The BehaviorTree class, as the name implies, represents the Behavior Tree structure.

There are two ways to construct a Behavior Tree: by manually setting the root node, or by loading it from a data structure (which can be loaded from a JSON). Both methods are shown in the examples below and better explained in the user guide.

The tick method must be called periodically, in order to send the tick signal to all nodes in the tree, starting from the root. The method BehaviorTree.tick receives a target object and a blackboard as parameters. The target object can be anything: a game agent, a system, a DOM object, etc. This target is not used by any piece of Behavior3JS, i.e., the target object will only be used by custom nodes.

The blackboard is obligatory and must be an instance of Blackboard. This requirement is necessary due to the fact that neither BehaviorTree or any node will store the execution variables in its own object (e.g., the BT does not store the target, information about opened nodes or number of times the tree was called). But because of this, you only need a single tree instance to control multiple (maybe hundreds) objects.

Manual construction of a Behavior Tree

var tree = new b3.BehaviorTree();

tree.root = new b3.Sequence({children:[
  new b3.Priority({children:[
    new MyCustomNode(),
    new MyCustomNode()
  ]}),
  ...
]});

Loading a Behavior Tree from data structure

var tree = new b3.BehaviorTree();

tree.load({
  'title'       : 'Behavior Tree title'
  'description' : 'My description'
  'root'        : 'node-id-1'
  'nodes'       : {
    'node-id-1' : {
      'name'        : 'Priority', // this is the node type
      'title'       : 'Root Node',
      'description' : 'Description',
      'children'    : ['node-id-2', 'node-id-3'],
    },
    ...
  }
})