fix: load scene over HTTP so tracking no longer depends on the WebSocket; HUD shows scene state and detected-vs-usable crests

public/js/exhibit.js

@@ -52,8 +52,10 @@ let detector, poseEst, fuser, cvSolver;
 let gradients = {}, modelManifest = null, characters = { defaults: {}, byId: {} };
 let ghostHeight = 4; // cm, from scene.ghostHeightCm
 const activeGhosts = new Map(); // uid -> { rec, group }
-let tracking = { markers: 0, lastSeen: 0 };
+let tracking = { markers: 0, raw: 0, rawIds: [], lastSeen: 0 };
 let netRef = null;
+let sceneLoaded = false;
+let anchorCount = 0;
 const rxLog = [];   // last few WS message types, newest last
 function rxTrace(t) { rxLog.push(t); if (rxLog.length > 6) rxLog.shift(); }
 const clockOffsetSamples = [];
@@ -71,7 +73,7 @@ let dbgPose = '';
 function dbgStatus() {
   const ws = netRef && netRef.ws ? ['conn','open','closing','closed'][netRef.ws.readyState] : 'none';
   return `ws ${ws}  rx ${rxLog.join(',') || '-'}\n` +
-         `ghost recs ${activeGhosts.size}\n`;
+         `scene ${sceneLoaded ? anchorCount + ' anchors' : 'NOT LOADED'}  ghost recs ${activeGhosts.size}\n`;
 }
 function paintDbg() { if (dbgEl) dbgEl.textContent = dbgStatus() + dbgPose + dbgAim; }
 
@@ -123,7 +125,7 @@ function updateDbg(fusedQuat, markerCount, extra) {
   dbgPose =
     `eng ${engine}  ${freezeGhosts ? 'FROZEN' : 'moving'}\n` +
     `${modeLine}\n` +
-    `markers ${markerCount}${extra}\n${rawLine}\nview ${v3(view)}\nup   ${v3(up)}\n` +
+    `markers ${markerCount}/${tracking.raw} seen [${tracking.rawIds.join(',')}]${extra}\n${rawLine}\nview ${v3(view)}\nup   ${v3(up)}\n` +
     `pos  ${v3(camera3.position)}`;
   paintDbg();
 }
@@ -222,6 +224,13 @@ async function start() {
   cvSolver = new CvBoardSolver();
   ensureOpenCV();
 
+  // scene over HTTP so tracking works even if the WebSocket is down
+  try {
+    applyScene(await (await fetch('/api/scene')).json());
+  } catch (e) {
+    reportError({ kind: 'scene', msg: `scene fetch failed: ${(e && e.message) || e}` });
+  }
+
   // dev-mode pose readout + tap-to-cycle modes
   if (info.mode === 'dev') {
     freezeGhosts = true;   // start static so tracking jitter is isolated from ghost float
@@ -266,11 +275,7 @@ async function start() {
   const net = new ExhibitNet();
   netRef = net;
   const on = (t, fn) => net.on(t, (m) => { rxTrace(t); return fn(m); });
-  on('scene', (m) => {
-       fuser.setScene(m.scene); cvSolver.setScene(m.scene); buildOcclusion(m.scene);
-       ghostHeight = m.scene.ghostHeightCm || 4;
-       for (const e of activeGhosts.values()) e.group.userData.setHeight(ghostHeight);
-     });
+  on('scene', (m) => applyScene(m.scene));
   on('characters', async (m) => {
        characters = m.characters || characters;
        const recs = [...activeGhosts.values()].map(e => e.rec);
@@ -301,6 +306,22 @@ function onResize() {
   camera3.updateProjectionMatrix();
 }
 
+/* Scene application. Tracking must NOT depend on the WebSocket: detection filters
+ * against the scene's marker IDs, so if the socket is slow or flapping the crest
+ * is detected and then silently discarded ("Point at a Newbury Crest" forever).
+ * We therefore load the scene over plain HTTP at start; the WS message just
+ * refreshes it when an operator edits the layout. */
+function applyScene(scene) {
+  if (!scene) return;
+  sceneLoaded = true;
+  anchorCount = (scene.anchors || []).filter(a => a.enabled !== false).length;
+  fuser.setScene(scene);
+  cvSolver.setScene(scene);
+  buildOcclusion(scene);
+  ghostHeight = scene.ghostHeightCm || 4;
+  for (const e of activeGhosts.values()) e.group.userData.setHeight(ghostHeight);
+}
+
 // ---------- occlusion: invisible depth-only building volumes ----------
 const occlusionGroup = new THREE.Group();
 function buildOcclusion(scene) {
@@ -374,6 +395,8 @@ function loop(t) {
 
     const markers = detectMarkers(detector, img, fuser.knownIds());
     tracking.markers = markers.length;
+    tracking.raw = markers.rawCount || 0;
+    tracking.rawIds = markers.rawIds || [];
     if (dbgEl) updateAim(markers, W, H);
     if (markers.length) {
       tracking.lastSeen = performance.now();
@@ -421,7 +444,11 @@ function loop(t) {
   if ((frameCount++ & 15) === 0) {
     paintDbg();
     const stale = performance.now() - tracking.lastSeen > 1500;
-    $('#trk').textContent = stale ? 'Point at a Newbury Crest' : `Tracking ${tracking.markers} crest${tracking.markers === 1 ? '' : 's'}`;
+    $('#trk').textContent = !stale
+      ? `Tracking ${tracking.markers} crest${tracking.markers === 1 ? '' : 's'}`
+      : (tracking.raw > 0
+          ? `Crest ${tracking.rawIds.join(',')} not in this layout`   // detected, but no anchor for it
+          : 'Point at a Newbury Crest');
     $('#trk').classList.toggle('warn', stale || tracking.markers < 2);
     $('#cnt').textContent = `${activeGhosts.size} ghost${activeGhosts.size === 1 ? '' : 's'} nearby`;
   }