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d03762b | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | """Hex grid utilities for Civ6 offset coordinate system.
Civ6 uses an "odd-r" (odd-row) horizontal offset coordinate system.
Odd rows are shifted right by half a hex.
This module provides pure functions for hex math operations.
All functions are stateless and easily unit testable.
"""
from typing import List, Tuple, Optional
# Direction offsets for hex neighbors
# Civ6 uses "odd-r" offset coordinates (odd ROWS shifted right)
# Index corresponds to edge direction: 0=E, 1=NE, 2=NW, 3=W, 4=SW, 5=SE
# For EVEN rows (y % 2 == 0)
DIRECTIONS_EVEN_ROW = [
(1, 0), # 0: East
(0, -1), # 1: Northeast
(-1, -1), # 2: Northwest
(-1, 0), # 3: West
(-1, 1), # 4: Southwest
(0, 1), # 5: Southeast
]
# For ODD rows (y % 2 == 1)
DIRECTIONS_ODD_ROW = [
(1, 0), # 0: East
(1, -1), # 1: Northeast (shifted right for odd rows)
(0, -1), # 2: Northwest
(-1, 0), # 3: West
(0, 1), # 4: Southwest
(1, 1), # 5: Southeast (shifted right for odd rows)
]
def get_neighbors(x: int, y: int) -> List[Tuple[int, int]]:
"""Get all 6 neighboring hex coordinates.
Args:
x: Column
y: Row
Returns:
List of (x, y) tuples for all 6 neighbors
Example:
>>> get_neighbors(21, 14) # y=14 is even row
[(22, 14), (21, 13), (20, 13), (20, 14), (20, 15), (21, 15)]
"""
directions = DIRECTIONS_ODD_ROW if y % 2 == 1 else DIRECTIONS_EVEN_ROW
return [(x + dx, y + dy) for dx, dy in directions]
def get_neighbor_at_direction(x: int, y: int, direction: int) -> Tuple[int, int]:
"""Get neighbor coordinate in a specific direction.
Args:
x, y: Current position
direction: Edge direction (0-5)
Returns:
(x, y) of neighbor in that direction
"""
directions = DIRECTIONS_ODD_ROW if y % 2 == 1 else DIRECTIONS_EVEN_ROW
dx, dy = directions[direction]
return (x + dx, y + dy)
def get_direction_to_neighbor(x1: int, y1: int, x2: int, y2: int) -> Optional[int]:
"""Get the direction from (x1,y1) to adjacent tile (x2,y2).
Args:
x1, y1: Source position
x2, y2: Target position (must be adjacent)
Returns:
Direction index (0-5) or None if not adjacent
Example:
>>> get_direction_to_neighbor(5, 5, 6, 5)
0 # East
"""
neighbors = get_neighbors(x1, y1)
try:
return neighbors.index((x2, y2))
except ValueError:
return None
def hex_distance(x1: int, y1: int, x2: int, y2: int) -> int:
"""Calculate hex distance between two positions.
Uses cube coordinate conversion for accurate distance.
Civ6 uses "odd-r" offset coordinates (odd rows shifted right).
Args:
x1, y1: First position
x2, y2: Second position
Returns:
Integer distance in hex tiles
Example:
>>> hex_distance(0, 0, 3, 0)
3
>>> hex_distance(0, 0, 1, 1)
1
"""
# Convert offset (odd-r) to cube coordinates
def offset_to_cube(col: int, row: int) -> Tuple[int, int, int]:
cx = col - (row - (row & 1)) // 2
cz = row
cy = -cx - cz
return cx, cy, cz
cx1, cy1, cz1 = offset_to_cube(x1, y1)
cx2, cy2, cz2 = offset_to_cube(x2, y2)
return (abs(cx1 - cx2) + abs(cy1 - cy2) + abs(cz1 - cz2)) // 2
def is_adjacent(x1: int, y1: int, x2: int, y2: int) -> bool:
"""Check if two hexes are adjacent.
Example:
>>> is_adjacent(5, 5, 6, 5)
True
>>> is_adjacent(0, 0, 2, 0)
False
"""
return hex_distance(x1, y1, x2, y2) == 1
def get_tiles_in_range(x: int, y: int, radius: int) -> List[Tuple[int, int]]:
"""Get all tiles within a given range of a center tile.
Args:
x, y: Center position
radius: Maximum distance (inclusive)
Returns:
List of (x, y) positions within range (excluding center)
Example:
>>> len(get_tiles_in_range(5, 5, 1))
6 # Just the immediate neighbors
>>> len(get_tiles_in_range(5, 5, 2))
18 # Two rings
"""
tiles = []
for dx in range(-radius, radius + 1):
for dy in range(-radius, radius + 1):
nx, ny = x + dx, y + dy
if (nx, ny) != (x, y) and hex_distance(x, y, nx, ny) <= radius:
tiles.append((nx, ny))
return tiles
def get_opposite_direction(direction: int) -> int:
"""Get the opposite direction (180 degrees).
Example:
>>> get_opposite_direction(0) # East
3 # West
"""
return (direction + 3) % 6
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