Newton’s Orchard

A serverless web app for building and viewing realistic solar systems in 3D: N-body gravity simulation, time scrubbing, and full control over planet creation (name, color, type, mass, radius, spin, axial tilt, orbit).

Svelte 5 + Vite + TypeScript + Three.js.

Development

npm i
npm run dev

Other scripts: npm run build, npm run preview, npm run check (type checking), npm test.

Using it

• System menu (tree icon, top left) — load a preset, save named systems to the browser, or export/import a system as JSON.
• Add (side panel) — create a body by orbital elements around a parent, or by raw position and velocity.
• Time bar — play/pause with a warp preset, or drag the shuttle to scrub. The shuttle sets a rate of travel through time and springs back to center; while it's off center it overrides play/pause entirely.
• Frame (top right) — view the system from the barycenter or from any body. Picking a body also parks the camera on it, so the Moon's orbit reads as an ellipse rather than a helix.
• Display (top right) — radius exaggeration, trails, labels, axes, predicted orbits, and the star bloom toggle (turn it off on weak GPUs).

Distances are true to scale; body radii are exaggerated for visibility, since at true scale an Earth radius is ~4e-5 of its orbit.

Saving

The current system autosaves to localStorage and restores on reload. Only body definitions and the current time are stored — the trajectory is deterministic, so everything else is recomputed on load. Named save slots and JSON export/import live in the System menu; exported files are pretty-printed and hand-editable, and imports are validated with errors that name the offending field.

Deploying

The build is a static dist/ directory with no backend, so any static host works.

npm run build
npm run preview   # serve dist/ locally at http://localhost:5317

Vercel. vercel.json is checked in and configures the build, output directory, and an SPA rewrite. Either import the repo at vercel.com/new or run npx vercel --prod.

GitHub Pages. Pages serves from a subpath, so the build needs a matching base path, otherwise every asset 404s:

npx vite build --base=/<repo-name>/

Then publish dist/ to the gh-pages branch (npx gh-pages -d dist) and point Pages at that branch. A user/organization site served from the domain root needs no --base.

Netlify / Cloudflare Pages. Build command npm run build, publish directory dist. Add a catch-all redirect to /index.html if you add routing later; the app currently has none.

Contributing & support

This is a personal project. No support is provided. The repo is public, and while issues and PRs are welcome, you may not receive a response.

License

MIT