Learning Game AI Programming with Lua
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Group steering

Group steering can be broken down into three main steering behaviors: alignment, cohesion, and separation. An alignment steering force has the agent's face in the same forward direction as the rest of the agents in the group. Cohesion is a force that keeps the agents within the group together. Separation is the opposite of cohesion and forces the agents within the group to keep minimum distance from one another.

Using a combination of these three steering behaviors, which are also known as flocking, you can create groups of agents that are driven to move together yet not run into each other.

Alignment

To calculate a steering vector that will align our agent to a group of other agents, we can use the ForceToSeparate function.

local forceToAlign =
    agent:ForceToSeparate(maxDistance, maxAngle, agents);

Cohesion

To keep our agent together with a group of other agents, we can calculate a steering force for combining using the ForceToCombine function.

local forceToCombine =
    agent:ForceToCombine(maxDistance, maxAngle, agents);

Separation

To keep our agent apart from a group of other agents, we can use the ForceToSeparate function.

local forceToSeparate =
    agent:forceToSeparate(minDistance, maxAngle, agents);