union( box ) {

		this.min.min( box.min );
		this.max.max( box.max );

		return this;

	}
Computes the union of this box and another and the given one, setting the upper
bound of this box to the greater of the two boxes' upper bounds and the
lower bound of this box to the lesser of the two boxes' lower bounds.

@param {Box3} box - The bounding box that will be unioned with this instance.
@return {Box3} A reference to this bounding box.