How to get the absolute position of a vertex in three.js?

Question

As far as I know var point = object.geometry.vertices[i]; will return with the relative position for the x, y and z of the point inside the geometry of the object.

How to get the absolute position, if the object was moved, rotated or scaled?

Answer 1

You can get the world position of a vertex like so:

const vertex = new THREE.Vector3(); // create once and reuse

const attribute = object.geometry.getAttribute( 'position' );

vertex.fromBufferAttribute( attribute, index );

object.localToWorld( vertex );

three.js r151

Answer 2

Recent versions of Three.js (v50+) provide this functionality built into the THREE.Object3D class. In particular, to get the world coordinates of a local THREE.Vector3 instance named vector, use the localToWorld method:

object.localToWorld( vector );

Similarly, there is a worldToLocal method for converting world coordinates into local coordinates, which is slightly more complicated, mathematically speaking. To translate a world vector into the objects local coordinate space:

object.worldToLocal( vector );