@tastic/grid

Pure coordinate math and BFS reachability for tile/board-based games: bounds checks, cell/pixel conversion, adjacency, and flood-fill reachability queries. No React or React Native dependency in src/ itself.

Part of the @tastic package ecosystem (the game-focused corner of the @rific/InfiniteToken fleet). Re-exports Direction/flipDirection/isOppositeDirection from @tastic/input rather than redefining them, so every fleet game shares one direction vocabulary.

Install

npm install @tastic/grid @tastic/input

Usage

import { cellKey, computeGridSize, distanceToNearestTarget, isInBounds, stepCell } from '@tastic/grid'

const grid = computeGridSize(320, 320, 32) // { cols: 10, rows: 10 }

const occupied = new Set(['3,3', '3,4', '3,5'])
const next = stepCell({ x: 2, y: 4 }, 'right')
if (isInBounds(next, grid) && !occupied.has(cellKey(next))) {
  // move is legal
}

// Is an enemy at (0, 0) able to reach the player at (5, 5) at all, given the current walls/blocks?
const reachable = distanceToNearestTarget({ x: 0, y: 0 }, grid, occupied, new Set([cellKey({ x: 5, y: 5 })]))
const isTrapped = reachable === null

API

• GridCell, GridSize - plain coordinate/dimension shapes
• ALL_DIRECTIONS: the 4 cardinal directions, fixed order
• computeGridSize(width, height, cellPx): how many whole cells fit a pixel area
• cellToPixel(cell, cellPx) / pixelToCell(point, cellPx) - inverse conversions between grid and pixel space
• cellKey(cell): stable string key for Set/Map occupancy tracking
• isInBounds(cell, grid): bounds check
• wrapCell(cell, grid): re-enters an off-grid cell from the opposite edge, for wrap-around/torus topology
• stepCell(cell, direction): one step in a cardinal direction
• isAdjacent(a, b): true when two cells are exactly one step apart
• countReachableCells(start, grid, occupied, maxCount?): BFS: how many cells are reachable from start without crossing occupied cells or the grid edge
• distanceToNearestTarget(start, grid, occupied, targets, maxCount?): BFS: shortest step-distance from start to any cell in targets, or null if none is reachable - the shape a "can this entity still reach that cell" / trapped check needs
• Direction, flipDirection, isOppositeDirection - re-exported from @tastic/input

License

MIT