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Objects, properties and constructor arguments

All the effective ways of using React Three Fiber

Declaring objects

You can use three.js's entire object catalogue and all properties. When in doubt, always consult the docs.

โŒ You could lay out an object like this:

<mesh
  visible
  userData={{ hello: 'world' }}
  position={new THREE.Vector3(1, 2, 3)}
  rotation={new THREE.Euler(Math.PI / 2, 0, 0)}
  geometry={new THREE.SphereGeometry(1, 16, 16)}
  material={new THREE.MeshBasicMaterial({ color: new THREE.Color('hotpink'), transparent: true })}
/>

โœ… The problem is that all of these properties will always be re-created. Instead, you should define properties declaratively.

<mesh visible userData={{ hello: 'world' }} position={[1, 2, 3]} rotation={[Math.PI / 2, 0, 0]}>
  <sphereGeometry args={[1, 16, 16]} />
  <meshStandardMaterial color="hotpink" transparent />
</mesh>

Constructor arguments

In three.js objects are classes that are instantiated. These classes can receive one-time constructor arguments (new THREE.SphereGeometry(1, 32)), and properties (someObject.visible = true). In react-three-fiber, constructor arguments are always passed as an array via args. If args change later on, the object must naturally get reconstructed from scratch!

<sphereGeometry args={[1, 32]} />

Shortcuts

Set

All properties whose underlying object has a .set() method can directly receive the same arguments that set would otherwise take. For example THREE.Color.set can take a color string, so instead of color={new THREE.Color('hotpink')} you can simply write color="hotpink". Some set methods take multiple arguments, for instance THREE.Vector3, give it an array in that case position={[100, 0, 0]}.

<mesh position={[1, 2, 3]} />
  <meshStandardMaterial color="hotpink" />

SetScalar

Properties that have a setScalar method (for instance Vector3) can be set like so:

// Translates to <mesh scale={[1, 1, 1]} />
<mesh scale={1} />

Dealing with non-scene objects

You can put non-Object3D primitives (geometries, materials, etc) into the render tree as well. They take the same properties and constructor arguments they normally would.

You might be wondering why you would want to put something in the "scene" that normally would not be part of it, in a vanilla Three.js app at least. For the same reason you declare any object: it becomes managed, reactive and auto-disposes. These objects are not technically part of the scene, but they "attach" to a parent which is.

Attach

Use attach to bind objects to their parent. If you unmount the attached object it will be taken off its parent automatically.

The following attaches a material to the material property of a mesh and a geometry to the geometry property:

<mesh>
  <meshBasicMaterial attach="material">
  <boxGeometry attach="geometry">
All native elements ending with "Material" receive attach="material", and all elements ending with "Geometry" receive attach="geometry". So you do not have to type it out any longer.
<mesh>
  <meshBasicMaterial />
  <boxGeometry />

Nesting

You can nest primitive objects, too:

<mesh>
  <meshBasicMaterial attach="material">
    <texture attach="map" image={img} onUpdate={self => (self.needsUpdate = true)} />

AttachArray

Sometimes attaching isn't enough. The following example attaches effects to an array called "passes" of the parent effectComposer. attachArray adds the object to the target array and takes it out on unmount:

<effectComposer>
  <renderPass attachArray="passes" scene={scene} camera={camera} />
  <glitchPass attachArray="passes" renderToScreen />

AttachObject

You can also attach to named parent properties using attachObject={[target, name]}, which adds the object and takes it out on unmount. The following adds a buffer-attribute to parent.attributes.position.

<bufferGeometry attach="geometry">
  <bufferAttribute attachObject={['attributes', 'position']} count={v.length / 3} array={v} itemSize={3} />

AttachFns

Some objects have special add/remove function, you can't easily attach objects. In that case attachFns gives you full control.

The following uses the effect composer from the vanruesc/postprocessing library, which works differently than three/examples/jsm. You need to call Composer.addPass to add an effect and Composer.removePass to remove it.

<effectComposer>
  <renderPass attachFns={["addPass", "removePass"]} args={[scene, camera]} />

And in the case the add/remove functions are more complex:

<effectComposer>
  <renderPass
    args={[scene, camera]}
    attachFns={[
      (parent, self) => parent.addPass(self), 
      (parent, self) => parent.removePass)(self)
    ]} />

Piercing into nested properties

If you want to reach into nested attributes (for instance: mesh.rotation.x), just use dash-case.

<mesh rotation-x={1} material-uniforms-resolution-value={[512, 512]} />

Putting already existing objects into the scene-graph

You can use the primitive placeholder for that. You can still give it properties or attach nodes to it. Never add the same object multiple times, this is not allowed in three.js! Primitives will not dispose of the object they carry on unmount, you are responsible for disposing of it!

const mesh = new THREE.Mesh(geometry, material)

function Component() {
  return <primitive object={mesh} position={[10, 0, 0]} />

Using 3rd-party objects declaratively

The extend function extends three-fiber's catalogue of JSX elements. Components added this way can then be referenced in the scene-graph using camel casing similar to other primitives.

import { extend } from '@react-three/fiber'
import { OrbitControls, TransformControls } from 'three-stdlib'
extend({ OrbitControls, TransformControls })

// ...
return (
  <>
    <orbitControls />
    <transformControls />

Disposal

Freeing resources is a manual chore in three.js, but React is aware of object-lifecycles, hence three-fiber will attempt to free resources for you by calling object.dispose(), if present, on all unmounted objects.

If you manage assets by yourself, globally or in a cache, this may not be what you want. You can switch it off by placing dispose={null} onto meshes, materials, etc, or even on parent containers like groups, it is now valid for the entire tree.

const globalGeometry = new THREE.BoxGeometry()
const globalMaterial = new THREE.MeshBasicMaterial()

function Mesh() {
  return (
    <group dispose={null}>
      <mesh geometry={globalGeometry} material={globalMaterial} />