Re: [Flightgear-devel] RFD: FlightGear and the changing state of air navigation

[Richard H. <rj...@za...>]

> Modern navigators are astoundingly-complex devices — probably an 
> order of magnitude more lines of code than FlightGear itself

Complex yes; but not that complex; it is important that the emulated
device operates exactly as the actual device, but (for example) it's not
as important if there are slight differences in the route that it chooses.

If you have a perfect knowledge of the device being simulated mostly
it's a coding exercise; as FG already has most of the support required
to build the pages, animate the buttons, and control the logic.

The difficult part of emulating any device is understanding it[1]
sufficiently to be able to build the pages - most of these devices are
still page oriented.

In 2007 I built a considerable portion of an EX5000 emulator[2] - took
me months, but the hardest part was understanding how it worked,
emulating it from the documentation alone. Then there was the the
navdata which required an ARINC-424 importer, the terrain data, the
approach plates using a Jeppesen product, and finding a performant way
of rendering the terrain data, together with figuring out how to make
the buttons and other events work dynamically with the pages.

The MFD framework that is used on the Shuttle is more than capable of
supporting a most of the requirements; Canvas is capable of rendering
the displays.

So it's possible to do this; but I'm not volunteering to do it; although
if anyone does undertake it I will be happy to help with getting a
framework together - it's the pages and the logic that will require
understanding of the device, understanding that I don't have (and don't really
want to acquire)


-------------
[1] Using the freely available Garmin trainers would be a good place to
start to build an emulator
http://www8.garmin.com/support/download_details.jsp?id=9256  - rather
than the documentation
[2]http://chateau-logic.com/portfolio/direct-to-learning.png