doesn't sound like much, other than more eye candy to eat up system resources, but personally I like it. Please note that the videos uploaded with this article may show jerky motion, but in reality, the motion is smooth.

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High Resolution Video of Outer Cube

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High Resolution Video of Inner Cube

At the moment, Xgl must be used together with a compositor/window manager in order to exhibit all of its capabilities. The presently available compositor utility, which was developed in conjunction with Xgl is Compiz. Compiz runs on top of the DE and provides the fancy animations i.e. transparency, cube, zoom etc. At the time of writing Xgl/Compiz works quite well with Gnome and XFCE. According to KDE web site, KDE support is still under development and should be ready soon.

Some of you may be wondering what kind of system will be required to run this? Well, I tried it on 3 different computers by means of the Kororaa live cd (see below). Their relevant specs are as follows -

System 1(Desktop):     AMD Athlon XP 1800
                                   512 MB DDR RAM
                                   32 MB GeForce 2 Integrated graphics

System 2 (Laptop):      Intel Mobile Pentium 4 3.2 GHz HT
                                   512 MB DDR RAM (Dual Channel)
                                   64 MB Mobility Radeon 9700 Pro graphics

System 3 (Desktop):    AMD Athlon 64 3000
                                   1024 MB DDR RAM (Dual Channel)
                                   128 MB Radeon X300 PCI-E graphics

Yes, the Radeon's do run with 3D support with fglrx drivers, glxgears gives ~500 fps for the 9700 Pro, ~350fps for the X300 in full screen at a resolution of 1024x768 and ~55 fps for the GeForce 2. See here for a list of supported and unsupported cards. I also tried it on a workhorse Pentium 3 733 computer, sadly as I expected, Kororaa didn't load as the i810 graphics chip that the computer uses isn't supported.

As I mentioned before, Xgl is quite a memory hog. At any given instant, it is using ~50MB of RAM and while creating the flash videos uploaded with this article, the vast majority of swap space available on my hard drive was swallowed up (A first for me since I have been running on 2.6 kernels). On system's 2 and 3, the fancy animations were smooth and rendered perfectly, however on system 1, there was a slight lag in rendering the animations which became more pronounced as videos were created and as more applications were loaded up. No doubt this was due to the combination of using a live cd and outdated graphics chipset. Since I have a policy of not messing with my system too much during semester, I can't say for sure how these computers will perform had Xgl been natively installed i.e. not running off a live cd.

I am guessing that you may be wondering how you can also try this, or which distro has this kind of features enabled. There are a few distros which have Xgl either in their upcoming releases or in their package repositories. Below are the distros which either have Xgl in their repositories or will have an upcoming release which supports this:

    * Fedora Core 5, Fedora doesn't use Xgl per se, rather it uses AIGLX which provides the same functionality. The reason behind this was that during a part of the development time for Xgl, it was closed source in order to get it ready quickly. You can read more about it here

    * SUSE 10.1, due to be released April 13th 2006. You can install Xgl on prior versions of SUSE, for more info see this page

    * Gentoo, Xgl is available in Portage's masked packages, see the Gentoo Wiki for more info.

    * Arch Linux has it available in its repositories. See here for more info.

    * Mandriva presently doesn't support Xgl, however they have provided this howto to get it running.

    * Ubuntu is rumored to provide it in its next update Dapper Drake

For those of you still undecided about whether to upgrade to Xgl, I suggest you try out a live cd by the name of Kororaa. Kororaa is a Gentoo based live cd compiled for i686 class machines, it comes with Gnome, Firefox and some media players, most importantly it comes with Xgl enabled. I experienced some problems running Kororaa on the AMD 64 system, due to the X300 card and the ati drivers present on the cd. I experienced random lockups during use, this issue can be fixed by using the latest fglrx drivers, or by waiting for the next release of the Kororaa live cd.

Some people may be thinking, what is the use of all this, I mean it is just more eye candy which will eat up precious system resources. That may be true, but looking to the future it is easily seen that an increasing number of OS's will move to a more 3D like platform, so if there was a unified 2D/3D rendering engine there will be a smaller codebase from which the graphical system is controlled. It also removes all driver-dependent code from the X server itself, and allows for accelerated Compose and Render operations which are needed for transparent windows to be independent of the graphics driver.

In conclusion, Xgl is an exciting technology, it still needs some work to be done mainly to do with non nvidia/ati graphics cards and extending support to a wider variety of graphics chipsets. I for one will wait a bit longer (until the holidays) before attempting to install it onto my computer, perhaps by then more animations/plugins will be made available and support for other DE's would be available.