feat(hex): rename offsetToAxial() to offsetToCube() and make it retur…

…n cube coordinates

This is more in line with the pointToCube() function and hey, why not throw in a free s coordinate?

BREAKING CHANGE: offsetToAxial() is now offsetToCube()

src/grid/functions/neighborOf.ts

@@ -1,5 +1,5 @@
 import { CompassDirection } from '../../compass'
-import { AxialCoordinates, Hex, offsetToAxialFlat, offsetToAxialPointy } from '../../hex'
+import { AxialCoordinates, Hex, offsetToCubeFlat, offsetToCubePointy } from '../../hex'
 
 const DIRECTIONS_POINTY = [
   null, // ambiguous
@@ -25,7 +25,7 @@ const DIRECTIONS_FLAT = [
 export const neighborOfPointy = <T extends Hex>({ offset, q, r, col, row }: T, direction: CompassDirection) => {
   if (direction === CompassDirection.S || direction === CompassDirection.N) {
     const nextRow = direction === CompassDirection.S ? row + 1 : row - 1
-    return offsetToAxialPointy(col, nextRow, offset)
+    return offsetToCubePointy(col, nextRow, offset)
   }
   const neighbor = DIRECTIONS_POINTY[direction]
   return { q: q + neighbor.q, r: r + neighbor.r }
@@ -34,7 +34,7 @@ export const neighborOfPointy = <T extends Hex>({ offset, q, r, col, row }: T, d
 export const neighborOfFlat = <T extends Hex>({ offset, q, r, col, row }: T, direction: CompassDirection) => {
   if (direction === CompassDirection.E || direction === CompassDirection.W) {
     const nextCol = direction === CompassDirection.E ? col + 1 : col - 1
-    return offsetToAxialFlat(nextCol, row, offset)
+    return offsetToCubeFlat(nextCol, row, offset)
   }
   const neighbor = DIRECTIONS_FLAT[direction]
   return { q: q + neighbor.q, r: r + neighbor.r }

src/hex/functions/cloneHex.ts

@@ -1,11 +1,11 @@
 import { isOffset } from '../../utils'
 import { Hex, HexCoordinates } from '../types'
-import { offsetToAxial } from './offsetToAxial'
+import { offsetToCube } from './offsetToCube'
 
 export const cloneHex = <T extends Hex>(hex: T, newProps: Partial<T> | HexCoordinates = {}): T => {
   if (isOffset(newProps)) {
     const { col, row, ...otherProps } = newProps
-    const coordinates = offsetToAxial({ col, row }, hex)
+    const coordinates = offsetToCube({ col, row }, hex)
     return Object.assign(Object.create(Object.getPrototypeOf(hex)), hex, coordinates, otherProps)
   }
 

src/hex/functions/createHex.ts

@@ -1,7 +1,7 @@
 import { isOffset } from '../../utils'
 import { Hex, HexCoordinates } from '../types'
 import { isHex } from './isHex'
-import { offsetToAxial } from './offsetToAxial'
+import { offsetToCube } from './offsetToCube'
 
 export const createHex = <T extends Hex>(prototypeOrHex: T, props: Partial<T> | HexCoordinates = { q: 0, r: 0 }): T => {
   if (isHex(prototypeOrHex)) {
@@ -10,7 +10,7 @@ export const createHex = <T extends Hex>(prototypeOrHex: T, props: Partial<T> |
 
   if (isOffset(props)) {
     const { col, row, ...otherProps } = props
-    const coordinates = offsetToAxial({ col, row }, prototypeOrHex)
+    const coordinates = offsetToCube({ col, row }, prototypeOrHex)
     return Object.assign(Object.create(prototypeOrHex), coordinates, otherProps)
   }
 

src/hex/functions/index.ts

@@ -9,7 +9,7 @@ export * from './hexToPoint'
 export * from './isFlat'
 export * from './isHex'
 export * from './isPointy'
-export * from './offsetToAxial'
+export * from './offsetToCube'
 export * from './pointToCube'
 export * from './round'
 export * from './toString'

src/hex/functions/offsetToCube.test.ts

@@ -0,0 +1,13 @@
+import { offsetToCube } from './offsetToCube'
+
+test('returns axial coordinates bases on the passed offset coordinates', () => {
+  expect(offsetToCube({ col: 1, row: 4 }, { offset: -1, isPointy: true })).toEqual({ q: -1, r: 4, s: -3 })
+  expect(offsetToCube({ col: 1, row: 4 }, { offset: 1, isPointy: true })).toEqual({ q: -1, r: 4, s: -3 })
+  expect(offsetToCube({ col: 1, row: 4 }, { offset: -1, isPointy: false })).toEqual({ q: 1, r: 4, s: -5 })
+  expect(offsetToCube({ col: 1, row: 4 }, { offset: 1, isPointy: false })).toEqual({ q: 1, r: 3, s: -4 })
+
+  expect(offsetToCube({ col: 4, row: 1 }, { offset: -1, isPointy: true })).toEqual({ q: 4, r: 1, s: -5 })
+  expect(offsetToCube({ col: 4, row: 1 }, { offset: 1, isPointy: true })).toEqual({ q: 3, r: 1, s: -4 })
+  expect(offsetToCube({ col: 4, row: 1 }, { offset: -1, isPointy: false })).toEqual({ q: 4, r: -1, s: -3 })
+  expect(offsetToCube({ col: 4, row: 1 }, { offset: 1, isPointy: false })).toEqual({ q: 4, r: -1, s: -3 })
+})

src/hex/functions/offsetToCube.ts

@@ -0,0 +1,21 @@
+import { offsetFromZero } from '../../utils'
+import { CubeCoordinates, HexPrototype, OffsetCoordinates } from '../types'
+
+export const offsetToCubePointy = (col: number, row: number, offset: number): CubeCoordinates => {
+  const q = col - offsetFromZero(offset, row)
+  const r = row
+  const s = -q - r
+  return { q, r, s }
+}
+
+export const offsetToCubeFlat = (col: number, row: number, offset: number): CubeCoordinates => {
+  const q = col
+  const r = row - offsetFromZero(offset, col)
+  const s = -q - r
+  return { q, r, s }
+}
+
+export const offsetToCube = (
+  { col, row }: OffsetCoordinates,
+  { offset, isPointy }: Pick<HexPrototype, 'offset' | 'isPointy'>,
+) => (isPointy ? offsetToCubePointy(col, row, offset) : offsetToCubeFlat(col, row, offset))