Typescript asynchronous A-Star pathfinding

Pathfinding algorithm with Synchronous/Asynchronous modes. Can be switched between A-Star and breadth-first search.

Install

npm install aastar --save

How to use

Import classes and interfaces to your project:

import { IAAStarField, IAAStarFieldNode, AAStar, AAStarSimpleField, SimpleNode } from "aastar";

Create new AAStar instance and pass your game field instance as a parameter (you can use one of standard game fields located in fields folder):

let aastar:AAStar = new AAStar(gameField, defaultOptions);

If necessary, you can pass options to constructor. The options cintains properties:

• iterationsPerFrame - how many calculation steps will be maked during the frame (recommended values: 10 - 100). Default: 10
• cacheResults - if true, results will be saved for future use
• useWideSearch - if true, heuristic will be disabled, result will contain the shortest path, but calculation time will be increased

Call aastar.calculatePath(startNode, endNode); or aastar.calculatePathAsynch(startNode, endNode); to calculate path in synchronous or asynchronous mode accordingly. In asynchronous mode you will get the Promise as a result.

Create custom game field type

If you want to use your own type of game field, you need to implement 2 Interfaces:

• IAAStarField - this is your custom game field, it should be able to:

  • getNearNodes(node:IAAStarFieldNode):Array<IAAStarFieldNode> - returns Array of nodes, that located near the given one
  • heuristicDistance(a:IAAStarFieldNode, b:IAAStarFieldNode):number - returns heuristic distance between any two nodes (can returrn constant, if you don't want to use heuristic in your algorithm, in this case it's recommended to you to enable { useWideSearch: true } option)

• IAAStarFieldNode - this is a game cell, that gamefield contains of. Every two cells with the same coordinates MUST BE the same object, otherwise getNearNodes method will be working incorrect.

  • getMoveCost() - Game cell should be able to return it's own move cost (if cell is not walkable, must return -1)

Examples

Synchronous method usage with a Simple Game field

import { IAAStarField, IAAStarFieldNode, AAStar, AAStarSimpleField, SimpleNode } from "aastar";

let simpleField:AAStarSimpleField = new AAStarSimpleField([
            [1, -1, -1, 1],
            [1, -1,  0, 1],
            [1,  2, -1, 1],
            [1,  1,  1, 1],
        ], false)

let startPoint:SimpleNode = simpleField.getNodeAt(0,0);
let endPoint:SimpleNode = simpleField.getNodeAt(3,0);

let astar:AAStar = new AAStar(simpleField);

astar.calculatePath(startPoint, endPoint)
    .forEach ((v:SimpleNode, i:number) => {
        console.log(i + "=" + v.x + "," + v.y);
    });

Asynchronous method usage (with options)

let options:IAlgorhitmOptions = {cacheResults:true, iterationsPerFrame:10, useWideSearch:true};

aStar.calculatePathAsync(startPoint, endPoint, options)
        .then((r) => {
            r.forEach((v:SimpleNode, i:number) => {
                console.log(i + "=" + v.x + "," + v.y);
            });
        })