fix(sky): keep the Sun and Moon, settle outside the ICRF tables

- Pass the custom sky box to the Viewer instead of `skyBox: false`, which
  also stopped CesiumWidget from creating the Sun and the Moon. Guarded by
  scripts/qa-sky-sun-moon.mjs.
- Outside the IAU 2006 tables (before 1975, after ~2050) the preload
  resolves without data; remember that span and stay on TEME instead of
  preloading and rendering every frame.
- The anime style no longer cel-shades the far plane, where four bands
  turned the faint Milky Way into blotches.
- Paint the planets out after the star-removing opening and with the
  ring median, so no brighter plateau is left; faces rebuilt.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

scripts/build-milky-way.mjs

@@ -15,12 +15,12 @@
  *
  * Transform (deterministic):
  *   1. Resample to WORK_WIDTH×WORK_WIDTH/2 and convert sRGB to linear light.
- *   2. Paint out the planets the 2008–2010 exposures caught (PLANETS): they
- *      sit where today's sky has nothing and are far brighter than any star.
- *   3. Remove stars with a morphological opening (minimum, then maximum, over
+ *   2. Remove stars with a morphological opening (minimum, then maximum, over
  *      a (2·OPEN_RADIUS+1)² window): anything smaller than the window — every
  *      star — drops to the surrounding sky; the renderer draws catalogue stars
  *      itself, sharp and in the right place.
+ *   3. Paint out the planets the 2008–2010 exposures caught (PLANETS): they
+ *      sit where today's sky has nothing and are far brighter than any star.
  *   4. Blur with a three-pass box approximation of a Gaussian, σ = BLUR_DEG on
  *      the sky: rows wrap in longitude and widen by 1/cos(latitude) so the
  *      blur stays round towards the poles.
@@ -234,16 +234,18 @@ function galacticVector(l, b) {
 }
 
 /**
- * Replace a disc of the sky with the mean of the ring just outside it, per
- * channel. The blur that follows hides the seam.
+ * Replace a disc of the sky with the median of the ring just outside it, per
+ * channel. A median, not a mean: the planet's diffraction spikes reach far
+ * past the disc and would lift a mean well above the sky. The blur that
+ * follows hides the seam.
  */
 function paintOut(planes, width, height, { l, b, radiusDeg }) {
   const centre = galacticVector(l, b);
   const inner = Math.cos((radiusDeg * Math.PI) / 180);
-  const outer = Math.cos(((radiusDeg + 0.5) * Math.PI) / 180);
+  const outer = Math.cos(((radiusDeg + 1) * Math.PI) / 180);
   const disc = [];
   const ring = [];
-  const span = Math.ceil(((radiusDeg + 0.5) / 180) * height);
+  const span = Math.ceil(((radiusDeg + 1) / 180) * height);
   const row = Math.round((0.5 - b / 180) * height);
   for (let y = Math.max(0, row - span); y < Math.min(height, row + span); y++) {
     const latitude = 90 - ((y + 0.5) * 180) / height;
@@ -256,10 +258,9 @@ function paintOut(planes, width, height, { l, b, radiusDeg }) {
     }
   }
   for (const plane of planes) {
-    let sum = 0;
-    for (const index of ring) sum += plane[index];
-    const mean = sum / ring.length;
-    for (const index of disc) plane[index] = mean;
+    const values = Float32Array.from(ring, (index) => plane[index]).sort();
+    const median = values[values.length >> 1];
+    for (const index of disc) plane[index] = median;
   }
 }
 
@@ -323,12 +324,14 @@ async function main() {
   const { default: sharp } = await import('sharp');
   const { width, height, planes } = await decodePanorama(sharp, file);
   const sigmaPx = (BLUR_DEG / 180) * height;
-  for (const planet of PLANETS) paintOut(planes, width, height, planet);
   for (const plane of planes) {
     extremumPlane(plane, width, height, OPEN_RADIUS, Math.min);
     extremumPlane(plane, width, height, OPEN_RADIUS, Math.max);
-    blurPlane(plane, width, height, sigmaPx);
   }
+  // After the opening: it sinks the starry sky to the dark gaps between
+  // stars, and a fill taken before it would stay brighter than the sky.
+  for (const planet of PLANETS) paintOut(planes, width, height, planet);
+  for (const plane of planes) blurPlane(plane, width, height, sigmaPx);
   const black = luminancePercentile(planes, BLACK_PERCENTILE);
   const white = luminancePercentile(planes, WHITE_PERCENTILE);
   let total = 0;

scripts/format-scope.json

@@ -1067,5 +1067,6 @@
   "scripts/build-milky-way.mjs",
   "src/sky/stars.test.mjs",
   "src/sky/starrySky.test.mjs",
-  "src/tooling/skyAssets.test.mjs"
+  "src/tooling/skyAssets.test.mjs",
+  "src/tooling/skyAssets.paintOut.test.mjs"
 ]

scripts/qa-sky-sun-moon.mjs

@@ -0,0 +1,96 @@
+#!/usr/bin/env node
+/**
+ * qa-sky-sun-moon — the custom sky must keep Cesium's Sun and Moon.
+ *
+ * CesiumWidget creates `scene.sun` and `scene.moon` only when the `skyBox`
+ * option is not `false`, so replacing the sky box the wrong way silently
+ * removes the Sun disc and its bloom. Points the camera at the Sun from
+ * 22 000 km and fails unless both bodies exist; saves a screenshot.
+ *
+ * Usage: node scripts/qa-sky-sun-moon.mjs [--url http://localhost:4317] [--out qa-shots/sky-sun.png]
+ */
+import puppeteer from 'puppeteer';
+import { mkdirSync } from 'node:fs';
+import path from 'node:path';
+
+const argv = process.argv;
+const option = (name, fallback) =>
+  argv.includes(name) ? argv[argv.indexOf(name) + 1] : fallback;
+const url = option('--url', 'http://localhost:4317');
+const out = option('--out', 'qa-shots/sky-sun.png');
+mkdirSync(path.dirname(out), { recursive: true });
+
+const browser = await puppeteer.launch({
+  headless: 'new',
+  args: ['--no-sandbox', '--ignore-gpu-blocklist'],
+});
+try {
+  const page = await browser.newPage();
+  await page.setViewport({ width: 1280, height: 800 });
+  await page.evaluateOnNewDocument(() =>
+    localStorage.setItem('gev:first-run-mission:v1', 'suppressed'),
+  );
+  await page.goto(url, { waitUntil: 'domcontentloaded' });
+  await page.waitForFunction(() => window.__godsEyeView?.viewer?.scene, {
+    timeout: 90_000,
+  });
+  await new Promise((r) => setTimeout(r, 10_000));
+  const info = await page.evaluate(async () => {
+    // The page's own Cesium instance, as Vite served it.
+    const entry = performance
+      .getEntriesByType('resource')
+      .map((e) => e.name)
+      .find((n) => /\.vite\/deps\/cesium\.js/.test(n));
+    const C = await import(entry);
+    const { viewer } = window.__godsEyeView;
+    const scene = viewer.scene;
+    scene.camera.cancelFlight();
+    const time = viewer.clock.currentTime;
+    const sun = C.Cartesian3.normalize(
+      C.Matrix3.multiplyByVector(
+        C.Transforms.computeTemeToPseudoFixedMatrix(time),
+        C.Simon1994PlanetaryPositions.computeSunPositionInEarthInertialFrame(
+          time,
+        ),
+        new C.Cartesian3(),
+      ),
+      new C.Cartesian3(),
+    );
+    // Off to the side of the Earth, looking straight at the Sun.
+    const side = C.Cartesian3.normalize(
+      C.Cartesian3.cross(sun, C.Cartesian3.UNIT_Z, new C.Cartesian3()),
+      new C.Cartesian3(),
+    );
+    const destination = C.Cartesian3.add(
+      C.Cartesian3.multiplyByScalar(side, 2.2e7, new C.Cartesian3()),
+      C.Cartesian3.multiplyByScalar(sun, -0.6e7, new C.Cartesian3()),
+      new C.Cartesian3(),
+    );
+    const up = C.Cartesian3.normalize(
+      C.Cartesian3.cross(
+        C.Cartesian3.cross(sun, C.Cartesian3.UNIT_Z, new C.Cartesian3()),
+        sun,
+        new C.Cartesian3(),
+      ),
+      new C.Cartesian3(),
+    );
+    scene.camera.setView({ destination, orientation: { direction: sun, up } });
+    scene.requestRender();
+    return {
+      sun: Boolean(scene.sun),
+      moon: Boolean(scene.moon),
+      skyBox: scene.skyBox?.constructor?.name,
+    };
+  });
+  await new Promise((r) => setTimeout(r, 4_000));
+  await page.evaluate(() => window.__godsEyeView.viewer.scene.requestRender());
+  await new Promise((r) => setTimeout(r, 1_500));
+  await page.screenshot({ path: out });
+  console.log(JSON.stringify({ url, ...info, screenshot: out }));
+  if (!info.sun || !info.moon) {
+    console.error('FAIL: scene.sun and scene.moon must both exist');
+    process.exitCode = 1;
+  }
+} finally {
+  await browser.close();
+}