Player heading as a route number

Hoping it can be useful for somebody, below there is a component function (so, not a complete script) which returns the player heading as a route number, as used in aircraft / ship navigation (N = 360, E= 090, S = 180, W = 270 and other in between). There is plenty of script examples into which to plug this function and have an on-screen output.

Notes:

1) The function accepts as parameter an event, of the same type of the events passed to many on<Event> callback functions.

2) It is customary to represent routes as 3-digit number with 0 padding (as in 090 for E); the function just returns an integer, to be formatted at wish.

3) For N only 360 is normally used, never 000. The function returns 360 if coming from W and 0 if coming from E; adjust if this disturbs you.

4) I exceeded with comments to clarify the steps; reduce them, if you prefer.

5) Even if the scripting framework is going to change to Java, for a purely computational function like this, conversion should be straightforward.

-- global variable: 180 / PI to convert radians to degrees
rad2deg    = 57.295779513;


function playerHeading(event)
    -- Get the rotation of the player
    local playerRot    = event.player:getViewDirection();
    -- x- and z-components of the viewing vector
    local rotX        = playerRot.x;
    local rotZ        = playerRot.z;
    -- if the viewing vector is not horizontal but slanted up or down,
    -- the x and z components are shortened: scale them up until
    -- they are the catheti of a triangle whose hypotenuse is long 1
    local scale        = math.sqrt(rotX*rotX + rotZ*rotZ);
    local scaledZ    = rotZ / scale;
    -- get the angle and convert to degrees
    local heading    = math.acos(scaledZ) * rad2deg;
    -- hdg is correct from N (0°) through E (90°) to S (180°)
    -- then, when view is toward W, it decreases down to 0° again
    -- when view is toward W, correct by taking the complementary angle
    if rotX > 0 then
        heading = 360 - heading;
    end
    -- round to integer
    heading    = math.floor(heading + 0.5);
    return heading;
end

Thanks, Legens. Just for info, a complete script adapted from Yahgiggle and Richies script for the Rising City server and using this function is posted here.