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Raycaster Measurements

Video Lecture

Raycaster Measurements

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Description

Using the Raycaster to assist in measuring the distance between points.

This example demonstrates,

  • Using the Raycaster, along with pointer events to start and draw a line from point A to B.
  • Using the CSS2DRenderer and CSS2DObject to create measurement labels.
  • Using Vector3.lerpVectors to position a label between 2 points.
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Lesson 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;
      }

      .measurementLabel {
        font-family: monospace;
        background-color: black;
        color: white;
      }
    </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'
import { CSS2DRenderer, CSS2DObject } from 'three/examples/jsm/renderers/CSS2DRenderer'

const scene = new THREE.Scene()

const light = new THREE.SpotLight(0xffffff, 1000)
light.position.set(12.5, 12.5, 12.5)
light.castShadow = true
light.shadow.mapSize.width = 1024
light.shadow.mapSize.height = 1024
scene.add(light)

const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.set(15, 15, 15)

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

const labelRenderer = new CSS2DRenderer()
labelRenderer.setSize(window.innerWidth, window.innerHeight)
labelRenderer.domElement.style.position = 'absolute'
labelRenderer.domElement.style.top = '0px'
labelRenderer.domElement.style.pointerEvents = 'none'
document.body.appendChild(labelRenderer.domElement)

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

const pickableObjects: THREE.Mesh[] = []

const loader = new GLTFLoader()
loader.load(
  'models/simplescene.glb',
  function (gltf) {
    gltf.scene.traverse(function (child) {
      if ((child as THREE.Mesh).isMesh) {
        const m = child as THREE.Mesh
        switch (m.name) {
          case 'Plane':
            m.receiveShadow = true
            break
          default:
            m.castShadow = true
        }
        pickableObjects.push(m)
      }
    })
    scene.add(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)
  labelRenderer.setSize(window.innerWidth, window.innerHeight)
  render()
}

let ctrlDown = false
let lineId = 0
let line: THREE.Line
let drawingLine = false
const measurementLabels: { [key: number]: CSS2DObject } = {}

window.addEventListener('keydown', function (event) {
  if (event.key === 'Control') {
    ctrlDown = true
    controls.enabled = false
    renderer.domElement.style.cursor = 'crosshair'
  }
})

window.addEventListener('keyup', function (event) {
  if (event.key === 'Control') {
    ctrlDown = false
    controls.enabled = true
    renderer.domElement.style.cursor = 'pointer'
    if (drawingLine) {
      //delete the last line because it wasn't committed
      scene.remove(line)
      scene.remove(measurementLabels[lineId])
      drawingLine = false
    }
  }
})

const raycaster = new THREE.Raycaster()
let intersects: THREE.Intersection[]
const mouse = new THREE.Vector2()

renderer.domElement.addEventListener('pointerdown', onClick, false)
function onClick() {
  if (ctrlDown) {
    raycaster.setFromCamera(mouse, camera)
    intersects = raycaster.intersectObjects(pickableObjects, false)
    if (intersects.length > 0) {
      if (!drawingLine) {
        //start the line
        const points = []
        points.push(intersects[0].point)
        points.push(intersects[0].point.clone())
        const geometry = new THREE.BufferGeometry().setFromPoints(points)
        line = new THREE.LineSegments(
          geometry,
          new THREE.LineBasicMaterial({
            color: 0xffffff,
            transparent: true,
            opacity: 0.75,
            // depthTest: false,
            // depthWrite: false
          })
        )
        line.frustumCulled = false
        scene.add(line)

        const measurementDiv = document.createElement('div') as HTMLDivElement
        measurementDiv.className = 'measurementLabel'
        measurementDiv.innerText = '0.0m'
        const measurementLabel = new CSS2DObject(measurementDiv)
        measurementLabel.position.copy(intersects[0].point)
        measurementLabels[lineId] = measurementLabel
        scene.add(measurementLabels[lineId])
        drawingLine = true
      } else {
        //finish the line
        const positions = (line.geometry.attributes.position as THREE.BufferAttribute).array
        positions[3] = intersects[0].point.x
        positions[4] = intersects[0].point.y
        positions[5] = intersects[0].point.z
        line.geometry.attributes.position.needsUpdate = true
        lineId++
        drawingLine = false
      }
    }
  }
}

document.addEventListener('mousemove', onDocumentMouseMove, false)
function onDocumentMouseMove(event: MouseEvent) {
  event.preventDefault()

  mouse.x = (event.clientX / renderer.domElement.clientWidth) * 2 - 1
  mouse.y = -(event.clientY / renderer.domElement.clientHeight) * 2 + 1

  if (drawingLine) {
    raycaster.setFromCamera(mouse, camera)
    intersects = raycaster.intersectObjects(pickableObjects, false)
    if (intersects.length > 0) {
      const positions = (line.geometry.attributes.position as THREE.BufferAttribute).array
      const v0 = new THREE.Vector3(positions[0], positions[1], positions[2])
      const v1 = new THREE.Vector3(intersects[0].point.x, intersects[0].point.y, intersects[0].point.z)
      positions[3] = intersects[0].point.x
      positions[4] = intersects[0].point.y
      positions[5] = intersects[0].point.z
      line.geometry.attributes.position.needsUpdate = true
      const distance = v0.distanceTo(v1)
      measurementLabels[lineId].element.innerText = distance.toFixed(2) + 'm'
      measurementLabels[lineId].position.lerpVectors(v0, v1, 0.5)
    }
  }
}

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

function animate() {
  requestAnimationFrame(animate)

  controls.update()

  render()

  stats.update()
}

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

animate()