The Multi-Pointer X server

worufu writes "Some weeks after releasing the MPX (Multi-Pointer X Server), the Linux world slowly seems to draw attention to the project which opens up the limits of simultaneous input devices of the current X server. The future possibities are unlimited and I cannot wait to see some nice applications supporting the advantages of multiple input devices.
From the project description: 'The Multi-Pointer X Server is an enhanced X server to support multiple mice. It provides users with one cursor per device. Each cursor can operate independently. A multicursor windowing system allows two-handed interaction with legacy applications, but also the creation of innovative applications and user interfaces.'"

Comments

Re:I wonder...

[mr_jrt]

Windows had this at a low level ages ago, and DirectX supports multiple mice too. In the switch to Win2K+ however, Microsoft deemed it a security issue and made it damn near impossible to query multiple mice easily. Can still be done now, but you have to go much lower level to do so (capturing raw mouse events and decoding them yourself). Annoyed the hell out of me when my multiple mice were only ever being detected by DX9 as a single device trying to play multiplayer air hockey.

Re:I wonder...

[Anonymous Coward]

Oh, you mean this?

http://research.microsoft.com/displayArticle.aspx? id=1471

Lemmings

[bhaak1]

Lemmings also had two mice support in the two player levels.

As did a lot of games back on the Amiga, even PD games.

I remember an Asteroid PD clone where you moved the character with one joystick and with the other joystick you controlled the fire beam.

Was quite an immersive feeling.

Re:I would be a lot more impressed

[ratboy666]

X "natively" does support more than three buttons. AFAIR (and, its been a while since I've worked on the X server input section), the limit is 128 buttons.

Ratboy.

Re:I would be a lot more impressed

[isj]

The X protocol directly supports 5 buttons. Additional buttons can be supported by X Input Extension (XIE). The scroll wheel is usually handled via XIE.

Re:2 person PC

[lazarusdishwasher]

I have a link that will let you use the equipment you mentioned handle two seperate logins.http://blog.chris.tylers.info/index.php?/ar chives/14-Multiseat-X-Under-X11R6.97.0.html

I have never tried this solution but from what I have read in the past it seems to be getting easier to handle multiple input devices and displays. I would agree with others that if you wanted the same login to hanle both sets of keyboards mice and monitors you run the risk of confusing the operators or the programs.

Re:Race conditions

[ultranova]

What an excellent way to make every toolkit vulnerable to thousands of race conditions ;)

Um, what race conditions ? Here's the basic pseudocode to an X application:

1. Initialize.
2. Get next event from X-server.
3. React to the event if neccessary.
4. Go to 2.

I don't really see how having 2, 20 or 200 pointing devices could cause any race conditions here. You just get 2, 20 or 200 times the amount of mouse events (assuming they are all actually used and won't just lie there) than before.

You can probably crash 99% of all X11 applications using two pointers

Can anyone out there test this ? Did your Gnome / KDE / Whatever desktop crash with two pointers ?

Re:I would be a lot more impressed

[IBitOBear]

I don't knw what you've tried, but I find that for my hardware and software auto-selection is a simple matter of _not_ _setting_ any refresh rate at all in the monitor section and then enabling DPMS. Your milage will vary of course depending on the hardware and driver in use.

Notice what I commented out:

Section "Monitor"
                #DisplaySize 360 270 # mm
                Identifier "Monitor1"
                VendorName "VSC"
                ModelName "A91f+"
                #HorizSync 30.0 - 86.0
                #VertRefresh 808531264.0 - 808792640.0
                Option "DPMS"
EndSection

The problem is _actually_ that a lot of the configuration tools are not as well maintained as the server itself, so the data and patterns in the configuration programs are "a bit off".

As a matter of course I generally configure by hand. First I do "X -configure" to get a good starter file. Then I comment out the sync rates as above and add "DefaultDepth 24" to the screen section.

Also, if you use a KVM you have to be switched to the X machine when X starts or the DPMS can not do the configs.

Next I make sure that I boot linux with psmouse.proto=any (to maximize the /dev/input/mice functionality).

Finally I try to switch all the mice to evdev if there isn't a spesific driver with more functionality.

Yea, it isn't effort free, but it is easy and optimal.

Re:I would be a lot more impressed

[netfunk]

The scroll wheel is usually handled via XIE

No it's not. It generally maps to buttons 4 and 5, specified in your X server config file, and causes problems for hardware with more than 5 buttons. XInput is rarely used by most apps (and most X servers), and there're lots of programs out there now that would fail if you mapped the mousewheel to different buttons, since it's a de facto standard to have them on buttons 4 and 5.

Drives me nuts when people say fundamentally incorrect things with authority, since they always get modded "Insightful."

--ryan.