Casting Digital Extras Dr. Paul A. Kruszewski President, GRIP

Overview Where we are coming from Where we are coming from Where we are at Where we are at Where we are going Where we are going

Who is GRIP? A game AI software company in Montreal A game AI software company in Montreal The guys who created AI.implant The guys who created AI.implant 2002 Best AI tool (Game Developer Magazine Frontline Award) 2002 Best AI tool (Game Developer Magazine Frontline Award) 2006 Best middleware (Game Developer Magazine Frontline Award) 2006 Best middleware (Game Developer Magazine Frontline Award) GRIP credits include GRIP credits include Army of TWO: the 40th day™, Deus Ex 3, Tron:evolution Army of TWO: the 40th day™, Deus Ex 3, Tron:evolution GRIP customers include GRIP customers include Autodesk, BioWare, Disney, EA, Eidos & Intel Autodesk, BioWare, Disney, EA, Eidos & Intel

What Does GRIP do? Develop next-gen game AI products for AAA games Develop next-gen game AI products for AAA games Digital Extra System Digital Extra System Crowd simulator Crowd simulator “real-time Massive for games ” “real-time Massive for games ” Character Control System Character Control System High level NPC AI High level NPC AI “MS Dev for game brains ” “MS Dev for game brains ”

What is an Extra? Like a movie extra Like a movie extra Anyone you are not supposed to deeply interact with Anyone you are not supposed to deeply interact with The more the interactivity, the less its an extra The more the interactivity, the less its an extra “Clutter” “Clutter” Background characters Background characters Aesthetic Aesthetic Large numbers Large numbers Computationally cheap Computationally cheap Controlled en masse Controlled en masse

Shipped Examples Army of TWO: the 40 th day Army of TWO: the 40 th day Tron:evolution Tron:evolution

Core Elements Core behaviour Core behaviour Mill around and interact with the ambient world Mill around and interact with the ambient world Be aware of other people including player Be aware of other people including player Panic when a bad thing happens Panic when a bad thing happens Required tech Required tech Flows Flows Obstacle avoidance Obstacle avoidance Action stations Action stations Spawners Spawners Brains Brains

Flows Goal Goal Have lots of people move around a world seemingly with purpose Have lots of people move around a world seemingly with purpose Problems Problems Computationally slow; Little control; Sidewalk problem Computationally slow; Little control; Sidewalk problem Method Method Flow network tells extras where to go Flow network tells extras where to go Advantages Advantages Computationally simple and cheap; Expressive: extras go where they are told Computationally simple and cheap; Expressive: extras go where they are told Rocket Science Rocket Science Dynamic lane forming; Dynamic splines Dynamic lane forming; Dynamic splines

Obstacle Avoidance Goal Goal Have extras avoid running into each other in a natural looking way Have extras avoid running into each other in a natural looking way Problems Problems Twitching; Getting stuck (piling up) Twitching; Getting stuck (piling up) Method Method Case sensitive steering behaviours; Social rules / self organizing lanes; Tie into the animation system Case sensitive steering behaviours; Social rules / self organizing lanes; Tie into the animation system Advantages Advantages Very robust; Looks good Very robust; Looks good Rocket Science Rocket Science Knowing when to stop and circumvent Knowing when to stop and circumvent

Action Stations Goal Goal Add variety and realism to the movement behaviours by adding animations to show interactivity with environment Add variety and realism to the movement behaviours by adding animations to show interactivity with environment Problems Problems Scalability Scalability Interpretability Interpretability Method Method Smart objects that suck extras off flows and play animations that look like complex behaviours Smart objects that suck extras off flows and play animations that look like complex behaviours Advantages Advantages Looks good. Most AI behaviours are actually animations; Scales with animators not programmers Looks good. Most AI behaviours are actually animations; Scales with animators not programmers Rocket Science Rocket Science Context switching / interrupting; pathological players; queuing Context switching / interrupting; pathological players; queuing

Spawners Goal Goal Maximize the user’s perception of the extras Maximize the user’s perception of the extras Problems Problems Pre-roll; Spacing Pre-roll; Spacing Method Method Spawn on point / zone / flow; Despawn into pools Spawn on point / zone / flow; Despawn into pools Advantages Advantages Precise control of user experience Precise control of user experience Rocket Science Rocket Science A million little details A million little details

Brain Authoring Goal Goal Create behaviours of increasing complexity Create behaviours of increasing complexity Problems Problems State machines: state explosion; Script / coding: too unconstrained / requires highly specializes skills; Planners: incomprehensible State machines: state explosion; Script / coding: too unconstrained / requires highly specializes skills; Planners: incomprehensible Method Method Behaviour trees; Graphic editor / debugger Behaviour trees; Graphic editor / debugger Advantages Advantages Coder / designer literally on the same page; Encourages scalability, modularity and re-use Coder / designer literally on the same page; Encourages scalability, modularity and re-use Rocket Science Rocket Science Control flow / exception & interrupt handling / blackboard Control flow / exception & interrupt handling / blackboard

Future Directions Greater Fidelity Greater Fidelity Transitions to NPCs Transitions to NPCs Props Props Greater Breadth Greater Breadth Ambient vehicles Ambient vehicles Different engines Different engines