A Behavior Language: Joint Action and Behavioral Idioms

Abstract

This chapter presents ABL (A Behavior Language, pronounced “able”), a language specifically designed to support the creation of life-like computer characters (believable agents). Concurrent with our development of ABL, we are using the language to implement the believable agent layer of our interactive drama project, Façade. With code examples and case studies we describe the primary features of ABL, including sequential and parallel behaviors, joint goals and behaviors for multi-agent coordination, and reflective programming (meta-behaviors). Specific idioms are detailed for using ABL to author story-based believable agents that can maintain reactive, moment-by-moment believability while simultaneously performing in tightly coordinated, long-term dramatic sequences.