Toward Solving Pathfinding Kevin Dill Chris Jurney Alex Champandard

Why Isn’t It Solved Yet? Search is expensive Limited resources Huge environments Dynamic maps Varied terrain & travel costs Limited resources Not everyone gets to work on the 360 or PS3 We still have to fight with the graphics guys… * Ken Forbus story

Ok… Why Else Is It Hard? Incredible variety of requirements Unit widths Varied (and dynamic) formation sizes Varied traversability Dynamic obstacles (i.e. other actors) Crowds Tight spaces * Uncle Steve story

Beyond Path Planning Believable motion Decision making Soldier vs. tank vs. truck vs. … puppy?!!? Unusual motion (jumping, gliding, flying, etc.) Coordinating with animation Decision making Realistic distances Screening forces Traffic prediction * Uncle Steve story

Optimizations & Other Tricks Time slice (or multithread) But what to do while you wait? Hierarchical spatial representation But what if the map changes? My heuristic *was* admissible… Precompute and/or cache results Time / space considerations Consistency

Toward Solving Pathfinding Kevin Dill Chris Jurney Alex Champandard

BUILDING NAVIGATION DATA Topic 1 BUILDING NAVIGATION DATA

Voxelization of Meshes Most scalable and efficient solution yet! Outperforms mesh simplification techniques. Also very robust with clean output. Example from Mikko Mononen’s R&D.

3D Rasterization Project by Mikko Mononen, 2009.

Area Contour Creation Project by Mikko Mononen, 2009.

Triangulation Project by Mikko Mononen, 2009.

Scaling Up Project by Mikko Mononen, 2009.

PATH Following Diversity Topic 2 PATH Following Diversity

Corridor Map R. Geraerts et al., 2008.

References Using the Corridor Map Method for Path Planning for a Large Number of Characters R. Geraerts, A. Kamphuis, I. Karamouzas, and M. Overmars. Proceedings of Motion in Games, 2008 Adding Variation to Path Planning I. Karamouza and M. Overmars. Computer Animation and Virtual Worlds Journal, 2008.

Ideas & Applications Corridor lanes, people travel on the right. Shortest path vs. longest path preferences. Varied path following with Perlin noise.

Corridor Map R. Geraerts et al., 2008.

Strategic PATHFINDING Topic 3 Strategic PATHFINDING

Potential Fields J. Hagelbäck et al., 2008.

References Using Multi-agent Potential Fields in Real-time Strategy Games J. Hagelbäck and S. Johansson Autonomous Agents and Multi-agent Systems, 2008. A Multiagent Potential Field-Based Bot for RTS Games Journal of Computer Games Technology, 2009.

Advantages Scalable to thousands of units. Emergent coordination. Simple to implement.

Multiwinia

Toward Solving Pathfinding Kevin Dill Chris Jurney Alex Champandard