@react-三/纤维

React-Three-Fiber 是 ThreeJS 的 React 渲染器。

使用可重用、独立的组件以声明方式构建场景，这些组件对状态做出反应，易于交互并且可以参与 React 的生态系统。

npm install three @types/three @react-three/fiber

它有限制吗？

没有任何。在 Threejs 中工作的所有内容都可以在这里工作，无一例外。

它比普通的 Threejs 慢吗？

不会。没有任何开销。组件在 React 之外渲染。由于 React 的调度能力，它在规模上优于 Threejs。

它能跟上 Threejs 频繁的功能更新吗？

是的。它只是在 JSX 中表达 Threejs，动态地变成new THREE.Mesh() 。如果新的 Threejs 版本添加、删除或更改功能，您将立即可以使用它，而无需依赖于此库的更新。

它看起来像什么？

让我们创建一个可重用的组件，它有自己的状态，对用户输入做出反应并参与渲染循环。（现场演示）。

 import { createRoot } from 'react-dom/client'
import React , { useRef , useState } from 'react'
import { Canvas , useFrame } from '@react-three/fiber'

function Box ( props ) {
  // This reference gives us direct access to the THREE.Mesh object
  const ref = useRef ( )
  // Hold state for hovered and clicked events
  const [ hovered , hover ] = useState ( false )
  const [ clicked , click ] = useState ( false )
  // Subscribe this component to the render-loop, rotate the mesh every frame
  useFrame ( ( state , delta ) => ( ref . current . rotation . x += delta ) )
  // Return the view, these are regular Threejs elements expressed in JSX
  return (
    < mesh
      { ... props }
      ref = { ref }
      scale = { clicked ? 1.5 : 1 }
      onClick = { ( event ) => click ( ! clicked ) }
      onPointerOver = { ( event ) => hover ( true ) }
      onPointerOut = { ( event ) => hover ( false ) } >
      < boxGeometry args = { [ 1 , 1 , 1 ] } / >
      < meshStandardMaterial color = { hovered ? 'hotpink' : 'orange' } / >
    < / mesh >
  )
}

createRoot ( document . getElementById ( 'root' ) ) . render (
  < Canvas >
    < ambientLight intensity = { Math . PI / 2 } / >
    < spotLight position = { [ 10 , 10 , 10 ] } angle = { 0.15 } penumbra = { 1 } decay = { 0 } intensity = { Math . PI } / >
    < pointLight position = { [ - 10 , - 10 , - 10 ] } decay = { 0 } intensity = { Math . PI } / >
    < Box position = { [ - 1.2 , 0 , 0 ] } / >
    < Box position = { [ 1.2 , 0 , 0 ] } / >
  < / Canvas > ,
)

显示 TypeScript 示例

npm install @types/three

 import * as THREE from 'three'
import { createRoot } from 'react-dom/client'
import React , { useRef , useState } from 'react'
import { Canvas , useFrame , ThreeElements } from '@react-three/fiber'

function Box ( props : ThreeElements [ 'mesh' ] ) {
  const ref = useRef < THREE . Mesh > ( null ! )
  const [ hovered , hover ] = useState ( false )
  const [ clicked , click ] = useState ( false )
  useFrame ( ( state , delta ) => ( ref . current . rotation . x += delta ) )
  return (
    < mesh
      { ... props }
      ref = { ref }
      scale = { clicked ? 1.5 : 1 }
      onClick = { ( event ) => click ( ! clicked ) }
      onPointerOver = { ( event ) => hover ( true ) }
      onPointerOut = { ( event ) => hover ( false ) } >
      < boxGeometry args = { [ 1 , 1 , 1 ] } / >
      < meshStandardMaterial color = { hovered ? 'hotpink' : 'orange' } / >
    < / mesh >
  )
}

createRoot ( document . getElementById ( 'root' ) as HTMLElement ) . render (
  < Canvas >
    < ambientLight intensity = { Math . PI / 2 } / >
    < spotLight position = { [ 10 , 10 , 10 ] } angle = { 0.15 } penumbra = { 1 } decay = { 0 } intensity = { Math . PI } / >
    < pointLight position = { [ - 10 , - 10 , - 10 ] } decay = { 0 } intensity = { Math . PI } / >
    < Box position = { [ - 1.2 , 0 , 0 ] } / >
    < Box position = { [ 1.2 , 0 , 0 ] } / >
  < / Canvas > ,
)

现场演示：https://codesandbox.io/s/icy-tree-brnsm?file=/src/App.tsx

显示 React Native 示例

此示例依赖于react 18并使用expo-cli ，但您可以使用其模板或react-native CLI创建一个裸项目。

 # Install expo-cli, this will create our app
npm install expo-cli -g
# Create app and cd into it
expo init my-app
cd my-app
# Install dependencies
npm install three @react-three/fiber@beta react@rc
# Start
expo start

如果您使用useLoader或 Drei 抽象（例如useGLTF和useTexture ，则可能需要进行一些配置来告诉 Metro 捆绑程序有关您的资产的信息：

 // metro.config.js
module . exports = {
  resolver : {
    sourceExts : [ 'js' , 'jsx' , 'json' , 'ts' , 'tsx' , 'cjs' ] ,
    assetExts : [ 'glb' , 'png' , 'jpg' ] ,
  } ,
}

 import React , { useRef , useState } from 'react'
import { Canvas , useFrame } from '@react-three/fiber/native'
function Box ( props ) {
  const mesh = useRef ( null )
  const [ hovered , setHover ] = useState ( false )
  const [ active , setActive ] = useState ( false )
  useFrame ( ( state , delta ) => ( mesh . current . rotation . x += delta ) )
  return (
    < mesh
      { ... props }
      ref = { mesh }
      scale = { active ? 1.5 : 1 }
      onClick = { ( event ) => setActive ( ! active ) }
      onPointerOver = { ( event ) => setHover ( true ) }
      onPointerOut = { ( event ) => setHover ( false ) } >
      < boxGeometry args = { [ 1 , 1 , 1 ] } / >
      < meshStandardMaterial color = { hovered ? 'hotpink' : 'orange' } / >
    < / mesh >
  )
}
export default function App ( ) {
  return (
    < Canvas >
      < ambientLight intensity = { Math . PI / 2 } / >
      < spotLight position = { [ 10 , 10 , 10 ] } angle = { 0.15 } penumbra = { 1 } decay = { 0 } intensity = { Math . PI } / >
      < pointLight position = { [ - 10 , - 10 , - 10 ] } decay = { 0 } intensity = { Math . PI } / >
      < Box position = { [ - 1.2 , 0 , 0 ] } / >
      < Box position = { [ 1.2 , 0 , 0 ] } / >
    < / Canvas >
  )
}