PBC-ECS
Entity Component-System heavily based on TinyEcs, with one big difference - predefined systems to improve performance. All heavily-used systems can be added before-hand, with a callback function to be called for entities in the system, greatly reducing the number of list manipulations as opposed to just using queryComponent.
TinyECS
A mean lean Entity-Component-System library.
TinyECS is not a ready-to-go game engine framework, it is a small library of some very performance critical pieces and common utility classes that can be used to make a game from scratch.
See also:
- tiny-ecs-physics
- tiny-ecs-canvas-2d
Installation
Works on the server or the browser (via Browserify):
npm install tiny-ecs
Usage
Manage your entities via an EntityManager
instance:
var EntityManager = require('tiny-ecs').EntityManager;
var entities = new EntityManager();
Creating Entities
Create an entity with the default Transform
component:
var hero = entities.create();
Or if you don't want to include the Transform
component:
var hero = entities.createEntity();
Adding Components
A component is just a basic Javascript class.
function PlayerControlled()
{
this.gamepad = 1;
}
function Sprite()
{
this.image = 'hero.png';
}
Add the components:
hero.addComponent(Damager).addComponent(Sprite);
We now have new data members on our entity for the components. TinyECS will add an instance member that is the name of the component constructor, lowercased:
hero.playerControlled.gamepad = 2;
hero.sprite.image === 'hero.png'; // true
Add arbitrary text tags to an entity:
hero.addTag('player');
You can also remove components and tags in much the same way:
hero.removeComponent(Sprite);
hero.removeTag('player');
To determine if an entity has a specific component:
if (hero.hasComponent(Transform)) { ... }
And to check if an entity has ALL of a set of components:
if (hero.hasAllComponents([Transform, Sprite])) { ... }
Querying Entities
The entity manager is setup with indexed queries, allowing extremely fast querying of the current entities. Querying entities returns an array of entities.
Get all entities that have a specific set of components:
var toDraw = entities.queryComponents([Transform, Sprite]);
Get all entities with a certain tag:
var enemies = entities.queryTag('enemy');
Removing Entities
hero.remove();
Creating Components
Any object constructor can be used as a component, nothing special required. Components should be lean, primarily data containers, leaving all the heavy lifting for the systems.
Creating Systems
In TinyECS, there is no formal notion of a system. A system is considered any context in which entities and their components are updated. As to how this occurs will vary depending on your use.
In the example of a game, mainting a list of systems that are instantiated with some sort of IoC container that request a list of entities seems like a good idea.
function PhysicsSystem(entities)
{
// Dependency inject -- reference to our EntityManager
this.entities = entities;
}
PhysicsSystem.prototype.update = function(dt, time)
{
var toUpdate = this.entities.queryComponents([Transform, RigidBody]);
toUpdate.forEach(function(entity) { ... });
...
}
Tern Support
The source files are all decorated with JSDoc3-style
annotations that work great with the Tern code inference
system. Combined with the Node plugin (see this project's .tern-project
file), you can have intelligent autocomplete for methods in this library.
Testing
Testing is done with Tape and can be run
with the command npm test
.
Automated CI cross-browser testing is provided by Testling.
License
Copyright 2014 Brandon Valosek
TinyECS is released under the MIT license.