Games Programming III (TGP2281) – T1, 2010/2011 Game AI Fundamentals John See 15 November 2010

Games Programming III (TGP2281) – T1, 2010/2011 What is AI? “Making computers able to perform the thinking tasks that humans and animals are capable of” Academia vs. Game Developers

Games Programming III (TGP2281) – T1, 2010/2011 Academic AI (in a 3-period nutshell) Early Days –What produces thought? Could you give life to an inanimate object? –The Turing Test The Symbolic Era –2 components – A set of knowledge (or symbols) and a reasoning algorithm that manipulates those symbols –Expert System –Pathfinding, decision trees, state machines, steering algorithms –Knowledge vs. Reasoning tradeoff The Natural Era –Symbolic techniques lack ability to emulate human intelligence –Natural computing techniques inspired by biology –Neural Networks, Genetic Algorithms

Games Programming III (TGP2281) – T1, 2010/2011 Game AI (in a bigger shell) PacMan (1979) - [ Golden Axe (1987) Metal Gear Solid (1988) – Sense simulation Warcraft (1994) – Pathfinding Warhammer: Dark Omen (1998) – Formation motion Creatures (1997) – Neural-network brain for each unit The Sims (2000), Black and White (2001) – AI as main point of attraction in game

Games Programming III (TGP2281) – T1, 2010/ basic needs for Modern Game AI Ability to move characters Ability to make decisions about where to move Ability to think tactically and strategically

Games Programming III (TGP2281) – T1, 2010/2011 Millington's Game AI Model

Games Programming III (TGP2281) – T1, 2010/2011 What levels of AI do games require? Board games like Chess or Risk? Platform action-games like Mario Bros.? PacMan? Full-fledge RTS like Warcraft? FPS games like Half Life?

Games Programming III (TGP2281) – T1, 2010/2011 “Agent”-based AI Producing autonomous characters, that –Take in information from the game data –Determine what actions to take based on the information –Carry out the actions Bottom-up design What about non-agent-based AI? Top-down design? Millington opts not to use the term “agent”

Games Programming III (TGP2281) – T1, 2010/2011 Case Study: Pac-Man Play the Pac-Man game. Discuss how AI is implemented in this classic game... What are some possible fundamental structures you observe from this game?

Games Programming III (TGP2281) – T1, 2010/2011 Complexity Fallacy When Simple Things Look Good When Complex Things Look Bad The Perception Window Changes of Behavior

Games Programming III (TGP2281) – T1, 2010/2011 The Kind of AI in Games Hacks Heuristics –Common heuristics: Most Constrained, Do The Most Difficult Thing First, Try The Most Promising Thing First

Games Programming III (TGP2281) – T1, 2010/2011 AI Engine A change in the way games are developed in the last 10 years Initial style: Bits of AI code intermingled with other game code, AI written for each game and each character, each character's behavior controlled by a small program Now: AI Engine –Building tools that can be reused –Integrated as part of Game Engines – a technical platform for building games ubiquitously E.g. LucasArts SCUMM engine – tailor-made for their point- and-click adventure games

Games Programming III (TGP2281) – T1, 2010/2011 Structure of an AI Engine Infrastructures –A general mechanism for managing AI behaviors (decide what gets run, etc.) –A world-interfacing system for getting information into the AI From AI to Screen –Whatever the AI wants to do should translate to screen action (normally, movement, pathfinding, etc.) or background computation (tactics, strategies to win) Standard liaising behavior structure –Having all AI conform to the same structure for easy development of future code