Vector 如何得到一条直线的端点，旋转三次，js？

我试图计算一条线的端点，并应用旋转，但似乎无法得到正确的结果

我目前正在以以下方式进行尝试：

function createLine(x, y, z, length, zrad, xrad)
{
  var points = [
    new THREE.Vector3(0, 0, 0),
    new THREE.Vector3(length/8, length*0.75, 0),
    new THREE.Vector3(0, length, 0),
  ];

  var spline = new THREE.SplineCurve3(points);

  var material = new THREE.LineBasicMaterial({
      color: 0xff00f0,
  });

  var geometry = new THREE.Geometry();
  var splinePoints = spline.getPoints(numPoints);

  for(var i = 0; i < splinePoints.length; i++){
      geometry.vertices.push(splinePoints[i]);  
  }

  var line = new THREE.Line(geometry, material);

  line.position.x = x;
  line.position.y = y;
  line.position.z = z;

  line.rotateZ(zrad);
  line.rotateX(xrad);

  // This is probably not the proper way to store the length of the Line
  line.length = length;

  return line;
}

function splitLine(line){
  var lines = [];

  var vector = new THREE.Vector3(0, line.length, 0);
  vector.applyAxisAngle(new THREE.Vector3(0, 0, 1), line.rotation.z);
  vector.applyAxisAngle(new THREE.Vector3(1, 0, 0), line.rotation.x);

  var endPoint = vector.add(line.position);

  console.log(endPoint);

  lines.push(createLine(endPoint.x, endPoint.y, endPoint.z, line.length/1.3, line.rotation.z - 45 * (Math.PI/180),  line.rotation.x - 45 * (Math.PI/180))) //line.rotation.y - 45 * (Math.PI/180)));
  lines.push(createLine(endPoint.x, endPoint.y, endPoint.z, line.length/1.3, line.rotation.z + 45 * (Math.PI/180),  line.rotation.x + 45 * (Math.PI/180))) //line.rotation.y + 45 * (Math.PI/180)));

  return lines;
}

函数createLine（x，y，z，length，zrad，xrad）
{
变量点=[
新的三个矢量3（0，0，0），
新的三矢量3（长度/8，长度*0.75,0），
新的三个矢量3（0，长度，0），
];
var spline=新的三个。SplineCurve3（点）；
var材料=新的三线基本材料({
颜色：0xff00f0，
});
var geometry=new THREE.geometry（）；
var splinePoints=spline.getPoints（numPoints）；
对于（变量i=0；i

其中

var endPoint=vector.add（line.position）给出了错误的位置。
奇怪的是，如果
line.rotation.x=0，它给出了正确的坐标