Implement Follow Flow Field Force

[lxfschr]

Figure 11: flow field following
Flow field following steering behavior provides a useful tool for directing the motion of characters based on their position within an environment. It is particularly valuable in some production teams because it allows motion specification to be made without use of programming and so can used by the art staff directly. In the case of game production this person might be a “level designer” and in animation production they might be a “scene planner” or “layout artist.”
In flow field following behavior the character steers to align its motion with the local tangent of a flow field (also known as a force field or a vector field). The flow field defines a mapping from a location in space to a flow vector: imagine for example a floor with arrows painted on it. Such a map, typically representing the floor plan of an environment, can be easily created by an artist with a special purpose “paint” program which allows them to draw the desired traffic flow with a paint brush. The implementation of flow field following is very simple. The future position of a character is estimated and the flow field is sampled at that location. This flow direction (vector F in Figure 11) is the “desired velocity” and the steering direction (vector S) is simply the difference between the current velocity (vector V) and the desired velocity.

From http://www.red3d.com/cwr/steer/gdc99/