Contribution by Alexandre Brenta, taking and adjusting turrets.nas by 5H1N0B1
from the B-17.
* Models/Guns/guns.xml: rotate vertically with a parameter.
* Models/b24.xml:
- rotate the dorsal turret horizontally. Note: some interior elements do not
rotate yet; they are part of the fuselage and should be separated from it.
This is a planned enhancement.
- rotate the guns vertically, passing various parameters as overlays to each
gun. This makes it very easy to add more animations for the other views in the
future by changing only turrets.nas.
Planned enhancements:
* Split from the fuselage the elements that should be part of turrets; in particular
in the tail turret and the interior of the dorsal turret.
* Write the missing animations for the tail turret, waist and nose guns.
