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Planning as Simulation

One of the really wonderful things about the Sim family of games is that they are complex simulation systems fitted with nice interfaces. Basically, any aspiring Pierre L'Enfant can whip up a little petri dish of a community and watch it develop without waiting for hundreds of years or facing criminal charges for tampering with the treasury.

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Eastern New Jersey. Road networks presented a challenge for the isometric projection used in newer versions of the software.

SimCity utilizes a "tile" system for laying out utility and road networks. In the initial versions of the software these tiles existed in a plane, viewed from above. The introduction of SimCity 2000 brought with it a new rendering scheme, isometric rather than a strict plan view. Needless to say, this introduced a new set of challenges when laying out the various networks required to sustain a silicon city. Further complicating matters, newer versions allow for nonflat terrain, which strenuously challenges the layout algorithms.

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Layout. Users lay out roads and utilities by drawing a path on the network tiles (here seen in blue), and the resulting graphical elements, a road here, are fit to the tiles. Mathematica code is used to define the replacement rules employed in selecting the proper graphical elements.

When laying out the networks, various graphical elements need to be placed on the terrain to indicate the use of that particular tile. Roadways, utility lines, subways, water pipes, and other networks have to be connected and visually represented in an æsthetically pleasing way. For simple linear structures this really is not much of a problem; graphical elements can be linked together much like pieces of model railroad track. Problems occur when curves, overpasses and underpasses, and intersections enter the picture. To handle these cases, earlier versions of SimCity employed a simple scheme that used the four adjacent (Greek-cross) neighbors to obtain a unique solution for almost all possible cases of intersections, curves, or terminations. For SimCity 3000 the art directors wanted more flexibility in the visual design of the networks' graphical elements. As with most complex systems of this sort, some small additions and perturbations to the basic set of rules resulted in a large increase in the complexity of the resulting system. Coding all of the possible situations by hand was going to be a tedious task at best. The designers wanted a solution more data- than algorithm-driven so configural changes could be accomplished in a more straightforward and intuitive way.

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Complicated Intersections. SimCity 3000  increases the complexity of the graphical elements of the various networks. Here we see a four-lane divided highway, complete with on and off ramps, exit signs, and underpasses.

Converted by Mathematica      April 24, 2000

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