NodeCanvas | Visual Behaviour Trees and State Machines for Unity

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13.5.Creating a Behaviour in Code

This is obviously a very advanced topic, but it is very possible to create a graph completely in code. In this example bellow, a simple BehaviourTree is created.

using UnityEngine;

using NodeCanvas.Framework;

using NodeCanvas.BehaviourTrees;

using NodeCanvas.Tasks.Actions;

//Attach this component on a gameobject that has a BehaviourTreeOwner already attached.

public class CreateBTInCode : MonoBehaviour {

void Awake(){

var owner = GetComponent<BehaviourTreeOwner>();

if (owner == null){

return;

}

//Create the Behaviour Tree

var bt = ScriptableObject.CreateInstance<BehaviourTree>();

//Sequencer Node

var seqNode = bt.AddNode<Sequencer>();

//First ActionNode

var actNode1 = bt.AddNode<ActionNode>(seqNode.nodePosition + new Vector2(-100, 100));

var actTask1 = Task.Create<Wait>(bt);

actTask1.waitTime = 1f; //set waitTime directly.

actNode1.task = actTask1;

//Second ActionNode

var actNode2 = bt.AddNode<ActionNode>(seqNode.nodePosition + new Vector2(100, 100));

var actTask2 = Task.Create<Wait>(bt);

actTask2.waitTime.name = "MyFloatVariable"; //set waitTime to read from a Blackboard Variable.

actNode2.task = actTask2;

//Connect the Nodes

bt.ConnectNodes(seqNode, actNode1);

bt.ConnectNodes(seqNode, actNode2);

//Assign the BehaviourTree to the owner and enable it

owner.StartBehaviour(bt);

}

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