Re: [Flightgear-devel] Object placement in flightgear scenery

[<Wol...@t-...>]

Norman wrote:

> sgmap_vec_onto_cur_surface_plane()

Ah, this is like what I wanted to code, only that it is a bit more
complex. It does:

    sgAddVec3(tmp, v0, vec);
    sgSubVec3(v, tmp, u1);
    // printf("  v =3D %.2f, %.2f, %.2f\n", v[0], v[1], v[2]);

    // Calculate the vector "result" which is "v" - "v0" which is a
    // directional vector pointing from v0 towards v

    // result =3D v - v0

    sgSubVec3(result, v, v0);

Obviously, adding and then subtracting v0 is unecessary.
Actually, v0 is not used otherwise, so you can remove the parameter
v0. This is intuitively clear; A directional vector does depend on the
normal of the plane, but not on the plane's position.

Does that mean I am on the right track?
Is heading indeed the angle versus north (and not, for example,
south)?

>Norman

Bye bye,
Wolfram.