效果：淡入，靠近物体

代码：

<template>
  <div>
    <el-container>
      <el-main>
        <div class="box-card-left">
          <div id="threejs" style="border: 1px solid red"></div>
          <div class="box-right">
            <el-button type="primary" @click="lookFor('设备A')"
              >设备A</el-button
            >
            <el-button type="primary" @click="lookFor('设备B')"
              >设备B</el-button
            >
            <el-button type="primary" @click="lookAll">整体</el-button>
            <el-button type="primary" @click="saveImg">保存图片</el-button>
          </div>
        </div>
      </el-main>
    </el-container>
  </div>
</template>
<script>
// 引入轨道控制器扩展库OrbitControls.js
import { OrbitControls } from "three/examples/jsm/controls/OrbitControls.js";
import TWEEN from "@tweenjs/tween.js";

export default {
  data() {
    return {
      scene: null,
      camera: null,
      renderer: null,
      mesh: null,
      geometry: null,
      group: null,
      material: null,
      clock: null,
      mixer: null,
    };
  },
  created() {},
  mounted() {
    this.name = this.$route.query.name;
    this.init();
    // 监听点击事件
    this.addClickEventListener();
  },
  methods: {
    goBack() {
      this.$router.go(-1);
    },
    init() {
      // 创建场景对象
      this.scene = new this.$three.Scene();
      this.group = new this.$three.Group();
      this.createMesh({
        x: 50,
        y: 50,
        z: 50,
        name: "设备A",
      });
      this.createMesh({
        x: -50,
        y: 50,
        z: 50,
        name: "设备B",
      });

      this.scene.add(this.group);
      const axesHelper = new this.$three.AxesHelper(150);
      this.scene.add(axesHelper);
      // 创建环境光对象
      const ambientLight = new this.$three.AmbientLight(0xffffff);
      this.scene.add(ambientLight);
      // 创建相机对象
      this.camera = new this.$three.PerspectiveCamera();
      this.camera.position.set(300, 300, 300);
      this.camera.lookAt(0, 0, 0);
      // 创建渲染器对象
      this.renderer = new this.$three.WebGLRenderer({
        preserveDrawingBuffer: true, // 把画布内容保存为图片时，需要设置为true
      });
      this.renderer.setSize(1000, 800);
      this.renderer.render(this.scene, this.camera);
      window.document
        .getElementById("threejs")
        .append(this.renderer.domElement);

      // 创建相机空间轨道控制器对象
      this.controls = new OrbitControls(this.camera, this.renderer.domElement);
      this.controls.addEventListener("change", () => {
        this.renderer.render(this.scene, this.camera);
        console.log(
          " this.camera.position",
          this.camera.position.x,
          this.camera.position.y,
          this.camera.position.z
        );
      });
    },
    // 创建网格模型的方法
    createMesh(obj) {
      // 创建立方缓冲几何体对象
      const geometry = new this.$three.BoxGeometry(obj.x, obj.y, obj.z);
      // 创建材质对象
      const material = new this.$three.MeshLambertMaterial({
        color: this.randomColor(),
        transparent: true,//开启透明计算
        opacity: 0.0//完全透明
      });
      const mesh = new this.$three.Mesh(geometry, material);
      mesh.position.set(obj.x, obj.y, obj.z);
      mesh.name = obj.name;
      if (this.group) {
        this.group.add(mesh);
      }
    },
    lookFor(name) {
      if (this.scene && this.scene.getObjectByName(name)) {
        // 通过 getObjectByName() 方法获取name为设备A的模型
        const equipment_A = this.scene.getObjectByName(name);
        // 创建Vector3类型的位置对象
        const position = new this.$three.Vector3();
        // 获取设置A的世界坐标并赋值到position对象中
        equipment_A.getWorldPosition(position);
        // 向量x,y,z坐标值在position的基础上增加50，
        const position_scalar = position.clone().addScalar(100);
        // 创建TWEEN对象并调用Tween方法
        new TWEEN.Tween({
          x: this.camera.position.x,
          y: this.camera.position.y,
          z: this.camera.position.z,
          px: this.controls.target.x,
          py: this.controls.target.y,
          pz: this.controls.target.z,
          opacity: equipment_A.material.opacity//完全透明
        })
          .to(
            {
              x: position_scalar.x,
              y: position_scalar.y,
              z: position_scalar.z,
              px: equipment_A.position.x,
              py: equipment_A.position.y,
              pz: equipment_A.position.z,
              opacity: 1.0
            },
            3000
          )
          .onUpdate((obj) => {
            // 设置相机位置
            this.camera.position.set(obj.x, obj.y, obj.z);
            // 设置控制器指向
            this.controls.target.set(obj.px, obj.py, obj.pz);
            // 更新控制器
            this.controls.update();
            equipment_A.material.opacity = obj.opacity;
          })
          .onComplete(obj => {
            equipment_A.material.transparent = false;
          })
          .start()
          .easing(TWEEN.Easing.Sinusoidal.InOut); //使用二次缓动函数;
        /**
            easing()语法格式
         * // easing函数：缓动算法(运动效果)
            // easing类型：定义缓动算法起作用地方
            tween.easing(TWEEN.Easing.easing函数.easing类型); 
            // easing类型  In , Out ， InOut

            Linear:默认效果可以不设置，可以理解为没有加速过程直接进入匀速状态，或者说没有减速过程，直接刹车

            Quadratic：二次方的缓动(t^2)

            Cubic：三次方的缓动(t^3)

            Quartic：四次方的缓动(t^4)

            Quintic：五次方的缓动(t^5)

            Sinusoidal：正弦曲线的缓动(sin(t))

            Exponential：指数曲线的缓动(2^t)启动非常慢，后面快

            Circular：圆形曲线的缓动(sqrt(1-t^2))会有弹性衰减往复运动感

            Elastic：指数衰减的正弦曲线缓动；TWEEN.Easing.Elastic.inout 会有弹性衰减往复运动感

            Back：超过范围的三次方缓动((s+1)*t^3 – s*t^2)会有弹性衰减往复运动感

            Bounce：指数衰减的反弹缓动。会有弹性衰减往复运动感
         *  */

        this.loop();
      }
    },
    loop() {
      this.renderer.render(this.scene, this.camera);
      TWEEN.update();
      window.requestAnimationFrame(this.loop);
    },
    lookAll() {
      /**
       * 查看整体的思路：
       * 用包围盒 Box3, 将场景中所有的模型包裹起来，计算出
       * (box3.min.x + box.max.x) / 2 = centerX
       * (box.min.y + box.max.y) / 2 = centerY
       * (box.min.z + box.max.z) / 2 = centerZ
       * , 计算出 centerX， centerY, centerZ  整体的中心坐标，
       *  为了显示包围盒的边界，可以使用Box3Helper辅助对象;
       * 相机的位置position要从当前位置定位到
       *
       *  */
      // 创建包围盒对象
      const box3 = new this.$three.Box3();
      // 设置包围盒中的对象
      const groupBox = box3.expandByObject(this.group);
      console.log(groupBox);
      const box3Helper = new this.$three.Box3Helper(box3, 0xffffff);
      this.scene.add(box3Helper);
      let max_x = groupBox.max.x;
      let max_y = groupBox.max.y;
      let max_z = groupBox.max.z;
      let min_x = groupBox.min.x;
      let min_y = groupBox.min.y;
      let min_z = groupBox.min.z;
      let center_x = (max_x + min_x) / 2;
      let center_y = (max_y + min_y) / 2;
      let center_z = (max_z + min_z) / 2;
      //
      let increment_x =
        Math.abs(max_x) > Math.abs(min_x) ? Math.abs(max_x) : Math.abs(min_y);
      let increment_y =
        Math.abs(max_y) > Math.abs(min_y) ? Math.abs(max_y) : Math.abs(min_y);
      let increment_z =
        Math.abs(max_z) > Math.abs(min_z) ? Math.abs(max_z) : Math.abs(min_z);

      new TWEEN.Tween({
        x: this.camera.position.x,
        y: this.camera.position.y,
        z: this.camera.position.z,
        px: this.controls.target.x,
        py: this.controls.target.y,
        pz: this.controls.target.z,
      })
        .to(
          {
            x: center_x + increment_x * 2,
            y: center_y + increment_y * 2,
            z: center_z + increment_z * 2,
            px: center_x,
            py: center_y,
            pz: center_z,
          },
          1200
        )
        .onUpdate((obj) => {
          this.camera.position.set(obj.x, obj.y, obj.z);
          this.controls.target.set(obj.px, obj.py, obj.pz);
          this.controls.update();
        })
        .start();
      this.loop();
    },
    saveImg() {
      const link = document.createElement("a");
      const canvas = this.renderer.domElement;
      link.href = canvas.toDataURL("image/png");
      link.download = "threejs.png";
      link.click();
    },
    randomColor() {
      const numbers = Array.from({ length: 255 }, (_, i) => i);
      const color = [...numbers];
      // 要生成min-max之间的随机数，公式为：Math.random()*(max-min+1)+min
      let i = Math.floor(Math.random() * (color.length - 0 + 1) + 0);
      let j = Math.floor(Math.random() * (color.length - 0 + 1) + 0);
      let k = Math.floor(Math.random() * (color.length - 0 + 1) + 0);
      return new this.$three.Color("rgb(" + i + ", " + j + ", " + k + ")");
    },
    // 在canvas画布上添加监听点击的事件
    addClickEventListener() {
      // 获取id 是 threejs 的元素；
      const dom = window.document.getElementById("threejs");
      const canvasWidth = dom.clientWidth; // 获取元素的宽度
      const canvasHeight = dom.clientHeight; // 获取元素的高度
      dom.addEventListener("click", (e) => {
        const x = e.offsetX; // 获取鼠标当前点击的点距离dom元素左上角原点  在x轴方向上的距离
        const y = e.offsetY; // 获取鼠标当前点击的点距离dom元素左上角原点  在y轴方向上的距离
        console.log(x, y);
        // 由于canvas画布上的坐标值与普通2d页面的坐标值是不一样的；
        // 在canvas画布上的坐标轴是以画布的中心点为原点，左右x轴，值 -1 ~ 1,，上下y轴，值-1 ~ 1；
        // 坐标需要进行坐标转换
        const pos_x = (x / canvasWidth) * 2 - 1; // 转换后的x坐标
        const pos_y = -(y / canvasHeight) * 2 + 1; // 转换后的y坐标
        // 创建射线投射器对象（可以在初始化方法中创建，每次点击时创建有些浪费资源）
        const rayCaster = new this.$three.Raycaster();
        // 计算射线（在点击位置创建一条射线，用来拾取模型对象）
        rayCaster.setFromCamera(
          new this.$three.Vector2(pos_x, pos_y),
          this.camera
        );
        const mesh_list = [];
        // traverse 是threejs中的递归遍历方法；找出group中的mesh
        this.group.traverse((obj) => {
          if (obj.isMesh) {
            mesh_list.push(obj);
          }
        });
        // 射线交叉计算（计算出与自身射线相交的网格模型）
        const intersects = rayCaster.intersectObjects(mesh_list);
        if (intersects && intersects.length > 0) {
          console.log(intersects[0]);
          this.lookFor(intersects[0].object.name);
        }
      });
    },
  },
};
</script>
//
<style lang="less" scoped>
.box-card-left {
  display: flex;
  align-items: flex-start;
  flex-direction: row;

  width: 100%;

  .box-right {
    img {
      width: 500px;
      user-select: none;
    }
  }
}
</style>