three.js - Raycaster and Mouse Events

  • A raycaster can cast a ray in a specific direction and test what objects intersect with it
  • Set up
<script setup>
  import * as THREE from 'three'
  import {OrbitControls} from 'three/addons/controls/OrbitControls.js'

  /**
   * scene
  */
  const scene = new THREE.Scene()

  /**
   * object
  */
  const object1 = new THREE.Mesh(
    new THREE.SphereGeometry(0.5, 16, 16),
    new THREE.MeshBasicMaterial({ color: '#ff0000' })
  )
  object1.position.x = - 2

  const object2 = new THREE.Mesh(
    new THREE.SphereGeometry(0.5, 16, 16),
    new THREE.MeshBasicMaterial({ color: '#ff0000' })
  )

  const object3 = new THREE.Mesh(
    new THREE.SphereGeometry(0.5, 16, 16),
    new THREE.MeshBasicMaterial({ color: '#ff0000' })
  )
  object3.position.x = 2

  scene.add(object1, object2, object3)

  /**
   * camera
  */
  const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    100
  )
  camera.position.z = 3

  /**
   * renderer
  */
  const renderer = new THREE.WebGLRenderer()
  renderer.setSize(window.innerWidth, window.innerHeight)
  document.body.appendChild(renderer.domElement)

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

    renderer.setSize(window.innerWidth, window.innerHeight)
    renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2))
  })

  /**
   * axesHelper
  */
  const axesHelper = new THREE.AxesHelper(5)
  scene.add(axesHelper)

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

  /**
   * render
  */
  const clock = new THREE.Clock()
  const tick = () => {
    const elapsedTime = clock.getElapsedTime()

    // update
    controls.update()
    requestAnimationFrame(tick)
    renderer.render(scene, camera)
  }
  tick()
</script>
set up.png
  • Create the Raycaster
    • if we're shooting a ray in a direction, we need to tell the origin of the ray and the direction of the ray, we can use set() to set them
    • the direction has to be normalized
  /**
   * raycaster
  */
  const raycaster = new THREE.Raycaster()

  const rayOrigin = new THREE.Vector3(-3, 0, 0)
  const rayDirection = new THREE.Vector3(10, 0, 0)
  rayDirection.normalize()  // 单位向量，保持方向

  raycaster.set(rayOrigin, rayDirection)
  • Cast a Ray
    • intersectObject() to test one object, its value also be an array, because a ray can go through the same object multiple times
    • intersectObjects() to test an array of objects
    • each object value of the array has some useful information:
      1. distance - distance between the origin of the ray and the collision point
      2. face - the face of the geometry that was hit by the ray
      3. faceIndex - the index of the face
      4. object - what object is concerned by the collision
      5. point - a Vector3 of the exact position of the collision
      6. uv - the uv coordinates in that geometry
  const intersect = raycaster.intersectObject(object3)
  console.log(intersect);

  const intersects = raycaster.intersectObjects([object1, object2, object3])
  console.log(intersects);
cast a ray.png
  • Test on each frame
    • we're going to animate the spheres and turn them blue when the ray intersects with them
    • remove the code we did previously and only keep the raycaster instantiation
    /**
 * raycaster
*/
const raycaster = new THREE.Raycaster()
    • animate the spheres by using the elapsed time and Math.sin() in the tick() 
    /**
 * render
*/
const clock = new THREE.Clock()
const tick = () => {
  const elapsedTime = clock.getElapsedTime()

  // animate objects
  object1.position.y = Math.sin(elapsedTime * 0.3) * 1.5
  object2.position.y = Math.sin(elapsedTime * 0.8) * 1.5
  object3.position.y = Math.sin(elapsedTime * 1.4) * 1.5

  // update
  ...
}
    • update the caster in the tick() 
    /**
 * render
*/
const clock = new THREE.Clock()
const tick = () => {
  const elapsedTime = clock.getElapsedTime()

  // animate objects
  ...

  // cast a ray
  const rayOrigin = new THREE.Vector3(-3, 0, 0)
  const rayDirection = new THREE.Vector3(1, 0, 0)
  rayDirection.normalize()
  raycaster.set(rayOrigin, rayDirection)

  // update
  ...
}
    • cast a ray and color the objects
    /**
 * render
*/
const clock = new THREE.Clock()
const tick = () => {
  const elapsedTime = clock.getElapsedTime()

  // animate objects
  ...

  // cast a ray
  ...

  const objectsToTest = [object1, object2, object3]
  const intersects = raycaster.intersectObjects(objectsToTest)
  
  for(const object of objectsToTest) {
    object.material.color.set(0xff0000)
  }
  
  for(const intersect of intersects) {
    intersect.object.material.color.set('#0000ff')
  }

  // update
  ...
}
test on each frame.png
  • Use the raycaster with the mouse
    • hovering, we need the coordinates of the mouse, but not in pixel, we need a value goes from -1 to 1 in horizon and vertical axes 
    /**
 * mouse
*/
const mouse = new THREE.Vector2()

window.addEventListener('mousemove', (event) => {
  mouse.x = (event.clientX / window.innerWidth) * 2 - 1
  mouse.y = - (event.clientY / window.innerHeight) * 2 + 1
})
    • use the setFromCamera() method to orient the ray in the right direction
    /**
 * render
*/
const clock = new THREE.Clock()
const tick = () => {
  const elapsedTime = clock.getElapsedTime()

  // animate objects
  object1.position.y = Math.sin(elapsedTime * 0.3) * 1.5
  object2.position.y = Math.sin(elapsedTime * 0.8) * 1.5
  object3.position.y = Math.sin(elapsedTime * 1.4) * 1.5

  // cast a ray from the mouse
  raycaster.setFromCamera(mouse, camera)  // 根据camera的位置设置方向

  const objectsToTest = [object1, object2, object3]
  const intersects = raycaster.intersectObjects(objectsToTest)

  for(const object of objectsToTest) {
    object.material.color.set(0xff0000)
  }
  
  for(const intersect of intersects) {
    intersect.object.material.color.set('#0000ff')
  }

  // update
  controls.update()
  requestAnimationFrame(tick)
  renderer.render(scene, camera)
}
    悬停后的sphere变成蓝色.png
    • mouse enter and mouse leave, we need to create a 'witness' variable containing the currently hovered object
    /**
 * render
*/
const clock = new THREE.Clock()

let currentIntersect = null

const tick = () => {
  const elapsedTime = clock.getElapsedTime()

  // animate objects
  object1.position.y = Math.sin(elapsedTime * 0.3) * 1.5
  object2.position.y = Math.sin(elapsedTime * 0.8) * 1.5
  object3.position.y = Math.sin(elapsedTime * 1.4) * 1.5

  // cast a ray from the mouse
  raycaster.setFromCamera(mouse, camera)  // 根据camera的位置设置方向

  const objectsToTest = [object1, object2, object3]
  const intersects = raycaster.intersectObjects(objectsToTest)

  for(const object of objectsToTest) {
    object.material.color.set(0xff0000)
  }
  
  for(const intersect of intersects) {
    intersect.object.material.color.set('#0000ff')
  }

  // cast a ray from the mouse
  raycaster.setFromCamera(mouse, camera)

  if(intersects.length) {
    // console.log('enter');
    currentIntersect = intersects[0]
  }else {
    // console.log('leave');
    currentIntersect = null
  }

  // update
  controls.update()
  requestAnimationFrame(tick)
  renderer.render(scene, camera)
}
    • mouse click event, we can test which sphere got clicked
    /**
 * mouse
*/
...
...
window.addEventListener('click', () => {
  if(currentIntersect) {
    switch(currentIntersect.object) {
      case object1:
        console.log('click obj1');
        break
      case object2:
        console.log('click obj2');
        break
      case object3:
        console.log('click obj3');
        break
    }
  }
})
  • Raycasting with models
    • load the model
    import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
...
...
/**
 * gltfLoader
*/
const gltfLoader = new GLTFLoader()
let model = null
gltfLoader.load('../public/models/Duck/glTF-Binary/Duck.glb', (gltf) => {
  model = gltf.scene
  model.position.y = - 1.2
  scene.add(model)
})
    • lights, the model is MeshStandardMaterial, it needs lights to be seen
    /**
 * light
*/
const ambientLight = new THREE.AmbientLight(0xffffff, 0.3)
scene.add(ambientLight)

const directionalLight = new THREE.DirectionalLight(0xffffff, 0.7)
directionalLight.position.set(1, 2, 3)
scene.add(directionalLight)
    model.png
    • intersect the model, we want the model to get larger when we hover it and when we leave it with mouse it will get back to the initial scale
    const tick = () => {
  ...
  ...
  // test intersect with a model
  if(model) {
    const modelIntersects = raycaster.intersectObject(model)
    if(modelIntersects.length) {
      model.scale.set(1.2, 1.2, 1.2)
    }else {
      model.scale.set(1, 1, 1)
    }
  }
  ...
}
raycasting with models.png
最后编辑于 ：
©著作权归作者所有,转载或内容合作请联系作者
  • 人面猴
    序言：七十年代末，一起剥皮案震惊了整个滨河市，随后出现的几起案子，更是在滨河造成了极大的恐慌，老刑警刘岩，带你破解...
    沈念sama阅读 216,744评论 6赞 502
  • 死咒
    序言：滨河连续发生了三起死亡事件，死亡现场离奇诡异，居然都是意外死亡，警方通过查阅死者的电脑和手机，发现死者居然都...
    沈念sama阅读 92,505评论 3赞 392
  • 救了他两次的神仙让他今天三更去死
    文/潘晓璐 我一进店门，熙熙楼的掌柜王于贵愁眉苦脸地迎上来，“玉大人，你说我怎么就摊上这事。” “怎么了？”我有些...
    开封第一讲书人阅读 163,105评论 0赞 353
  • 道士缉凶录：失踪的卖姜人
    文/不坏的土叔 我叫张陵，是天一观的道长。 经常有香客问我，道长，这世上最难降的妖魔是什么？ 我笑而不...
    开封第一讲书人阅读 58,242评论 1赞 292
  • 港岛之恋（遗憾婚礼）
    正文 为了忘掉前任，我火速办了婚礼，结果婚礼上，老公的妹妹穿的比我还像新娘。我一直安慰自己，他们只是感情好，可当我...
    茶点故事阅读 67,269评论 6赞 389
  • 恶毒庶女顶嫁案：这布局不是一般人想出来的
    文/花漫 我一把揭开白布。 她就那样静静地躺着，像睡着了一般。 火红的嫁衣衬着肌肤如雪。 梳的纹丝不乱的头发上，一...
    开封第一讲书人阅读 51,215评论 1赞 299
  • 城市分裂传说
    那天，我揣着相机与录音，去河边找鬼。 笑死，一个胖子当着我的面吹牛，可吹牛的内容都是我干的。 我是一名探鬼主播，决...
    沈念sama阅读 40,096评论 3赞 418
  • 双鸳鸯连环套：你想象不到人心有多黑
    文/苍兰香墨 我猛地睁开眼，长吁一口气：“原来是场噩梦啊……” “哼！你这毒妇竟也来了？” 一声冷哼从身侧响起，我...
    开封第一讲书人阅读 38,939评论 0赞 274
  • 万荣杀人案实录
    序言：老挝万荣一对情侣失踪，失踪者是张志新（化名）和其女友刘颖，没想到半个月后，有当地人在树林里发现了一具尸体，经...
    沈念sama阅读 45,354评论 1赞 311
  • 护林员之死
    正文 独居荒郊野岭守林人离奇死亡，尸身上长有42处带血的脓包…… 初始之章·张勋 以下内容为张勋视角 年9月15日...
    茶点故事阅读 37,573评论 2赞 333
  • 白月光启示录
    正文 我和宋清朗相恋三年，在试婚纱的时候发现自己被绿了。 大学时的朋友给我发了我未婚夫和他白月光在一起吃饭的照片。...
    茶点故事阅读 39,745评论 1赞 348
  • 活死人
    序言：一个原本活蹦乱跳的男人离奇死亡，死状恐怖，灵堂内的尸体忽然破棺而出，到底是诈尸还是另有隐情，我是刑警宁泽，带...
    沈念sama阅读 35,448评论 5赞 344
  • 日本核电站爆炸内幕
    正文 年R本政府宣布，位于F岛的核电站，受9级特大地震影响，放射性物质发生泄漏。R本人自食恶果不足惜，却给世界环境...
    茶点故事阅读 41,048评论 3赞 327
  • 男人毒药：我在死后第九天来索命
    文/蒙蒙 一、第九天 我趴在偏房一处隐蔽的房顶上张望。 院中可真热闹，春花似锦、人声如沸。这庄子的主人今日做“春日...
    开封第一讲书人阅读 31,683评论 0赞 22
  • 一桩弑父案，背后竟有这般阴谋
    文/苍兰香墨 我抬头看了看天上的太阳。三九已至，却和暖如春，着一层夹袄步出监牢的瞬间，已是汗流浃背。 一阵脚步声响...
    开封第一讲书人阅读 32,838评论 1赞 269
  • 情欲美人皮
    我被黑心中介骗来泰国打工， 没想到刚下飞机就差点儿被人妖公主榨干…… 1. 我叫王不留，地道东北人。 一个月前我还...
    沈念sama阅读 47,776评论 2赞 369
  • 代替公主和亲
    正文 我出身青楼，却偏偏与公主长得像，于是被迫代替她去往敌国和亲。 传闻我的和亲对象是个残疾皇子，可洞房花烛夜当晚...
    茶点故事阅读 44,652评论 2赞 354