gistfile1.txt

extends Node

const DIR_N  = 1 << 0
const DIR_NE = 1 << 1
const DIR_E  = 1 << 2
const DIR_SE = 1 << 3
const DIR_S  = 1 << 4
const DIR_SW = 1 << 5
const DIR_W  = 1 << 6
const DIR_NW = 1 << 7

func direction_bitfield(vec: Vector2) -> int:
    if vec.length() == 0.0:
        return 0

    # Godot measures angles starting from the right-hand side,
    # which is a bit awkward when all you want is north at the top.
    # So we grab the angle as Godot gives it…
    var ang = atan2(vec.y, vec.x)

    # …then we shift it so that pointing upwards becomes the “start”
    # of the circle instead of pointing right.
    ang -= PI / 2.0

    # If the angle dips below zero, we just wrap it back around
    # so everything sits nicely between 0 and a full turn.
    if ang < 0.0:
        ang += PI * 2.0

    # The full circle is chopped into eight equal pieces.
    # Each piece is 45 degrees, so this works out neatly.
    var slice = PI / 4.0
    var sector = int(floor(ang / slice))

    # Whatever slice we landed in, we convert that number into a single bit.
    return 1 << sector

func _ready():
    var v = Vector2(1, -1)     # roughly north-east
    var d = direction_bitfield(v)
    print("bit:", d)

totally untested