✨ add translate() function

It translates a hex or partial cube coordinates to another "position".

examples/line-of-sight/index.ts

@@ -3,15 +3,14 @@ import {
   assertCubeCoordinates,
   createHex,
   createHexPrototype,
-  CubeCoordinates,
   fromCoordinates,
   Grid,
   HexCoordinates,
   hexToPoint,
   line,
-  PartialCubeCoordinates,
   repeatWith,
   ring,
+  translate,
   Traverser,
   TupleCoordinates,
 } from '../../src'
@@ -73,7 +72,7 @@ function fieldOfView(start: HexCoordinates): Traverser<Tile> {
   return repeatWith(
     ring({
       center: start,
-      start: translate(startTile, { r: -config.viewDistanceInTiles }),
+      start: translate(startTile, { q: startTile.q, r: -config.viewDistanceInTiles }),
     }),
     lineOfSight(start),
     { includeSource: false },
@@ -104,11 +103,3 @@ function coordinatesFromTarget(target: EventTarget) {
   const id = SVG(target).parent('[data-id]')?.data('id')
   return typeof id === 'string' ? (id.split(',').map(Number) as TupleCoordinates) : null
 }
-
-// todo: move to honeycomb
-// todo: rename to add?
-function translate(hex: PartialCubeCoordinates, delta: Partial<CubeCoordinates>) {
-  const { q = 0, r = 0, s = 0 } = delta
-  const hexS = hex.s ?? -hex.q - hex.r
-  return { q: hex.q + q, r: hex.r + r, s: hexS + s }
-}

src/hex/functions/index.ts

@@ -16,4 +16,5 @@ export * from './offsetToCube'
 export * from './pointToCube'
 export * from './round'
 export * from './toString'
+export * from './translate'
 export * from './width'

src/hex/functions/translate.ts

@@ -0,0 +1,25 @@
+import { CubeCoordinates, Hex, PartialCubeCoordinates } from '../types'
+import { assertCubeCoordinates } from './assertCubeCoordinates'
+import { completeCubeCoordinates } from './completeCubeCoordinates'
+import { isHex } from './isHex'
+
+// todo: add to hex prototype
+/**
+ * @category Hex
+ */
+export function translate<T extends Hex>(hex: T, delta: PartialCubeCoordinates): T
+export function translate(coordinates: PartialCubeCoordinates, delta: PartialCubeCoordinates): CubeCoordinates
+export function translate<T extends Hex>(
+  input: T | PartialCubeCoordinates,
+  delta: PartialCubeCoordinates,
+): T | CubeCoordinates {
+  const { q: deltaQ, r: deltaR, s: deltaS } = completeCubeCoordinates(delta)
+
+  if (isHex(input)) {
+    const { q, r, s } = assertCubeCoordinates(input, input)
+    return input.clone({ q: q + deltaQ, r: r + deltaR, s: s + deltaS })
+  }
+
+  const { q, r, s } = completeCubeCoordinates(input)
+  return { q: q + deltaQ, r: r + deltaR, s: s + deltaS }
+}