@olemop/behavior-tree - behavior tree for node.js

• [ ] 测试

@olemop/behavior-tree is a Behavior-Tree module for olemop project to implement AI. More information about Behavior-Tree please refer other articles from Internet, such as Understanding Behavior Trees.

Installation

npm install @olemop/behavior-tree

Behavior tree nodes

Node

The base class of all the behavior tree node classes. Its constructor receives a blackboard instance as parameter.

Each node class provides a doAction method to fire the behavior of current node instance. All the children should implement their own doAction. And the doAction method sould report a result code to the parent when it return. The result code is one of below:

• RES_SUCCESS: the behavior finished successfully.
• RES_FAIL: the behavior fails.
• RES_WAIT: the behavior is running and should be continued in next tick. The parent node makes its decision based on the result code.

Composite

The base class of all the composite nodes. A composite node has arbitrary child nodes and it has a addChild method to add child node.

Decorator

The base class of all the decorator nodes. A decorator node has the ability to decorate the result for its child node. A decorator node has only one child node and has a setChild method to set the child node.

Followings are some behavior node types provided in @olemop/behavior-tree.

Composite nodes

Sequence

Implementation of sequence semantics.

Sequence(opts)

• opts.blackboard - blackboard instance for the behavior node.

Parallel

Implementation of parallel semantics.

Parallel(opts)

• opts.blackboard - blackboard instance for the behavior node.
• opts.policy - Failure strategy for Parallel node: Parallel.POLICY_FAIL_ON_ONE(default) return RES_FAIL if one child node fail, Parallel.POLICY_FAIL_ON_ALL return RES_FAIL only on all the child nodes fail.

Selector

Implementation of selector semantics.

Selector(opts)

• opts.blackboard - blackboard instance for the behavior node.

Decorator nodes

Loop

Implementation of loop semantics.

Loop(opts)

• opts.blackboard - blackboard instance for the behavior node.
• opts.child - child node for the decorator node。
• opts.loopCond(blackboard) - loop condition function. return true to continue the loop and false to break the loop.

Condition

Return RES_SUCESS if the condition is true otherwise return RES_FAIL.

Condition(opts)

• opts.blackboard - blackboard instance for the behavior node.
• opts.cond(blackboard) - condition function, return true or false.

Other nodes

If

Implementation of loop semantics. If the condition is true, then fire the child node.

If(opts)

• opts.blackboard - blackboard instance for the behavior node.
• opts.action - child node.
• opts.cond(blackboard) - condition function, return true or false.

Usage

const bt = require('@olemop/behavior-tree')
const { Sequence, Node } = bt

// define some action nodes
class HelloNode extends Node {
  constructor (blackboard) {
    super(blackboard)
  }

  doAction () {
    console.log('Hello ')
    return bt.RES_SUCCESS
  }
}

class WorldNode extends Node {
  constructor (blackboard) {
    super(blackboard)
  }

  doAction () {
    console.log('World')
    return bt.RES_SUCCESS
  }
}

const blackboard = {}

// composite your behavior tree
const seq = new Sequence({ blackboard: blackboard })
const hello = new HelloNode(blackboard)
const world = new WorldNode(blackboard)

seq.addChild(hello)
seq.addChild(world)

// run the behavior tree
seq.doAction()