Hooks
Hooks are the heart of react-three-fiber
Hooks allow you to tie or request specific information to your component. For instance, components that want to participate in the renderloop can use useFrame
, components that need to be informed of three.js specifics can use useThree
and so on. All hooks clean up after themselves once the component unmounts.
Hooks can only be used inside the Canvas element because they rely on context!
❌ You cannot expect something like this to work:
import { useThree } from '@react-three/fiber'
function App() {
const { size } = useThree() // This will just crash
return (
<Canvas>
<mesh>
✅ Do this instead:
function Foo() {
const { size } = useThree()
...
}
function App() {
return (
<Canvas>
<Foo />
useThree
This hook gives you access to the state model which contains the default renderer, the scene, your camera, and so on. It also gives you the current size of the canvas in screen and viewport coordinates.
import { useThree } from '@react-three/fiber'
function Foo() {
const state = useThree()
The hook is reactive, if you resize the browser for instance, you get fresh measurements, same applies to any of the state objects that may change.
state
properties
Prop | Description | Type |
---|---|---|
gl | Renderer | THREE.WebGLRenderer |
scene | Scene | THREE.Scene |
camera | Camera | THREE.PerspectiveCamera |
controls | A [makeDefault] *Controls | THREE.EventDispatcher or null |
raycaster | Default raycaster | THREE.Raycaster |
pointer | Contains updated, normalized, centric pointer coordinates | THREE.Vector2 |
mouse | Note: this is deprecated, use pointer instead! Normalized event coordinates | THREE.Vector2 |
clock | Running system clock | THREE.Clock |
linear | True when the colorspace is linear | boolean |
flat | True when no tonemapping is used | boolean |
legacy | Disables global color management via THREE.ColorManagement | boolean |
frameloop | Render mode: always, demand, never | always , demand , never |
performance | System regression | { current: number, min: number, max: number, debounce: number, regress: () => void } |
size | Canvas size in pixels | { width: number, height: number, top: number, left: number, updateStyle?: boolean } |
viewport | Canvas viewport size in three.js units. Note: This is different from gl.getViewport which returns the drawbuffer size | { width: number, height: number, initialDpr: number, dpr: number, factor: number, distance: number, aspect: number, getCurrentViewport: (camera?: Camera, target?: THREE.Vector3, size?: Size) => Viewport } |
xr | XR interface, manages WebXR rendering | { connect: () => void, disconnect: () => void } |
set | Allows you to set any state property | (state: SetState<RootState>) => void |
get | Allows you to retrieve any state property non-reactively | () => GetState<RootState> |
invalidate | Request a new render, given that frameloop === 'demand' | () => void |
advance | Advance one tick, given that frameloop === 'never' | (timestamp: number, runGlobalEffects?: boolean) => void |
setSize | Resize the canvas | (width: number, height: number, updateStyle?: boolean, top?: number, left?: number) => void |
setDpr | Set the pixel-ratio | (dpr: number) => void |
setFrameloop | Shortcut to set the current render mode | (frameloop?: 'always', 'demand', 'never') => void |
setEvents | Shortcut to setting the event layer | (events: Partial<EventManager<any>>) => void |
onPointerMissed | Response for pointer clicks that have missed a target | () => void |
events | Pointer-event handling | { connected: TargetNode, handlers: Events, connect: (target: TargetNode) => void, disconnect: () => void } |
Selector
You can also select properties, this allows you to avoid needless re-render for components that are interested only in particulars. Reactivity does not include deeper three.js internals!
// Will only trigger re-render when the default camera is exchanged
const camera = useThree((state) => state.camera)
// Will only re-render on resize changes
const viewport = useThree((state) => state.viewport)
// ❌ You cannot expect reactivity from three.js internals!
const zoom = useThree((state) => state.camera.zoom)
Reading state from outside of the component cycle
function Foo() {
const get = useThree((state) => state.get)
...
get() // Get fresh state from anywhere you want
Exchanging defaults
function Foo() {
const set = useThree((state) => state.set)
...
useEffect(() => {
set({ camera: new THREE.OrthographicCamera(...) })
}, [])
useFrame
This hook allows you to execute code on every rendered frame, like running effects, updating controls, and so on. You receive the state (same as useThree
) and a clock delta. Your callback function will be invoked just before a frame is rendered. When the component unmounts it is unsubscribed automatically from the render-loop.
import { useFrame } from '@react-three/fiber'
function Foo() {
useFrame((state, delta, xrFrame) => {
// This function runs at the native refresh rate inside of a shared render-loop
})
Be careful about what you do inside useFrame! You should never setState in there! Your calculations should be slim and you should mind all the commonly known pitfalls when dealing with loops in general, like re-use of variables, etc.
Taking over the render-loop
If you need more control you may pass a numerical renderPriority
value. This will cause React Three Fiber to disable automatic rendering altogether. It will now be your responsibility to render, which is useful when you're working with effect composers, heads-up displays, etc.
function Render() {
// Takes over the render-loop, the user has the responsibility to render
useFrame(({ gl, scene, camera }) => {
gl.render(scene, camera)
}, 1)
function RenderOnTop() {
// This will execute *after* Render's useframe
useFrame(({ gl, ... }) => {
gl.render(...)
}, 2)
Callbacks will be executed in order of ascending priority values (lowest first, highest last.), similar to the DOM's z-order.
Negative indices
Using negative indices will not take over the render loop, but it can be useful if you really must order the sequence of useFrames across the component tree.
function A() {
// This will execute first
useFrame(() => ..., -2)
function B() {
// This useFrame will execute *after* A's
useFrame(() => ..., -1)
useLoader
This hook loads assets and suspends for easier fallback- and error-handling. It can take any three.js loader as its first argument: GLTFLoader, OBJLoader, TextureLoader, FontLoader, etc. It is based on React.Suspense, so fallback-handling and error-handling happen at the parental level.
import { Suspense } from 'react'
import { useLoader } from '@react-three/fiber'
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader'
function Model() {
const result = useLoader(GLTFLoader, '/model.glb')
// You don't need to check for the presence of the result, when we're here
// the result is guaranteed to be present since useLoader suspends the component
return <primitive object={result.scene} />
}
function App() {
return (
<Suspense fallback={<FallbackComponent /> /* or null */}>
<Model />
</Suspense>
)
}
Assets loaded with useLoader are cached by default. The urls given serve as cache-keys. This allows you to re-use loaded data everywhere in the component tree.
Be very careful with mutating or disposing of loaded assets, especially when you plan to re-use them. Refer to the automatic disposal section in the API.
Loader extensions
You can provide a callback as the third argument if you need to configure your loader:
import { DRACOLoader } from 'three/examples/jsm/loaders/DRACOLoader'
useLoader(GLTFLoader, url, (loader) => {
const dracoLoader = new DRACOLoader()
dracoLoader.setDecoderPath('/draco-gltf/')
loader.setDRACOLoader(dracoLoader)
})
Loading multiple assets at once
It can also make multiple requests in parallel:
const [bumpMap, specMap, normalMap] = useLoader(TextureLoader, [url1, url2, url2])
Loading status
You can get the loading status from a callback you provide as the fourth argument. Though consider alternatives like THREE.DefaultLoadingManager or better yet, Drei's loading helpers.
useLoader(loader, url, extensions, (xhr) => {
console.log((xhr.loaded / xhr.total) * 100 + '% loaded')
})
Special treatment of GLTFLoaders and all loaders that return a scene prop
If a result.scene
prop is found the hook will automatically create a object & material collection: { nodes, materials }
. This lets you build immutable scene graphs selectively. You can also specifically alter the data without having to traverse it. GLTFJSX specifically relies on this data.
const { nodes, materials } = useLoader(GLTFLoader, url)
Pre-loading assets
You can pre-load assets in global space so that models can be loaded in anticipation before they're mounted in the component tree.
useLoader.preload(GLTFLoader, '/model.glb' /* extensions */)
useGraph
Convenience hook which creates a memoized, named object/material collection from any Object3D
.
import { useLoader, useGraph } from '@react-three/fiber'
function Model(url) {
const scene = useLoader(OBJLoader, url)
const { nodes, materials } = useGraph(scene)
return <mesh geometry={nodes.robot.geometry} material={materials.metal} />
}