React Three Start

react-three-start

@react-three/start is a client-first app shell for React Three Fiber. It owns Vite/React bootstrapping, the root element, a fullscreen Canvas, scene discovery, DOM overlays, and wrapper composition. The app author mostly adds files under src/.

Project Shape

src/
  cube.scene.tsx      # rendered inside <Canvas>
  lights.scene.tsx    # rendered inside <Canvas>
  hud.dom.tsx         # rendered in the DOM overlay
start.config.ts       # optional framework config

Use react-three-start dev, react-three-start build, and react-three-start preview; r3s is the short alias. Create apps with npx @react-three/start create my-app.

Entry Files

• src/**/*.scene.tsx files are the 3D layer. Default-export R3F objects, lights, cameras, controls, physics bodies, or providers.
• src/**/*.dom.tsx files are the DOM overlay layer. Default-export normal React DOM UI.
• Entries are discovered automatically and sorted by path. Do not create a manual scene registry for ordinary app composition.
• DOM overlay content is fixed over the viewport. With the default injected Canvas, the overlay container has pointer-events: none, so interactive DOM controls should set pointerEvents: 'auto'.

Slots And Wrappers

Import Scene or Dom from @react-three/start only inside discovered *.scene.tsx and *.dom.tsx entry files. The Vite plugin rewrites those imports to continuation components.

A scene file that imports and renders <Scene /> becomes a scene wrapper. Use wrappers for providers that must surround the rest of the 3D scene: XR, physics, Suspense, controls, environment setup. Sorted filenames define nesting order.

// src/00-xr.scene.tsx
import { Scene } from '@react-three/start'
import { Physics } from '@react-three/rapier'

export default function PhysicsWrapper() {
  return (
    <Physics>
      <Scene />
    </Physics>
  )
}

00-xr.scene.tsx       # outer wrapper
10-physics.scene.tsx  # inner wrapper
cube.scene.tsx        # leaf scene entry

A DOM file that imports and renders <Dom /> becomes a DOM wrapper. A DOM file may also import <Scene /> when manually owning the Canvas.

Manual Canvas

By default, react-three-start injects a fullscreen Canvas and renders <Scene /> inside it. When layout, shadows, camera props, XR buttons, or multiple panels need ownership, disable injection and render the Canvas from a DOM entry.

// start.config.ts
export default {
  injectCanvas: false,
  title: 'My R3F app'
}

// src/app.dom.tsx
import { Canvas } from '@react-three/fiber'
import { Scene } from '@react-three/start'

export default function App() {
  return (
    <Canvas shadows camera={{ position: [0, 2, 6], fov: 45 }}>
      <Scene />
    </Canvas>
  )
}

start.config.ts may export injectCanvas, title, and a nested vite config object. The CLI merges vite with the generated Vite config and passes the remaining options to reactThreeStart(). Prefer start.config.ts; add vite.config.ts only when normal Vite ownership is needed.

Agent Rules Of Thumb

• Add new visual content as small *.scene.tsx leaves unless it must wrap other scene entries.
• Add UI as *.dom.tsx; keep interactive overlay elements explicitly pointer-enabled.
• Use numeric filename prefixes for wrapper order, not import order.
• Keep Scene and Dom imports in entry files only; pass ordinary React components through normal imports.
• Reach for manual Canvas only when the default fullscreen Canvas is too limiting.