react-spring/docs/app/routes/docs.guides.react-three-fiber.mdx

---
meta:
  title: React Three Fiber | React Spring
  'og:title': React Three Fiber | React Spring
  'twitter:title': React Three Fiber | React Spring
  description: A detailed guide to using React Spring with React Three Fiber.
  'og:description': A detailed guide to using React Spring with React Three Fiber.
  'twitter:description': A detailed guide to using React Spring with React Three Fiber.
  'og:url': https://www.react-spring.dev/docs/guides/react-three-fiber
  'twitter:url': https://www.react-spring.dev/docs/guides/react-three-fiber
sidebar_position: 1
---

import { formatFrontmatterToRemixMeta } from '../helpers/meta'

export const meta = formatFrontmatterToRemixMeta(frontmatter)

# React Three Fiber

:::note
It's assumed you have a base understanding of `react-spring` and `react-three-fiber`. If you're new to
either, check out our [getting started](/docs/getting-started) or alternatively, the [react-three-fiber](https://docs.pmnd.rs/react-three-fiber) docs.
:::

## Introduction

In this guide we'll explore why `react-spring` is a valuable addition to your `react-three-fiber` project, working with the `imperative API`
to create performant animation updates on objects in the scene graph and with the [event system](/docs/advanced/events) of the library
to update parts of your scene that are not wrapped in our [`animated` HOC](/docs/concepts/animated-elements). To work with `react-spring`
and `react-three-fiber` you'll need to install the `@react-spring/three` package.

```bash
yarn add @react-spring/three @react-three/fiber three
```

## Why use the library?

A common question asked is why use `react-spring` with `react-three-fiber` when you can use the `useFrame` hook to update your meshes & objects
instead without knowing another API. Well this is a great question – its critical of motion design for animations to look realistic, and the beauty
of `react-spring` is the animations are physically correct.

When we consider that the animations you create with `react-spring` can not be interrupted per se, that is when you edit the value you don't have
the animation halt and start again, it responds to it's new goal value creating a seamless experience incredibly valuable to a 3D scene, you don't
see items in real life free fall and when an external force is applied they stall, they react accordingly. The dampening of a spring gives you the
additional feeling of real life physics whilst in combination of even the three most basic config parameter `mass`, `tension` and `friction` you can
create a wide range of animations that belong to different objects in your scenes, you might have a metal-like sphere that needs to move slowly compared
to your light translucent sphere that should be falling and bouncing around the scene.

Furthermore, the flexibility to start/stop and replay animations, particularly with state and device motion preferences, makes this a uniquely
accessible library from both a DX and UX perspective. Lets take a look at a simple use-case.

I have a distortion blob and I want to it to change color on click. You could do this with `useFrame` to perform frame by frame updates, `useRef`
to access the material object and use the `THREE.Color.lerp` function, slowly incrementing by the lerp value until the color is reached. But this then
requires that I keep track of a `THREE` instance of `Color` which _can_ lead to memory leaks if not handled correctly and not only that, but it would
be a lot of code. Then you'd need to think about writing your own easing functions. With `react-spring` you can do this in a few lines of code.

```tsx live=true template=r3f showLineNumbers lines=9,12,20 defaultOpen=true
import { useState } from 'react'
import { useSpring, animated } from '@react-spring/three'
import { MeshDistortMaterial } from '@react-three/drei'
import { Canvas } from '@react-three/fiber'

const AnimatedMeshDistortMaterial = animated(MeshDistortMaterial)

const MyScene = () => {
  const [clicked, setClicked] = useState(false)

  const springs = useSpring({
    color: clicked ? '#569AFF' : '#ff6d6d',
  })

  const handleClick = () => setClicked(s => !s)

  return (
    <mesh onClick={handleClick}>
      <sphereGeometry args={[1.5, 64, 32]} />
      <AnimatedMeshDistortMaterial
        speed={5}
        distort={0.5}
        color={springs.color}
      />
    </mesh>
  )
}

export default function MyComponent() {
  return (
    <Canvas>
      <ambientLight intensity={0.8} />
      <pointLight intensity={1} position={[0, 6, 0]} />
      <MyScene />
    </Canvas>
  )
}
```

## Use the imperative API

The example above demonstrates the declarative approach to using `react-spring` hooks by passing a `config` object to the hook.
However, it can also receive a function argument instead, similar to react's `useEffect` hook.

In the example below, we use the power of the `react-spring`'s api to lean into the imperative requirements
of working with performant webGL scenes. The blob follows you round the canvas (lines 70-82) & scales on
interaction (lines 46-56) without a single react render to cause these updates.

In addition we use the provide a function to the `config` prop instead of an object to deliver a more sticky
config for the spring in general, but to give the blob a bouncy feel when the `scale` key is changed – lines 18-30.

Finally, because we're using the position of the mouse which can be considered a `Vector2` and the `position`
of a `mesh` is a `Vector3` we use a custom interpolation via the `to` method of a `SpringValue` to interpolate
the array, this can be seen on line 97 (also see [imperative API](/docs/concepts/imperative-api) and
[interpolation](/docs/advanced/interpolation)).

```tsx live=true template=r3f lines=18-30,46-56,70-82,97 showLineNumbers defaultOpen=true
import { useRef, useEffect, useCallback } from 'react'
import { useSpring, animated } from '@react-spring/three'
import { Canvas, useThree } from '@react-three/fiber'
import { MeshDistortMaterial } from '@react-three/drei'

const AnimatedMeshDistortMaterial = animated(MeshDistortMaterial)

const MyScene = () => {
  const isOver = useRef(false)

  const { width, height } = useThree(state => state.size)

  const [springs, api] = useSpring(
    () => ({
      scale: 1,
      position: [0, 0],
      color: '#ff6d6d',
      config: key => {
        switch (key) {
          case 'scale':
            return {
              mass: 4,
              friction: 10,
            }
          case 'position':
            return { mass: 4, friction: 220 }
          default:
            return {}
        }
      },
    }),
    []
  )

  const handleClick = useCallback(() => {
    let clicked = false

    return () => {
      clicked = !clicked
      api.start({
        color: clicked ? '#569AFF' : '#ff6d6d',
      })
    }
  }, [])

  const handlePointerEnter = () => {
    api.start({
      scale: 1.5,
    })
  }

  const handlePointerLeave = () => {
    api.start({
      scale: 1,
    })
  }

  const handleWindowPointerOver = useCallback(() => {
    isOver.current = true
  }, [])

  const handleWindowPointerOut = useCallback(() => {
    isOver.current = false

    api.start({
      position: [0, 0],
    })
  }, [])

  const handlePointerMove = useCallback(
    e => {
      if (isOver.current) {
        const x = (e.offsetX / width) * 2 - 1
        const y = (e.offsetY / height) * -2 + 1

        api.start({
          position: [x * 5, y * 2],
        })
      }
    },
    [api, width, height]
  )

  useEffect(() => {
    window.addEventListener('pointerover', handleWindowPointerOver)
    window.addEventListener('pointerout', handleWindowPointerOut)
    window.addEventListener('pointermove', handlePointerMove)

    return () => {
      window.removeEventListener('pointerover', handleWindowPointerOver)
      window.removeEventListener('pointerout', handleWindowPointerOut)
      window.removeEventListener('pointermove', handlePointerMove)
    }
  }, [handleWindowPointerOver, handleWindowPointerOut, handlePointerMove])

  return (
    <animated.mesh
      onPointerEnter={handlePointerEnter}
      onPointerLeave={handlePointerLeave}
      onClick={handleClick()}
      scale={springs.scale}
      position={springs.position.to((x, y) => [x, y, 0])}
    >
      <sphereGeometry args={[1.5, 64, 32]} />
      <AnimatedMeshDistortMaterial
        speed={5}
        distort={0.5}
        color={springs.color}
      />
    </animated.mesh>
  )
}

export default function MyComponent() {
  return (
    <Canvas>
      <ambientLight intensity={0.8} />
      <pointLight intensity={1} position={[0, 6, 0]} />
      <MyScene />
    </Canvas>
  )
}
```

## Syncing spring values

Sometimes, it's necessary to sync the state of a spring with an external source. This can be done with the [event system](/docs/advanced/events)
built into react-spring.

Take the following example, we have multiple blobs on our screen that start in different places and a component higher in our scene graph needs to to know
the position of each blob. Because the `position` is controlled by `useSpring` you can't simple submit `springs.position` to the store because you'll
be dispatching the whole `SpringValue` object, which is unnecessary and can weigh down your external store.

Instead, you can use the `onChange` event handler to `get` the value of your springs and react to them accordingly. The code below is a convoluted example
but demonstrates how you _could_ use the `onChange` event handler to sync a `THREE.Vector2` that is then returned when the parent component requires it via
`useImperativeHandle`.

```tsx live=true template=r3f defaultOpen=true showLineNumbers lines=11,20-22,40-42,114-125
import {
  useRef,
  useEffect,
  useCallback,
  forwardRef,
  useState,
  useImperativeHandle,
} from 'react'
import { useSpring, animated } from '@react-spring/three'
import { Canvas, useThree } from '@react-three/fiber'
import { MeshDistortMaterial } from '@react-three/drei'
import { Vector2 } from 'three'

const AnimatedMeshDistortMaterial = animated(MeshDistortMaterial)

const MyScene = forwardRef(({}, ref) => {
  const isOver = useRef(false)
  const [vector2] = useState(() => new Vector2())

  const { width, height } = useThree(state => state.size)

  const [springs, api] = useSpring(
    () => ({
      scale: 1,
      position: [0, 0],
      color: '#ff6d6d',
      onChange: ({ value }) => {
        vector2.set(value.position[0], value.position[1])
      },
      config: key => {
        switch (key) {
          case 'scale':
            return {
              mass: 4,
              friction: 10,
            }
          case 'position':
            return { mass: 4, friction: 220 }
          default:
            return {}
        }
      },
    }),
    []
  )

  useImperativeHandle(ref, () => ({
    getCurrentPosition: () => vector2,
  }))

  const handleClick = useCallback(() => {
    let clicked = false

    return () => {
      clicked = !clicked
      api.start({
        color: clicked ? '#569AFF' : '#ff6d6d',
      })
    }
  }, [])

  const handlePointerEnter = () => {
    api.start({
      scale: 1.5,
    })
  }

  const handlePointerLeave = () => {
    api.start({
      scale: 1,
    })
  }

  const handleWindowPointerOver = useCallback(() => {
    isOver.current = true
  }, [])

  const handleWindowPointerOut = useCallback(() => {
    isOver.current = false

    api.start({
      position: [0, 0],
    })
  }, [])

  const handlePointerMove = useCallback(
    e => {
      if (isOver.current) {
        const x = (e.offsetX / width) * 2 - 1
        const y = (e.offsetY / height) * -2 + 1

        api.start({
          position: [x * 5, y * 2],
        })
      }
    },
    [api, width, height]
  )

  useEffect(() => {
    window.addEventListener('pointerover', handleWindowPointerOver)
    window.addEventListener('pointerout', handleWindowPointerOut)
    window.addEventListener('pointermove', handlePointerMove)

    return () => {
      window.removeEventListener('pointerover', handleWindowPointerOver)
      window.removeEventListener('pointerout', handleWindowPointerOut)
      window.removeEventListener('pointermove', handlePointerMove)
    }
  }, [handleWindowPointerOver, handleWindowPointerOut, handlePointerMove])

  return (
    <animated.mesh
      onPointerEnter={handlePointerEnter}
      onPointerLeave={handlePointerLeave}
      onClick={handleClick()}
      scale={springs.scale}
      position={springs.position.to((x, y) => [x, y, 0])}
    >
      <sphereGeometry args={[1.5, 64, 32]} />
      <AnimatedMeshDistortMaterial
        speed={5}
        distort={0.5}
        color={springs.color}
      />
    </animated.mesh>
  )
})

export default function MyComponent() {
  const blobApi = useRef(null)

  useEffect(() => {
    const interval = setInterval(() => {
      if (blobApi.current) {
        const { x, y } = blobApi.current.getCurrentPosition()
        console.log('the blob is at position', { x, y })
      }
    }, 2000)

    return () => clearInterval(interval)
  }, [])

  return (
    <Canvas>
      <ambientLight intensity={0.8} />
      <pointLight intensity={1} position={[0, 6, 0]} />
      <MyScene ref={blobApi} />
    </Canvas>
  )
}
```

## Troubleshooting

### Experiencing Jank?

Whilst jank in `react-three-fiber` cannot be purely blamed on `react-spring` you
might find toward the end of an animation that there's a subtle jump,
which is visible in [this demo](https://y18m1.csb.app/). It's not pretty, is it?

Whilst by default it would be nice to have this issue resolved without you having
to interact and this is something we'll consider for the next `breaking change`
in the meantime what you can use is the [`precision` config prop](/common/configs#configs) to avoid this.

```tsx
import { useSpring } from '@react-spring/three'

export default function MyComponent() {
  const [springs, api] = useSpring(() => ({
    position: [0, 0, 0],
    config: {
      precision: 0.0001,
    },
  }))

  // ...
}
```

By setting the prop to a value like `0.0001` you can notice there is no jump towards 0.
This is because the precision prop is used to figure out how close the animated value
can get to the end goal before we consider the animated value to be equal to the end goal.