Pretty soon it should be pretty easy to get all these fancy special effects running.
AIGLX is now part of X.org by default (I think). It provides all the OpenGL acceleration you need to get compiz working and get all those fancy special effects.
I find it's easier to understand what is going on when you can understand the definitions of terms related to X. X is a pretty complex animal and it has all sorts of weird conventions and names that don't realy make sense to most of us PC users.
For instance X server vs X client seems a bit odd. X server is always local to your machine (unless your running VNC). It sort of 'serves' out your input and output to 'X clients' which are applications, typically.
For related definitions:
X Windows = It's actually a network protocol. Think of it like HTTP. The web pages are like 'X clients' that have their output displayed on your machine. The 'X server' is like your web browser. Most of the time it's only used locally though in a fasion that makes it act like a typical Windows or MacOS GUI display. Typically the network is only local operating on fast local sockets (so no TCP/IP overhead). Remote access is usually dispabled by default for security reasons although Linux users will often use OpenSSH's X support to run remote X apps safely and securely.
X Server = the item responsable for displaying windows and widgets and such on your desktop. Controls the display, controls your input devices also. Without anything running on it it will just display a ugly gray screen with a ugly X cursor.
X Clients = applications that display output on the X server. Your file manager, firefox, window manger, panel, openoffice.org, quake3 are examples of 'X clients' They can be ran from a remote computer on your network or on local machine as is typical for Windows or OS X. (although currently only local apps can get OpenGL acceleration)
Window Manager = a application that controls windows and provides basic functionality. It's what draws borders around windows, provides open/close/minimize buttons. It provides the ability to switch focus from window to window. Some Window managers provide basic desktop functionality like a menu that pops up when you click on the background or a simple dock like what is used in Fluxbox.
Desktop Environment = A collection of applications (window managers, file managers, office productivity tools, media playback, themes, small games, applets, etc etc) that are designed to provide a complete desktop system that people need typically to do their work or expect to have on a computer. Gnome and KDE are the big ones, but other ones include XFCE, Enlightenment (although they call themselves a 'shell', not a 'DE'), and WindowMaker/GNUstep environment.
Also they provide development tools and API's for application development.
For instance Gnome provides:
Gnome Office, which is mainly Abiword word proccessor and Gnumeric spreedsheet applicaiton.
Metacity window manager
Nautilus file manager
Totem media player
Gnome games (solitare for instance.. has many dozens of variations on the game)
Epiphany web browser
Evolution email and group-ware client
Tomboy note taking application
C programming APIs and proccess communication features. Python bindings, C# bindings.
Then there are numerious 'Gnome' add-ons to increase functionality of the Desktop. Stuff like Beagle desktop search or the Deskbar applet for consolidating different searches (beagle desktop search, address bar/send mail, tomboy notes, web server, dictionary search, etc)
Xrender = extension for X to allow more effective 2d acceleration and effects.
XAA = 2d acceleration drivers for X.
EXA = New 2D acceleration drivers that fixes XAA's issues and makes Xrender work more effectively.
GLX = extension for X originally created by SGI to allow OpenGL acceleration on X windows.
Mesa = Standard open source OpenGL protocol stack. OpenGL is a programming API that is designed to be accelerated, but not nessicarially so. Mesa provides the basic libraries and such needed to do OpenGL applications on Linux and many other operating systems. Although vendors such as Nvidia will provide their own propriatory OpenGL stack as is typical for operationg systems like Linux or Windows.
DRI = Direct Rendering Infrastructure. This is X's solution to provide OpenGL acceleration for video cards. Based off of Mesa they take what portions of OpenGL they can and program them to be performed on the video card instead of the central CPU.
DRM = Direct Rendering Manager. It's the Linux kernel level driver to allow applications to access the Video card for opengl acceleration.
Direct Rendering = The name for how DRI allows applications to seize control over their own display output so that they can get good 3d acceleration.
Indirect Rendering = Fallback for applications that can't get direct rendering for whatever reason (no drivers, incorrect setup, programming error, remote application, etc). Currrently this is very slow as it runs completely in software.
Composition = How the new fancy effects are able to be done. Compisition happens with OS X's Aqua, with Vista's Areo effects, and with X's 'XGL' effects. How it basicly works is that instead of rendering windows directly to your screen they are rendered in a off screen buffer which each window exists in it's own little world. Then you use a display manager or 'compositor' to layer these windows together so that you create your desktop. SO it's kinda like you render everything off screen, take a snapshot of it, and paint the contents to a 2d rectangle which you can then manage in different fancy ways and get it going all fast with 3d acceleration.
XGLX = What Novell calls 'XGL'. It's their X server that is full OpenGL driven. Runs on top of a regular X server. It's what you see in the videos mostly. This can be confusing because with Xorg's own lingo XGL may mean the 'XGL core' and they call Novell's XGL XGLX to try to avoid confusion.
AIGLX = Developed originally by Redhat. It's OpenGL extensions to the existing X server. It's suppose to allow for acceleration of indirect rendering which should be very cool. (but it won't be as fast as direct rendering still) It's now incorporated into Xorg's official releases, which is somethign that is probably never going to happen with XGLX.
XeGL = Possible 'next generation' X server from X.org. There are currently limitations in the OpenGL API that restricts it from being able to be used fully for a complete display solution. Since it was designed to provide application programming interface it lacks some stuff like being able to control the display resolution directly or to control lower level aspects of input things. So current opengl X servers need the legacy 2d-only X server to run with in order to perform those things.
A company called Kronos developed the OpenGL-ES, which is extensions to OpenGL that provides a stripped down opengl environment specificly designed for embedded device programming. As part of that they developed the basis for 'EGL' which allows for managing the display using OpenGL.. as was needed in a embedded programming since there was no other display management system.
http://www.khronos.org/egl/
X.org folks would like to have drivers support and get EGL into the standard OpenGL spec so that they can use EGL to move to a pure OpenGL environment.
XGL = The 'core' of the OpenGL stuff from X.org. It is being tweaked and developed by people working on XGLX and AIGLX.
Very recently Kronos has aquired the ability to control the future directions of OpenGL API specifications from the ARB. ARB is the 'Architecture Review Board' is a consortium of various corporations and groups interested in OpenGL development. These include Apple, SGI, 3DLabs, Dell, Nvidia, ATI, Sun Microsystems, and Intel.
http://www.khronos.org/news/press/Relea...opengl_specification_to_khronos_group/
This should help out with OpenGL lagging behind Direct3d on new features, hopefully. Currently OpenGL can do everything Direct3d can do.. but it has to use extensions like the ARB extensions that haven't made it into official OpenGL specs or propriatory Nvidia or ATI extensions designed specificly for their cards.
Compiz = Novell's fancy 'compisitor'. It's what makes the windows wobbly or transparent. It needs a OpenGL accelerted environment to do this in and that is why you need to run it on XGLX or AIGLX. They took Compiz and turned it into a Window Manager..
Btw Metacity has been extended to incorporate compositioning features also. So Compiz = compositor + window manager add-ons, and very new Metacity versions = window manager + compositor add-ons. Kinda interesting.
X.org = Current development project for open source X windows. Took over for XFree86 for numerious political/technical issues.
Keep in mind that X.org has a number of different X servers it handles. These things are called DDX sometimes. They have the OpenGL stuff that is new, but also the legacy 2d acceleration stuff. They also have DDX for OS X and even Windows. In X.org's terms XGL is the DDX and AIGLX and XGLX are implimentations of that DDX. Sort a. Don't understand it all myself.
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