Returns the centroid of a geometry, or the component of the centroid.


## Description

It takes 1 or 2 arguments.

`centroid(input_index_or_node_path, vector_component)`

- `input_index_or_node_path` is a number or a string
- `vector_component` is a string, either 'x', 'y' or 'z'

## Usage

- `centroid(0)` - returns the centroid of the input node, as a THREE.Box3
- `centroid('/geo1/box')` - returns the centroid of the node /geo1/box, as a THREE.Box3
- `centroid('/geo1/box', 'x')` - returns the x component of centroid of the bbox, as a number