How get points from Mesh in Three.js

Question

generate a circle by points

let arc = new THREE.ArcCurve(0, 0, 200, 0, 2 * Math.PI, true);
let points = arc.getPoints(50);
let geometry = new THREE.BufferGeometry().setFromPoints(points);
geometry.attributes.position.needsUpdate = true;
let material = new THREE.LineBasicMaterial({ color: 0x00ff00 });
let circle = new THREE.Line(geometry, material);

do some translate

circle.translateX(100);
circle.translateY(100);
circle.translateZ(100);
circle.rotation.y = Math.PI / 2;
scene.add(circle);

and now, i want to get points from Mesh circle

1.i can't find function from mesh to get points

2.i have tried to see circle.geometry.getAttribute('position').array and i write i float32ArrayToVector3Array like this

const float32ArrayToVector3Array = (arr: any) => {
  let _arr: THREE.Vector3[] = [];
  for (let i = 0; i < arr.length; i += 3) {
    _arr.push(new THREE.Vector3(arr[i], arr[i + 1], arr[i + 2]));
  }
  return _arr;
};

but circle.geometry.getAttribute('position').array seem like is not newest points

so i want to know how to get points from Mesh

prisoner849 · Accepted Answer · 2021-09-18 13:18:30Z

3

.translateX doesn't change vertices, it changes mesh's matrix.

To get coordinates in world space, try this:

let gp = mesh.geometry.attributes.position;
let wPos = [];
for(let i = 0;i < gp.count; i++){
    let p = new THREE.Vector3().fromBufferAttribute(gp, i); // set p from `position`
    mesh.localToWorld(p); // p has wordl coords
    wPos.push(p);
}

answered Sep 18, 2021 at 13:18

prisoner849

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