Introduction to BTs
A BT is a hierarchical tree of nodes that controls the AI character's behavior flow. It can also be used to coordinate groups of characters (for example, to model the attack pattern of a small platoon), or even disembodied agents such as an AI story director.
When we execute a BT's node, the node can return three states: success, failure, or running (if the node's execution is spread over multiple frames, for instance, if it plays an animation). When the BT executor runs a tree, it starts from the root and executes every node in order, according to rules written in the nodes themselves.
A node can be of three types:
- A task (a node without children), also called a leaf.
- A decorator (a node with a single child)
- A composite (a node with multiple children)
In general, leaves represent the Action that the characters can do or know (that is why they are commonly called an Action or Task); they may be actions such as GoToTarget...
