refactor: add point hashing function, offsetNeighbors

src/utility/const.ts

@@ -2,9 +2,42 @@ import { Point } from './pointfacade';
 
 export const HEX_WIDTH_PX = 90;
 export const HEX_HEIGHT_PX = (HEX_WIDTH_PX / Math.sqrt(3)) * 2 * 0.75;
+
 export function offsetCoordsToPx(point: Point) {
 	return {
 		x: (point.y % 2 === 0 ? point.x + 0.5 : point.x) * HEX_WIDTH_PX,
 		y: point.y * HEX_HEIGHT_PX,
 	};
 }
+
+const n2_16 = Math.pow(2, 16);
+
+function isValid(point: Point) {
+	return 0 <= point.x && point.x < n2_16 && 0 <= point.y && point.y < n2_16;
+}
+
+export function offsetNeighbors(point: Point): Point[] {
+	if (point.y % 2 === 0) {
+		return [
+			{ x: point.x + 1, y: point.y },
+			{ x: point.x + 1, y: point.y + 1 },
+			{ x: point.x, y: point.y + 1 },
+			{ x: point.x - 1, y: point.y },
+			{ x: point.x, y: point.y - 1 },
+			{ x: point.x + 1, y: point.y - 1 },
+		].filter(isValid);
+	} else {
+		return [
+			{ x: point.x + 1, y: point.y },
+			{ x: point.x, y: point.y + 1 },
+			{ x: point.x - 1, y: point.y + 1 },
+			{ x: point.x - 1, y: point.y },
+			{ x: point.x - 1, y: point.y - 1 },
+			{ x: point.x, y: point.y - 1 },
+		].filter(isValid);
+	}
+}
+
+export function hashOffsetCoords(point: Point) {
+	return (point.x << 16) ^ point.y;
+}