game-loop-dispatch

A low level game loop that emits events

npm install game-loop-dispatch
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Game Loop Dispatch

A low level game-loop for nodejs that provides the basic events. Game Loop Dispatch is small maybe 40 lines of code and just extends node's built-in EventEmitter. Being able to modify/extend the event hooks one can customize the loop for their game.

Install

Use npm

npm install game-loop-dispatch

Usage

The below code samples are included in the examples folder and can be run with the following

node examples/basic.js
node examples/advanced.js

Basic Usage

To start with just include and instantiate the game loop

var GameLoopDispatch = require('game-loop-dispatch');

var gameLoop = new GameLoopDispatch({
    // only require value is the interval in milliseconds
    'interval':1000
});

gameLoop.tick = function(){
    console.log('tick');
};

gameLoop.start();

You should see in a stdout every second

tick
tick
tick

Advanced Usage

Advanced usage showing how you can add an additional event hooks to extend the loop functionality. In this example we will add tickStart and tickEnd so that we can pause/start the gameloop while it is processing async calls. Otherwise the loop would continue to fire every 1 sec and things would get out of control.

var GameLoopDispatch = require('game-loop-dispatch');

var gameLoop = new GameLoopDispatch({
    // only require value is the interval in milliseconds
    'interval':1000
});

gameLoop.tick = function(){
    // hack to rescope this because of setTimeout 
    //var self = this; 

    // GameLoopDispatch extends eventEmitter so `emit` is
    // provided internally.  In this example a `tickStart`
    // event is emited at the start of every `tick` event
    this.emit('tickStart');

    // our standard tick marker
    console.log('tick');

    // imagine this was some async call to a processingQueue
    // for AI Entities or Player Movements that takes 4 seconds
    // to process
    setTimeout(function(){
        // now that everything was process broadcast
        // an event for tickEnd
        // note we use gameLoop because `this` is wrong context
        gameLoop.emit('tickEnd');
    }, 4000);

};

//
// Create Listeners for our new Event hooks
//
gameLoop.on('tickStart', function(){
    console.log('top of tick phase');
    // lets pause the loop while we process
    gameLoop.pause();

});

gameLoop.on('tickEnd', function(){
    console.log('end of tick phase');
    // now that tick is complete lets restart the loop
    gameLoop.start();
});

gameLoop.start();

Todo / Contributions

This is an initial release as I'm prototyping a game. Some additional low-level events are still needed such as some 'loader' event system for static content and or other async behavior. Open to suggestions and ideally would like to build this like lodash where one can generate the game-loop function hooks they need.

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