getObjectById( id ) {

		return this.getObjectByProperty( 'id', id );

	}
Searches through the 3D object and its children, starting with the 3D object
itself, and returns the first with a matching ID.

@param {number} id - The id.
@return {Object3D|undefined} The found 3D object. Returns `undefined` if no 3D object has been found.