IBlackboardObserver

Remarks

This is what makes an event-driven behaviour tree possible: a decorator with an observer registers on the keys it reads, and a write to one of them re-evaluates it. A tree whose world has not changed does nothing at all.

⚠ An observer is told, it does not act. A notification arrives during somebody else's write, which may well be the running task writing its own result — so the correct response is to enqueue work, never to abort, re-enter or tick anything. The stepper services what was enqueued at the top of the next step, when nothing is part-way. docs/plan/37 § D6 is the argument, and the one-frame latency it costs is stated in the guide rather than hidden.

Methods (1)

• void OnBlackboardChanged(Blackboard blackboard, BlackboardKey key)

  The key changed.

Used by (5)

• BehaviorTreeInstanceVixen.Ai
• BlackboardVixen.Ai
• CountingObserverVixen.Ai.Tests
• DelegateObserverVixen.Ai.Tests
• ObserverSlotVixen.Ai