Path Planning For Games

In games entities move around and must find their routes to various locations. These routes must be collision free, natural, and computed very fast. This is a major challenge and many games solve this by using precomputed waypoints, scripting, or simple but fast methods based on grid search or potential fields. Also very often they cheat or accept the fact that characters walk through objects. The problem becomes even more complicated when entities in games must move in groups. They should behave as a natural group does, but the flocking techniques that are often exploited for this can lead to rather unexpected and unwanted results. In this paper we discuss a different approach to path planning that has been developed primarily in the area of robotics. This technique can efficiently deal with moving entities in very complicated scenes and can guarantee path quality and clearance constraints. This is achieved by combining automatic preprocessing on the static part of the scene and adaptation to dynamic changes during path execution. We will also show how such techniques can be applied to the motion of groups of entities and how they can effectively be combined with the animation.