fix(globe): tighten the engine contract after review

Engine events get their own documented semantics (single registration,
branded instances); the fake follows Cesium's roll sign, angle ranges,
synchronous zero-duration flights, flyToSphere defaults and
computeViewRectangle. The contract adds viewProjection, horizonVisible,
flightActive, lookAtTransform/transform, zoomIn/zoomOut, input modifiers,
terrainHeight and clampToHeight, with geometric suite checks. Engine
import rules now follow each engine graph transitively.

docs/CODE-BOUNDARIES.md

@@ -67,8 +67,10 @@ platform names such as `document` and `window` in these modules; it is an
 architectural check, not a JavaScript sandbox. The globe contract
 (`src/globe/*.js` and `src/globe/testing/**`) cannot reach `cesium`,
 `@cesium/*`, `three`, `postprocessing` or `@navaramap/*`, directly or through
-helpers, nor import an engine implementation; `src/globe/cesium/**` imports no
-Navara/three package and `src/globe/navara/**` no Cesium package. Common voice controls cannot depend on a
+helpers, nor import an engine implementation; the `src/globe/cesium/**` graph
+reaches no Navara/three package or `src/globe/navara/**` module, and the
+`src/globe/navara/**` graph no Cesium package or `src/globe/cesium/**` module,
+through helpers too. Common voice controls cannot depend on a
 Realtime protocol implementation. Negative fixtures cover indirect helpers,
 self-package imports, symlinks and unreachable files.
 

scripts/check-import-directions.mjs

@@ -257,15 +257,28 @@ export function checkImportDirections(root) {
     }
   }
   for (const file of files.filter(globeContract)) globe(file);
-  for (const file of files.filter(globeEngine)) {
-    const navara = file.startsWith('src/globe/navara/');
-    for (const specifier of load(file)?.external || []) {
-      if ((navara ? cesiumPackage : navaraPackage).test(specifier))
-        report(
-          file,
-          `${navara ? 'Navara' : 'Cesium'} globe engine imports ${specifier}`,
-        );
-    }
+  // Each engine graph stays on its own engine, through helpers too.
+  for (const start of files.filter(globeEngine)) {
+    const navara = start.startsWith('src/globe/navara/');
+    const label = navara ? 'Navara globe engine' : 'Cesium globe engine';
+    const foreignPackage = navara ? cesiumPackage : navaraPackage;
+    const foreignEngine = navara ? 'src/globe/cesium/' : 'src/globe/navara/';
+    const seen = new Set();
+    const visit = (file) => {
+      if (seen.has(file) || !code.test(file)) return;
+      seen.add(file);
+      const info = load(file);
+      if (!info) return;
+      for (const specifier of info.external)
+        if (foreignPackage.test(specifier))
+          report(file, `${label} reaches ${specifier}`);
+      for (const to of info.edges) {
+        if (to.startsWith(foreignEngine))
+          report(file, `${label} reaches ${to}`);
+        else visit(to);
+      }
+    };
+    visit(start);
   }
   // Common voice controls may use their DOM view, but never a protocol implementation.
   const voiceSeen = new Set();

src/globe/contract.js

@@ -1,30 +1,44 @@
 // The engine-neutral globe contract. The application shell talks to a globe
 // engine (Cesium today, Navara next) only through these small capability
-// objects. Positions are src/geo values, angles are radians and screen
-// coordinates are CSS pixels from the canvas's top-left corner. This module
-// and src/globe/testing/** never import cesium, three or @navaramap/*; see
-// docs/CODE-BOUNDARIES.md.
+// objects. Positions are src/geo values in Earth-fixed metres, angles are
+// radians and screen coordinates are CSS pixels from the canvas's top-left
+// corner. This module and src/globe/testing/** never import cesium, three or
+// @navaramap/*; see docs/CODE-BOUNDARIES.md.
 
 /**
  * @typedef {{ x: number, y: number }} Cartesian2
  * @typedef {{ x: number, y: number, z: number }} Cartesian3
  * @typedef {{ longitude: number, latitude: number, height: number }} Cartographic
+ * @typedef {number[]} Matrix4 16 numbers, column-major (m[column * 4 + row]).
  * @typedef {(...args: any[]) => void} Listener
  *
  * @typedef {object} EngineEvent
+ *   The contract's own event semantics (engines expose createEngineEvent()
+ *   instances, never a raw Cesium.Event):
+ *   - listeners run in registration order;
+ *   - adding a function that is already registered is a no-op (it stays
+ *     registered once and fires once), so re-initialisation cannot double-fire;
+ *   - a listener removed during dispatch is not called in that dispatch;
+ *   - a listener added during dispatch runs from the next dispatch, and one
+ *     removed then re-added during dispatch stays registered;
+ *   - every remover handle is idempotent and only removes the registration it
+ *     was returned for.
  * @property {(listener: Listener) => () => void} addEventListener
- *   Returns a function that removes this registration (idempotent).
  * @property {(listener: Listener) => boolean} removeEventListener
  *
  * @typedef {object} CameraPose
- * @property {Cartesian3} position
+ *   Angles follow Cesium's camera: heading in [0, 2π) clockwise from north,
+ *   pitch in [−π/2, π/2] (negative looks down), roll in [0, 2π) with positive
+ *   roll tilting `up` toward the camera's right; roll is 0 and heading follows
+ *   `up` when looking (nearly, within 1e-3) straight up or down.
+ * @property {Cartesian3} position World position (Cesium's positionWC).
  * @property {Cartographic} cartographic
  * @property {number} heading
  * @property {number} pitch
  * @property {number} roll
  * @property {Cartesian3} direction
  * @property {Cartesian3} up
- * @property {Cartesian3} right
+ * @property {Cartesian3} right direction × up
  * @property {number} fovy Vertical field of view.
  *
  * @typedef {{ heading: number, pitch: number, roll: number }
@@ -32,21 +46,49 @@
  *
  * @typedef {object} FlightOptions
  * @property {Cartesian3} destination
- * @property {Orientation} [orientation]
- * @property {number} [duration] Seconds; 0 lands on the next frame.
+ * @property {Orientation} [orientation] Missing angles keep the current ones.
+ * @property {number} [duration] Seconds. 0 (or less) sets the view and calls
+ *   `complete` synchronously, before flyTo returns, as Cesium does.
  * @property {'cubicInOut'|'sinusoidalInOut'|'linear'} [easing]
  * @property {() => void} [complete]
  * @property {() => void} [cancel] Called by cancelFlight or a newer flight.
  *
+ * @typedef {{ heading: number, pitch: number, range: number }} HeadingPitchRange
+ *   Offset from a target in its local east-north-up frame; the camera looks at
+ *   the target along heading/pitch from `range` metres away.
+ *
+ * @typedef {object} SphereFlightOptions
+ *   Defaults are Cesium's: heading 0, pitch −π/4 and, when range is missing or
+ *   0, range = max(r / tan(fovx/2), r / tan(fovy/2)), never below 100 m.
+ * @property {number} [heading]
+ * @property {number} [pitch]
+ * @property {number} [range]
+ * @property {number} [duration]
+ * @property {() => void} [complete]
+ * @property {() => void} [cancel]
+ *
  * @typedef {object} GlobeCamera
  * @property {() => CameraPose} pose Fresh values on every call.
  * @property {(view: { destination: Cartesian3, orientation?: Orientation }) => void} setView
- * @property {(options: FlightOptions) => void} flyTo
- * @property {(sphere: { center: Cartesian3, radius: number }, options?: { heading?: number, pitch?: number, range?: number, duration?: number, complete?: () => void, cancel?: () => void }) => void} flyToSphere
- * @property {(target: Cartesian3, offset: { heading: number, pitch: number, range: number }) => void} lookAt
- * @property {() => void} release Leaves lookAt (Cesium's lookAtTransform(IDENTITY)).
+ * @property {(options: FlightOptions) => void} flyTo Cancels a running flight first.
+ * @property {(sphere: { center: Cartesian3, radius: number }, options?: SphereFlightOptions) => void} flyToSphere
+ *   Ends unlocked (identity transform).
+ * @property {() => boolean} flightActive
+ * @property {(target: Cartesian3, offset: HeadingPitchRange) => void} lookAt
+ *   lookAtTransform(eastNorthUp(target), offset).
+ * @property {(transform: Matrix4, offset?: HeadingPitchRange | Cartesian3) => void} lookAtTransform
+ *   Locks the camera to `transform`; a Cartesian3 offset is the camera position
+ *   in that frame, looking at its origin with the frame's +Z as "up". Without
+ *   an offset the camera keeps its world pose.
+ * @property {() => Matrix4} transform A copy of the current camera transform.
+ * @property {() => void} release lookAtTransform(IDENTITY).
  * @property {() => void} cancelFlight
+ * @property {(amount?: number) => void} zoomIn Moves `amount` metres along direction.
+ * @property {(amount?: number) => void} zoomOut Moves `amount` metres against direction.
  * @property {() => ({ west: number, south: number, east: number, north: number } | undefined)} viewRectangle
+ *   Cesium's computeViewRectangle: undefined when the globe is out of view;
+ *   west > east across the antimeridian; ±π longitudes and a ±π/2 latitude
+ *   over a pole; the whole globe when fewer than two canvas corners hit it.
  * @property {(screen: Cartesian2) => (Cartesian3 | undefined)} pickEllipsoid
  * @property {(screen: Cartesian2) => { origin: Cartesian3, direction: Cartesian3 }} pickRay
  * @property {EngineEvent} changed Listener receives the change fraction.
@@ -55,18 +97,51 @@
  * @property {number} percentageChanged
  *
  * @typedef {'click'|'doubleClick'|'move'|'down'|'up'} InputType
+ * @typedef {'ctrl'|'shift'|'alt'} InputModifier
  * @typedef {{ position?: Cartesian2, startPosition?: Cartesian2, endPosition?: Cartesian2 }} InputEvent
  *
+ * @typedef {object} GlobeProjector
+ * @property {(position: Cartesian3, result?: Cartesian2) => (Cartesian2 | undefined)} worldToWindow
+ *   Undefined behind the camera; fills and returns `result` when given.
+ * @property {(result?: Matrix4) => Matrix4} viewProjection
+ *   World → clip matrix consistent with worldToWindow: clip = M·[x, y, z, 1],
+ *   in front when clip.w > 0, window = ((clip.x/clip.w + 1)/2 · width,
+ *   (1 − clip.y/clip.w)/2 · height).
+ * @property {(position: Cartesian3) => boolean} horizonVisible
+ *   False when the WGS84 ellipsoid hides the point from the camera
+ *   (Cesium's EllipsoidalOccluder.isPointVisible).
+ *
+ * @typedef {object} GlobeSurface
+ * @property {(cartographic: Cartographic, exclude?: any[]) => (number | undefined)} sampleHeight
+ *   Height of the rendered scene (tiles, models) under a point.
+ * @property {boolean} supported Whether sampleHeight works.
+ * @property {(cartographic: Cartographic) => (number | undefined)} terrainHeight
+ *   Height of the terrain/globe surface only (Cesium's globe.getHeight).
+ * @property {boolean} terrainHeightSupported
+ * @property {(position: Cartesian3, exclude?: any[]) => (Cartesian3 | undefined)} clampToHeight
+ *   The position moved onto the rendered scene along the geodetic normal.
+ * @property {boolean} clampToHeightSupported
+ * @property {() => boolean} tilesLoaded
+ *
+ * @typedef {object} GlobeRender
+ * @property {() => void} request Renders a frame soon in request mode.
+ * @property {(enabled: boolean) => void} setContinuous
+ *   Owns whatever the engine needs to render every frame or only on request
+ *   (Cesium: requestRenderMode and maximumRenderTimeChange = Infinity).
+ * @property {() => boolean} isContinuous
+ *
  * @typedef {object} GlobeEngine
  * @property {'cesium'|'navara'} kind
  * @property {{ container: object, canvas: object, size: () => { width: number, height: number } }} host
  * @property {GlobeCamera} camera
  * @property {{ pick: (screen: Cartesian2, width?: number, height?: number) => ({ id: any, primitive: any } | undefined), drillPick: (screen: Cartesian2, limit?: number) => any[], pickPosition: (screen: Cartesian2) => (Cartesian3 | undefined), pickPositionSupported: boolean }} picker
- * @property {{ worldToWindow: (position: Cartesian3, result?: Cartesian2) => (Cartesian2 | undefined) }} projector
+ * @property {GlobeProjector} projector
  * @property {{ preUpdate: EngineEvent, preRender: EngineEvent, postRender: EngineEvent }} frames Listeners receive a timestamp in ms.
- * @property {{ request: () => void, setContinuous: (enabled: boolean) => void, isContinuous: () => boolean }} render
- * @property {{ sampleHeight: (cartographic: Cartographic, exclude?: any[]) => (number | undefined), supported: boolean, tilesLoaded: () => boolean }} surface
- * @property {{ on: (type: InputType, listener: (event: InputEvent) => void) => () => void, setCameraInputs: (enabled: boolean) => void }} input
+ * @property {GlobeRender} render
+ * @property {GlobeSurface} surface
+ * @property {{ on: (type: InputType, listener: (event: InputEvent) => void, options?: { modifier?: InputModifier }) => () => void, setCameraInputs: (enabled: boolean) => void }} input
+ *   As in Cesium, a listener with a modifier fires only while that key is
+ *   held and one without fires only while no modifier is held.
  * @property {{ addStatic: (html: string, options?: { onScreen?: boolean }) => () => void }} credits
  * @property {{ setBaseImagery: (source: object) => void, setTerrain: (source: object) => void, setPhotorealTiles: (source: object | null) => void, photorealActive: () => boolean }} maps
  *   Sources are maps/registry.js descriptions; the engine builds its own providers.
@@ -81,26 +156,30 @@ export const INPUT_TYPES = Object.freeze([
   'down',
   'up',
 ]);
+export const MODIFIERS = Object.freeze(['ctrl', 'shift', 'alt']);
 export const FLIGHT_EASINGS = Object.freeze([
   'cubicInOut',
   'sinusoidalInOut',
   'linear',
 ]);
 
+const ENGINE_EVENT = Symbol('gev.globe.engineEvent');
+
+/** Whether a value is an event made by createEngineEvent. */
+export const isEngineEvent = (value) =>
+  value != null && value[ENGINE_EVENT] === true;
+
 /**
- * An event with Cesium.Event semantics: listeners run in registration order,
- * removal during dispatch is deferred safely, and listeners added during
- * dispatch run from the next raise. `raiseEvent` is for engine implementations.
+ * An event with the contract's semantics (see EngineEvent). `raiseEvent` is
+ * for engine implementations; a listener that throws propagates, and the
+ * event stays usable.
  */
 export function createEngineEvent() {
   let entries = [];
   let depth = 0;
   let removedDuringRaise = false;
-  const compact = () => {
-    if (depth || !removedDuringRaise) return;
-    entries = entries.filter((entry) => entry.listener);
-    removedDuringRaise = false;
-  };
+  const active = (listener) =>
+    entries.find((entry) => entry.listener === listener);
   const removeEntry = (entry) => {
     if (!entry.listener) return false;
     entry.listener = null;
@@ -108,7 +187,7 @@ export function createEngineEvent() {
     else entries.splice(entries.indexOf(entry), 1);
     return true;
   };
-  return {
+  const event = {
     get numberOfListeners() {
       return entries.reduce(
         (count, entry) => count + (entry.listener ? 1 : 0),
@@ -118,16 +197,17 @@ export function createEngineEvent() {
     addEventListener(listener) {
       if (typeof listener !== 'function')
         throw new TypeError('Engine event listener must be a function');
-      const entry = { listener };
-      entries.push(entry);
+      let entry = active(listener);
+      if (!entry) {
+        entry = { listener };
+        entries.push(entry);
+      }
       return () => {
         removeEntry(entry);
       };
     },
     removeEventListener(listener) {
-      const entry = entries.find(
-        (candidate) => candidate.listener === listener,
-      );
+      const entry = active(listener);
       return entry ? removeEntry(entry) : false;
     },
     raiseEvent(...args) {
@@ -141,19 +221,20 @@ export function createEngineEvent() {
         }
       } finally {
         depth--;
-        compact();
+        if (!depth && removedDuringRaise) {
+          entries = entries.filter((entry) => entry.listener);
+          removedDuringRaise = false;
+        }
       }
     },
   };
+  Object.defineProperty(event, ENGINE_EVENT, { value: true });
+  return event;
 }
 
 const isFunction = (value) => typeof value === 'function';
 const isObject = (value) =>
   value != null && (typeof value === 'object' || typeof value === 'function');
-const isEvent = (value) =>
-  isObject(value) &&
-  isFunction(value.addEventListener) &&
-  isFunction(value.removeEventListener);
 const isBoolean = (value) => typeof value === 'boolean';
 const isNumber = (value) => typeof value === 'number' && Number.isFinite(value);
 
@@ -165,15 +246,20 @@ const SHAPE = {
     setView: isFunction,
     flyTo: isFunction,
     flyToSphere: isFunction,
+    flightActive: isFunction,
     lookAt: isFunction,
+    lookAtTransform: isFunction,
+    transform: isFunction,
     release: isFunction,
     cancelFlight: isFunction,
+    zoomIn: isFunction,
+    zoomOut: isFunction,
     viewRectangle: isFunction,
     pickEllipsoid: isFunction,
     pickRay: isFunction,
-    changed: isEvent,
-    moveStart: isEvent,
-    moveEnd: isEvent,
+    changed: isEngineEvent,
+    moveStart: isEngineEvent,
+    moveEnd: isEngineEvent,
     percentageChanged: isNumber,
   },
   picker: {
@@ -182,8 +268,16 @@ const SHAPE = {
     pickPosition: isFunction,
     pickPositionSupported: isBoolean,
   },
-  projector: { worldToWindow: isFunction },
-  frames: { preUpdate: isEvent, preRender: isEvent, postRender: isEvent },
+  projector: {
+    worldToWindow: isFunction,
+    viewProjection: isFunction,
+    horizonVisible: isFunction,
+  },
+  frames: {
+    preUpdate: isEngineEvent,
+    preRender: isEngineEvent,
+    postRender: isEngineEvent,
+  },
   render: {
     request: isFunction,
     setContinuous: isFunction,
@@ -192,6 +286,10 @@ const SHAPE = {
   surface: {
     sampleHeight: isFunction,
     supported: isBoolean,
+    terrainHeight: isFunction,
+    terrainHeightSupported: isBoolean,
+    clampToHeight: isFunction,
+    clampToHeightSupported: isBoolean,
     tilesLoaded: isFunction,
   },
   input: { on: isFunction, setCameraInputs: isFunction },

src/globe/contract.test.mjs

@@ -3,8 +3,10 @@ import test from 'node:test';
 import {
   ENGINE_KINDS,
   INPUT_TYPES,
+  MODIFIERS,
   assertGlobeEngine,
   createEngineEvent,
+  isEngineEvent,
 } from './contract.js';
 import { createFakeEngine } from './testing/fakeEngine.js';
 import {
@@ -44,7 +46,7 @@ test('engine event passes every argument and rejects non-functions', () => {
   assert.throws(() => event.addEventListener(null), TypeError);
 });
 
-test('removing listeners during dispatch is safe, as with Cesium.Event', () => {
+test('a listener removed during dispatch is not called in that dispatch', () => {
   const event = createEngineEvent();
   const seen = [];
   let removeLater;
@@ -76,23 +78,60 @@ test('listeners added during dispatch run from the next raise', () => {
   assert.deepEqual(seen, ['first', 'first', 'added']);
 });
 
-test('a listener can be added again after removal, and each handle removes its own entry', () => {
+test('adding the same listener twice registers it once; every remover handle is idempotent', () => {
   const event = createEngineEvent();
   let count = 0;
   const listener = () => count++;
   const first = event.addEventListener(listener);
-  first();
-  first();
   const second = event.addEventListener(listener);
-  const third = event.addEventListener(listener);
+  assert.equal(event.numberOfListeners, 1);
   event.raiseEvent();
-  assert.equal(count, 2);
+  assert.equal(count, 1);
   second();
+  second();
+  first();
   event.raiseEvent();
-  assert.equal(count, 3);
-  third();
+  assert.equal(count, 1);
+  assert.equal(event.numberOfListeners, 0);
+  const again = event.addEventListener(listener);
+  first();
   event.raiseEvent();
-  assert.equal(count, 3);
+  assert.equal(count, 2, 'a stale handle removed a newer registration');
+  again();
+  assert.equal(event.numberOfListeners, 0);
+});
+
+test('removing and re-adding a listener during dispatch leaves it registered', () => {
+  const event = createEngineEvent();
+  const seen = [];
+  const later = () => seen.push('later');
+  event.addEventListener(() => {
+    seen.push('first');
+    if (seen.length > 1) return;
+    event.removeEventListener(later);
+    event.addEventListener(later);
+  });
+  event.addEventListener(later);
+  event.raiseEvent();
+  assert.equal(event.numberOfListeners, 2);
+  event.raiseEvent();
+  assert.deepEqual(seen, ['first', 'first', 'later']);
+});
+
+test('engine events are branded so a raw Cesium.Event fails the shape check', () => {
+  assert.equal(isEngineEvent(createEngineEvent()), true);
+  const raw = { addEventListener() {}, removeEventListener() {} };
+  assert.equal(isEngineEvent(raw), false);
+  const engine = createFakeEngine();
+  assert.throws(
+    () =>
+      assertGlobeEngine({
+        ...engine,
+        frames: { ...engine.frames, preRender: raw },
+      }),
+    /frames\.preRender/,
+  );
+  assert.deepEqual(MODIFIERS, ['ctrl', 'shift', 'alt']);
 });
 
 test('a throwing listener does not leave the event stuck in dispatch', () => {
@@ -168,3 +207,32 @@ test('the contract suite reports failures of a misbehaving engine', async () =>
   assert.ok(failed.every((result) => result.error instanceof Error));
   assert.ok(results.some((result) => result.ok));
 });
+
+test('the contract suite rejects a raw Cesium-style event that double-registers', async () => {
+  const engine = createFakeEngine();
+  // Cesium.Event pushes a listener again when it is added twice.
+  const listeners = [];
+  const raw = {
+    addEventListener(listener) {
+      listeners.push(listener);
+      return () => raw.removeEventListener(listener);
+    },
+    removeEventListener(listener) {
+      const index = listeners.indexOf(listener);
+      if (index >= 0) listeners.splice(index, 1);
+      return index >= 0;
+    },
+  };
+  engine.frames.postRender.addEventListener((time) => {
+    for (const listener of [...listeners]) listener(time);
+  });
+  const wrapped = { ...engine, frames: { ...engine.frames, postRender: raw } };
+  const results = await runContractSuite(wrapped, {
+    waitFrames: async (count) => engine.fake.frames(count),
+  });
+  const failed = results.filter((result) => !result.ok).map((r) => r.name);
+  assert.ok(
+    failed.some((name) => /twice/.test(name)),
+    failed.join('\n'),
+  );
+});

src/globe/testing/contractSuite.mjs

@@ -10,9 +10,9 @@
 // Each check sets the view it needs; checks may leave the camera anywhere.
 
 import * as geo from '../../geo/index.js';
-import { INPUT_TYPES, assertGlobeEngine } from '../contract.js';
+import { INPUT_TYPES, MODIFIERS, assertGlobeEngine } from '../contract.js';
 
-const { cartesian2, cartesian3, cartographic, ellipsoid, math } = geo;
+const { cartesian2, cartesian3, cartographic, ellipsoid, math, matrix4 } = geo;
 const WGS84 = ellipsoid.WGS84;
 
 class ContractError extends Error {
@@ -42,6 +42,23 @@ const isCartesian3 = (value) =>
   Number.isFinite(value.y) &&
   Number.isFinite(value.z);
 
+// The local east/north/up axes at a position.
+function localAxes(position) {
+  const frame = geo.transforms.eastNorthUpToFixedFrame(position, WGS84);
+  return {
+    frame,
+    east: cartesian3.create(frame[0], frame[1], frame[2]),
+    north: cartesian3.create(frame[4], frame[5], frame[6]),
+    up: cartesian3.create(frame[8], frame[9], frame[10]),
+  };
+}
+
+const inRange = (value, low, high, label) =>
+  ensure(
+    typeof value === 'number' && value >= low && value < high,
+    `${label} ${value} is outside [${low}, ${high})`,
+  );
+
 const unit = (vector) => cartesian3.normalize(vector, cartesian3.create());
 const along = (origin, direction, distance) =>
   cartesian3.add(
@@ -313,7 +330,7 @@ export function createContractSuite(
       },
     ],
     [
-      'camera.flyTo: duration 0 lands on the destination and completes',
+      'camera.flyTo: duration 0 lands and completes before flyTo returns',
       async () => {
         await nadirView();
         const destination = cartesian3.fromDegrees(-3.7, 40.4, 50000);
@@ -325,8 +342,11 @@ export function createContractSuite(
           complete: () => outcome.push('complete'),
           cancel: () => outcome.push('cancel'),
         });
-        await until(() => outcome.length > 0, 'flight completion');
-        ensure(outcome.join() === 'complete', `flight ended with ${outcome}`);
+        ensure(
+          outcome.join() === 'complete',
+          `flyTo returned with [${outcome}] instead of [complete]`,
+        );
+        ensure(!camera.flightActive(), 'a duration-0 flight is still active');
         const pose = camera.pose();
         near(
           cartesian3.distance(pose.position, destination),
@@ -595,8 +615,30 @@ export function createContractSuite(
       },
     ],
     [
-      'surface: supported, tilesLoaded and sampleHeight shapes',
+      'surface: flags, tilesLoaded, sampleHeight, terrainHeight and clampToHeight shapes',
       async () => {
+        for (const flag of ['terrainHeightSupported', 'clampToHeightSupported'])
+          ensure(
+            typeof engine.surface[flag] === 'boolean',
+            `${flag} is not boolean`,
+          );
+        const place = cartographic.fromDegrees(20, 10, 0);
+        if (engine.surface.terrainHeightSupported) {
+          const terrain = engine.surface.terrainHeight(place);
+          ensure(
+            terrain === undefined || Number.isFinite(terrain),
+            `terrainHeight returned ${terrain}`,
+          );
+        }
+        if (engine.surface.clampToHeightSupported) {
+          const clamped = engine.surface.clampToHeight(
+            cartesian3.fromDegrees(20, 10, 5000),
+          );
+          ensure(
+            clamped === undefined || isCartesian3(clamped),
+            'clampToHeight is not a Cartesian3',
+          );
+        }
         ensure(
           typeof engine.surface.supported === 'boolean',
           'supported is not boolean',
@@ -619,13 +661,15 @@ export function createContractSuite(
       'input: every type subscribes and unsubscribes; camera inputs toggle',
       async () => {
         for (const type of INPUT_TYPES) {
-          const off = engine.input.on(type, () => {});
-          ensure(
-            typeof off === 'function',
-            `input.on('${type}') returned no remover`,
-          );
-          off();
-          off();
+          for (const modifier of [undefined, ...MODIFIERS]) {
+            const off = engine.input.on(type, () => {}, { modifier });
+            ensure(
+              typeof off === 'function',
+              `input.on('${type}', ${modifier}) returned no remover`,
+            );
+            off();
+            off();
+          }
         }
         engine.input.setCameraInputs(false);
         engine.input.setCameraInputs(true);
@@ -652,6 +696,457 @@ export function createContractSuite(
         );
       },
     ],
+    [
+      'events: adding a listener twice registers it once',
+      async () => {
+        let once = 0;
+        let twice = 0;
+        const reference = () => once++;
+        const listener = () => twice++;
+        const removers = [
+          engine.frames.postRender.addEventListener(reference),
+          engine.frames.postRender.addEventListener(listener),
+          engine.frames.postRender.addEventListener(listener),
+        ];
+        try {
+          await until(() => once >= 2, 'postRender');
+        } finally {
+          for (const remove of removers) remove();
+        }
+        ensure(
+          twice === once,
+          `a listener added twice fired ${twice} times in ${once} frames`,
+        );
+        removers[1]();
+        removers[2]();
+        await settle(2);
+        ensure(twice === once, 'a removed listener still fired');
+      },
+    ],
+    [
+      'events: removal during dispatch skips the listener; re-adding keeps it',
+      async () => {
+        const event = engine.frames.postRender;
+        const seen = [];
+        const victim = () => seen.push('victim');
+        const survivor = () => seen.push('survivor');
+        let dispatches = 0;
+        const remover = () => {
+          dispatches++;
+          if (dispatches !== 1) return;
+          event.removeEventListener(victim);
+          event.removeEventListener(survivor);
+          event.addEventListener(survivor);
+        };
+        event.addEventListener(remover);
+        event.addEventListener(victim);
+        event.addEventListener(survivor);
+        try {
+          await until(() => dispatches >= 3, 'three postRender dispatches');
+        } finally {
+          for (const listener of [remover, victim, survivor])
+            event.removeEventListener(listener);
+        }
+        ensure(
+          !seen.includes('victim'),
+          'a listener removed during dispatch ran',
+        );
+        ensure(
+          seen.includes('survivor'),
+          'a listener removed and re-added during dispatch was lost',
+        );
+      },
+    ],
+    [
+      'camera.pose: angle ranges follow Cesium',
+      async () => {
+        const destination = cartesian3.fromDegrees(30, 20, 20000);
+        camera.setView({
+          destination,
+          orientation: { heading: -0.5, pitch: -0.4, roll: -0.2 },
+        });
+        await settle();
+        let pose = camera.pose();
+        inRange(pose.heading, 0, math.TWO_PI, 'heading');
+        inRange(pose.roll, 0, math.TWO_PI, 'roll');
+        near(pose.heading, math.TWO_PI - 0.5, 1e-6, 'heading of −0.5');
+        near(pose.roll, math.TWO_PI - 0.2, 1e-6, 'roll of −0.2');
+        ensure(
+          pose.pitch >= -math.PI_OVER_TWO && pose.pitch <= math.PI_OVER_TWO,
+          `pitch ${pose.pitch} outside [−π/2, π/2]`,
+        );
+        camera.setView({
+          destination,
+          orientation: { heading: 0.7, pitch: -math.PI_OVER_TWO, roll: 0.3 },
+        });
+        await settle();
+        pose = camera.pose();
+        near(pose.roll, 0, 0, 'roll looking straight down');
+        inRange(pose.heading, 0, math.TWO_PI, 'heading looking straight down');
+      },
+    ],
+    [
+      'camera.setView: heading π/2 at pitch 0 looks east',
+      async () => {
+        const destination = cartesian3.fromDegrees(-120, 35, 3000);
+        camera.setView({
+          destination,
+          orientation: { heading: math.PI_OVER_TWO, pitch: 0, roll: 0 },
+        });
+        await settle();
+        const pose = camera.pose();
+        const axes = localAxes(pose.position);
+        near(
+          cartesian3.dot(pose.direction, axes.east),
+          1,
+          1e-6,
+          'direction·east',
+        );
+        near(cartesian3.dot(pose.up, axes.up), 1, 1e-6, 'up·localUp');
+      },
+    ],
+    [
+      'camera.setView: pitch −π/2 looks down the local up',
+      async () => {
+        const destination = cartesian3.fromDegrees(-120, 35, 3000);
+        camera.setView({
+          destination,
+          orientation: { heading: 0, pitch: -math.PI_OVER_TWO, roll: 0 },
+        });
+        await settle();
+        const pose = camera.pose();
+        const axes = localAxes(pose.position);
+        near(cartesian3.dot(pose.direction, axes.up), -1, 1e-6, 'direction·up');
+        near(
+          cartesian3.dot(pose.up, axes.north),
+          1,
+          1e-6,
+          'up·north at heading 0',
+        );
+      },
+    ],
+    [
+      'camera.setView: positive roll tilts up toward the camera right',
+      async () => {
+        const destination = cartesian3.fromDegrees(10, 45, 3000);
+        camera.setView({
+          destination,
+          orientation: { heading: 0.4, pitch: -0.2, roll: 0 },
+        });
+        await settle();
+        const level = camera.pose();
+        camera.setView({
+          destination,
+          orientation: { heading: 0.4, pitch: -0.2, roll: 0.3 },
+        });
+        await settle();
+        const rolled = camera.pose();
+        near(
+          cartesian3.dot(rolled.up, level.right),
+          Math.sin(0.3),
+          1e-6,
+          'up·levelRight',
+        );
+        near(
+          cartesian3.dot(rolled.direction, level.direction),
+          1,
+          1e-9,
+          'roll changed the direction',
+        );
+      },
+    ],
+    [
+      'camera.flightActive: true during a flight, false after it ends',
+      async () => {
+        await nadirView();
+        ensure(!camera.flightActive(), 'a flight is active before flyTo');
+        camera.flyTo({
+          destination: cartesian3.fromDegrees(100, 0, 5e6),
+          duration: 5,
+        });
+        ensure(camera.flightActive(), 'no flight is active after flyTo');
+        camera.cancelFlight();
+        ensure(
+          !camera.flightActive(),
+          'the flight is active after cancelFlight',
+        );
+      },
+    ],
+    [
+      'camera.flyToSphere: Cesium default heading, pitch and range',
+      async () => {
+        await nadirView();
+        const center = cartesian3.fromDegrees(2.35, 48.85, 100);
+        const radius = 1000;
+        let done = false;
+        camera.flyToSphere(
+          { center, radius },
+          { duration: 0, complete: () => (done = true) },
+        );
+        ensure(
+          done,
+          'a duration-0 sphere flight did not complete synchronously',
+        );
+        const pose = camera.pose();
+        const { width, height } = engine.host.size();
+        const tanPhi = Math.tan(pose.fovy / 2);
+        const tanTheta = (width / height) * tanPhi;
+        const range = Math.max(100, radius / tanTheta, radius / tanPhi);
+        near(
+          cartesian3.distance(pose.position, center),
+          range,
+          range * 1e-6,
+          'range (m)',
+        );
+        const axes = localAxes(center);
+        const toCamera = unit(
+          cartesian3.subtract(pose.position, center, cartesian3.create()),
+        );
+        near(
+          cartesian3.dot(toCamera, axes.up),
+          Math.sin(Math.PI / 4),
+          1e-6,
+          'pitch −π/4',
+        );
+        near(
+          cartesian3.dot(toCamera, axes.east),
+          0,
+          1e-6,
+          'heading 0 (east offset)',
+        );
+        ensure(
+          cartesian3.dot(toCamera, axes.north) < 0,
+          'camera is not south of the centre',
+        );
+        camera.flyToSphere({ center, radius: 0 }, { duration: 0 });
+        near(
+          cartesian3.distance(camera.pose().position, center),
+          100,
+          1e-3,
+          'minimum range (m)',
+        );
+        const identity = camera.transform();
+        for (let index = 0; index < 16; index++)
+          near(
+            identity[index],
+            matrix4.IDENTITY[index],
+            0,
+            `transform[${index}]`,
+          );
+      },
+    ],
+    [
+      'camera.lookAtTransform: heading/pitch/range and Cartesian offsets, transform and release',
+      async () => {
+        await nadirView();
+        const target = cartesian3.fromDegrees(-0.12, 51.5, 0);
+        const { frame, up } = localAxes(target);
+        camera.lookAtTransform(frame, {
+          heading: 0.4,
+          pitch: -0.7,
+          range: 2000,
+        });
+        await settle();
+        let pose = camera.pose();
+        near(
+          cartesian3.distance(pose.position, target),
+          2000,
+          1e-3,
+          'range (m)',
+        );
+        const aim = () =>
+          cartesian3.dot(
+            unit(
+              cartesian3.subtract(
+                target,
+                camera.pose().position,
+                cartesian3.create(),
+              ),
+            ),
+            camera.pose().direction,
+          );
+        near(aim(), 1, 1e-9, 'direction·toTarget');
+        const held = camera.transform();
+        for (let index = 0; index < 16; index++)
+          near(held[index], frame[index], 1e-6, `transform[${index}]`);
+        camera.lookAtTransform(frame, cartesian3.create(0, -1000, 1000));
+        await settle();
+        pose = camera.pose();
+        near(
+          cartesian3.distance(pose.position, target),
+          Math.SQRT2 * 1000,
+          1e-3,
+          'Cartesian offset range (m)',
+        );
+        near(aim(), 1, 1e-9, 'Cartesian offset direction·toTarget');
+        ensure(
+          cartesian3.dot(pose.up, up) > 0,
+          'up does not follow the frame +Z',
+        );
+        camera.release();
+        await settle();
+        near(
+          cartesian3.distance(camera.pose().position, pose.position),
+          0,
+          0.01,
+          'release moved the camera (m)',
+        );
+        const released = camera.transform();
+        for (let index = 0; index < 16; index++)
+          near(
+            released[index],
+            matrix4.IDENTITY[index],
+            0,
+            `released transform[${index}]`,
+          );
+      },
+    ],
+    [
+      'camera.zoomIn and zoomOut move along the view direction',
+      async () => {
+        camera.setView({
+          destination: cartesian3.fromDegrees(20, 10, 50000),
+          orientation: { heading: 0.3, pitch: -0.9, roll: 0 },
+        });
+        await settle();
+        const start = camera.pose();
+        camera.zoomIn(2000);
+        await settle();
+        const zoomed = camera.pose().position;
+        const moved = cartesian3.subtract(
+          zoomed,
+          start.position,
+          cartesian3.create(),
+        );
+        near(
+          cartesian3.dot(moved, start.direction),
+          2000,
+          1e-3,
+          'zoomIn distance (m)',
+        );
+        near(
+          cartesian3.magnitude(moved),
+          2000,
+          1e-3,
+          'zoomIn stays on the view axis',
+        );
+        camera.zoomOut(500);
+        await settle();
+        near(
+          cartesian3.distance(camera.pose().position, start.position),
+          1500,
+          1e-3,
+          'zoomOut distance (m)',
+        );
+      },
+    ],
+    [
+      'camera.viewRectangle: wraps west > east across the antimeridian',
+      async () => {
+        camera.setView({
+          destination: cartesian3.fromDegrees(180, 0, 1e6),
+          orientation: { heading: 0, pitch: -math.PI_OVER_TWO, roll: 0 },
+        });
+        await settle();
+        const rectangle = camera.viewRectangle();
+        ensure(rectangle, 'no view rectangle over the antimeridian');
+        ensure(
+          rectangle.west > rectangle.east,
+          `west ${rectangle.west} is not east of east ${rectangle.east}`,
+        );
+        ensure(
+          rectangle.west > 0 && rectangle.east < 0,
+          'the rectangle does not cross ±180°',
+        );
+        ensure(
+          rectangle.south < 0 && rectangle.north > 0,
+          'the rectangle misses the equator',
+        );
+      },
+    ],
+    [
+      'camera.viewRectangle: spans all longitudes over a pole',
+      async () => {
+        camera.setView({
+          destination: cartesian3.fromDegrees(0, 89, 1e6),
+          orientation: { heading: 0, pitch: -math.PI_OVER_TWO, roll: 0 },
+        });
+        await settle();
+        const rectangle = camera.viewRectangle();
+        ensure(rectangle, 'no view rectangle over the pole');
+        near(rectangle.west, -Math.PI, 1e-9, 'west');
+        near(rectangle.east, Math.PI, 1e-9, 'east');
+        near(rectangle.north, math.PI_OVER_TWO, 1e-9, 'north');
+        ensure(
+          rectangle.south > 0,
+          `south ${rectangle.south} crosses the equator`,
+        );
+      },
+    ],
+    [
+      'projector.viewProjection: agrees with worldToWindow',
+      async () => {
+        camera.setView({
+          destination: cartesian3.fromDegrees(20, 10, 30000),
+          orientation: { heading: 0.6, pitch: -0.5, roll: 0.1 },
+        });
+        await settle();
+        const { width, height } = engine.host.size();
+        const result = new Array(16).fill(0);
+        const matrix = engine.projector.viewProjection(result);
+        ensure(
+          matrix === result,
+          'viewProjection did not fill its result argument',
+        );
+        ensure(
+          matrix.length === 16 && matrix.every(Number.isFinite),
+          'not 16 finite numbers',
+        );
+        let compared = 0;
+        for (const [x, y] of [
+          [width / 2, height / 2],
+          [width / 5, height / 4],
+          [width * 0.9, height * 0.8],
+        ]) {
+          const point = camera.pickEllipsoid(cartesian2.create(x, y));
+          if (!point) continue;
+          const window = engine.projector.worldToWindow(point);
+          ensure(window, 'a picked point did not project');
+          const clip = [0, 1, 2, 3].map(
+            (row) =>
+              matrix[row] * point.x +
+              matrix[4 + row] * point.y +
+              matrix[8 + row] * point.z +
+              matrix[12 + row],
+          );
+          ensure(clip[3] > 0, 'a visible point has clip.w <= 0');
+          near(((clip[0] / clip[3] + 1) / 2) * width, window.x, 0.5, 'x (px)');
+          near(((1 - clip[1] / clip[3]) / 2) * height, window.y, 0.5, 'y (px)');
+          compared++;
+        }
+        ensure(compared >= 2, 'too few screen points hit the globe');
+      },
+    ],
+    [
+      'projector.horizonVisible: the nadir is visible and the far side hidden',
+      async () => {
+        await nadirView();
+        ensure(
+          engine.projector.horizonVisible(cartesian3.fromDegrees(20, 10, 0)),
+          'the nadir is hidden',
+        );
+        ensure(
+          !engine.projector.horizonVisible(
+            cartesian3.fromDegrees(-160, -10, 0),
+          ),
+          'the antipode is visible',
+        );
+        ensure(
+          engine.projector.horizonVisible(cartesian3.fromDegrees(-70, 10, 2e7)),
+          'a high point beside the limb is hidden',
+        );
+      },
+    ],
   ];
   return checks.map(([name, run]) => ({ name, run }));
 }

src/globe/testing/fakeEngine.js

@@ -3,12 +3,29 @@
 // against it, records every contract call and lets tests emit events, drive
 // input, advance frames and script pick/height/projection results through
 // `engine.fake`. It passes src/globe/testing/contractSuite.mjs.
+//
+// Simplifications against Cesium, which shell tests must not rely on:
+// - a flight interpolates the position linearly (eased) through space and
+//   snaps the orientation at the end; Cesium arcs over the globe and turns
+//   gradually. A flight without a duration lasts 3 s of fake frame time.
+// - moveStart/changed/moveEnd are detected once per `fake.frame()`, and
+//   moveEnd fires after one frame without movement; Cesium waits 500 ms
+//   (scene.cameraEventWaitTime) of wall time.
+// - nothing occludes picks or projection except where the contract says so
+//   (horizonVisible); there is no terrain or scene geometry unless scripted.
 
 import * as geo from '../../geo/index.js';
-import { INPUT_TYPES, createEngineEvent } from '../contract.js';
+import { INPUT_TYPES, MODIFIERS, createEngineEvent } from '../contract.js';
 
 const { cartesian2, cartesian3, cartographic, ellipsoid, math, matrix4 } = geo;
 const WGS84 = ellipsoid.WGS84;
+const RADII = WGS84.radii;
+const MAXIMUM_RADIUS = Math.max(RADII.x, RADII.y, RADII.z);
+const DEFAULT_FLIGHT_SECONDS = 3;
+const DEFAULT_ZOOM_AMOUNT = 100000; // Cesium's camera.defaultZoomAmount
+const MINIMUM_SPHERE_RANGE = 100;
+const NEAR = 1;
+const FAR = 1e9;
 const SCRIPTABLE = new Set([
   'pick',
   'drillPick',
@@ -16,6 +33,8 @@ const SCRIPTABLE = new Set([
   'pickEllipsoid',
   'viewRectangle',
   'sampleHeight',
+  'terrainHeight',
+  'clampToHeight',
   'tilesLoaded',
   'worldToWindow',
 ]);
@@ -27,11 +46,26 @@ const EASINGS = {
 };
 
 const copy3 = (value) => cartesian3.create(value.x, value.y, value.z);
+const scaled = (vector, scalar) =>
+  cartesian3.multiplyByScalar(vector, scalar, cartesian3.create());
+const sum = (...vectors) =>
+  vectors.reduce(
+    (total, vector) => cartesian3.add(total, vector, total),
+    cartesian3.create(),
+  );
+const unit = (vector) => cartesian3.normalize(vector, cartesian3.create());
+const cross = (left, right) =>
+  cartesian3.cross(left, right, cartesian3.create());
+
+// An angle in [0, 2π), as Cesium's camera reports it.
+function wrapAngle(angle) {
+  const value = math.zeroToTwoPi(angle);
+  return value < 1e-12 || math.TWO_PI - value < 1e-12 ? 0 : value;
+}
 
 // The local east/north/up axes at a position, in Earth-fixed coordinates.
 function localAxes(position) {
-  const frame = matrix4.create();
-  geo.transforms.eastNorthUpToFixedFrame(position, WGS84, frame);
+  const frame = geo.transforms.eastNorthUpToFixedFrame(position, WGS84);
   return {
     east: cartesian3.create(frame[0], frame[1], frame[2]),
     north: cartesian3.create(frame[4], frame[5], frame[6]),
@@ -40,14 +74,16 @@ function localAxes(position) {
 }
 
 const combine = (axes, e, n, u) =>
-  cartesian3.create(
-    axes.east.x * e + axes.north.x * n + axes.up.x * u,
-    axes.east.y * e + axes.north.y * n + axes.up.y * u,
-    axes.east.z * e + axes.north.z * n + axes.up.z * u,
-  );
+  sum(scaled(axes.east, e), scaled(axes.north, n), scaled(axes.up, u));
+const toLocal = (axes, vector) => ({
+  e: cartesian3.dot(vector, axes.east),
+  n: cartesian3.dot(vector, axes.north),
+  u: cartesian3.dot(vector, axes.up),
+});
 
-// Direction and up for a heading/pitch/roll in the local frame at position.
-// Heading 0 looks north, positive pitch looks up, as in Cesium.
+// Direction and up for a heading/pitch/roll in the local frame at position,
+// as Cesium's setView builds them: heading 0 looks north, positive pitch looks
+// up, positive roll tilts `up` toward the camera's right.
 function orientationVectors(position, heading, pitch, roll) {
   const axes = localAxes(position);
   const cosPitch = Math.cos(pitch);
@@ -58,54 +94,50 @@ function orientationVectors(position, heading, pitch, roll) {
     Math.sin(pitch),
   );
   const levelRight = combine(axes, Math.cos(heading), -Math.sin(heading), 0);
-  const levelUp = cartesian3.cross(levelRight, direction, cartesian3.create());
-  const up = cartesian3.create();
-  cartesian3.add(
-    cartesian3.multiplyByScalar(levelUp, Math.cos(roll), cartesian3.create()),
-    cartesian3.multiplyByScalar(
-      levelRight,
-      -Math.sin(roll),
-      cartesian3.create(),
-    ),
-    up,
+  const levelUp = cross(levelRight, direction);
+  const up = sum(
+    scaled(levelUp, Math.cos(roll)),
+    scaled(levelRight, Math.sin(roll)),
   );
-  return { direction, up: cartesian3.normalize(up, up) };
+  return { direction: unit(direction), up: unit(up) };
 }
 
+// Cesium's Camera heading/pitch/roll getters, in the local frame at position.
 function headingPitchRoll(position, direction, up) {
   const axes = localAxes(position);
-  const e = cartesian3.dot(direction, axes.east);
-  const n = cartesian3.dot(direction, axes.north);
-  const u = cartesian3.dot(direction, axes.up);
-  const pitch = Math.asin(math.clamp(u, -1, 1));
-  // Looking straight up or down, heading follows the camera's up vector.
-  const heading =
-    Math.hypot(e, n) > 1e-9
-      ? math.zeroToTwoPi(Math.atan2(e, n))
-      : math.zeroToTwoPi(
-          Math.atan2(
-            cartesian3.dot(up, axes.east) * -Math.sign(u),
-            cartesian3.dot(up, axes.north) * -Math.sign(u),
-          ),
-        );
-  const level = orientationVectors(position, heading, pitch, 0);
-  const levelRight = cartesian3.cross(
-    level.direction,
-    level.up,
-    cartesian3.create(),
+  const d = toLocal(axes, direction);
+  const u = toLocal(axes, up);
+  const r = toLocal(axes, cross(direction, up));
+  const vertical = Math.abs(Math.abs(d.u) - 1) <= 1e-3;
+  const raw = vertical
+    ? Math.atan2(u.n, u.e) - math.PI_OVER_TWO
+    : Math.atan2(d.n, d.e) - math.PI_OVER_TWO;
+  return {
+    heading: wrapAngle(math.TWO_PI - math.zeroToTwoPi(raw)),
+    pitch: math.PI_OVER_TWO - Math.acos(math.clamp(d.u, -1, 1)),
+    roll: vertical ? 0 : wrapAngle(Math.atan2(-r.u, u.u)),
+  };
+}
+
+// Camera offset from a target for a HeadingPitchRange, in the target's frame.
+function offsetFromHeadingPitchRange(heading, pitch, range) {
+  const p = math.clamp(pitch, -math.PI_OVER_TWO, math.PI_OVER_TWO);
+  const cosPitch = Math.cos(p);
+  return cartesian3.create(
+    -Math.sin(heading) * cosPitch * range,
+    -Math.cos(heading) * cosPitch * range,
+    -Math.sin(p) * range,
   );
-  const roll = Math.atan2(
-    -cartesian3.dot(up, levelRight),
-    cartesian3.dot(up, level.up),
-  );
-  return { heading, pitch, roll: Math.abs(roll) < 1e-12 ? 0 : roll };
 }
 
 // Nearest intersection of a ray with the WGS84 ellipsoid, if any.
 function intersectEllipsoid(origin, direction) {
-  const r = WGS84.radii;
-  const o = [origin.x / r.x, origin.y / r.y, origin.z / r.z];
-  const d = [direction.x / r.x, direction.y / r.y, direction.z / r.z];
+  const o = [origin.x / RADII.x, origin.y / RADII.y, origin.z / RADII.z];
+  const d = [
+    direction.x / RADII.x,
+    direction.y / RADII.y,
+    direction.z / RADII.z,
+  ];
   const a = d[0] * d[0] + d[1] * d[1] + d[2] * d[2];
   const b = 2 * (o[0] * d[0] + o[1] * d[1] + o[2] * d[2]);
   const c = o[0] * o[0] + o[1] * o[1] + o[2] * o[2] - 1;
@@ -115,11 +147,60 @@ function intersectEllipsoid(origin, direction) {
   const near = (-b - root) / (2 * a);
   const t = near > 0 ? near : (-b + root) / (2 * a);
   if (!(t > 0)) return undefined;
-  return cartesian3.add(
-    origin,
-    cartesian3.multiplyByScalar(direction, t, cartesian3.create()),
-    cartesian3.create(),
+  return sum(origin, scaled(direction, t));
+}
+
+// Cesium's computeHorizonQuad: four limb points around the camera's nadir.
+function horizonQuad(position) {
+  const q = cartesian3.create(
+    position.x / RADII.x,
+    position.y / RADII.y,
+    position.z / RADII.z,
   );
+  const qMagnitude = cartesian3.magnitude(q);
+  const qUnit = unit(q);
+  let east;
+  let north;
+  if (cartesian3.equalsEpsilon(qUnit, cartesian3.UNIT_Z, math.EPSILON10)) {
+    east = cartesian3.create(0, 1, 0);
+    north = cartesian3.create(0, 0, 1);
+  } else {
+    east = unit(cross(cartesian3.UNIT_Z, qUnit));
+    north = unit(cross(qUnit, east));
+  }
+  const center = scaled(qUnit, 1 / qMagnitude);
+  const offset =
+    Math.sqrt(Math.max(0, cartesian3.magnitudeSquared(q) - 1)) / qMagnitude;
+  const point = (n, e) => {
+    const p = sum(center, scaled(north, n * offset), scaled(east, e * offset));
+    return cartesian3.create(p.x * RADII.x, p.y * RADII.y, p.z * RADII.z);
+  };
+  // Same order as the corner picks: upper-left, lower-left, lower-right, upper-right.
+  return [point(1, -1), point(-1, -1), point(-1, 1), point(1, 1)];
+}
+
+// Cesium's Rectangle.fromCartographicArray, including the antimeridian case.
+function rectangleFromCartographics(points) {
+  let west = Infinity;
+  let east = -Infinity;
+  let westOverIDL = Infinity;
+  let eastOverIDL = -Infinity;
+  let south = Infinity;
+  let north = -Infinity;
+  for (const { longitude, latitude } of points) {
+    west = Math.min(west, longitude);
+    east = Math.max(east, longitude);
+    south = Math.min(south, latitude);
+    north = Math.max(north, latitude);
+    const adjusted = longitude >= 0 ? longitude : longitude + math.TWO_PI;
+    westOverIDL = Math.min(westOverIDL, adjusted);
+    eastOverIDL = Math.max(eastOverIDL, adjusted);
+  }
+  if (east - west > eastOverIDL - westOverIDL) {
+    west = westOverIDL > Math.PI ? westOverIDL - math.TWO_PI : westOverIDL;
+    east = eastOverIDL > Math.PI ? eastOverIDL - math.TWO_PI : eastOverIDL;
+  }
+  return { west, south, east, north };
 }
 
 /**
@@ -153,6 +234,7 @@ export function createFakeEngine(options = {}) {
   };
   const inputs = new Map(INPUT_TYPES.map((type) => [type, new Set()]));
   const scripts = new Map();
+  let transform = [...matrix4.IDENTITY];
   let percentageChanged = 0.5;
   let continuous = false;
   let flight = null;
@@ -172,85 +254,63 @@ export function createFakeEngine(options = {}) {
   };
   const record = (method, args) => fake.calls.push({ method, args });
 
-  function setOrientation(position, orientation) {
-    if (orientation && 'direction' in orientation) {
-      state.position = copy3(position);
-      state.direction = cartesian3.normalize(
-        orientation.direction,
-        cartesian3.create(),
-      );
-      state.up = cartesian3.normalize(orientation.up, cartesian3.create());
-      return;
-    }
-    // Missing angles keep the current ones, measured where the camera is now.
-    const current = poseAngles();
-    state.position = copy3(position);
+  const aspect = () => width / height;
+  const right = () => unit(cross(state.direction, state.up));
+  const poseAngles = () =>
+    headingPitchRoll(state.position, state.direction, state.up);
+
+  // The pose for a destination and orientation; missing angles use `fallback`.
+  function viewFor(position, orientation, fallback) {
+    if (orientation && 'direction' in orientation)
+      return {
+        position: copy3(position),
+        direction: unit(orientation.direction),
+        up: unit(orientation.up),
+      };
     const vectors = orientationVectors(
-      state.position,
-      orientation?.heading ?? current.heading,
-      orientation?.pitch ?? current.pitch,
-      orientation?.roll ?? current.roll,
+      position,
+      orientation?.heading ?? fallback.heading,
+      orientation?.pitch ?? fallback.pitch,
+      orientation?.roll ?? fallback.roll,
     );
-    state.direction = vectors.direction;
-    state.up = vectors.up;
+    return { position: copy3(position), ...vectors };
+  }
+  // Cesium's setView/flyTo defaults for missing angles.
+  const CESIUM_DEFAULTS = { heading: 0, pitch: -math.PI_OVER_TWO, roll: 0 };
+
+  function apply(view) {
+    state.position = copy3(view.position);
+    state.direction = copy3(view.direction);
+    state.up = copy3(view.up);
   }
 
-  function poseAngles() {
-    if (cartesian3.magnitudeSquared(state.direction) === 0)
-      return { heading: 0, pitch: -math.PI_OVER_TWO, roll: 0 };
-    return headingPitchRoll(state.position, state.direction, state.up);
+  function setTransform(next, target) {
+    transform = [...next];
+    lookAtTarget = target ? copy3(target) : null;
   }
 
-  function right() {
-    const result = cartesian3.cross(
-      state.direction,
-      state.up,
-      cartesian3.create(),
-    );
-    return cartesian3.normalize(result, result);
-  }
-
-  // Camera placed at `range` from target, looking at it, with heading/pitch
-  // measured in the target's local frame (Cesium's HeadingPitchRange).
-  function offsetView(target, heading, pitch, range) {
-    const toTarget = orientationVectors(target, heading, pitch, 0);
-    const position = cartesian3.subtract(
-      target,
-      cartesian3.multiplyByScalar(
-        toTarget.direction,
-        range,
-        cartesian3.create(),
-      ),
-      cartesian3.create(),
-    );
-    return { position, direction: toTarget.direction, up: toTarget.up };
-  }
-
-  function scripted(name, args, fallback) {
-    if (!scripts.has(name)) return fallback();
-    const value = scripts.get(name);
-    return typeof value === 'function' ? value(...args) : value;
-  }
-
-  function startFlight(options, target) {
-    if (flight) cancelCurrentFlight();
-    const duration = Math.max(0, options.duration ?? 3);
-    flight = {
-      start: copy3(state.position),
-      target,
-      duration: duration * 1000,
-      elapsed: 0,
-      ease: EASINGS[options.easing] ?? EASINGS.cubicInOut,
-      complete: options.complete,
-      cancel: options.cancel,
-    };
-    if (duration === 0) applyFlightTarget(flight.target);
-  }
-
-  function applyFlightTarget(target) {
-    state.position = copy3(target.position);
-    state.direction = copy3(target.direction);
-    state.up = copy3(target.up);
+  function lookAtFrame(frame, offset) {
+    const local =
+      offset && 'heading' in offset
+        ? offsetFromHeadingPitchRange(
+            offset.heading,
+            offset.pitch,
+            offset.range,
+          )
+        : copy3(offset);
+    const localDirection = unit(cartesian3.negate(local, cartesian3.create()));
+    let localRight = cross(localDirection, cartesian3.UNIT_Z);
+    if (cartesian3.magnitudeSquared(localRight) < math.EPSILON10)
+      localRight = copy3(cartesian3.UNIT_X);
+    localRight = unit(localRight);
+    const localUp = unit(cross(localRight, localDirection));
+    const vector = (value) =>
+      unit(matrix4.multiplyByPointAsVector(frame, value, cartesian3.create()));
+    apply({
+      position: matrix4.multiplyByPoint(frame, local, cartesian3.create()),
+      direction: vector(localDirection),
+      up: vector(localUp),
+    });
   }
 
   function cancelCurrentFlight() {
@@ -259,12 +319,29 @@ export function createFakeEngine(options = {}) {
     current?.cancel?.();
   }
 
+  function startFlight(flightOptions, target) {
+    cancelCurrentFlight();
+    const duration = flightOptions.duration ?? DEFAULT_FLIGHT_SECONDS;
+    if (duration <= 0) {
+      apply(target);
+      flightOptions.complete?.();
+      return;
+    }
+    flight = {
+      start: copy3(state.position),
+      target,
+      duration: duration * 1000,
+      elapsed: 0,
+      ease: EASINGS[flightOptions.easing] ?? EASINGS.cubicInOut,
+      complete: flightOptions.complete,
+      cancel: flightOptions.cancel,
+    };
+  }
+
   function advanceFlight(dt) {
     if (!flight) return;
     flight.elapsed += dt;
-    const t = flight.duration
-      ? Math.min(1, flight.elapsed / flight.duration)
-      : 1;
+    const t = Math.min(1, flight.elapsed / flight.duration);
     if (t < 1) {
       cartesian3.lerp(
         flight.start,
@@ -276,7 +353,7 @@ export function createFakeEngine(options = {}) {
     }
     const current = flight;
     flight = null;
-    applyFlightTarget(current.target);
+    apply(current.target);
     current.complete?.();
   }
 
@@ -333,8 +410,7 @@ export function createFakeEngine(options = {}) {
     const depth = cartesian3.dot(offset, state.direction);
     if (!(depth > 0)) return undefined;
     const tangent = Math.tan(fovy / 2);
-    const ndcX =
-      cartesian3.dot(offset, right()) / (depth * tangent * (width / height));
+    const ndcX = cartesian3.dot(offset, right()) / (depth * tangent * aspect());
     const ndcY = cartesian3.dot(offset, state.up) / (depth * tangent);
     const x = ((ndcX + 1) / 2) * width;
     const y = ((1 - ndcY) / 2) * height;
@@ -344,48 +420,136 @@ export function createFakeEngine(options = {}) {
     return result;
   }
 
+  function viewProjection(result = matrix4.create()) {
+    const f = 1 / Math.tan(fovy / 2);
+    const rows = [
+      [right(), f / aspect()],
+      [state.up, f],
+    ];
+    const D = state.direction;
+    const P = state.position;
+    for (const [row, [axis, scale]] of rows.entries()) {
+      result[row] = axis.x * scale;
+      result[4 + row] = axis.y * scale;
+      result[8 + row] = axis.z * scale;
+      result[12 + row] = -cartesian3.dot(axis, P) * scale;
+    }
+    // Eye z is −direction·(p − position); clip.w = −z_eye.
+    const A = (FAR + NEAR) / (NEAR - FAR);
+    const B = (2 * FAR * NEAR) / (NEAR - FAR);
+    result[2] = -D.x * A;
+    result[6] = -D.y * A;
+    result[10] = -D.z * A;
+    result[14] = cartesian3.dot(D, P) * A + B;
+    result[3] = D.x;
+    result[7] = D.y;
+    result[11] = D.z;
+    result[15] = -cartesian3.dot(D, P);
+    return result;
+  }
+
+  // Cesium's EllipsoidalOccluder.isPointVisible.
+  function horizonVisible(position) {
+    const camera = cartesian3.create(
+      state.position.x / RADII.x,
+      state.position.y / RADII.y,
+      state.position.z / RADII.z,
+    );
+    const limbSquared = cartesian3.magnitudeSquared(camera) - 1;
+    const target = cartesian3.create(
+      position.x / RADII.x,
+      position.y / RADII.y,
+      position.z / RADII.z,
+    );
+    const vt = cartesian3.subtract(target, camera, cartesian3.create());
+    const vtDotVc = -cartesian3.dot(vt, camera);
+    const occluded =
+      limbSquared < 0
+        ? vtDotVc > 0
+        : vtDotVc > limbSquared &&
+          (vtDotVc * vtDotVc) / cartesian3.magnitudeSquared(vt) > limbSquared;
+    return !occluded;
+  }
+
   function ray(screen) {
     const tangent = Math.tan(fovy / 2);
     const ndcX = (2 * screen.x) / width - 1;
     const ndcY = 1 - (2 * screen.y) / height;
-    const direction = combine(
-      { east: right(), north: state.up, up: state.direction },
-      ndcX * tangent * (width / height),
-      ndcY * tangent,
-      1,
+    const direction = sum(
+      state.direction,
+      scaled(right(), ndcX * tangent * aspect()),
+      scaled(state.up, ndcY * tangent),
     );
-    return {
-      origin: copy3(state.position),
-      direction: cartesian3.normalize(direction, direction),
-    };
+    return { origin: copy3(state.position), direction: unit(direction) };
   }
 
+  // Whether the sphere around the Earth is fully outside the view frustum.
+  function globeOutsideFrustum() {
+    const toCentre = cartesian3.negate(state.position, cartesian3.create());
+    const D = state.direction;
+    const tanY = Math.tan(fovy / 2);
+    const tanX = tanY * aspect();
+    const R = right();
+    const U = state.up;
+    const planes = [
+      [D, NEAR],
+      [unit(sum(scaled(R, -1), scaled(D, tanX))), 0],
+      [unit(sum(R, scaled(D, tanX))), 0],
+      [unit(sum(scaled(U, -1), scaled(D, tanY))), 0],
+      [unit(sum(U, scaled(D, tanY))), 0],
+    ];
+    return planes.some(
+      ([normal, offset]) =>
+        cartesian3.dot(normal, toCentre) - offset < -MAXIMUM_RADIUS,
+    );
+  }
+
+  // Cesium's Camera.computeViewRectangle.
   function computedViewRectangle() {
-    const corners = [
+    if (globeOutsideFrustum()) return undefined;
+    const horizon = horizonQuad(state.position);
+    let hits = 0;
+    const points = [
       [0, 0],
-      [width, 0],
       [0, height],
       [width, height],
-      [width / 2, 0],
-      [width / 2, height],
-      [0, height / 2],
-      [width, height / 2],
-    ].map(([x, y]) =>
-      intersectEllipsoid(
+      [width, 0],
+    ].map(([x, y], index) => {
+      const hit = intersectEllipsoid(
         state.position,
         ray(cartesian2.create(x, y)).direction,
-      ),
-    );
-    if (corners.some((corner) => !corner)) return undefined;
-    const points = corners.map((corner) =>
-      cartographic.fromCartesian(corner, WGS84),
-    );
-    return {
-      west: Math.min(...points.map((point) => point.longitude)),
-      south: Math.min(...points.map((point) => point.latitude)),
-      east: Math.max(...points.map((point) => point.longitude)),
-      north: Math.max(...points.map((point) => point.latitude)),
-    };
+      );
+      if (hit) hits++;
+      return cartographic.fromCartesian(hit ?? horizon[index], WGS84);
+    });
+    if (hits < 2)
+      return {
+        west: -Math.PI,
+        south: -math.PI_OVER_TWO,
+        east: Math.PI,
+        north: math.PI_OVER_TWO,
+      };
+    const rectangle = rectangleFromCartographics(points);
+    let travelled = 0;
+    let last = points[3].longitude;
+    for (const { longitude } of points) {
+      const step = Math.abs(longitude - last);
+      travelled += step > Math.PI ? math.TWO_PI - step : step;
+      last = longitude;
+    }
+    if (math.equalsEpsilon(Math.abs(travelled), math.TWO_PI, 1e-9)) {
+      rectangle.west = -Math.PI;
+      rectangle.east = Math.PI;
+      if (points[0].latitude >= 0) rectangle.north = math.PI_OVER_TWO;
+      else rectangle.south = -math.PI_OVER_TWO;
+    }
+    return rectangle;
+  }
+
+  function scripted(name, args, fallback) {
+    if (!scripts.has(name)) return fallback();
+    const value = scripts.get(name);
+    return typeof value === 'function' ? value(...args) : value;
   }
 
   const camera = {
@@ -407,54 +571,84 @@ export function createFakeEngine(options = {}) {
       record('camera.setView', [view]);
       if (!view?.destination)
         throw new TypeError('setView needs a destination');
-      setOrientation(view.destination, view.orientation);
+      apply(viewFor(view.destination, view.orientation, CESIUM_DEFAULTS));
     },
     flyTo(flightOptions) {
       record('camera.flyTo', [flightOptions]);
       if (!flightOptions?.destination)
         throw new TypeError('flyTo needs a destination');
+      startFlight(
+        flightOptions,
+        viewFor(
+          flightOptions.destination,
+          flightOptions.orientation,
+          CESIUM_DEFAULTS,
+        ),
+      );
+    },
+    flyToSphere(sphere, sphereOptions = {}) {
+      record('camera.flyToSphere', [sphere, sphereOptions]);
+      setTransform(matrix4.IDENTITY);
+      let range = sphereOptions.range;
+      if (!range) {
+        const tanPhi = Math.tan(fovy / 2);
+        const tanTheta = aspect() * tanPhi;
+        range = Math.max(
+          MINIMUM_SPHERE_RANGE,
+          Math.max(sphere.radius / tanTheta, sphere.radius / tanPhi),
+        );
+      }
+      const frame = geo.transforms.eastNorthUpToFixedFrame(
+        sphere.center,
+        WGS84,
+      );
       const saved = {
         position: state.position,
         direction: state.direction,
         up: state.up,
       };
-      setOrientation(flightOptions.destination, flightOptions.orientation);
+      lookAtFrame(frame, {
+        heading: sphereOptions.heading ?? 0,
+        pitch: sphereOptions.pitch ?? -Math.PI / 4,
+        range,
+      });
       const target = {
         position: state.position,
         direction: state.direction,
         up: state.up,
       };
-      Object.assign(state, saved);
-      startFlight(flightOptions, target);
-    },
-    flyToSphere(sphere, sphereOptions = {}) {
-      record('camera.flyToSphere', [sphere, sphereOptions]);
-      const range =
-        sphereOptions.range ??
-        Math.max(sphere.radius / Math.sin(fovy / 2), 100);
-      const target = offsetView(
-        sphere.center,
-        sphereOptions.heading ?? 0,
-        sphereOptions.pitch ?? -0.5,
-        range,
-      );
+      apply(saved);
       startFlight(sphereOptions, target);
     },
+    flightActive: () => flight != null,
     lookAt(target, offset) {
       record('camera.lookAt', [target, offset]);
-      lookAtTarget = copy3(target);
-      applyFlightTarget(
-        offsetView(target, offset.heading, offset.pitch, offset.range),
-      );
+      const frame = geo.transforms.eastNorthUpToFixedFrame(target, WGS84);
+      setTransform(frame, target);
+      lookAtFrame(frame, offset);
     },
+    lookAtTransform(frame, offset) {
+      record('camera.lookAtTransform', [frame, offset]);
+      setTransform(frame, cartesian3.create(frame[12], frame[13], frame[14]));
+      if (offset) lookAtFrame(frame, offset);
+    },
+    transform: () => [...transform],
     release() {
       record('camera.release', []);
-      lookAtTarget = null;
+      setTransform(matrix4.IDENTITY);
     },
     cancelFlight() {
       record('camera.cancelFlight', []);
       cancelCurrentFlight();
     },
+    zoomIn(amount = DEFAULT_ZOOM_AMOUNT) {
+      record('camera.zoomIn', [amount]);
+      state.position = sum(state.position, scaled(state.direction, amount));
+    },
+    zoomOut(amount = DEFAULT_ZOOM_AMOUNT) {
+      record('camera.zoomOut', [amount]);
+      state.position = sum(state.position, scaled(state.direction, -amount));
+    },
     viewRectangle() {
       record('camera.viewRectangle', []);
       return scripted('viewRectangle', [], computedViewRectangle);
@@ -514,6 +708,8 @@ export function createFakeEngine(options = {}) {
           return cartesian2.clone(value, result);
         return value;
       },
+      viewProjection,
+      horizonVisible,
     },
     frames: {
       preUpdate: events['frames.preUpdate'],
@@ -537,14 +733,27 @@ export function createFakeEngine(options = {}) {
         return scripted('sampleHeight', [position, exclude], () => undefined);
       },
       supported: true,
+      terrainHeight(position) {
+        record('surface.terrainHeight', [position]);
+        return scripted('terrainHeight', [position], () => 0);
+      },
+      terrainHeightSupported: true,
+      clampToHeight(position, exclude) {
+        record('surface.clampToHeight', [position, exclude]);
+        return scripted('clampToHeight', [position, exclude], () => undefined);
+      },
+      clampToHeightSupported: true,
       tilesLoaded: () => scripted('tilesLoaded', [], () => true),
     },
     input: {
-      on(type, listener) {
-        record('input.on', [type]);
+      on(type, listener, inputOptions = {}) {
+        record('input.on', [type, inputOptions]);
         const listeners = inputs.get(type);
         if (!listeners) throw new TypeError(`Unknown input type: ${type}`);
-        const entry = (event) => listener(event);
+        const modifier = inputOptions.modifier;
+        if (modifier !== undefined && !MODIFIERS.includes(modifier))
+          throw new TypeError(`Unknown input modifier: ${modifier}`);
+        const entry = { listener, modifier };
         listeners.add(entry);
         return () => listeners.delete(entry);
       },
@@ -598,11 +807,12 @@ export function createFakeEngine(options = {}) {
           pose.height ?? 1e7,
           WGS84,
         );
-      setOrientation(
-        position,
-        pose.direction
-          ? { direction: pose.direction, up: pose.up }
-          : { heading: pose.heading, pitch: pose.pitch, roll: pose.roll },
+      apply(
+        viewFor(
+          position,
+          pose.direction ? { direction: pose.direction, up: pose.up } : pose,
+          poseAngles(),
+        ),
       );
     },
     setSize(nextWidth, nextHeight) {
@@ -620,11 +830,15 @@ export function createFakeEngine(options = {}) {
       if (!event) throw new TypeError(`Unknown engine event: ${name}`);
       event.raiseEvent(...args);
     },
-    /** Delivers an input event to `engine.input.on(type)` subscribers. */
-    input(type, event) {
+    /**
+     * Delivers input to `engine.input.on(type)` subscribers registered for
+     * `modifier` (none by default), as Cesium's ScreenSpaceEventHandler does.
+     */
+    input(type, event, modifier) {
       const listeners = inputs.get(type);
       if (!listeners) throw new TypeError(`Unknown input type: ${type}`);
-      for (const listener of [...listeners]) listener(event);
+      for (const entry of [...listeners])
+        if (entry.modifier === modifier) entry.listener(event);
     },
     /** Replaces a result with a value or a function of the call's arguments. */
     script(name, valueOrFunction) {
@@ -635,7 +849,6 @@ export function createFakeEngine(options = {}) {
     unscript(name) {
       scripts.delete(name);
     },
-    flying: () => flight != null,
     lookAtTarget: () => (lookAtTarget ? copy3(lookAtTarget) : undefined),
     /** Runs one frame: preUpdate, flight progress, preRender, camera events, postRender. */
     frame(dt = 16) {
@@ -651,14 +864,18 @@ export function createFakeEngine(options = {}) {
     },
   });
 
-  fake.setPose({
-    longitude: options.longitude ?? 0,
-    latitude: options.latitude ?? 0,
-    height: options.altitude ?? 1e7,
-    heading: 0,
-    pitch: -math.PI_OVER_TWO,
-    roll: 0,
-  });
+  apply(
+    viewFor(
+      cartesian3.fromRadians(
+        options.longitude ?? 0,
+        options.latitude ?? 0,
+        options.altitude ?? 1e7,
+        WGS84,
+      ),
+      CESIUM_DEFAULTS,
+      CESIUM_DEFAULTS,
+    ),
+  );
   lastFramePose = {
     position: copy3(state.position),
     direction: copy3(state.direction),

src/globe/testing/fakeEngine.test.mjs

@@ -67,7 +67,7 @@ test('fake flights advance with frames and finish or cancel exactly once', () =>
     complete: () => outcomes.push('complete'),
     cancel: () => outcomes.push('cancel'),
   });
-  assert.equal(engine.fake.flying(), true);
+  assert.equal(engine.camera.flightActive(), true);
   engine.fake.frames(30, 16);
   assert.deepEqual(outcomes, []);
   engine.fake.frames(40, 16);
@@ -87,9 +87,9 @@ test('fake flights advance with frames and finish or cancel exactly once', () =>
     duration: 0,
     complete: () => outcomes.push('second'),
   });
-  assert.deepEqual(outcomes, ['complete', 'cancel']);
-  engine.fake.frame();
+  // Duration 0 lands and completes before flyTo returns, as in Cesium.
   assert.deepEqual(outcomes, ['complete', 'cancel', 'second']);
+  assert.equal(engine.camera.flightActive(), false);
 });
 
 test('fake events can be emitted by hand and frames fire in order', () => {
@@ -184,3 +184,97 @@ test('fake credits, maps and destroy keep inspectable state', () => {
   engine.destroy();
   assert.equal(engine.fake.destroyed, true);
 });
+
+test('the fake camera follows Cesium conventions for roll, angle ranges and zoom', () => {
+  const engine = createFakeEngine();
+  const destination = geo.cartesian3.fromDegrees(0, 0, 1000);
+  engine.camera.setView({
+    destination,
+    orientation: { heading: 0, pitch: 0, roll: 0.3 },
+  });
+  const pose = engine.camera.pose();
+  // Facing north at (0, 0), east is +Y: positive roll tilts up toward east.
+  close(pose.up.y, Math.sin(0.3), 1e-9, 'up east component');
+  close(pose.roll, 0.3, 1e-9, 'roll');
+  engine.camera.setView({
+    destination,
+    orientation: { heading: -0.5, pitch: 0, roll: -0.2 },
+  });
+  const wrapped = engine.camera.pose();
+  close(wrapped.heading, 2 * Math.PI - 0.5, 1e-9, 'heading in [0, 2π)');
+  close(wrapped.roll, 2 * Math.PI - 0.2, 1e-9, 'roll in [0, 2π)');
+  engine.camera.setView({
+    destination,
+    orientation: { heading: 0.4, pitch: -Math.PI / 2, roll: 0.3 },
+  });
+  assert.equal(engine.camera.pose().roll, 0);
+  engine.camera.setView({
+    destination: geo.cartesian3.fromDegrees(0, 0, 5000),
+  });
+  const before = engine.camera.pose();
+  engine.camera.zoomIn(1000);
+  const after = engine.camera.pose();
+  close(
+    geo.cartesian3.distance(before.position, after.position),
+    1000,
+    1e-6,
+    'zoomIn',
+  );
+  engine.camera.zoomOut(400);
+  close(engine.camera.pose().cartographic.height, 5000 - 600, 1e-3, 'zoomOut');
+});
+
+test('fake lookAtTransform keeps the transform until release', () => {
+  const engine = createFakeEngine();
+  const target = geo.cartesian3.fromDegrees(10, 10, 0);
+  const frame = geo.transforms.eastNorthUpToFixedFrame(target);
+  engine.camera.lookAtTransform(frame, {
+    heading: 0,
+    pitch: -0.5,
+    range: 1000,
+  });
+  assert.deepEqual(engine.camera.transform(), [...frame]);
+  engine.camera.transform()[0] = 42;
+  assert.notEqual(engine.camera.transform()[0], 42);
+  engine.camera.release();
+  assert.deepEqual(engine.camera.transform(), [...geo.matrix4.IDENTITY]);
+  engine.camera.lookAt(target, { heading: 0, pitch: -0.5, range: 1000 });
+  assert.deepEqual(engine.camera.transform(), [...frame]);
+  assert.deepEqual(engine.fake.lookAtTarget(), target);
+});
+
+test('fake input honours modifiers like Cesium: unmodified listeners skip modified input', () => {
+  const engine = createFakeEngine();
+  const seen = [];
+  engine.input.on('click', () => seen.push('plain'));
+  engine.input.on('click', () => seen.push('ctrl'), { modifier: 'ctrl' });
+  engine.fake.input('click', { position: geo.cartesian2.create(1, 1) });
+  engine.fake.input('click', { position: geo.cartesian2.create(1, 1) }, 'ctrl');
+  engine.fake.input(
+    'click',
+    { position: geo.cartesian2.create(1, 1) },
+    'shift',
+  );
+  assert.deepEqual(seen, ['plain', 'ctrl']);
+  assert.throws(
+    () => engine.input.on('click', () => {}, { modifier: 'meta' }),
+    /Unknown input modifier/,
+  );
+});
+
+test('fake terrain height and clamp results default to the bare ellipsoid and can be scripted', () => {
+  const engine = createFakeEngine();
+  const place = geo.cartographic.fromDegrees(1, 2, 0);
+  assert.equal(engine.surface.terrainHeight(place), 0);
+  assert.equal(
+    engine.surface.clampToHeight(geo.cartesian3.fromDegrees(1, 2, 50)),
+    undefined,
+  );
+  engine.fake.script('terrainHeight', 12);
+  engine.fake.script('clampToHeight', (position) => position);
+  assert.equal(engine.surface.terrainHeight(place), 12);
+  const position = geo.cartesian3.fromDegrees(1, 2, 50);
+  assert.equal(engine.surface.clampToHeight(position), position);
+  assert.equal(engine.surface.terrainHeightSupported, true);
+  assert.equal(engine.surface.clampToHeightSupported, true);
+});

src/tooling/importDirections.test.mjs

@@ -134,12 +134,45 @@ for (const [name, files, pattern] of [
   [
     'Cesium globe engine imports Navara',
     { 'src/globe/cesium/engine.js': "import '@navaramap/three';" },
-    /Cesium globe engine imports @navaramap\/three/,
+    /Cesium globe engine reaches @navaramap\/three/,
   ],
   [
     'Navara globe engine imports Cesium',
     { 'src/globe/navara/engine.js': "import { Cartesian3 } from 'cesium';" },
-    /Navara globe engine imports cesium/,
+    /Navara globe engine reaches cesium/,
+  ],
+  [
+    'Navara globe engine reaches Cesium through a helper',
+    {
+      'src/globe/navara/engine.js': "import '../../maps/helper.js';",
+      'src/maps/helper.js': "export * from 'cesium';",
+    },
+    /src\/maps\/helper\.js: Navara globe engine reaches cesium/,
+  ],
+  [
+    'Navara globe engine imports the Cesium engine',
+    {
+      'src/globe/navara/engine.js': "import '../cesium/camera.js';",
+      'src/globe/cesium/camera.js': '',
+    },
+    /src\/globe\/navara\/engine\.js: Navara globe engine reaches src\/globe\/cesium\/camera\.js/,
+  ],
+  [
+    'Cesium globe engine reaches three through a helper',
+    {
+      'src/globe/cesium/engine.js': "import '../../ui/helper.js';",
+      'src/ui/helper.js': "import 'three/addons/controls.js';",
+    },
+    /src\/ui\/helper\.js: Cesium globe engine reaches three\/addons\/controls\.js/,
+  ],
+  [
+    'Cesium globe engine reaches the Navara engine through a helper',
+    {
+      'src/globe/cesium/engine.js': "import '../shared.js';",
+      'src/globe/shared.js': "import('./navara/engine.js');",
+      'src/globe/navara/engine.js': '',
+    },
+    /Cesium globe engine reaches src\/globe\/navara\/engine\.js/,
   ],
   [
     'browser imports Node without prefix',