Enter Luc Barthelet. Luc is the general manager of Maxis, the arm of Electronic Arts responsible for the Sim family of products. He is a long-time user of Mathematica and has found it invaluable for a variety of problems involved in the research and development of projects like SimCity.
Barthelet's plan was to use Mathematica to develop a set of graphical replacement rules for "solving" the graphic-selection process based on the constraints present in the neighborhood of the target tile. The graphic design team developed a taxonomy of intersection graphics and Barthelet created Mathematica notebooks that would isolate some key features of the neighborhood and propagate a solution using a set of simple replacement rules.
Rule. A rule that finishes the connection of two diagonal roads using a diagonal curve.
Rule. A cleaned-up four-lane highway curve.
Rule. A construction of one-half of an elevated highway and intersection; the second half is easily obtained via symmetry.
Barthelet's rules consider the 4, 8, or 24 connected neighbors to a given tile to decide whether to leave some tiles' graphics unchanged, add additional graphic elements, or replace them with other graphical elements. The illustrations above demonstrate a few of the rules used with road networks. Similar sets of rules exist for the various utilities and other transportation systems.
Converted by Mathematica April 24, 2000