computeBoundingBox() {

		const geometry = this.geometry;

		if ( this.boundingBox === null ) {

			this.boundingBox = new Box3();

		}

		this.boundingBox.makeEmpty();

		const positionAttribute = geometry.getAttribute( 'position' );

		for ( let i = 0; i < positionAttribute.count; i ++ ) {

			this.getVertexPosition( i, _vertex );
			this.boundingBox.expandByPoint( _vertex );

		}

	}
Computes the bounding box of the skinned mesh, and updates {@link SkinnedMesh#boundingBox}.
The bounding box is not automatically computed by the engine; this method must be called by your app.
If the skinned mesh is animated, the bounding box should be recomputed per frame in order to reflect
the current animation state.