Added FlightGear viewer capabilty

[David Culp]

I've added a button which will send net_fdm information to FlightGear. This allows FlightGear to be used as a viewer. So far it works for about 30 seconds and then FlightGear segfaults. I'm not sure what the problem is yet.

In order to use this feature first start FlightGear with the following command line arguments:

--fdm=null --native-fdm=socket,in,60,,5508,udp

I'm also using these command line arguments:

--prop:/sim/ai/enabled=false \
--disable-sound \
--aircraft=737-300 \
--airport=KLAX \
--runway=25R \
--timeofday=noon 

[David Culp]

Here's a screenshot of both viewers open at the same time:

[David Culp]

I'm using a minimal airplane "set" file in FlightGear in order to help track down the instability causing FlightGear to segfault. Here's the file:

<PropertyList>
  <sim>
    <description>737</description>
    <author></author>
    <status></status>
    <flight-model>ufo</flight-model>
    <allow-toggle-cockpit >true</allow-toggle-cockpit>
    <chase-distance-m>-40</chase-distance-m>
    <model>
      <path>Aircraft/737-300/Models/737-300.xml</path>
    </model>

   <startup>
     <splash-texture>Aircraft/737-300/737-300.png</splash-texture>
   </startup>

    <view>
      <internal archive="y">true</internal>
      <config>
        <!-- x/y/z == right/up/back -->
        <x-offset-m archive="y">-0.470</x-offset-m>
        <y-offset-m archive="y">1.23</y-offset-m>
        <z-offset-m archive="y">2.83</z-offset-m>

        <pitch-offset-deg archive="y">-4.0</pitch-offset-deg>
        <default-field-of-view-deg type="double">65.0</default-field-of-view-deg>
      </config>
    </view>

    <systems>
    </systems>

    <sound>
    </sound>

    <hud>
      <enable3d n="1">true</enable3d>
    </hud>

  </sim>

  <controls>
  </controls>

  <fdm>
  </fdm>

  <systems>
  </systems>

</PropertyList>

[David Culp]

Instability is solved. It turns out that you can't turn off too many systems or the app becomes unstable.

[David Culp]

I just tested the FlightGear viewer option using FlightGear v2019.1.1. For the LAX area I downloaded the Scenery 2.0 version of "w120n30" and extracted it into a directory I call ~/Scenery, which is where I keep my scenery tiles.

Start FlightGear first using the above launch script (with paths edited to match your installation). Then start QtJSBSim. After you start JSBSim and connect to it the data will start going to FlightGear. Here's a screenshot on a raw-data ILS final: