Procedural Generation of Virtual Cities for Computer Game Application Bruce Megget Andrew Gits Francois Grobbelaar Liz Harte

Introduction Virtual City Virtual City –Creation of an entire city using procedural techniques –Population of the city with buildings, roads, people, and other objects Benefits of Procedural Generation Benefits of Procedural Generation –Much faster development time with generated city –Enables almost endless amount of maps for gamer Challenges Challenges –Can require a large amount of computer resources –Difficult to generate a “convincing” city

Background Existing city-based games Existing city-based games Two ways to generate Two ways to generate –Before Execution –Real-time AI in games AI in games

Existing Games with Cities Sim City 4 Sim City 4 –Creation of unique cities –However, not procedurally generated - requires user interaction. Burnout 3: Takedown Burnout 3: Takedown –Massive detailed city –Painstakingly created from scratch by 3D artists, taking months of production time

Pre-Execution Generation Lechner et al Lechner et al –City “grows”, following rules, simulating the growth of a real city. Parish and Muller Parish and Muller –Realistic road system generation using rules and constraints, based on existing road systems

Real-time Generation Greuter et al Greuter et al –Generation of buildings geometry and texturing –Follows a grid-like road system Descensor Engine Descensor Engine –Generation of random worlds, following basic rules –Only generates as much detail as computer can handle

AI in Games Textbooks Textbooks –Practical advice on building game AI Bots Bots –Half Life & Quake –Monster AI –MODs

Goals Creation of an immersive “living” city Creation of an immersive “living” city –Everything looks realistic –Elaborate visual detail –“living”  people/cars moving about independently –Each generated city is unique AI AI –People, interact with the environment around them –Cars following road system, traffic rules

Immersive “living” city Common city elements Common city elements –Traffic lights/road signs –Rubbish –Phone booths etc People and Cars People and Cars Environment Environment –Weather –Day/Night (lighting of scene) Advertising Advertising Anything else Anything else

AI in the city Agents traversing Agents traversing –Active/Reactive –Wander –Goal Driven Cars driving Cars driving –Traffic signals –Road rules –Pedestrians

Project Plan so far Choose an engine (week 2) Choose an engine (week 2) Finished collaborative framework (week 4) Finished collaborative framework (week 4) Include road generation (week 4) Include road generation (week 4) Finished building textures, building shapes and size generation, building placement etc (week 7) Finished building textures, building shapes and size generation, building placement etc (week 7) Incorporated AI agents (week 8) Incorporated AI agents (week 8) Realistic details of city (extras) completed (week 9) Realistic details of city (extras) completed (week 9)

Starting point Commercial game engines Commercial game engines –Usually only game-code source is available –Much more stable, very easy to use Open Source game engines Open Source game engines –Ability to modify any part of the engine source –Large community of developers continually improving engine

Commercial Game Engines Quake (1, 2, or 3) Quake (1, 2, or 3) –Older technology –Fast, efficient Unreal 2 Unreal 2 –Relatively old, but powerful –Similar to Quake engines “Source” (Half-life 2) “Source” (Half-life 2) –Newer than previous two –Better for large open areas

Open Source Game Engines OGRE OGRE Crystal Space Crystal Space Irrlicht Irrlicht The Nebula Device The Nebula Device

Conclusion Many different paths to take Many different paths to take Aim to create an immersive living environment in the limited time we have Aim to create an immersive living environment in the limited time we have Any Questions? Any Questions?