[NTLUG:Discuss] graphicx pkg on Linux run from Windows?

[Steve Baker]

Fred James wrote:
 
> We are a household in the process of converting to Linux - about 50%
> done by most counts, but at our speed that can still be measured in years.

"Just say No".
 
> I just bought the Linux version of a well known graphics package, but it
> would be good if one could access and run it using a Windows 95
> "terminal", at least for now - it would just make life so much easier
> right now.
> 
> I have never done anything like this before except on SGI, and that was
> SGI to SGI.

Linux to Linux, SGI to Linux and Linux to SGI all work too...for most
programs.

(Funny story:  Only my machine is on the Internet, my son has to 'rlogin' to my
machine and run Netscape remotely.  He'd been doing that - shut down Netscape
but forgot to logout from my machine.  Hours later a friend comes around and
he starts to show him the latest version of the game we are writing...only
it doesn't seem to work - it doesn't respond to the joystick.  So he walks
over to my machine and starts running the game there...a few moments later,
he notices that the character in the game on the other computer is also moving?!?
In fact, whatever he does to the character on my computer is also happening
on his - although in a different place in the game?!?  One jumps - so does
the other...one runs left - so does the other.  He asked me what was happening
and I really couldn't imagine how this could possibly be happening...until
I realised that BOTH copies of the game were in fact running on my computer
- with one of them having it's OpenGL output redirected to my son's machine!!
Hence they were both reading the exact same joystick input!  Very weird!

What tipped me off was that they were both running at rather low frame rates
and there was no sound on my son's PC.

> Can it be done?
> If so, how?
> What boogers am I looking at?
> Any clues?

Well, it somewhat depends on what kind of graphics the program is using.

The reason this stuff works under UNIX/Linux systems is because of the
way X windows is designed.  It's a client/server system where the
programs send their graphics and GUI commands via a UNIX socket to the
X server that does all the actual rendering.

Since it's using a socket, it's a simple matter to disconnect the
applications' socket from the local X server and plug it into the
actual network so it pops out on another machine where it'll plug
into that machine's X server.  Hence, you can run the application
on one machine and view the graphics on the other.  Keyboard and
mouse activity flow the other way.

So, if the machine that's going to be rendering the graphics is
running Windoze (which DOESN'T have this rather elegant property),
you are going to have to run an X server on your windoze box.

Whilst there are certainly versions of X that run under Windoze,
I don't know how well they implement X's network protocols - or
how compatible they would be.  Not all UNIX-to-UNIX combinations
work perfectly - some SGI programs don't like being run with
a Linux X...and vice-versa - so you could easily imagine problems
when one of those X's is really Windoze.

That's OK for simple X graphics...but if you are planning on running
OpenGL programs remotely, things suddenly get much harder.

Firstly, your Windoze machine has to have an OpenGL implementation
that works with whatever X implementation you get...that's gonna
be problematic.

Secondly, Microsoft are trying to **KILL** OpenGL, and have steadfastly
refused to progress beyond OpenGL 1.1 - where *ALL* Linux OpenGL's are
up to 1.2.1 and some are even implementing 1.3.  Theoretically, a well-written
Linux OpenGL program ought to be aware of the possibility that the OpenGL
it's connecting to is some older version than is on the local machine - but
that's probably not well tested.

SUMMARY:

  1) You'll have to be running X on top of Windoze for this to
     work...for sure.

  2) That *might* not work - although it should in theory if you get
     a well written X-for-Windoze.

  3) I would be quite suprised if OpenGL worked well that way...good luck!

----------------------------- Steve Baker -------------------------------
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