Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Comment Re:UDF? Seriously? (Score 1) 484

Plain UDF 2.01, the kind you'd use on a hard drive or USB flash drive, is readable in Windows XP (I tested this recently), and is read/write in Vista and Win7. It's also supported in recent versions of OSX. Unless one needs to support old operating systems, UDF seems like a reasonable choice.

Comment Re:Choosing the correct abstraction layer (Score 1) 542

You have to use window manager hacks to get any extra utility from these cards at all on a X11 desktop, where newer versions of Windows and OS X have hardware/GPU accelerated rendering and compositing APIs. Where are those in X11?

By "window manager hacks" you mean switching to a compositing window manager like Compiz, right? What Compiz (or any compositing manager) does is not really very different from what its counterparts in Windows and OS X do. What you're complaining about is the fact that X11 allows a choice of window managers, and not all X11-based desktops use a compositing one yet, as opposed to the Windows and Mac platforms where there's essentially only one window manager available (it's built-in) and it's a compositing one.

As for new APIs, not really. Applications don't have to do anything different to display themselves on a composited desktop instead of a non-composited one. All the work for that is done by one program, the compositing manager, and the X enhancements needed to make its job possible (a new X11 protocol extension and a new GLX extension) were implemented in Xorg several years ago.

At this point, the lack of out-of-the-box compositing on Linux desktops is due mostly to accelerated 3D drivers (for the most common GPUs) not being installed by default for licensing reasons, not some fundamental problem with X.

Comment Re:Choosing the correct abstraction layer (Score 1) 542

Since those X11 extensions are hacks onto X11 to enable such exposure, I'd say the GP is right. X11 doesn't expose that kind of stuff.

They're not hacked on, you're just misunderstanding what the word "extension" means in X11 terminology. X11 extensions are named groups of commands that an X server can optionally implement. The core X protocol includes commands for checking what extensions are available, so that applications can use those additional commands when they're supported, or work around the lack of them (or just display an error message) if not.

This is a designed-in extensibility mechanism, not some afterthought kluge. Many "standard" facilities are provided through X11 extensions, such as displaying anti-aliased text (with the RENDER extension, though it can also be done in a slower way if RENDER isn't available), overlay-based video playback (with the XVideo extension), changing screen resolutions (RANDR), turning off the monitor to save power when idle (DPMS), and OpenGL (GLX).

OpenGL, by the way, has a similar extension mechanism, and that's what allowed it to support new GPU features (such as multitexturing and pixel shaders) as they were developed, without requiring a whole new version of the core OpenGL spec.

Desktop compositing in X11 is done by asking the X server to give each window an offscreen area of video memory to draw itself into, rather than drawing directly on the screen, and then asking the OpenGL implementation to make these offscreen areas accessible as OpenGL textures. The compositing manager paints the windows onto the screen by putting these textures on rectangles, applying whatever visual effects it wants to display (like the Compiz cube), using normal OpenGL drawing operations. The command to make the X server redirect window drawing to offscreen pixmaps is provided by the COMPOSITE extension, and exposing those pixmaps as OpenGL textures is done with a GLX command, GLX_EXT_texture_from_pixmap.

I've used Compiz and Beryl, they both crash regularly and slow my laptop significantly (a couple years old, but runs Vista just fine). Gnome-Shell looks ok, but it isn't exactly out yet (you can get a preview from so it's hard to compare it.

If Compiz is unstable, that's an application bug that doesn't really have anything to do with the design of X11. The compositor in Metacity (the GNOME window manager) is pretty stable (I've been using it for several years), and its scenegraph-based successor (called Mutter) is the foundation for Gnome-Shell.

Comment Re:you're wrong. (Score 3, Insightful) 406

Americans won't stand for it. They want to know NOW damnit, not tomorrow.

I don't think the American public would really be all that upset if the election results didn't come in until the next morning. I suspect it's actually the news media that wants the results ASAP, in order to get everyone watching the election day evening news so that they can charge more for ad space.

Slashdot Top Deals

I judge a religion as being good or bad based on whether its adherents become better people as a result of practicing it. - Joe Mullally, computer salesman