fix(geo): wrap longitude differences across the antimeridian in point distances (#1304)

Wrap longitude differences in annotation proximity checks and nearby-place distances so points across the antimeridian remain close.

Original contribution by quanticsoul4772.

Co-authored-by: quanticsoul4772 <[email protected]>

changelog.d/1304-antimeridian-distances.md

@@ -0,0 +1,2 @@
+- Point distances wrap longitude differences across the antimeridian, in voice
+  proximity checks and `places_nearby` (quanticsoul4772, #1304).

docs/CURRENT-STATE.md

@@ -5515,6 +5515,11 @@ easier to meet (detection is now on more often), but does not create it.
   short-way-round longitude span and wraps the padded edges, so a dateline-
   crossing box stays its true width. Raw subtraction inflated a 0.41° metro box
   to 86.7° and a 60° territory to 132°.
+- **Point distances take the short way round 180°.** The annotation
+  resolver's `approximateDistanceM` (voice "point out" proximity checks) and
+  `places_nearby` distances wrap the longitude difference. Raw subtraction put
+  Savusavu 38,148 km from a camera over the Lau Islands, so the proximity check
+  refused it, and sorted a place 2 km across 180° last.
 - CCTV calibration persists at `godsEyeView.cctv.calibration.v2` (v2 rebuild;
   the store was wiped clean, no import from the old `v1` key).
 - CCTV v3 floor QA pins are: zero samples for heading-only edits; zero transient

src/data/placeProviderPayloads.js

@@ -13,8 +13,11 @@ function approximateDistanceM(latA, lonA, latB, lonB) {
     return Number.MAX_SAFE_INTEGER;
   const latitudeScale = 111320;
   const longitudeScale = latitudeScale * Math.cos((latA * Math.PI) / 180);
+  // The short way round, so places either side of 180° stay close.
+  let dLon = lonB - lonA;
+  dLon -= 360 * Math.round(dLon / 360);
   return Math.round(
-    Math.hypot((latB - latA) * latitudeScale, (lonB - lonA) * longitudeScale),
+    Math.hypot((latB - latA) * latitudeScale, dLon * longitudeScale),
   );
 }
 

src/sources/featureGeometry.js

@@ -250,10 +250,13 @@ export function approximateAreaM2(coords) {
   return Math.abs(area) / 2;
 }
 
+/** Local equirectangular distance in metres, the short way round 180°. */
 export function approximateDistanceM(latA, lonA, latB, lonB) {
   const latScale = 111_320;
   const lonScale = latScale * Math.cos(((latA + latB) / 2) * (Math.PI / 180));
-  return Math.hypot((latB - latA) * latScale, (lonB - lonA) * lonScale);
+  let dLon = lonB - lonA;
+  dLon -= 360 * Math.round(dLon / 360);
+  return Math.hypot((latB - latA) * latScale, dLon * lonScale);
 }
 
 export function pointInPolygon(lon, lat, coords) {

src/sources/featureGeometry.test.mjs

@@ -0,0 +1,15 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { approximateDistanceM } from './featureGeometry.js';
+
+test('approximate distance takes the short way round 180°', () => {
+  // Lau Islands (-179.0) to Savusavu (179.33): about 178 km apart.
+  const across = approximateDistanceM(-17.5, -179.0, -16.78, 179.33);
+  assert.ok(across > 150_000 && across < 200_000, String(across));
+  assert.equal(
+    Math.round(approximateDistanceM(0, 179.9, 0, -179.9)),
+    Math.round(approximateDistanceM(0, -0.1, 0, 0.1)),
+  );
+  // Away from 180° nothing changes.
+  assert.equal(Math.round(approximateDistanceM(0, 0, 0, 1)), 111_320);
+});

src/tooling/placeProviders.test.mjs

@@ -81,6 +81,24 @@ test('nearby labels rank landmarks, deduplicate names/addresses and bound the pr
   assert.deepEqual(projectNearbyPlaces({}, 0, 0), []);
 });
 
+test('nearby place distances take the short way round 180°', () => {
+  const at = (name, longitude) => ({
+    id: name,
+    displayName: { text: name },
+    location: { latitude: -16.8, longitude },
+    types: ['point_of_interest'],
+  });
+  // From Taveuni at 179.98: 2 km east across 180°, 4 km west on this side.
+  const result = projectNearbyPlaces(
+    { places: [at('West', 179.942), at('East', -179.999)] },
+    -16.8,
+    179.98,
+  );
+  const byName = Object.fromEntries(result.map((p) => [p.name, p.distanceM]));
+  assert.ok(byName.East > 1500 && byName.East < 2500, String(byName.East));
+  assert.ok(byName.West > 3500 && byName.West < 4500, String(byName.West));
+});
+
 test('text search preserves bounds, rejects malformed bounds and tolerates absent locations', () => {
   const viewport = {
     low: { latitude: 1, longitude: 2 },