Question

TubeGeometry的功能就是通过一条曲线生成一个圆管。它的本质就是以曲线上顶点为基准，生成一系列曲线等径分布的顶点数据， 具体算法如何实现的可以查看three.js引擎源码。

构造函数格式：TubeGeometry(path, tubularSegments, radius, radiusSegments, closed)

参数	值
path	扫描路径，基本类是Curve的路径构造函数
tubularSegments	路径方向细分数，默认64
radius	管道半径，默认1
radiusSegments	管道圆弧细分数，默认8
closed	Boolean值，管道是否闭合

样条曲面生成圆管案例

//创建管道成型的路径(3D样条曲线)
var path = new THREE.CatmullRomCurve3([
  new THREE.Vector3(-10, -50, -50),
  new THREE.Vector3(10, 0, 0),
  new THREE.Vector3(8, 50, 50),
  new THREE.Vector3(-5, 0, 100)
]);
// path:路径   40：沿着轨迹细分数  2：管道半径   25：管道截面圆细分数
var geometry = new THREE.TubeGeometry(path, 40, 2, 25);

你也可以使用下面直线替换上面的样条曲线查看圆管生成效果。

// LineCurve3创建直线段路径
var path = new THREE.LineCurve3(new THREE.Vector3(0, 100, 0), new THREE.Vector3(0, 0, 0));

CurvePath多段路径生成管道案例

通过下面代码创建了一段样条曲线和两条直线拼接成的路径，然后通过曲线路径CurvePath把样条曲线和料条曲线合并成为一条路径。

// 创建多段线条的顶点数据
var p1 = new THREE.Vector3(-85.35, -35.36)
var p2 = new THREE.Vector3(-50, 0, 0);
var p3 = new THREE.Vector3(0, 50, 0);
var p4 = new THREE.Vector3(50, 0, 0);
var p5 = new THREE.Vector3(85.35, -35.36);
// 创建线条一：直线
let line1 = new THREE.LineCurve3(p1,p2);
// 重建线条2：三维样条曲线
var curve = new THREE.CatmullRomCurve3([p2, p3, p4]);
// 创建线条3：直线
let line2 = new THREE.LineCurve3(p4,p5);
var CurvePath = new THREE.CurvePath();// 创建CurvePath对象
CurvePath.curves.push(line1, curve, line2);// 插入多段线条
//通过多段曲线路径创建生成管道
//通过多段曲线路径创建生成管道，CCurvePath：管道路径
var geometry2 = new THREE.TubeGeometry(CurvePath, 100, 5, 25, false);