Reflector

Description

The Reflector object, included in the Threejs examples sub folders can be used to create mirrors.

The below example, extends the DragControls with GLTF Animations with several mirrors.

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The reflector object will mirror in one direction only. If you want to create an infinity mirror, you can place another Reflector in front of the existing Reflector, but placed some distance in front of it and facing back towards at the first Reflector.

The Reflectors will only reflect what they see in the current Render pass. So you won't get the realistic infinity mirror effect at first.

Since Reflectors, only Reflect in one direction, you can place another Reflector behind an Existing Reflector in series, and you will get a triple reflection in the other Reflector reflecting back at both the others placed in series.

In the example above, I have 4 Reflectors, all looking at each other. 2 are looking forward and 2 are looking back. And are all at different distances. Note that creating an infinity mirror using this technique will will require more CPU for each new Reflector added to the scene.

Code

./src/main.ts

import './style.css'
import * as THREE from 'three'
import { OrbitControls } from 'three/addons/controls/OrbitControls.js'
import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js'
import Stats from 'three/addons/libs/stats.module.js'
import { DragControls } from 'three/addons/controls/DragControls.js'
import { RGBELoader } from 'three/addons/loaders/RGBELoader.js'
import { Reflector } from 'three/addons/objects/Reflector.js'

const scene = new THREE.Scene()
scene.add(new THREE.AxesHelper(5))

const light = new THREE.DirectionalLight(0xffffff, Math.PI)
light.position.set(1, 1, 1)
light.castShadow = true
scene.add(light)

new RGBELoader().load('img/venice_sunset_1k.hdr', (texture) => {
  texture.mapping = THREE.EquirectangularReflectionMapping
  scene.environment = texture
  scene.background = scene.environment
  scene.backgroundBlurriness = 1.0
})

const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.01, 100)
camera.position.set(0.8, 1.4, 1.0)

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth, window.innerHeight)
renderer.shadowMap.enabled = true
document.body.appendChild(renderer.domElement)

const orbitControls = new OrbitControls(camera, renderer.domElement)
orbitControls.enableDamping = true
orbitControls.target.set(0, 1, 0)

const sceneMeshes: THREE.Mesh[] = []
let boxHelper: THREE.BoxHelper

const dragControls = new DragControls(sceneMeshes, camera, renderer.domElement)
dragControls.addEventListener('hoveron', function () {
  boxHelper.visible = true
  orbitControls.enabled = false
})
dragControls.addEventListener('hoveroff', function () {
  boxHelper.visible = false
  orbitControls.enabled = true
})
dragControls.addEventListener('drag', function (event) {
  event.object.position.y = 0
})
dragControls.addEventListener('dragstart', function () {
  boxHelper.visible = true
  orbitControls.enabled = false
})
dragControls.addEventListener('dragend', function () {
  boxHelper.visible = false
  orbitControls.enabled = true
})

const planeGeometry = new THREE.PlaneGeometry(25, 25)
const texture = new THREE.TextureLoader().load('img/grid.png')
const plane: THREE.Mesh = new THREE.Mesh(planeGeometry, new THREE.MeshStandardMaterial({ map: texture }))
plane.rotateX(-Math.PI / 2)
plane.receiveShadow = true
scene.add(plane)

let mixer: THREE.AnimationMixer
let modelReady = false
const gltfLoader: GLTFLoader = new GLTFLoader()
let modelGroup: THREE.Group
let modelDragBox: THREE.Mesh

gltfLoader.load(
  'models/eve@punching.glb',
  (gltf) => {
    gltf.scene.traverse(function (child) {
      if (child instanceof THREE.Group) {
        modelGroup = child
      }
      ;(child as THREE.Mesh).isMesh && (child.castShadow = true)
    })

    mixer = new THREE.AnimationMixer(gltf.scene)
    mixer.clipAction((gltf as any).animations[0]).play()

    modelDragBox = new THREE.Mesh(new THREE.BoxGeometry(0.5, 1.3, 0.5), new THREE.MeshBasicMaterial({ transparent: true, opacity: 0 }))
    modelDragBox.geometry.translate(0, 0.65, 0)
    scene.add(modelDragBox)
    sceneMeshes.push(modelDragBox)

    boxHelper = new THREE.BoxHelper(modelDragBox, 0xffff00)
    boxHelper.visible = false
    scene.add(boxHelper)

    scene.add(gltf.scene)

    modelReady = true
  },
  (xhr) => {
    console.log((xhr.loaded / xhr.total) * 100 + '% loaded')
  },
  (error) => {
    console.log(error)
  }
)

window.addEventListener('resize', () => {
  camera.aspect = window.innerWidth / window.innerHeight
  camera.updateProjectionMatrix()
  renderer.setSize(window.innerWidth, window.innerHeight)
})

const mirrorBack1: Reflector = new Reflector(new THREE.PlaneGeometry(2, 2), {
  color: new THREE.Color(0x7f7f7f),
  textureWidth: window.innerWidth * window.devicePixelRatio,
  textureHeight: window.innerHeight * window.devicePixelRatio,
})

mirrorBack1.position.y = 1
mirrorBack1.position.z = -1
scene.add(mirrorBack1)

const mirrorBack2: Reflector = new Reflector(new THREE.PlaneGeometry(2, 2), {
  color: new THREE.Color(0x7f7f7f),
  textureWidth: window.innerWidth * window.devicePixelRatio,
  textureHeight: window.innerHeight * window.devicePixelRatio,
})

mirrorBack2.position.y = 1
mirrorBack2.position.z = -2
scene.add(mirrorBack2)

const mirrorFront1: Reflector = new Reflector(new THREE.PlaneGeometry(2, 2), {
  color: new THREE.Color(0x7f7f7f),
  //clipBias: 0.003,
  textureWidth: window.innerWidth * window.devicePixelRatio,
  textureHeight: window.innerHeight * window.devicePixelRatio,
})
mirrorFront1.position.y = 1
mirrorFront1.position.z = 1
mirrorFront1.rotateY(Math.PI)
scene.add(mirrorFront1)

const mirrorFront2: Reflector = new Reflector(new THREE.PlaneGeometry(2, 2), {
  color: new THREE.Color(0x7f7f7f),
  //clipBias: 0.003,
  textureWidth: window.innerWidth * window.devicePixelRatio,
  textureHeight: window.innerHeight * window.devicePixelRatio,
})
mirrorFront2.position.y = 1
mirrorFront2.position.z = 2
mirrorFront2.rotateY(Math.PI)
scene.add(mirrorFront2)

const stats = new Stats()
document.body.appendChild(stats.dom)

const clock = new THREE.Clock()

function animate() {
  requestAnimationFrame(animate)

  orbitControls.update()

  if (modelReady) {
    mixer.update(clock.getDelta())
    modelGroup.position.copy(modelDragBox.position)
    boxHelper.update()
  }

  render()

  stats.update()
}

function render() {
  renderer.render(scene, camera)
}

animate()

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