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Raycaster

Tip

This course was updated in 2024. For the newer content, please visit Raycaster

Video Lecture

Raycaster

Description

Raycasting allows you to create a vector from a 3D point in the scene, and detect which object(s) the vector intersects.

The raycasting class is almost always used for mouse picking objects in the 3D scene.

We can set up the raycaster position and direction using the set or setFromCamera methods and then call its intersectObject or intersectObjects methods to tell us many things about the scene objects that were intersected by the ray, including,

  • the distance of the intersection from the Raycaster position,
  • the position of the intersection in the 3D scene,
  • the face of the object that was intersected,
  • the direction of the faces normal,
  • the UV coordinate of the intersection on the face
  • and a reference to the intersected object itself.
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Resources

We can use Blender to quickly create the model used in this lesson. If you don't want to use Blender to create the model, then you can direct download it and save into ./dist/client/models

Start Scripts

./dist/client/index.html

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>Three.js TypeScript Tutorials by Sean Bradley : https://sbcode.net/threejs</title>
    <style>
      body {
        overflow: hidden;
        margin: 0px;
      }
    </style>
  </head>

  <body>
    <script type="module" src="bundle.js"></script>
  </body>
</html>

./src/client/client.ts

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import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader'
import Stats from 'three/examples/jsm/libs/stats.module'

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

const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.z = 2

const renderer = new THREE.WebGLRenderer()
//renderer.physicallyCorrectLights = true //deprecated
renderer.useLegacyLights = false //use this instead of setting physicallyCorrectLights=true property
renderer.shadowMap.enabled = true
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

const controls = new OrbitControls(camera, renderer.domElement)
controls.enableDamping = true

// const material = new THREE.LineBasicMaterial({ color: 0xff0000 })
// const points = new Array()
// points.push( new THREE.Vector3( 0, 0, 0 ) )
// points.push( new THREE.Vector3( 0, 0, .25 ) )
// const geometry = new THREE.BufferGeometry().setFromPoints( points )
// const line = new THREE.Line( geometry, material )
// scene.add( line )

// const arrowHelper = new THREE.ArrowHelper(
//     new THREE.Vector3(),
//     new THREE.Vector3(),
//     .25,
//     0xffff00)
// scene.add(arrowHelper)

// const material = new THREE.MeshNormalMaterial()

// const boxGeometry = new THREE.BoxGeometry(.2, .2, .2)
// const coneGeometry = new THREE.ConeGeometry(.05, .2, 8)

// const raycaster = new THREE.Raycaster()
// const sceneMeshes: THREE.Object3D[] = []

const loader = new GLTFLoader()
loader.load(
  'models/monkey_textured.glb',
  function (gltf) {
    gltf.scene.traverse(function (child) {
      if ((child as THREE.Mesh).isMesh) {
        const m = child as THREE.Mesh
        m.receiveShadow = true
        m.castShadow = true
        // ;(m.material as THREE.MeshStandardMaterial).flatShading = true
        // sceneMeshes.push(m)
      }
      if ((child as THREE.Light).isLight) {
        const l = child as THREE.SpotLight
        l.castShadow = true
        l.shadow.bias = -0.003
        l.shadow.mapSize.width = 2048
        l.shadow.mapSize.height = 2048
      }
    })
    scene.add(gltf.scene)
    //sceneMeshes.push(gltf.scene)
  },
  (xhr) => {
    console.log((xhr.loaded / xhr.total) * 100 + '% loaded')
  },
  (error) => {
    console.log(error)
  }
)

window.addEventListener('resize', onWindowResize, false)
function onWindowResize() {
  camera.aspect = window.innerWidth / window.innerHeight
  camera.updateProjectionMatrix()
  renderer.setSize(window.innerWidth, window.innerHeight)
  render()
}

// renderer.domElement.addEventListener('dblclick', onDoubleClick, false)
// renderer.domElement.addEventListener('mousemove', onMouseMove, false)

// function onMouseMove(event: MouseEvent) {
//     const mouse = {
//         x: (event.clientX / renderer.domElement.clientWidth) * 2 - 1,
//         y: -(event.clientY / renderer.domElement.clientHeight) * 2 + 1
//     } as THREE.Vector2

//     // console.log(mouse)

//     // raycaster.setFromCamera(mouse, camera);

//     // const intersects = raycaster.intersectObjects(sceneMeshes, false)

//     // if (intersects.length > 0) {
//     //     // console.log(sceneMeshes.length + " " + intersects.length)
//     //     // console.log(intersects[0])
//     //     // console.log(intersects[0].object.userData.name + " " + intersects[0].distance + " ")
//     //     // console.log((intersects[0].face as THREE.Face).normal)
//     //     // line.position.set(0, 0, 0)
//     //     // line.lookAt((intersects[0].face as THREE.Face).normal)
//     //     // line.position.copy(intersects[0].point)

//     //     // const n = new THREE.Vector3();
//     //     // n.copy((intersects[0].face as THREE.Face).normal);
//     //     // n.transformDirection(intersects[0].object.matrixWorld);

//     //     // arrowHelper.setDirection(n);
//     //     // arrowHelper.position.copy(intersects[0].point);
//     // }
// }

// function onDoubleClick(event: MouseEvent) {
//     const mouse = {
//         x: (event.clientX / renderer.domElement.clientWidth) * 2 - 1,
//         y: -(event.clientY / renderer.domElement.clientHeight) * 2 + 1
//     } as THREE.Vector2

//     raycaster.setFromCamera(mouse, camera)

//     const intersects = raycaster.intersectObjects(sceneMeshes, false)

//     if (intersects.length > 0) {

//         const n = new THREE.Vector3()
//         n.copy((intersects[0].face as THREE.Face).normal)
//         n.transformDirection(intersects[0].object.matrixWorld)

//         const cube = new THREE.Mesh(boxGeometry, material)
//         // const cube = new THREE.Mesh(coneGeometry, material)

//         cube.lookAt(n)
//         // cube.rotateX(Math.PI / 2)
//         cube.position.copy(intersects[0].point)
//         // cube.position.addScaledVector(n, .1)

//         scene.add(cube)
//         // sceneMeshes.push(cube)
//     }
// }

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

function animate() {
  requestAnimationFrame(animate)

  controls.update()

  // if (sceneMeshes.length > 1) {
  //     sceneMeshes[0].rotation.x += .002
  // }

  render()

  stats.update()
}

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

animate()

Final Script

./src/client/client.ts

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import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader'
import Stats from 'three/examples/jsm/libs/stats.module'

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

const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.z = 2

const renderer = new THREE.WebGLRenderer()
//renderer.physicallyCorrectLights = true //deprecated
renderer.useLegacyLights = false //use this instead of setting physicallyCorrectLights=true property
renderer.shadowMap.enabled = true
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

const controls = new OrbitControls(camera, renderer.domElement)
controls.enableDamping = true

// const material = new THREE.LineBasicMaterial({ color: 0xff0000 })
// const points = new Array()
// points.push( new THREE.Vector3( 0, 0, 0 ) )
// points.push( new THREE.Vector3( 0, 0, .25 ) )
// const geometry = new THREE.BufferGeometry().setFromPoints( points )
// const line = new THREE.Line( geometry, material )
// scene.add( line )

const arrowHelper = new THREE.ArrowHelper(new THREE.Vector3(), new THREE.Vector3(), 0.25, 0xffff00)
scene.add(arrowHelper)

const material = new THREE.MeshNormalMaterial()

const boxGeometry = new THREE.BoxGeometry(0.2, 0.2, 0.2)
const coneGeometry = new THREE.ConeGeometry(0.05, 0.2, 8)

const raycaster = new THREE.Raycaster()
const sceneMeshes: THREE.Object3D[] = []

const loader = new GLTFLoader()
loader.load(
  'models/monkey_textured.glb',
  function (gltf) {
    gltf.scene.traverse(function (child) {
      if ((child as THREE.Mesh).isMesh) {
        const m = child as THREE.Mesh
        m.receiveShadow = true
        m.castShadow = true
        ;(m.material as THREE.MeshStandardMaterial).flatShading = true
        sceneMeshes.push(m)
      }
      if ((child as THREE.Light).isLight) {
        const l = child as THREE.SpotLight
        l.castShadow = true
        l.shadow.bias = -0.003
        l.shadow.mapSize.width = 2048
        l.shadow.mapSize.height = 2048
      }
    })
    scene.add(gltf.scene)
    // sceneMeshes.push(gltf.scene)
  },
  (xhr) => {
    console.log((xhr.loaded / xhr.total) * 100 + '% loaded')
  },
  (error) => {
    console.log(error)
  }
)

window.addEventListener('resize', onWindowResize, false)
function onWindowResize() {
  camera.aspect = window.innerWidth / window.innerHeight
  camera.updateProjectionMatrix()
  renderer.setSize(window.innerWidth, window.innerHeight)
  render()
}

renderer.domElement.addEventListener('dblclick', onDoubleClick, false)
renderer.domElement.addEventListener('mousemove', onMouseMove, false)

const mouse = new THREE.Vector2()

function onMouseMove(event: MouseEvent) {
  mouse.set((event.clientX / renderer.domElement.clientWidth) * 2 - 1, -(event.clientY / renderer.domElement.clientHeight) * 2 + 1)

  // console.log(mouse)

  raycaster.setFromCamera(mouse, camera)

  const intersects = raycaster.intersectObjects(sceneMeshes, false)

  if (intersects.length > 0) {
    // console.log(sceneMeshes.length + " " + intersects.length)
    // console.log(intersects[0])
    // console.log(intersects[0].object.userData.name + " " + intersects[0].distance + " ")
    // console.log((intersects[0].face as THREE.Face).normal)
    // line.position.set(0, 0, 0)
    // line.lookAt((intersects[0].face as THREE.Face).normal)
    // line.position.copy(intersects[0].point)

    const n = new THREE.Vector3()
    n.copy((intersects[0].face as THREE.Face).normal)
    n.transformDirection(intersects[0].object.matrixWorld)

    arrowHelper.setDirection(n)
    arrowHelper.position.copy(intersects[0].point)
  }
}

function onDoubleClick(event: MouseEvent) {
  mouse.set((event.clientX / renderer.domElement.clientWidth) * 2 - 1, -(event.clientY / renderer.domElement.clientHeight) * 2 + 1)
  raycaster.setFromCamera(mouse, camera)

  const intersects = raycaster.intersectObjects(sceneMeshes, false)

  if (intersects.length > 0) {
    const n = new THREE.Vector3()
    n.copy((intersects[0].face as THREE.Face).normal)
    n.transformDirection(intersects[0].object.matrixWorld)

    // const cube = new THREE.Mesh(boxGeometry, material)
    const cube = new THREE.Mesh(coneGeometry, material)

    cube.lookAt(n)
    cube.rotateX(Math.PI / 2)
    cube.position.copy(intersects[0].point)
    cube.position.addScaledVector(n, 0.1)

    scene.add(cube)
    sceneMeshes.push(cube)
  }
}

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

function animate() {
  requestAnimationFrame(animate)

  controls.update()

  // if (sceneMeshes.length > 1) {
  //     sceneMeshes[0].rotation.x += .002
  // }

  render()

  stats.update()
}

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

animate()

Raycaster (Official Documentation)

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