getBoundingSphere( target ) {

		if ( this.isEmpty() ) {

			target.makeEmpty();

		} else {

			this.getCenter( target.center );

			target.radius = this.getSize( _vector$b ).length() * 0.5;

		}

		return target;

	}
Returns a bounding sphere that encloses this bounding box.

@param {Sphere} target - The target sphere that is used to store the method's result.
@return {Sphere} The bounding sphere that encloses this bounding box.