On Thu, Sep 30, 2004 at 10:49:33AM +0200, Boris Koenig wrote:
> I think it is *theoretically* possible, basically one would need to
> disable the standard FDMs (flight dynamic models) and let PS1 export the
> corresponding values via some simple IPC/sockets mechanism - how is this
> currently done ? I'd believe, they use FSUIPC for that purpose ?

Eventually yes (as that is/was the only known interface to MSFS; the monster
now seems to have an official NetPipes entry, too). But all data flows
through my Broker over plain ASCII TCP, and it is trivial to find out what
they use. As far as I know, weather tends to be gathered via existing MSFS
real weather programs, as MSFS can obviously do more tricks than PS1. But
even this can be arranged for, I'm sure.

Unlike most other flight sims, PS1 really is only treated as the systems
engine. It is a plane sim, not a flight sim. It certainly is no operating
system. All data exchange with the external world is not done by PS1 itself,
but by an external, specialised program (the Broker). All the other add-ons
are separate programs, written by a dozen or more authors in any language
imaginable, capable of being run anywhere on the network. So the complete
data interface is extremely thin: one single TCP pipe to the Broker, where
interested other applications can subscribe to particular data items and get
near-real-time updates. The system scales beyond imagination; I never
thought it would be able to drive Matt Sheil's rig:
But it does! I've been there, flew it, it really works very well. And my
recent visit to Lufthansa's sim base in Frankfurt (14+ hours in the sim, as
much time with my head inside the computers one floor below) revealed that
the real stuff uses nearly the same approach.

> My current impression is that this might not even be SUCH a big issue, but
> I may very well be wrong :-)

If FG would have a socket somewhere that will eat control data for the
position, attitude, and maybe some other variables to steer the virtual
windshield camera around, this certainly should be "easy." We don't want any
panel in view, just the forward view (and some people some side views on
separate machines).

> But how can you use "CLOSED SOURCE" with TCL/TK ? Do you additionally
> use binary libraries ? (that's what we were suggested to do ...)

>From the start I used TclPro, which has the required capabilities. It can
either compile Tcl source to a binary format and source this in instead of
plain ASCII (but the users must install TclPro, which I hate); or it can
"wrap" all Tcl source together with a virtual filesystem with other files
into one single executable for a great many platforms. I chose the latter
way since about January 2000 and VATSIM/IVAO never even blinked.


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