For the RAIN implementation of behavior trees, the behavior nodes are split into two categories: decisions and actions. Actions tell the AI system to actually do something; it is where the actual work of the AI is done. The most common action is the one we saw in the previous chapters, move, which tells the AI system to move a character. Besides move, here is a list of the current actions RAIN supports:
The Choose patrol path and Choose path waypoints: These nodes help to move the AI through a network of waypoints.
Detect: This finds other AI entities and areas marked in a scene. This node will be covered in Chapter 6, Sensors and Activities.
The Evaluate expression: This node evaluates some logic, using RAIN's custom logic system. We will be discussing this node more in this chapter.
Animate and Mechanism: These animation nodes manage different animations playing on the entity. We'll look at this node type more in Chapter 10, Animation and AI.