FlightGear uses a quasi-obsolete format for its 3d models called AC3D. The wiki says you can export materials and textures from Blender into this format, but I had issues with textures.
In the end I found it easier to edit the AC3D file directly with the texture. You can assign different materials to objects and even faces.
This is a rough model of the cockpit in order to fit the Drakken instruments we are keeping on the space plane.
The material properties don’t matter that much. This is the beginning of the AC3D file:
AC3Db
MATERIAL “Material” rgb 0.800 0.800 0.800 amb 0.800 0.800 0.800 emis 0.000 0.000 0.000 spec 0.500 0.500 0.500 shi 77 trans 0.000
OBJECT world
name “Blender_exporter_v5.0__interior textured sample.ac”
kids 7
OBJECT poly
name “Cube”
data 8
Cube.001
crease 40.0
numvert 8
-4.47101 -0.0453 0.5539
-4.47101 0.07509 0.5539
-4.47101 -0.0453 -0.5539
-4.47101 0.07509 -0.5539
-3.27063 -0.0453 0.5539
-3.27063 0.07509 0.5539
-3.27063 -0.0453 -0.5539
-3.27063 0.07509 -0.5539
numsurf 6
SURF 0X0
mat 0
refs 4
0 0.375 0
1 0.625 0
3 0.625 0.25
2 0.375 0.25
SURF 0X0
mat 0
refs 4
2 0.375 0.25
3 0.625 0.25
7 0.625 0.5
6 0.375 0.5
SURF 0X0
Note the material definition:
MATERIAL “Material” rgb 0.800 0.800 0.800 amb 0.800 0.800 0.800 emis 0.000 0.000 0.000 spec 0.500 0.500 0.500 shi 77 trans 0.000
And note how it is referenced for each face:
SURF 0X0
mat 0
You can add a texture file, which should be in the same folder as the AC3D file:
AC3Db
MATERIAL “Material” rgb 0.200 0.200 0.200 amb 0.100 0.100 0.100 emis 0.000 0.000 0.000 spec 0.500 0.500 0.500 shi 77 trans 0.000
OBJECT world
name “Blender_exporter_v5.0__spaceplane_internal_enclosure.ac”
texture “mytexture.png”
In this case the texture will be applied to all the objects in the file.
There’s more experimenting to be done, but you can still control the tint of the material with the amb variable:
amb 0.900 0.100 0.100
As always, please remember this is a WIP and not representative of the final product.