A method is provided for defining a cross section having an arbitrary shape. The method includes creating a vector graphic of the cross section. The method includes disassembling the vector graphic of the cross section into paths that represent an outline of the arbitrary shape of the cross section, each path a straight path or a curved path having respective endpoints including a first endpoint and a second endpoint. The method includes arranging the paths in an order in which the paths are connected in the vector graphic to form the outline of the arbitrary shape of the cross section, and generating an array of elements for the paths, including elements for successive pairs of adjacent straight paths in the order in which the paths are arranged. And the method incudes defining and thereby producing a definition of the cross section from the array of elements.