How to make a wave pattern circularly around a cylinder? - three.js

Question

Hello i'm trying to make a wave pattern on the surface of a cylinder. The waves should rotate with the rotation of the surface. and in a way the sine period is moving in circles, and the amplitudes are long mounds on the surface. Here's some pictures to better explain what i mean.
This is what i'm trying to get the top down view of the cylinder to look similar to:
this is the top view of my cylinder. I'd like the wave to change direction with the rotation of the circle, so it looks the same from all directions.
I feel like i'm very close, i'm just not sure what quaternion or angle to multiply against the vector:
var geometry = this.threeDHandler.threeD_meshes[0].geometry;
var vec3 = new THREE.Vector3(); // temp vector
for (let i = 0; i < geometry.vertices.length; i++) {
vec3.copy(geometry.vertices[i]); // copy current vertex to the temp vector
vec3.setX(0);
vec3.normalize(); // normalize
//part i'm confsude about
const quaternion = new THREE.Quaternion();
const xPos = geometry.vertices[i].x;
//trying to twist the sine around the circle
const twistAmount = 100;
const upVec = new THREE.Vector3(0, 0, 1);
quaternion.setFromAxisAngle(
upVec,
(Math.PI / 180) * (xPos / twistAmount)
);
vec3.multiplyScalar(Math.sin((geometry.vertices[i].x* Math.PI) * period) * amplitude) // multiply with sin function
geometry.vertices[i].add(vec3); // add the temp vector to the current vertex
geometry.vertices[i].applyQuaternion(quaternion);
}
geometry.verticesNeedUpdate = true;
geometry.computeVertexNormals();

Answer 1

You can use absolute value of the sin function of the angle, that a vertex belongs to.
In this case you can use THREE.Spherical() object that allows to get spherical coordinates of a vector:
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(60, window.innerWidth / window.innerHeight, 1, 1000);
camera.position.set(0, 0, 6);
var renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
var controls = new THREE.OrbitControls(camera, renderer.domElement);
var cylinderGeom = new THREE.CylinderGeometry(1, 1, 4, 128, 40, true);
var vec3 = new THREE.Vector3(); // temp vector
var vec3_2 = new THREE.Vector3(); // temp vector 2
var spherical = new THREE.Spherical();
cylinderGeom.vertices.forEach(v => {
vec3.copy(v); // copy current vertex to the temp vector
vec3.setY(0); // leave x and z (thus the vector is parallel to XZ plane)
vec3.normalize(); // normalize
vec3.multiplyScalar(Math.sin(v.y * Math.PI) * 0.25) // multiply with sin function
// radial wave
vec3_2.copy(v).setY(0).normalize();
spherical.setFromVector3(vec3_2);
vec3_2.setLength(Math.abs(Math.sin((spherical.theta * 4) + v.y * 2) * 0.25));
v.add(vec3).add(vec3_2); // add the temp vectors to the current vertex
})
cylinderGeom.computeVertexNormals();
var cylinder = new THREE.Mesh(cylinderGeom, new THREE.MeshNormalMaterial({
side: THREE.DoubleSide,
wireframe: false
}));
scene.add(cylinder);
renderer.setAnimationLoop(() => {
renderer.render(scene, camera);
})
body {
overflow: hidden;
margin: 0;
}
<script src="https://cdn.jsdelivr.net/npm/three#0.124.0/build/three.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/three#0.124.0/examples/js/controls/OrbitControls.js"></script>