Declarative Specification of Temporal Entities for Large-Scale Character Simulation

Abstract

Large-scale character simulations for games such as Dwarf Fortress and Bad News involve both large numbers of interacting sub-simulations, and very large numbers of entities being simulated. This combination of software complexity and real-time performance constraints make them difficult to develop. One recurring issue in these systems is the simulation of temporal entities: entities that come into and out of existence. The system must typically track the set of temporal entities that exist in the current simulation step, their states, the events of their creation and destruction, and, when needed, the set of all temporal entities that have ever existed. In this paper, we present Simulog, a very high-level declarative language for large scale character simulation based on ideas from the formal ontology literature. Simulog allows developers to declaratively specify temporal entities, and their relationships. It compiles these specifications to logic programs that are then compiled to C# for multithreaded execution, providing very high performance.