fourJS

2D, 2.5D and 3D graphics, animation, motion and physics over one shared scene graph. Not yet published to npm.

Demos

Interactive example sites, built with --base=/four.js/examples/<name>/ because Pages hosts this repository under a subpath. Each URL is a real Vite bundle.

• one-scene-everything-moves — the §118 flagship: 2D art, lit 3D meshes, bodies, joints, particles, world text and a screen-space UI panel in one scene, with pause / slow motion / single-step.
• motor-digital-twin — the §119 flagship: an electric-motor digital twin — a motorised, bearing-constrained rotor on a sprung mount, a PID speed loop, fault injection, engineering-unit readouts, waveform charts, and record / seek / replay with save and reload.
• first-2d-scene — shapes, input, picking, dragging, tweens and a timeline.
• first-3d-scene — perspective camera, lit 3D primitives.
• first-animated-scene — §93 name over first-2d-scene (tweens, clip, timeline).
• first-physics-scene — §93 name over physics-playground (gravity, collisions, impulses).
• mixed-scene — §93 name over physics-playground (2D and 3D worlds side by side).
• physics-playground — rigid bodies on the Rapier adapter, 2D + 3D through one API.
• mechanism — joints and a driven linkage.
• blending — the animation-to-physics pipeline (§19).
• particles-demo — CPU particle emitters.
• ui-demo — retained-mode UI nodes in the scene graph.
• character-controller — §12 swept controller, first-person look, and a plane-tier patrol.

API reference

• Generated API documentation — all 24 packages, from the TypeScript declarations.

Guides

Hosted here as HTML (rendered at deploy time from docs/guides/*.md). The Markdown on GitHub remains the editable source.

• Guides index — Markdown on GitHub.
• The scene graph and transforms — .md.
• Cameras and coordinate conversion — .md.
• Fixed-step simulation — .md.
• Transform authority — .md.
• Materials and the render graph — .md.
• Collision filtering — .md.
• Units and numerical stability — .md.
• Workers and cross-origin isolation — .md.
• Performance optimization — .md.
• Custom shaders — .md.
• Custom solver adapters — .md.
• The engineering dashboard — .md.
• The digital twin — .md.
• Security and untrusted content — .md.
• Raster painting and dynamic textures — .md.
• Custom renderer backends — .md.
• 3D geometry generators — .md.
• Development warnings — .md.

Specification

• Specification — the working reference the implementation follows.
• Compatibility tables — §90 browsers, render backends, solvers, formats, plugin API.
• Repository