Questions about Blackboard asset

[MorganHoarauUnity]

Hello @MOBILIN

Thanks for your interest, let me try to cover your questions:

@MOBILIN

Among the properties of the Variable added to the Blackboard asset, there are Exposed and Shared. How are these options used? I cannot understand what will change even if I change the option values.

The Expose option makes a Blackboard variable available in the Inspector window under Behavior Agent .

The Shared option marks a variable in the Blackboard as globally shared across different instances of the behavior graph.

For more details please refer to the documentation: Create and manage variables and Blackboards | Behavior | 1.0.6

@MOBILIN

We can use multiple Blackboard assets in a Behavior Graph, which one does BehaviorAgent.BlackboardReference refer to?

It refers to the blackboard that is embedded by default in the BehaviorGraph. Any additional linked blackboards are currently not available by code.

@MOBILIN

How do I change the value of a Variable registered in a Blackboard asset in C#?

I will link this other thread: Behaviour Graph Events to GameObjects without Behaviour Graphs - #2 by MorganHoarauUnity

It is not directly answering your question, but the idea is the same. You need a reference to a particular instance of BehaviorGraphAgent to retrieve a BlackboardVariable from it. From there you can work directly with a reference to the value (using BlackboardReference.GetVariable or BlackboardReference.SetVariableValue).

@MOBILIN

I can combine multiple Action nodes. In this case, how does the return value of each node affect the execution order of the combined Action nodes? What is the main purpose of merging Action nodes?

I assume you are referring about the ability to stack action nodes on top of each other. One of the goal of the tool is to make the creation and maintenance of Behavior Tree easy, and we believe that making it easier to read as one of the way of achieving that. As such, we got rid of redundant connectors by allowing users to stack nodes to create implicit sequence of action. This way you can read your action like a text, from top to bottom.

@MOBILIN

I want to implement a specific logic as a Sub Graph. For modularization, I also want to process the logic that terminates the execution of the Sub Graph in the Sub Graph. How can I terminate the Sub Graph itself and move the execution order to the parent graph?

1. RunSubgraph node will run as long as your Subgraph is running. So if all of your subgraph branches have ended or are aborted, the RunSubgraph node will be able to end.
2. It is possible to inject variable in your Subgraph. This way it is possible to send a value that can be set in your subgraph that would cause the parent graph from aborting its (the subgraph) execution.

Something that is done in the Demo is actually using this mechanism to send an Event Message to an Event Channel to allows the Subgraph to run in the background while running another state in the parent graph (see B_Character_Attack_Combo graph - more specifically how the combo subgraph is able to send the parent B_StateMachine_Character back to it’s idle state without stopping it’s own execution).

Hope this helps! Don’t hesitate if you have more question