Currently, there's a problem with our *-set.xml system for aircraft
selection. If I want to fly the YASim DC-3, say (I love that plane),
then I invoke FlightGear like this:
fgfs --aircraft=dc3-yasim
So far, so good. Now, let's say that someone prefers another 3D model
to my modest effort, or simply hates Canadians and doesn't want to fly
a plane with Trans Canada Airlines livery. She can start FlightGear
like this to get the different model:
fgfs --aircraft=dc3-yasim --prop:/sim/model/path=Aircraft/Models/dc3-usa.ac
That works, but it's annoying. She'll be tempted, then, to put the
second argument into her .fgfsrc so that she gets the right DC-3 model
automatically. Unfortunately, that means that she'll also get that
DC-3 model for the C-172, C-182, C-310, Harrier, and so on, since it
overrides the value in any of the *-set.xml files.
My proposed solution is to add a layer of abstraction to every
*-set.xml file. It will be annoying for John and me, but will make
things simpler for everyone else. What we do is add a new root level,
something like
/config/aircraft
and then put all the configuration properties under that, so that we
have
/config/aircraft/dc3-dpm/
/config/aircraft/c172-vfr/
and so on. This all happens in the *-set.xml file. Then we include
the top-level properties as aliases:
<config>
<aircraft>
<dc3-dpm>
<sim>
<model>
<path>Aircraft/dc3/Models/dc3-dpm.ac</path>
</model>
</sim>
</dc3-dpm>
</aircraft>
</config>
<sim>
<model>
<path alias="/config/aircraft/dc3-dpm/sim/model/path"/>
</model>
</sim>
This is a little ugly, but ordinary users should never have to see
it. Now, the user can put
-prop:/config/aircraft/dc3-dpm/sim/model/path=Models/dc3-usa.ac
in her .fgfsrc and get a different 3D model for the DC-3 without
screwing up the default configurations for any other aircraft. No C++
code changes are required, and I cannot think of any
backward-incompatibilities. This will work for *any* property
specified in the *-set.xml files, including default control positions,
starting altitudes, etc.
Comments?
All the best,
David
--
David Megginson
[EMAIL PROTECTED]
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