In X-Plane 9, road networks can be in DSF overlays. And in X-Plane 8 or 9, road types can be customized using a road.net file.
Within the road definition file, each road type can contain:
- “Segments” (textured quads that make the roads)
- Objects (placed along the road)
- Wires (for powerlines)
- Car lanes (that vehicles drive along)
The interesting thing is: none of these types are mandatory. So you can use any of these features without the others.
“Cars” are just objects too. So one way to make a vehicle drive around an airport would be:
- Create a road definition file with a new road type. That road type only has a car lane which references your vehicles OBJ model.
- Make an overlay DSF with this new road type, drawing the path the vehicle OBJ will randomly take.
- Package the overlay, .net file, and OBJ all together and you’ve got randomly generated vehicles moving around.
As Marginal pointed out on the .org forums, roads are currently not draped, so using them in overlays is a total PITA. This is something I hope to address in the 9.1 time-frame…draped roads are an important feature, but a little bit too invasive for the v9 betas.