From 3443c1c65e9f1753e1e656b35d08416c1fa298f2 Mon Sep 17 00:00:00 2001
From: godosa <godosa@godosa.eu>
Date: Wed, 7 Oct 2026 00:14:38 +0200
Subject: worldmap-viewer: initial public history

---
 viewer/js/units.js | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 viewer/js/units.js

(limited to 'viewer/js/units.js')

diff --git a/viewer/js/units.js b/viewer/js/units.js
new file mode 100644
index 0000000..4d9332f
--- /dev/null
+++ b/viewer/js/units.js
@@ -0,0 +1,22 @@
+// units.js — SI ↔ optional in-world units (spans, leagues; from /api/meta at startup). Without them: SI only.
+export const UNITS = { span_m: null, moment_s: null, league_km: null, day_hours: 24 };
+export function setUnits(u) { Object.assign(UNITS, u || {}); }
+export const kmToLeagues = km => km / UNITS.league_km;
+export const mToSpans = m => m / UNITS.span_m;
+export const km2ToSqLeagues = a => a / UNITS.league_km ** 2;
+export const walkDays = (km, kmPerDay = 30) => km / kmPerDay;
+const num = (v, d) => v.toLocaleString('en-US', { minimumFractionDigits: d, maximumFractionDigits: d });
+const spans = m => (UNITS.span_m ? ` · ${num(mToSpans(m), 0)} spans` : '');
+const leagues = (km, d) => (UNITS.league_km ? ` · ${num(kmToLeagues(km), d)} leagues` : '');
+export const fmtDistance = km => (km < 1
+  ? `${num(km * 1000, 0)} m${spans(km * 1000)}`
+  : `${num(km, km < 100 ? 1 : 0)} km${leagues(km, km < 100 ? 2 : 1)}`);
+export const fmtElev = m => `${num(m, 0)} m${spans(m)}`;
+export const fmtArea = km2 => `${num(km2, 0)} km²${UNITS.league_km ? ` · ${num(km2ToSqLeagues(km2), 0)} sq leagues` : ''}`;
+export function fmtWalk(km) { const d = walkDays(km); return `${num(d, d < 10 ? 1 : 0)} days on foot`; }
+export const fmtLatLon = (lat, lon) =>
+  `${Math.abs(lat).toFixed(3)}° ${lat >= 0 ? 'N' : 'S'}, ${Math.abs(lon).toFixed(3)}° ${lon >= 0 ? 'E' : 'W'}`;
+export function niceKm(km) {
+  const p = 10 ** Math.floor(Math.log10(km));
+  return p * [1, 2, 5].findLast(m => m * p <= km * (1 + 1e-12));
+}
-- 
cgit