gods-eye-view/src/director/timeline.test.mjs

import test from 'node:test';
import assert from 'node:assert/strict';
import {
  sceneTimingForShot,
  sceneSeekState,
  cameraAtProgress,
} from './timeline.js';
const camera = (lon, heading) => ({
  lat: 10,
  lon,
  alt: 1000,
  heading,
  pitch: -40,
  roll: 0,
});
const scene = {
  shots: [
    { id: 'a', durationSec: 2, holdSec: 1, camera: camera(20, 350) },
    { id: 'b', durationSec: 4, holdSec: 3, camera: camera(24, 10) },
  ],
};
const duration = (_, shot) => shot.durationSec + shot.holdSec;
const hold = (_, shot) => shot.holdSec;

test('scene time accounts for flight and hold; exact boundaries select the next shot', () => {
  const time = sceneTimingForShot(scene, scene.shots[1], duration);
  assert.equal(time.startElapsedSec, 3);
  assert.equal(time.endElapsedSec, 10);
  const seek = (progress) => sceneSeekState(scene, progress, duration, hold);
  assert.equal(seek(-1).shot.id, 'a');
  assert.equal(seek(0.3).shot.id, 'b');
  assert.equal(seek(0.3).cameraProgress, 0);
  assert.equal(seek(0.5).cameraProgress, 0.5);
  assert.equal(seek(0.5).camera.lon, 22);
  assert.equal(seek(0.8).holdElapsedSec, 1);
  assert.equal(seek(2).holdProgress, 1);
  assert.equal(seek(0).sceneElapsedSec, 0);
  assert.equal(sceneSeekState({ shots: [] }, 1, duration, hold), null);
});

test('camera seeking preserves cubic easing and shortest-angle orientation', () => {
  assert.equal(
    cameraAtProgress(camera(20, 350), camera(24, 10), 0.5).heading,
    360,
  );
  assert.equal(
    cameraAtProgress(camera(20, 350), camera(24, 10), 0.25).lon,
    20.25,
  );
  assert.deepEqual(cameraAtProgress(null, camera(20, 350), 0), camera(20, 350));
});