feat: add Nepal flood incident scene

src/data/bhoteKoshiShotPaths.js

@@ -0,0 +1,65 @@
+import { BHOTE_KOSHI_FLOOD_PATH } from './bhoteKoshiFloodPath.js';
+
+export const SOURCE_PATH_BEAT_IDS = Object.freeze([
+  'debris-dammed-lake', 'second-landslide', 'dhunche',
+  'mailung-upper-trishuli', 'mailung-bazzar', 'dandagaun',
+  'dandagaun-viewpoint', 'betrawati-bazaar', 'bhainse', 'bidur-trishuli-bridge',
+]);
+
+function nearestVertex(point, route) {
+  if (!point || !Number.isFinite(point.lon) || !Number.isFinite(point.lat)) return -1;
+  const longitudeScale = Math.cos(point.lat * Math.PI / 180);
+  let nearest = -1;
+  let distance = 1000; // Witness viewpoints can sit beside the river, not on it.
+  route.forEach(([lon, lat], index) => {
+    const metres = Math.hypot((lon - point.lon) * longitudeScale, lat - point.lat) * 111195;
+    if (metres < distance) { distance = metres; nearest = index; }
+  });
+  return nearest;
+}
+
+/** Split the already-bundled GeoPera centreline; never connect witness pins. */
+export function buildSourceShotPaths(event, route = BHOTE_KOSHI_FLOOD_PATH) {
+  const observations = new Map((event.evidenceSpine || []).map((point) => [point.id, point]));
+  const result = new Map();
+  const add = (id, from, to, { joinComparison = false } = {}) => {
+    let start = nearestVertex(from, route);
+    const end = nearestVertex(to, route);
+    if (start < 0 || end <= start) return;
+    const startHeight = from.fallbackElevationM ?? from.elevationM;
+    const endHeight = to.fallbackElevationM ?? to.elevationM;
+    if (!Number.isFinite(startHeight) || !Number.isFinite(endHeight)) return;
+    if (joinComparison) {
+      // The raster corridor ends between simplified centreline vertices.
+      // Snapping to its nearest vertex can move the head upstream on entry.
+      // Keep that already-sourced endpoint and continue to the next vertex
+      // downstream of it, rather than replaying the upstream half-segment.
+      const [lon, lat] = route[start];
+      const [nextLon, nextLat] = route[start + 1];
+      const scale = Math.cos(from.lat * Math.PI / 180);
+      const along = (from.lon - lon) * (nextLon - lon) * scale * scale
+        + (from.lat - lat) * (nextLat - lat);
+      if (along > 0) start++;
+    }
+    const coordinates = route.slice(start, end + 1);
+    if (joinComparison && (coordinates[0][0] !== from.lon || coordinates[0][1] !== from.lat)) {
+      coordinates.unshift([from.lon, from.lat]);
+    }
+    result.set(id, coordinates.map(([lon, lat], index) => ({
+      lon, lat,
+      // Stable source profile for explicit source-elevation shots; otherwise a
+      // fallback when neither rendered mesh nor elevation terrain can be sampled.
+      fallbackElevationM: startHeight + (endHeight - startHeight) * index / (coordinates.length - 1),
+    })));
+  };
+  add('debris-dammed-lake', observations.get('debris-dammed-lake'), observations.get('second-landslide'));
+  add('second-landslide', observations.get('second-landslide'), observations.get('gyirong-border-gate'));
+  let previous = event.reconstruction?.corridor?.at(-1);
+  for (const id of SOURCE_PATH_BEAT_IDS.slice(2)) {
+    const point = observations.get(id);
+    add(id, previous, point, { joinComparison: id === 'dhunche' });
+    // Missing coverage breaks continuity rather than inventing a long connector.
+    previous = point;
+  }
+  return result;
+}