projversor

Catalog data on a sphere that morphs between world projections (globe, Equal Earth, Mollweide, polar…), for standalone pages and stories. GeoVideo archives play as particles or rasters, with small GeoJSON and georeferenced images on top. Rendering primitives and the catalog come from zartigl (@fxi/zartigl/engine, /catalog, /story); projversor never touches MapLibre. In MapX, use zartigl's MapLibre layer instead.

Install

npm install @fxi/projversor @fxi/zartigl

An ES module with its types. @fxi/zartigl is a peer dependency, so a page that also imports zartigl loads one copy. d3 stays a dependency; the detailed coastlines load on demand.

API

import { Projversor } from "@fxi/projversor";

const pv = new Projversor(root, {
  preset: "globe", // projection preset; also rotate, zoom
  time: Date.parse("2025-03-15"), // playhead; default the latest month
  playing: true,
  interactive: true, // drag, pinch, wheel
  colors: { ocean: "#111d23" }, // over the css custom properties
  waitForLandDetail: true, // false: init() resolves before the 50m coastline
});
await pv.init(); // canvases in root, WebGL2; rejects without it

const currents = await pv.add("currents", "particles", {
  source: "ocean-current-velocity", // projversor layer id or catalog entry id
  tint: null, // particles colored by speed; or a scalar entry id
  style: { palette: "viridis" },
});
await pv.add("sst", "scalar", {
  source: "sea-water-temperature",
  timeRange: { start: "2026-05-01", end: "2026-10-31" }, // as zartigl's
});
await pv.add("photo", "image", {
  image: "https://example.org/map.png", // or a loaded image or canvas
  bounds: [120, -30, 240, 30], // west, south, east, north
  style: { opacity: 0.8 },
});
await pv.add("regions", "geojson", { data, style: { label: "name" } });

await currents.update({ particles: { density: 0.5 } }); // style override
await pv.replace("currents", "particles", { source: "surface-wind" });
await pv.update({ preset: "world", time, playing: false, speed: 2 });
pv.view.zoomBy(1.5); // goTo, rotateBy, setInset, outline, northAngle…
pv.on("month", ({ id, month }) => {}); // also status, palette, playing,
// preset, north, frame
await pv.remove("sst");
pv.destroy();

• Layers. Fields and images draw in the order added; GeoJSON (lines, fill, points with radius, labels) always above them. One particles layer at a time.
• Views. goTo onto the view already shown, and setInset to the current inset, do nothing: construct with the first view's preset, rotate and zoom to open on it without a morph.
• Time. One playhead. The first field layer drives it through its months; the others follow and load their own months. Its timeRange, the same as zartigl's ({ start?, end? } or { trailing: "P6M" }), loops playback over that window instead of the whole archive; null clears it. Share links carry it as tr=2026-05-01/2026-10-31 or tr=P6M.
• replace switches a layer's source, tint or style in place: the shown layer stays until the new month is decoded. A later call supersedes one still loading; a failed one keeps the shown layer.
• Look. Three canvases: ocean and land below, WebGL data in between, graticule, coastlines and GeoJSON above. Colors come from the css custom properties --ocean, --land, --coast, --graticule, --equator and --outline, read at init(); colors (option or update) overrides them at any time.
• Stories. ProjversorStoryView adapts a projversor to the @fxi/zartigl/story registry; a view config may carry a geojson and a timeRange.

Development

zartigl comes from npm. To work on both at once, link the sibling repository, then reinstall to return to the npm version:

npm run --prefix ../zartigl build:lib && npm link ../zartigl
npm install

npm test                # unit tests
npm run quality         # prettier, eslint, tsc
npm run build:lib       # dist/: the published package
npm run test:browser    # reference renders and app smoke tests
npm run dev:explorer    # also dev:story, dev:site, dev:minimal

Apps: apps/explorer (every catalog layer on the sphere), apps/story (a story), apps/site (home page with a scroll story) and apps/minimal (sea surface temperature anomaly and the Niño regions, the smallest page). npm run dev:explorer and the like serve each one; npm run build:apps builds them all into dist-apps/<name>/.

Docker

The image serves the apps with nginx on port 8080: the explorer at /, the story at /story/, the site at /site/ and the minimal page at /minimal/ (/healthz for health checks).

docker compose up -d --build   # from this folder; open http://localhost:8080
docker compose pull && docker compose up -d   # the published image

CI publishes ghcr.io/fxi/projversor from main (latest) and from v* tags.

The same apps are published to GitHub Pages from main (https://fxi.github.io/projversor/, story/, site/, minimal/).

Releases

npm run release:minor   # or release:patch, release:major

npm version bumps package.json, commits and tags vX.Y.Z, then the script pushes main with the tag. The tag publishes the package to npm (publish.yml, after quality, tests and build:lib) and the app image.