JavaScript code for finding the range of a HexTile in a hex-grid.

HexTile.js

var HexTile;

HexTile = (function() {

  function HexTile() {}

  HexTile.WIDTH = 83;

  HexTile.HEIGHT = 56;

  HexTile.OFFSETX = 42;

  HexTile.OFFSETY = 14;

  HexTile.EAST = 'east';

  HexTile.WEST = 'west';

  HexTile.SOUTHEAST = 'southEast';

  HexTile.NORTHEAST = 'northEast';

  HexTile.SOUTHWEST = 'southWest';

  HexTile.NORTHWEST = 'northWest';

  HexTile.deltaX = function(direction, isOddRow, index, i) {
    var result;
    if (index == null) index = 1;
    if (i == null) i = 0;
    result = 0;
    switch (direction) {
      case this.EAST:
        result += (isOddRow ? Math.floor(i * 0.5) * -1 : Math.ceil(i * 0.5) * -1) + index;
        break;
      case this.WEST:
        result += (isOddRow ? Math.ceil(i * 0.5) : Math.floor(i * 0.5)) - index;
        break;
      case this.SOUTHEAST:
        result += (isOddRow ? Math.ceil(index * 0.5) : Math.floor(index * 0.5)) - i;
        break;
      case this.NORTHEAST:
        result += Math.floor(index * 0.5) + i - Math.floor(i * 0.5);
        if (isOddRow) {
          if (index % 2 && (index + i) % 2) result++;
        } else {
          if (index % 2 === 0 && (index + i) % 2) result--;
        }
        break;
      case this.SOUTHWEST:
        result -= Math.ceil(index * 0.5) + i - Math.ceil(i * 0.5);
        if (isOddRow) {
          if (index % 2 && (index + i) % 2) result++;
        } else {
          if (index % 2 === 0 && (index + i) % 2) result--;
        }
        break;
      case this.NORTHWEST:
        result += (isOddRow ? Math.ceil(index * -0.5) : Math.floor(index * -0.5)) + i;
    }
    return result;
  };

  HexTile.deltaY = function(direction, isOddRow, index, i) {
    var result;
    if (index == null) index = 1;
    if (i == null) i = 0;
    result = 0;
    switch (direction) {
      case this.EAST:
        result += i;
        break;
      case this.WEST:
        result += i * -1;
        break;
      case this.SOUTHEAST:
        result += index;
        break;
      case this.SOUTHWEST:
        result += index - i;
        break;
      case this.NORTHEAST:
        result += (index * -1) + i;
        break;
      case this.NORTHWEST:
        result += index * -1;
    }
    return result;
  };

  HexTile.delta = function(centerX, centerY, direction, isOddRow, index) {
    var i, result;
    result = [];
    for (i = 1; 1 <= index ? i <= index : i >= index; 1 <= index ? i++ : i--) {
      result.push([centerX + this.deltaX(direction, isOddRow, index, i - 1), centerY + this.deltaY(direction, isOddRow, index, i - 1)]);
    }
    return result;
  };

  HexTile.adjacent = function(centerX, centerY, radius) {
    var adjacentTiles, east, i, isOddRow, northEast, northWest, southEast, southWest, west;
    if (radius == null) radius = 1;
    adjacentTiles = [];
    isOddRow = centerY % 2 > 0;
    radius = 4;
    for (i = 1; 1 <= radius ? i <= radius : i >= radius; 1 <= radius ? i++ : i--) {
      east = this.delta(centerX, centerY, this.EAST, isOddRow, i);
      adjacentTiles = adjacentTiles.concat(east);
      west = this.delta(centerX, centerY, this.WEST, isOddRow, i);
      adjacentTiles = adjacentTiles.concat(west);
      southEast = this.delta(centerX, centerY, this.SOUTHEAST, isOddRow, i);
      adjacentTiles = adjacentTiles.concat(southEast);
      northEast = this.delta(centerX, centerY, this.NORTHEAST, isOddRow, i);
      adjacentTiles = adjacentTiles.concat(northEast);
      southWest = this.delta(centerX, centerY, this.SOUTHWEST, isOddRow, i);
      adjacentTiles = adjacentTiles.concat(southWest);
      northWest = this.delta(centerX, centerY, this.NORTHWEST, isOddRow, i);
      adjacentTiles = adjacentTiles.concat(northWest);
    }
    return adjacentTiles;
  };

  return HexTile;

})();