[wind] add a vertical component to the wind vector

[gautierhattenberger]

• use new WIND_INFO message
• update state interface

[flixr]

Wondering if it is nice to change the return type to struct instead of keeping it as pointer to struct like in all the other cases that don't return a scalar...

[gautierhattenberger]

Returning a pointer is possible if we either only return the 3D wind vector or we split the horizontal and vertical part in state interface. In my mind, second option doesn't make much sense (although it avoids changing existing code, just extending it). First option needs to change a little bit the getter function (we can't really return a pointer to the horizontal part except with a brutal cast).

Actually, I don't mind to go back to pointers, but I did this for two reasons:

• other elements of the air/wind group are already returned as scalars (airspeed, aoa, sideslip)
• in a near future, I would like to make the state interface thread safe, which means returning pointers may not be possible anyway

[flixr]

Couldn't we just do something like

union windspeed_i {
  struct Int32Vect2 vect2;
  struct Int32Vect3 vect3;
}

and then still return pointers as &state.h_windspeed_i.vect2 or &state.h_windspeed_i.vect3 as needed?

I think that it is nicer to keep returning pointers for structs for now...
To make the state interface thread safe we also might want to consider other options?

[gautierhattenberger]

back to the pointers.

Regarding the state interface, I'll open an issue first to discuss possible options.

[flixr]

Looks good to me and while I don't see why using the union would create problems it would be good to have it checked before?
Did you test it?

[gautierhattenberger]

At least it works in simulation. I'll do more test in the coming weeks for a project, but it would help to have it in master already.