How to extrude a spline to scene's origin with THREE.js

问题

I'm having headaches when trying to extrude a spline to scene's origin. Here's what I'm trying to do :

I'm creating a spline with

let centerX = 0
let centerY = 0
let radius = 200
let coils = 50
let rotation = 2 * Math.PI
let thetaMax = coils * Math.PI
let awayStep = radius / thetaMax
let chord = 5
let vertices = []

for (let theta = chord / awayStep; theta <= thetaMax;) {
  let away = awayStep * theta
  let around = theta + rotation
  let x = centerX + Math.cos(around) * away
  let y = centerY + Math.sin(around) * away

  theta += chord / away

  let vec3 = new THREE.Vector3(x, y, 0)
  vertices.push(vec3)
}

let axisPoints = []

data.forEach((d, i) => {
  axisPoints.push(new THREE.Vector3(vertices[i].z, vertices[i].y / 2, vertices[i].x / 2))
})

let axis = new THREE.CatmullRomCurve3(axisPoints)
let geometry = new THREE.BufferGeometry().setFromPoints(axis.getPoints(axisPoints.length))
let material = new THREE.LineBasicMaterial({
  color: 0x481e34,
  transparent: true,
  opacity: 0.2
})
let splineObject = new THREE.Line(geometry, material)

scene.add(splineObject)

And I want to extrude a "mesh"/"face" along this spline which is going right to the scene's origin (0) exactly like this :

I've tried many things but I can't figure it out :( Any help would be very appreciated!

Thanks!

回答1:

As an option, you can modify arrays of coordinates of an open-ended cylinder buffer geometry with coordinates of your spline:

var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(60, window.innerWidth / window.innerHeight, 1, 1000);
camera.position.set(0, 5, 10);
var renderer = new THREE.WebGLRenderer({
  antialias: true
});
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);

var controls = new THREE.OrbitControls(camera, renderer.domElement);

scene.add(new THREE.GridHelper(10, 10, "white"));

var divisions = 100;
var points = [
  new THREE.Vector3(-5, 5, 0),
  new THREE.Vector3(-2, 2, 3),
  new THREE.Vector3(1, 3, 2),
  new THREE.Vector3(3, 5, -3),
  new THREE.Vector3(-3, 4, -2)
];

var curve = new THREE.CatmullRomCurve3(points);
curve.closed = true;
var upperPoints = curve.getPoints(divisions);
var lowerPoints = upperPoints.map(p => {
  return new THREE.Vector3(p.x, 0, p.z)
});
var upperGeom = new THREE.BufferGeometry().setFromPoints(upperPoints);
var lowerGeom = new THREE.BufferGeometry().setFromPoints(lowerPoints);

var cylGeom = new THREE.CylinderBufferGeometry(1, 1, 1, divisions, 1, true); // create an open-ended cylinder
cylGeom.attributes.position.array.set(upperGeom.attributes.position.array, 0); // set coordinates for upper points
cylGeom.attributes.position.array.set(lowerGeom.attributes.position.array, (divisions + 1) * 3); // set coordinates of lower points
cylGeom.computeVertexNormals();

var result = new THREE.Mesh(cylGeom, new THREE.MeshBasicMaterial({
  color: 0xaaaaaa,
  wireframe: true
}));
scene.add(result);


var upperLine = new THREE.Line(upperGeom, new THREE.LineBasicMaterial({
  color: "aqua"
}));
scene.add(upperLine);
var lowerLine = new THREE.Line(lowerGeom, new THREE.LineBasicMaterial({
  color: "yellow"
}));
scene.add(lowerLine);

renderer.setAnimationLoop(() => {
  renderer.render(scene, camera);
});

body {
  overflow: hidden;
  margin: 0;
}

<script src="https://threejs.org/build/three.min.js"></script>
<script src="https://threejs.org/examples/js/controls/OrbitControls.js"></script>

Depends on your needs, you can modify points of any primitive.

来源：https://stackoverflow.com/questions/55976036/how-to-extrude-a-spline-to-scenes-origin-with-three-js

标签

javascript

three.js