点对于某个对称轴镜像翻转，这里用二维演示，思路及外围办法都是统一的，二维能较好阐明。

找到在对称轴上与点最近的点

 // 将对称轴整成线段 const line = new THREE.Line3(axis, new THREE.Vector3(0, 0, 0)) const linePoint = new THREE.Vector3() line.closestPointToPoint(arr[i], false, linePoint) // linePOint就是arr[i]点在线段上最近的点

得出点与线段上的点的间隔S1

// linePoint是线段上的点  vec3是须要翻转的点const distance = linePoint.distanceTo(vec3)

按方向缩短S1的间隔至S点

 // 简略的勾股定理 const p = Math.sqrt(2) * 0.5 x = linePoint.x + p * distance y = linePoint.y - p * distance

须要进行判断

对于上方的后果只是点在对称轴左侧才成立, 须要判断点的方位

  /**   * 判断是否在左侧   * 因为数据是否在左右侧关系到xy的符号问题, 间隔是没有正数的，而坐标是存在正负的   */  function leftORRight() {    let left = true;    const line = new THREE.Line3(axis, new THREE.Vector3(0, 0, 0))    const linePoint = new THREE.Vector3()    for (let i = 0; i < arr.length; i++) {      line.closestPointToPoint(arr[i], false, linePoint)      if (linePoint.x < arr[i].x) {        // 右侧        left = false;        break;      }    }    return left;  }

All Code

import * as THREE from 'three'/** * 实现点绕制订对称轴镜像转换的性能 */function axisRound(scene) {  // const arr = [  //   new THREE.Vector3(-1, 1, 0),  //   new THREE.Vector3(-2, -1, 0),  //   new THREE.Vector3(-1, -1, 0),  //   new THREE.Vector3(-1, 2, 0),  // ]  // 提供测试的数据  const arr = [    new THREE.Vector3(1, -1, 0),    new THREE.Vector3(2, -1, 0),    new THREE.Vector3(1, 1, 0),    new THREE.Vector3(1, -2, 0),  ]  const material = new THREE.MeshBasicMaterial({ color: 'red', side: THREE.DoubleSide });    arr.forEach(row => {    const geometry = new THREE.PlaneGeometry(0.5, 0.5);    const plane = new THREE.Mesh(geometry, material);    scene.add(plane);    plane.position.set(row.x, row.y, row.z)  })  const axis = new THREE.Vector3(1, 1, 0)  {    const points = [];    points.push(axis);    points.push(new THREE.Vector3(-10, -10, 0))    points.push(new THREE.Vector3(10, 10, 0))    const geometry = new THREE.BufferGeometry().setFromPoints(points);    const line = new THREE.Line(geometry, material);    scene.add(line);  }  arr.forEach(row => {    const geometry = new THREE.PlaneGeometry(0.5, 0.5);    const plane = new THREE.Mesh(geometry, material);    scene.add(plane);    const n = t(row, axis)    console.log(n);    plane.position.set(n.x, n.y, n.z)  })  // 正式开始计算  function t(vec3, axis) {    const line = new THREE.Line3(axis, new THREE.Vector3(0, 0, 0))    const linePoint = new THREE.Vector3()    line.closestPointToPoint(vec3, false, linePoint)    // 得出2的算术平方根的1/2    const p = Math.sqrt(2) * 0.5    const distance = linePoint.distanceTo(vec3)    let x, y;    if (leftORRight()) {      x = linePoint.x + p * distance      y = linePoint.y - p * distance    } else {      x = linePoint.x - p * distance      y = linePoint.y + p * distance    }    return new THREE.Vector3(x, y, 0)  }  /**   * 判断是否在左侧   * 因为数据是否在左右侧关系到xy的符号问题, 间隔是没有正数的，而坐标是存在正负的   */  function leftORRight() {    let left = true;    const line = new THREE.Line3(axis, new THREE.Vector3(0, 0, 0))    const linePoint = new THREE.Vector3()    for (let i = 0; i < arr.length; i++) {      line.closestPointToPoint(arr[i], false, linePoint)      if (linePoint.x < arr[i].x) {        // 右侧        left = false;        break;      }    }    return left;  }}export { axisRound }