Hexmap (Tsukuba) distance

hexmap.py

import math
from collections import deque
from typing import NamedTuple

import matplotlib.pyplot as plt


class ObliqueVector(NamedTuple):
    xi: int
    eta: int

    def __mul__(self, other) -> float:
        if isinstance(other, self.__class__):
            return sum((a * b for a, b in zip(self.to_ortho(), other.to_ortho())))

    def __add__(self, other):
        if isinstance(other, self.__class__):
            return self.__class__(*(a + b for a, b in zip(self, other)))

    def __str__(self):
        return (tuple(self)).__str__()

    def to_ortho(self) -> tuple[float]:
        return (self.xi + self.eta / 2, self.eta * math.sqrt(3) / 2)

    @property
    def modtype(self) -> int:
        return (self.xi - self.eta) % 3


def get_dist_points(dist):
    moves = {
        0: [ObliqueVector(*v) for v in [(0, 1), (1, -1), (-1, 0)]],
        2: [ObliqueVector(*v) for v in [(1, 0), (-1, 1), (0, -1)]],
    }

    dists = {}
    deq = deque()
    deq.append((ObliqueVector(0, 0), 0))

    while len(deq) > 0:
        p = deq.popleft()
        if p[0] in dists and dists[p[0]] <= p[1]:
            continue
        dists[p[0]] = p[1]
        if p[1] == dist:
            continue

        for ds in moves[p[0].modtype]:
            if p[0] * ds < 0:
                continue
            deq.append((p[0] + ds, p[1] + 1))

    return [p for p in dists.keys() if dists[p] == dist]


ps = get_dist_points(31)

# visualize
plt.axes().set_aspect("equal")
plt.scatter(*zip(*[ov.to_ortho() for ov in ps]))
plt.show()