threejs 大量线段Line合并（贝塞尔曲线或者直线）

项目中，线段数据后端传过来上万个，如何我们一条一条线段往里面加，导致页面性能下降，这个时候，我们可以将所有线段合并成一个
老代码，也能实现功能

const lineGroup = new THREE.Group();
      this.bezierPathList.forEach((item) => {
        const [p1, p2, p3, p4] = item.coordinate;
        // 初始化数据，绘制曲线轨迹
        const curve = new THREE.CubicBezierCurve3(
          new THREE.Vector3(p1.x / 1000, 0.1, -p1.z / 1000), // z轴取反
          new THREE.Vector3(p2.x / 1000, 0.1, -p2.z / 1000),
          new THREE.Vector3(p3.x / 1000, 0.1, -p3.z / 1000),
          new THREE.Vector3(p4.x / 1000, 0.1, -p4.z / 1000)
        );
        const points = curve.getPoints(50);
        const geometry = new THREE.BufferGeometry().setFromPoints(points);
        const material = new THREE.LineBasicMaterial({ color: 0xffffff });
        const curveObject = new THREE.Line(geometry, material);
        lineGroup.add(curveObject);
      });
      scene.add(lineGroup);

1、使用new THREE.LineSegments，(LineSegments是不合并多条线段,具体介绍看官网)
2、生成一个geometry，对geometry设置position点（赋值所有的线段点）
代码如下
合并大量贝塞尔曲线

const geometry = new THREE.BufferGeometry();
      const points = [];
      this.bezierPathList.forEach((item) => {
        const [p1, p2, p3, p4] = item.coordinate;
        // 初始化数据，绘制曲线轨迹
        const curve = new THREE.CubicBezierCurve3(
          new THREE.Vector3(p1.x / 1000, 0.1, -p1.z / 1000), // z轴取反
          new THREE.Vector3(p2.x / 1000, 0.1, -p2.z / 1000),
          new THREE.Vector3(p3.x / 1000, 0.1, -p3.z / 1000),
          new THREE.Vector3(p4.x / 1000, 0.1, -p4.z / 1000)
        );
        const curves = curve.getPoints(49); // 将线段分割为49+1个点，需要是偶数，不然会出现奇数点连接问题
        curves.forEach(v => {
          points.push(v.x, v.y, v.z)
        })
      });
      geometry.setAttribute(
        'position',
        new THREE.Float32BufferAttribute(points, 3)
      );
      const lineMaterial = new THREE.LineBasicMaterial({ color: 0xffffff });
      const line = new THREE.LineSegments(geometry, lineMaterial);
      scene.add(line);

合并大量直线

const geometry = new THREE.BufferGeometry();
      const paths = [];
      this.linePathList.forEach((item) => {
        const [p1, p2] = item.coordinate;
        paths.push(
          new THREE.Vector3(p1.x / 1000, 0.1, -p1.z / 1000),
          new THREE.Vector3(p2.x / 1000, 0.1, -p2.z / 1000)
        ); // z轴取反
      });
      geometry.setFromPoints(paths);
      const lineMaterial = new THREE.LineBasicMaterial({ color: 0xffffff });
      const line = new THREE.LineSegments(geometry, lineMaterial);
      scene.add(line);