From 3ce3fce46f5ffd8bfdae8dd9cb153949b8ba4d35 Mon Sep 17 00:00:00 2001
From: Sameh Khamis <sameh@halfpixel.ai>
Date: Sun, 8 Nov 2026 13:25:55 -0800
Subject: [PATCH] fix(cockpit): the bridge reads its floor where the ship is
 now

The ground clamp read the floor at the ship's last AIS fix while the camera
rode that fix dead-reckoned up to 180 s ahead, so a quay or bridge deck at
the old position could lift the eye. Vessels now read the floor at the
dead-reckoned target, as the water read already does; aircraft are
unchanged.
---
 src/ui/cockpitBridge.test.mjs | 21 +++++++++++++++++++++
 src/ui/cockpitCamera.js       | 13 +++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/ui/cockpitBridge.test.mjs b/src/ui/cockpitBridge.test.mjs
index 1273b5617..b73ff2a1f 100644
--- a/src/ui/cockpitBridge.test.mjs
+++ b/src/ui/cockpitBridge.test.mjs
@@ -1077,6 +1077,27 @@ test('the water is read where the ship is now, not at its last report', async (t
   assert.ok(eastM > 300 && eastM < 450, `probed ${eastM.toFixed(0)} m east`);
 });
 
+test('the bridge floor is read where the ship is now, not at its last report', async (t) => {
+  const clock = manualClock(t, START_MS);
+  // Reported a minute ago at 12 kn on course 095: since then ~370 m east.
+  const record = { ...RECORD, lastPositionEpoch: (START_MS - 60_000) / 1000 };
+  const ship = fixture(t, { record });
+  const floors = [];
+  const cached = ship.cockpit.services.cachedGroundFloor;
+  ship.cockpit.services.cachedGroundFloor = (lat, lon) => {
+    floors.push({ lat, lon });
+    return cached(lat, lon);
+  };
+  ship.cockpit.enter();
+  await settle();
+  frames(ship.cockpit, clock, ship.shots, 20);
+  const first = floors[0];
+  assert.ok(first, 'the floor was read');
+  const eastM =
+    (first.lon - RECORD.lon) * 111_320 * Math.cos((RECORD.lat * Math.PI) / 180);
+  assert.ok(eastM > 300 && eastM < 450, `read ${eastM.toFixed(0)} m east`);
+});
+
 test('the radar centres where the camera rides, not at the last report', async (t) => {
   const clock = manualClock(t, START_MS);
   // Reported a minute ago at 12 kn on course 095: since then ~370 m east.
diff --git a/src/ui/cockpitCamera.js b/src/ui/cockpitCamera.js
index fd076663c..2a70ef280 100644
--- a/src/ui/cockpitCamera.js
+++ b/src/ui/cockpitCamera.js
@@ -401,9 +401,18 @@ function placeCamera(target, info, nowMs, dtSec, profile, look = null) {
     Cesium.Ellipsoid.WGS84,
     this.scratchTargetCartographic,
   );
+  // A bridge's target is its fix dead-reckoned up to minutes ahead: read
+  // the floor where the ship is now, as its water is.
+  const floorAt =
+    info.kind === 'vessel'
+      ? {
+          latitude: Cesium.Math.toDegrees(targetCartographic.latitude),
+          longitude: Cesium.Math.toDegrees(targetCartographic.longitude),
+        }
+      : info;
   let cockpitFloorM = this.services.cachedGroundFloor(
-    info.latitude,
-    info.longitude,
+    floorAt.latitude,
+    floorAt.longitude,
   );
   if (info.onGround === true) {
     const groundPoint = [{ lat: info.latitude, lon: info.longitude }];