updateMatrixWorld( force ) {

		const bones = this.bones;

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

		_matrixWorldInv.copy( this.root.matrixWorld ).invert();

		for ( let i = 0, j = 0; i < bones.length; i ++ ) {

			const bone = bones[ i ];

			if ( bone.parent && bone.parent.isBone ) {

				_boneMatrix.multiplyMatrices( _matrixWorldInv, bone.matrixWorld );
				_vector$2.setFromMatrixPosition( _boneMatrix );
				position.setXYZ( j, _vector$2.x, _vector$2.y, _vector$2.z );

				_boneMatrix.multiplyMatrices( _matrixWorldInv, bone.parent.matrixWorld );
				_vector$2.setFromMatrixPosition( _boneMatrix );
				position.setXYZ( j + 1, _vector$2.x, _vector$2.y, _vector$2.z );

				j += 2;

			}

		}

		geometry.getAttribute( 'position' ).needsUpdate = true;

		super.updateMatrixWorld( force );

	}
The list of bones that the helper visualizes.

@type {Array<Bone>}