SKILL.md
$2a
return (
<boxGeometry args={[1, 1, 1]} />
)
}
export default function App() {
return (
<Canvas camera={{ position: [0, 0, 5], fov: 75 }}>
<directionalLight position={[5, 5, 5]} />
)
}
## Canvas Component
The root component that creates the WebGL context, scene, camera, and renderer.
import { Canvas } from '@react-three/fiber'
function App() {
return (
<Canvas
// Camera configuration
camera={{
position: [0, 5, 10],
fov: 75,
near: 0.1,
far: 1000,
}}
// Or use orthographic
orthographic
camera={{ zoom: 50, position: [0, 0, 100] }}
// Renderer settings
gl={{
antialias: true,
alpha: true,
powerPreference: 'high-performance',
preserveDrawingBuffer: true, // For screenshots
}}
dpr={[1, 2]} // Pixel ratio min/max
// Shadows
shadows // or shadows="soft" | "basic" | "percentage"
// Color management
flat // Disable automatic sRGB color management
// Frame loop control
frameloop="demand" // 'always' | 'demand' | 'never'
// Event handling
eventSource={document.getElementById('root')}
eventPrefix="client" // 'offset' | 'client' | 'page' | 'layer' | 'screen'
// Callbacks
onCreated={(state) => {
console.log('Canvas ready:', state.gl, state.scene, state.camera)
}}
onPointerMissed={() => console.log('Clicked background')}
// Styling
style={{ width: '100%', height: '100vh' }}
>
<Scene />
</Canvas>
)
}
### Canvas Defaults
R3F sets sensible defaults:
- Renderer: antialias, alpha, outputColorSpace = SRGBColorSpace
- Camera: PerspectiveCamera at [0, 0, 5]
- Scene: Automatic resize handling
- Events: Pointer events enabled
## useFrame Hook
Subscribe to the render loop. Called every frame (typically 60fps).
import { useFrame } from '@react-three/fiber'
import { useRef } from 'react'
function AnimatedMesh() {
const meshRef = useRef()
useFrame((state, delta, xrFrame) => {
// state: Full R3F state (see useThree)
// delta: Time since last frame in seconds
// xrFrame: XR frame if in VR/AR mode
// Animate rotation
meshRef.current.rotation.y += delta
// Access clock
const elapsed = state.clock.elapsedTime
meshRef.current.position.y = Math.sin(elapsed) * 2
// Access pointer position (-1 to 1)
const { x, y } = state.pointer
meshRef.current.rotation.x = y * 0.5
meshRef.current.rotation.z = x * 0.5
})
return (
<mesh ref={meshRef}>
<boxGeometry />
<meshStandardMaterial color="orange" />
</mesh>
)
}
### useFrame with Priority
Control render order with priority (higher = later).
// Default priority is 0
useFrame((state, delta) => {
// Runs first
}, -1)
useFrame((state, delta) => {
// Runs after priority -1
}, 0)
// Manual rendering with positive priority
useFrame((state, delta) => {
// Take over rendering
state.gl.render(state.scene, state.camera)
}, 1)
### Conditional useFrame
function ConditionalAnimation({ active }) {
useFrame((state, delta) => {
if (!active) return // Skip when inactive
meshRef.current.rotation.y += delta
})
}
## useThree Hook
Access the R3F state store.
import { useThree } from '@react-three/fiber'
function CameraInfo() {
// Get full state (triggers re-render on any change)
const state = useThree()
// Selective subscription (recommended)
const camera = useThree((state) => state.camera)
const gl = useThree((state) => state.gl)
const scene = useThree((state) => state.scene)
const size = useThree((state) => state.size)
// Available state properties:
// gl: WebGLRenderer
// scene: Scene
// camera: Camera
// raycaster: Raycaster
// pointer: Vector2 (normalized -1 to 1)
// mouse: Vector2 (deprecated, use pointer)
// clock: Clock
// size: { width, height, top, left }
// viewport: { width, height, factor, distance, aspect }
// performance: { current, min, max, debounce, regress }
// events: Event handlers
// set: State setter
// get: State getter
// invalidate: Trigger re-render (for frameloop="demand")
// advance: Advance one frame (for frameloop="never")
return null
}
### Common useThree Patterns
// Responsive to viewport
function ResponsiveObject() {
const viewport = useThree((state) => state.viewport)
return (
<mesh scale={[viewport.width / 4, viewport.height / 4, 1]}>
<planeGeometry />
<meshBasicMaterial color="blue" />
</mesh>
)
}
// Manual render trigger
function TriggerRender() {
const invalidate = useThree((state) => state.invalidate)
const handleClick = () => {
// Trigger render when using frameloop="demand"
invalidate()
}
}
// Update camera
function CameraController() {
const camera = useThree((state) => state.camera)
const set = useThree((state) => state.set)
useEffect(() => {
camera.position.set(10, 10, 10)
camera.lookAt(0, 0, 0)
}, [camera])
}
## JSX Elements
All Three.js objects are available as JSX elements (camelCase).
### Meshes
// Basic mesh structure
<mesh
position={[0, 0, 0]} // x, y, z
rotation={[0, Math.PI, 0]} // Euler angles in radians
scale={[1, 2, 1]} // x, y, z or single number
visible={true}
castShadow
receiveShadow
>
<boxGeometry args={[1, 1, 1]} />
<meshStandardMaterial color="red" />
</mesh>
// With ref
const meshRef = useRef()
<mesh ref={meshRef} />
// meshRef.current is the THREE.Mesh
### Geometry args
Constructor arguments via `args` prop:
// BoxGeometry(width, height, depth, widthSegments, heightSegments, depthSegments)
<boxGeometry args={[1, 1, 1, 1, 1, 1]} />
// SphereGeometry(radius, widthSegments, heightSegments)
<sphereGeometry args={[1, 32, 32]} />
// PlaneGeometry(width, height, widthSegments, heightSegments)
<planeGeometry args={[10, 10]} />
// CylinderGeometry(radiusTop, radiusBottom, height, radialSegments)
<cylinderGeometry args={[1, 1, 2, 32]} />
### Groups
<group position={[5, 0, 0]} rotation={[0, Math.PI / 4, 0]}>
<mesh position={[-1, 0, 0]}>
<boxGeometry />
<meshStandardMaterial color="red" />
</mesh>
<mesh position={[1, 0, 0]}>
<boxGeometry />
<meshStandardMaterial color="blue" />
</mesh>
</group>
### Nested Properties
Use dashes for nested properties:
<mesh
position-x={5}
rotation-y={Math.PI}
scale-z={2}
>
<meshStandardMaterial
color="red"
metalness={0.8}
roughness={0.2}
/>
</mesh>
// Shadow camera properties
<directionalLight
castShadow
shadow-mapSize={[2048, 2048]}
shadow-camera-left={-10}
shadow-camera-right={10}
shadow-camera-top={10}
shadow-camera-bottom={-10}
/>
### attach Prop
Control how children attach to parents:
<mesh>
<boxGeometry />
{/ Default: attaches as 'material' /}
<meshStandardMaterial />
</mesh>
{/ Explicit attach /}
<mesh>
<boxGeometry attach="geometry" />
<meshStandardMaterial attach="material" />
</mesh>
{/ Array attachment /}
<mesh>
<boxGeometry />
<meshStandardMaterial attach="material-0" color="red" />
<meshStandardMaterial attach="material-1" color="blue" />
</mesh>
{/ Custom attachment with function /}
<someObject>
<texture
attach={(parent, self) => {
parent.map = self
return () => { parent.map = null } // Cleanup
}}
/>
</someObject>
## Event Handling
R3F provides React-style events on 3D objects.
function InteractiveBox() {
const [hovered, setHovered] = useState(false)
const [clicked, setClicked] = useState(false)
return (
<mesh
onClick={(e) => {
e.stopPropagation() // Prevent bubbling
setClicked(!clicked)
// Event properties:
console.log(e.object) // THREE.Mesh
console.log(e.point) // Vector3 - intersection point
console.log(e.distance) // Distance from camera
console.log(e.face) // Intersected face
console.log(e.faceIndex) // Face index
console.log(e.uv) // UV coordinates
console.log(e.normal) // Face normal
console.log(e.pointer) // Normalized pointer coords
console.log(e.ray) // Raycaster ray
console.log(e.camera) // Camera
console.log(e.delta) // Distance moved (drag events)
}}
onContextMenu={(e) => console.log('Right click')}
onDoubleClick={(e) => console.log('Double click')}
onPointerOver={(e) => {
e.stopPropagation()
setHovered(true)
document.body.style.cursor = 'pointer'
}}
onPointerOut={(e) => {
setHovered(false)
document.body.style.cursor = 'default'
}}
onPointerDown={(e) => console.log('Pointer down')}
onPointerUp={(e) => console.log('Pointer up')}
onPointerMove={(e) => console.log('Moving over mesh')}
onWheel={(e) => console.log('Wheel:', e.deltaY)}
scale={hovered ? 1.2 : 1}
>
<boxGeometry />
<meshStandardMaterial color={clicked ? 'hotpink' : 'orange'} />
</mesh>
)
}
### Event Propagation
Events bubble up through the scene graph:
<group onClick={(e) => console.log('Group clicked')}>
<mesh onClick={(e) => {
e.stopPropagation() // Stop bubbling to group
console.log('Mesh clicked')
}}>
<boxGeometry />
<meshStandardMaterial />
</mesh>
</group>
## primitive Element
Use existing Three.js objects directly:
import * as THREE from 'three'
// Existing object
const geometry = new THREE.BoxGeometry()
const material = new THREE.MeshStandardMaterial({ color: 'red' })
const mesh = new THREE.Mesh(geometry, material)
function Scene() {
return <primitive object={mesh} position={[0, 1, 0]} />
}
// Common with loaded models
function Model({ gltf }) {
return <primitive object={gltf.scene} />
}
## extend Function
Register custom Three.js classes for JSX use:
import { extend } from '@react-three/fiber'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
// Extend once (usually at module level)
extend({ OrbitControls })
// Now use as JSX
function Scene() {
const { camera, gl } = useThree()
return <orbitControls args={[camera, gl.domElement]} />
}
// TypeScript declaration
declare global {
namespace JSX {
interface IntrinsicElements {
orbitControls: ReactThreeFiber.Object3DNode<OrbitControls, typeof OrbitControls>
}
}
}
## Refs and Imperative Access
import { useRef, useEffect } from 'react'
import { useFrame } from '@react-three/fiber'
import * as THREE from 'three'
function MeshWithRef() {
const meshRef = useRef<THREE.Mesh>(null)
const materialRef = useRef<THREE.MeshStandardMaterial>(null)
useEffect(() => {
if (meshRef.current) {
// Direct Three.js access
meshRef.current.geometry.computeBoundingBox()
console.log(meshRef.current.geometry.boundingBox)
}
}, [])
useFrame(() => {
if (materialRef.current) {
materialRef.current.color.setHSL(Math.random(), 1, 0.5)
}
})
return (
<mesh ref={meshRef}>
<boxGeometry />
<meshStandardMaterial ref={materialRef} />
</mesh>
)
}
## Performance Patterns
### Avoiding Re-renders
// BAD: Creates new object every render
<mesh position={[x, y, z]} />
// GOOD: Mutate existing position
const meshRef = useRef()
useFrame(() => {
meshRef.current.position.x = x
})
<mesh ref={meshRef} />
// GOOD: Use useMemo for static values
const position = useMemo(() => [x, y, z], [x, y, z])
<mesh position={position} />
### Component Isolation
// Isolate animated components to prevent parent re-renders
function Scene() {
return (
<>
<StaticEnvironment />
<AnimatedObject /> {/ Only this re-renders on animation /}
</>
)
}
function AnimatedObject() {
const ref = useRef()
useFrame((_, delta) => {
ref.current.rotation.y += delta
})
return <mesh ref={ref}><boxGeometry /></mesh>
}
### Dispose
R3F auto-disposes geometries, materials, and textures. Override with:
<mesh dispose={null}> {/ Prevent auto-dispose /}
<boxGeometry />
<meshStandardMaterial />
</mesh>
## Common Patterns
### Fullscreen Canvas
// styles.css
html, body, #root {
margin: 0;
padding: 0;
width: 100%;
height: 100%;
}
// App.tsx
<Canvas style={{ width: '100%', height: '100%' }}>
### Responsive Canvas
function ResponsiveScene() {
const { viewport } = useThree()
return (
<mesh scale={Math.min(viewport.width, viewport.height) / 5}>
<boxGeometry />
<meshStandardMaterial />
</mesh>
)
}
### Forwarding Refs
import { forwardRef } from 'react'
const CustomMesh = forwardRef((props, ref) => {
return (
<mesh ref={ref} {...props}>
<boxGeometry />
<meshStandardMaterial color="orange" />
</mesh>
)
})
// Usage
const meshRef = useRef()
<CustomMesh ref={meshRef} position={[0, 1, 0]} />
## Debugging with Leva
Leva provides a GUI for tweaking parameters in real-time during development.
### Installation
npm install leva
### Basic Controls
import { useControls } from 'leva'
function DebugMesh() {
const { position, color, scale, visible } = useControls({
position: { value: [0, 0, 0], step: 0.1 },
color: '#ff0000',
scale: { value: 1, min: 0.1, max: 5, step: 0.1 },
visible: true,
})
return (
<mesh position={position} scale={scale} visible={visible}>
<boxGeometry />
<meshStandardMaterial color={color} />
</mesh>
)
}
### Organized Folders
import { useControls, folder } from 'leva'
function DebugScene() {
const { lightIntensity, lightColor, shadowMapSize } = useControls({
Lighting: folder({
lightIntensity: { value: 1, min: 0, max: 5 },
lightColor: '#ffffff',
shadowMapSize: { value: 1024, options: [512, 1024, 2048, 4096] },
}),
Camera: folder({
fov: { value: 75, min: 30, max: 120 },
near: { value: 0.1, min: 0.01, max: 1 },
}),
})
return (
<directionalLight
intensity={lightIntensity}
color={lightColor}
shadow-mapSize={[shadowMapSize, shadowMapSize]}
/>
)
}
### Button Actions
import { useControls, button } from 'leva'
function DebugActions() {
const meshRef = useRef()
useControls({
'Reset Position': button(() => {
meshRef.current.position.set(0, 0, 0)
}),
'Random Color': button(() => {
meshRef.current.material.color.setHex(Math.random() * 0xffffff)
}),
'Log State': button(() => {
console.log(meshRef.current.position)
}),
})
return <mesh ref={meshRef}>...</mesh>
}
### Hide in Production
import { Leva } from 'leva'
function App() {
return (
<>
{/ Hide Leva panel in production /}
<Leva hidden={process.env.NODE_ENV === 'production'} />
<Canvas>
<Scene />
</Canvas>
</>
)
}
### Monitor Values (Read-Only)
import { useControls, monitor } from 'leva'
import { useFrame } from '@react-three/fiber'
function PerformanceMonitor() {
const [fps, setFps] = useState(0)
useControls({
FPS: monitor(() => fps, { graph: true, interval: 100 }),
})
useFrame((state) => {
// Update FPS display
setFps(Math.round(1 / state.clock.getDelta()))
})
return null
}
### Integration with useFrame
function AnimatedDebugMesh() {
const meshRef = useRef()
const { speed, amplitude, enabled } = useControls('Animation', {
enabled: true,
speed: { value: 1, min: 0, max: 5 },
amplitude: { value: 1, min: 0, max: 3 },
})
useFrame(({ clock }) => {
if (!enabled) return
meshRef.current.position.y = Math.sin(clock.elapsedTime speed) amplitude
})
return (
<mesh ref={meshRef}>
<sphereGeometry />
<meshStandardMaterial color="cyan" />
</mesh>
)
}