ScribbleRig

A browser-based 2D physics sandbox in the spirit of The Incredible Machine — drop bodies into a room, connect them with springs, motors, welds, and pins, hit Play, and watch physics unfold. Everything is rendered in a hand-drawn doodle style, and a whole creation packs into a shareable URL — no account, no sign-in. A small Cloudflare Worker mints optional named shortlinks (/s/<id>) and renders OG previews; the URL-share path keeps working unchanged.

Try it →

Features

• Bodies & connectors — place balls and platforms; join them with springs, motors (live-tunable while running), welds, and pins.
• Build vs. run — edit the design while paused; Play compiles it into a live simulation and Reset replays it identically.
• Hand-drawn rendering — Rough.js doodles over a paper grid, with stable (non-shimmering) line wobble.
• Pan & zoom, optional grid snapping, and a mobile-friendly bottom-sheet UI.
• URL-encoded sharing — the scene is encoded straight into the URL, and decoding is tolerant so links keep working as the format evolves. A Cloudflare Worker mints optional named shortlinks (backed by KV) with OG previews; un-named scenes never touch a backend.
• Per-tab sessions + autosave — each tab holds its own build, with a Builds list (thumbnails) to reopen past creations.

Tech stack

Vite · TypeScript · React · Rapier (2D, WASM) for physics · Rough.js for rendering · Vitest for tests. Physics units are meters; the renderer scales to pixels.

Development

This project uses bun.

bun install      # install dependencies
bun run dev      # start the Vite dev server
bun run build    # type-check and build for production
bun run test     # run the test suite (vitest run)

Architecture

The design graph (the serializable scene) is the source of truth; the live simulation is a disposable instance compiled from it on Play and discarded on Reset. The physics engine is fully encapsulated by the sim module, so it stays swappable.

• CONTEXT.md — domain glossary and module map.
• docs/adr/ — architecture decision records.
• .scratch/scribblerig/ — the PRD and issue tracker.

License

ScribbleRig is licensed under the GNU Affero General Public License v3.0 — © 2026 Josiah Nunemaker.