Hexgrid with neighbor calculation

tests/hexgrid.spec.ts

@@ -1,15 +1,15 @@
-import { describe, it } from "mocha";
+import { beforeEach, describe, it } from "mocha";
 import { expect } from "chai";
 
 class Hex {
  private readonly parent: HexGrid;
  private readonly x: number;
  private readonly y: number;
 
- constructor(parent: HexGrid, x: number) {
+ constructor(parent: HexGrid, x: number, y: number) {
  this.parent = parent;
  this.x = x;
- this.y = 0;
+ this.y = y;
  }
 
  get neighbors(): Hex[] {
@@ -18,31 +18,58 @@ class Hex {
 }
 
 class HexGrid {
- private readonly hexArray: Hex[]
+ private readonly hexArray: Hex[][]
 
  constructor(width: number, height: number) {
- const size = width * height;
- this.hexArray = Array.from(new Array(size)).map((_, x) => new Hex(this, x));
+ this.hexArray = Array.from(new Array(height))
+ .map((_, y) => Array.from(new Array(width))
+ .map((_, x) => new Hex(this, x, y)));
  }
 
  at(x: number, y: number): Hex {
- return this.hexArray[x];
+ return this.hexArray[y][x];
  }
 
  neighborsOf(x: number, y: number): Hex[] {
+ const above = y - 1
+ const below = y + 1
  const left = x - 1;
  const right = x + 1;
+ const offset = y % 2 == 0 ? -1 : 1
 
- return [this.hexArray[left], this.hexArray[right]]
+ const row = this.hexArray[y];
+ const aboveRow = (this.hexArray[above] || []);
+ const belowRow = (this.hexArray[below] || []);
+
+ const leftHex = row[left];
+ const rightHex = row[right];
+ const aboveHex = aboveRow[x];
+ const belowHex = belowRow[x];
+ const aboveHex2 = aboveRow[x + offset];
+ const belowHex2 = belowRow[x + offset];
+
+ return [
+ leftHex,
+ rightHex,
+ aboveHex,
+ belowHex,
+ aboveHex2,
+ belowHex2
+ ]
  .filter(hex => hex !== undefined);
  }
 }
 
+// A B C
+// D E F
+// Z Y X
+// W V U
+
 describe('a hex grid', () => {
  describe('with a single hex', () => {
  it('has no neighbors', () => {
  const grid = new HexGrid(1, 1);
- const hex = grid.at(0,0);
+ const hex = grid.at(0, 0);
  expect(hex.neighbors).to.be.empty;
  });
  });
@@ -51,11 +78,138 @@ describe('a hex grid', () => {
  it('has neighbors left and right of tiles', () => {
  const grid = new HexGrid(5, 1);
 
- expect(grid.at(0,0).neighbors).to.have.members([grid.at(1,0)]);
- expect(grid.at(1,0).neighbors).to.have.members([grid.at(0,0), grid.at(2,0)]);
- expect(grid.at(2,0).neighbors).to.have.members([grid.at(1,0), grid.at(3,0)]);
- expect(grid.at(3,0).neighbors).to.have.members([grid.at(2,0), grid.at(4,0)]);
- expect(grid.at(4,0).neighbors).to.have.members([grid.at(3,0)]);
+ expect(grid.at(0, 0).neighbors).to.have.members([grid.at(1, 0)]);
+ expect(grid.at(1, 0).neighbors).to.have.members([grid.at(0, 0), grid.at(2, 0)]);
+ expect(grid.at(2, 0).neighbors).to.have.members([grid.at(1, 0), grid.at(3, 0)]);
+ expect(grid.at(3, 0).neighbors).to.have.members([grid.at(2, 0), grid.at(4, 0)]);
+ expect(grid.at(4, 0).neighbors).to.have.members([grid.at(3, 0)]);
+ });
+ });
+
+ describe('a completely vertical map', () => {
+ it('has neighbors above and below of tiles', () => {
+ const grid = new HexGrid(1, 5);
+
+ expect(grid.at(0, 0).neighbors).to.have.members([grid.at(0, 1)]);
+ expect(grid.at(0, 1).neighbors).to.have.members([grid.at(0, 0), grid.at(0, 2)]);
+ expect(grid.at(0, 2).neighbors).to.have.members([grid.at(0, 1), grid.at(0, 3)]);
+ expect(grid.at(0, 3).neighbors).to.have.members([grid.at(0, 2), grid.at(0, 4)]);
+ expect(grid.at(0, 4).neighbors).to.have.members([grid.at(0, 3)]);
+ });
+ });
+
+ describe('a full map', () => {
+ // A B C
+ // D E F
+ // Z Y X
+ // W V U
+ let grid: HexGrid;
+
+ beforeEach(() => {
+ grid = new HexGrid(3, 4);
+ });
+
+ it('A is neighbors to B and D', () => {
+ expect(grid.at(0, 0).neighbors).to.have.members([grid.at(0, 1), grid.at(1, 0)]);
+ });
+
+ it('B is neighbors to A, C, D, and E', () => {
+ expect(grid.at(1, 0).neighbors).to.have.members([
+ grid.at(0, 0),
+ grid.at(2, 0),
+ grid.at(0, 1),
+ grid.at(1, 1),
+ ]);
+ });
+
+ it('C is neighbors to B, E, and F', () => {
+ expect(grid.at(2, 0).neighbors).to.have.members([
+ grid.at(1, 0),
+ grid.at(1, 1),
+ grid.at(2, 1),
+ ]);
+ });
+
+ it('D is neighbors to A, B, E, Z, and Y', () => {
+ expect(grid.at(0, 1).neighbors).to.have.members([
+ grid.at(0, 0),
+ grid.at(1, 0),
+ grid.at(1, 1),
+ grid.at(0, 2),
+ grid.at(1, 2),
+ ]);
+ });
+
+ it('E is neighbors to B, C, D, E, F, Y, and X', () => {
+ expect(grid.at(1, 1).neighbors).to.have.members([
+ grid.at(1, 0),
+ grid.at(2, 0),
+ grid.at(0, 1),
+ grid.at(2, 1),
+ grid.at(1, 2),
+ grid.at(2, 2),
+ ]);
+ });
+
+ it('F is neighbors to C, E, and X', () => {
+ expect(grid.at(2, 1).neighbors).to.have.members([
+ grid.at(2, 0),
+ grid.at(1, 1),
+ grid.at(2, 2),
+ ]);
+ });
+
+ it('Z is neighbors to D, Y, and W', () => {
+ expect(grid.at(0, 2).neighbors).to.have.members([
+ grid.at(0, 1),
+ grid.at(1, 2),
+ grid.at(0, 3),
+ ]);
+ });
+
+ it('Y is neighbors to D, E, Z, X, W, and V', () => {
+ expect(grid.at(1, 2).neighbors).to.have.members([
+ grid.at(0, 1),
+ grid.at(1, 1),
+ grid.at(0, 2),
+ grid.at(2, 2),
+ grid.at(0, 3),
+ grid.at(1, 3),
+ ]);
+ });
+
+ it('X is neighbors to E, F, Y, V, and U', () => {
+ expect(grid.at(2, 2).neighbors).to.have.members([
+ grid.at(1, 1),
+ grid.at(2, 1),
+ grid.at(1, 2),
+ grid.at(1, 3),
+ grid.at(2, 3),
+ ]);
+ });
+
+ it('W is neighbors to Z, Y, and V', () => {
+ expect(grid.at(0, 3).neighbors).to.have.members([
+ grid.at(0, 2),
+ grid.at(1, 2),
+ grid.at(1, 3),
+ ]);
+ });
+
+ it('V is neighbors to Y, X, W, and U', () => {
+ expect(grid.at(1, 3).neighbors).to.have.members([
+ grid.at(1, 2),
+ grid.at(2, 2),
+ grid.at(0, 3),
+ grid.at(2, 3),
+ ]);
+ });
+
+ it('U is neighbors to V and X', () => {
+ expect(grid.at(2, 3).neighbors).to.have.members([
+ grid.at(2, 2),
+ grid.at(1, 3),
+ ]);
  });
  });
 });