Reuse aircraft render times and extrapolation frames

src/layers/flights/motion.test.mjs

@@ -0,0 +1,184 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import * as Cesium from 'cesium';
+import { createMotion } from './motion.js';
+import { arcOffsetEnu } from '../../data/motionModel.js';
+
+function fixture() {
+  const flightState = {
+    records: { data: new Map() },
+    _positionHistory: new Map(),
+    _focusEvidenceIds: new Set(),
+    _scratchArc: {},
+    _scratchOffset: new Cesium.Cartesian3(),
+    _scratchRenderTime: new Cesium.JulianDate(),
+  };
+  const motion = createMotion({
+    flightState,
+    services: { groundFloor: {}, camera: {}, focus: {} },
+    parts: {},
+  });
+  return { flightState, motion };
+}
+
+function expectedPosition(fix, dt, turnRate, transform) {
+  const arc = {};
+  arcOffsetEnu(fix.velocity, fix.track, turnRate, dt, arc);
+  return Cesium.Matrix4.multiplyByPoint(
+    transform(fix.position, Cesium.Ellipsoid.WGS84, new Cesium.Matrix4()),
+    new Cesium.Cartesian3(arc.east, arc.north, 0),
+    new Cesium.Cartesian3(),
+  );
+}
+
+function close(actual, expected) {
+  assert.ok(Cesium.Cartesian3.distance(actual, expected) < 1e-8);
+}
+
+test('extrapolation reuses fixed frames and invalidates corrected coordinates', (t) => {
+  const { motion } = fixture();
+  const transform = Cesium.Transforms.eastNorthUpToFixedFrame;
+  const spy = t.mock.method(
+    Cesium.Transforms,
+    'eastNorthUpToFixedFrame',
+    transform,
+  );
+  const fix = {
+    position: Cesium.Cartesian3.fromDegrees(-97, 30, 200),
+    velocity: 90,
+    track: 70,
+  };
+  const out = new Cesium.Cartesian3();
+  for (const dt of [-30, 5, 30, 60]) {
+    motion._extrapolateFix(fix, {}, dt, out, 1.5);
+    close(out, expectedPosition(fix, dt, 1.5, transform));
+  }
+  assert.equal(spy.mock.callCount(), 1);
+
+  // Ground reflooring mutates an existing fix's Cartesian in place.
+  Cesium.Cartesian3.fromDegrees(-97, 30, 350, undefined, fix.position);
+  motion._extrapolateFix(fix, {}, 30, out, 1.5);
+  close(out, expectedPosition(fix, 30, 1.5, transform));
+  assert.equal(spy.mock.callCount(), 2);
+
+  fix.position = Cesium.Cartesian3.fromDegrees(140, 80, 1000);
+  motion._extrapolateFix(fix, {}, 30, out, -2);
+  close(out, expectedPosition(fix, 30, -2, transform));
+  assert.equal(spy.mock.callCount(), 3);
+
+  fix.velocity = 210;
+  fix.track = 359;
+  motion._extrapolateFix(fix, {}, 15, out, -1);
+  close(out, expectedPosition(fix, 15, -1, transform));
+  assert.equal(spy.mock.callCount(), 3);
+
+  const replacement = { ...fix };
+  motion._extrapolateFix(replacement, {}, 15, out, -1);
+  close(out, expectedPosition(replacement, 15, -1, transform));
+  assert.equal(spy.mock.callCount(), 4);
+});
+
+test('stationary fixes do not build a frame until motion needs it', (t) => {
+  const { motion } = fixture();
+  const spy = t.mock.method(Cesium.Transforms, 'eastNorthUpToFixedFrame');
+  const fix = {
+    position: Cesium.Cartesian3.fromDegrees(0, 0, 0),
+    velocity: 0,
+    track: 90,
+  };
+  const out = new Cesium.Cartesian3();
+  close(motion._extrapolateFix(fix, {}, 30, out), fix.position);
+  fix.velocity = 10;
+  close(motion._extrapolateFix(fix, {}, 0, out), fix.position);
+  assert.equal(spy.mock.callCount(), 0);
+  motion._extrapolateFix(fix, {}, 30, out);
+  assert.equal(spy.mock.callCount(), 1);
+});
+
+test('fleet render time is shared without resampling or mutating the supplied instant', (t) => {
+  const { flightState, motion } = fixture();
+  const start = Cesium.JulianDate.fromIso8601('2026-10-24T12:00:00Z');
+  const end = Cesium.JulianDate.addSeconds(start, 60, new Cesium.JulianDate());
+  const renderTime = Cesium.JulianDate.addSeconds(
+    start,
+    30,
+    new Cesium.JulianDate(),
+  );
+  const savedTime = Cesium.JulianDate.clone(renderTime);
+  const history = [
+    {
+      time: start,
+      position: Cesium.Cartesian3.fromDegrees(-97, 30, 1000),
+      track: 90,
+    },
+    {
+      time: end,
+      position: Cesium.Cartesian3.fromDegrees(-96.99, 30, 1000),
+      track: 90,
+    },
+  ];
+  for (const id of ['one', 'two']) {
+    flightState.records.data.set(id, { velocity: 100, true_track: 90 });
+    flightState._positionHistory.set(id, history);
+  }
+  t.mock.method(Cesium.JulianDate, 'now', () => {
+    throw new Error('unexpected per-contact clock read');
+  });
+  const expected = Cesium.Cartesian3.lerp(
+    history[0].position,
+    history[1].position,
+    0.5,
+    new Cesium.Cartesian3(),
+  );
+  for (const id of ['one', 'two'])
+    close(
+      motion._deadReckon(id, new Cesium.Cartesian3(), renderTime),
+      expected,
+    );
+  assert.ok(Cesium.JulianDate.equals(renderTime, savedTime));
+});
+
+test('tracked callers still sample a fresh delayed time without a fleet epoch', (t) => {
+  const { flightState, motion } = fixture();
+  const start = Cesium.JulianDate.fromIso8601('2026-10-24T12:00:00Z');
+  const history = [
+    {
+      time: start,
+      position: Cesium.Cartesian3.fromDegrees(-97, 30, 1000),
+      track: 90,
+    },
+    {
+      time: Cesium.JulianDate.addSeconds(start, 60, new Cesium.JulianDate()),
+      position: Cesium.Cartesian3.fromDegrees(-96.99, 30, 1000),
+      track: 90,
+    },
+  ];
+  flightState.records.data.set('tracked', { velocity: 100, true_track: 90 });
+  flightState._positionHistory.set('tracked', history);
+  let elapsed = 60;
+  const spy = t.mock.method(Cesium.JulianDate, 'now', (result) => {
+    assert.equal(result, flightState._scratchRenderTime);
+    return Cesium.JulianDate.addSeconds(start, elapsed, result);
+  });
+  const out = new Cesium.Cartesian3();
+  close(
+    motion._deadReckon('tracked', out),
+    Cesium.Cartesian3.lerp(
+      history[0].position,
+      history[1].position,
+      0.5,
+      new Cesium.Cartesian3(),
+    ),
+  );
+  elapsed = 75;
+  close(
+    motion._deadReckon('tracked', out),
+    Cesium.Cartesian3.lerp(
+      history[0].position,
+      history[1].position,
+      0.75,
+      new Cesium.Cartesian3(),
+    ),
+  );
+  assert.equal(spy.mock.callCount(), 2);
+});