Not an ECS

NECS is not an ECS.

It take some principles from the ECS pattern but break some of its rules.

In short:

• Entity, Components and Systems.
• Components are not pure data, they can have 'code' and can replace systems in some cases.
• There is an entity tree: each entity can have child entities. That means there is one 'super entity' which own all entities from your world.
• On calling update() to an entity, all its childs and component will have earlyUpdate() and lateUpdate() called.

It is like the GameObject (entity) and MonoBehaviour (components) from Unity.

Core design principles:

• Small and easy to read/edit.
• It does only one small thing.
• As it is not super-evolved, it may not fit your needs. It will not be efficient for big datasets.
• Battle tested and production tested.
• Fail-fast. Every function call is type and error checked and throw errors: no silent error that will blow somewhere sometime.
• We use lodash but do require only the functions we need and we do not use chains. It drastically lower the memory footprint.
• Sub-classing components is supported. One limitation: you must not insert many components sharing a common super class (excepted for AComponent). This limitation is not strictly checked in code due to limitations from Javascript. Making components as mixins may fix the limitation on a later update.

Use cases

It fits cases when you need efficient entity hierarchy for small data set, fast prototyping and easy to maintain production code.

Examples

What you could easily implement:

const world = Entity.createWorld();
world.add(SystemComponent); // This entity is now able to run systems
world.systems.add(DrawSystem); // DrawSystem draw each sprites on-screen

const wall = world.createChild('wall'); // Create an entity in your world. It represent nothing yet
wall.add(SpriteComponent, 'wall.png'); // Your entity will now be drawed on-screen using 'wall.png'
wall.sprite.position.x = 10;
wall.sprite.position.y = 10;

const player = world.createChild('player');
player.add(SpriteComponent, 'player.png');

world.update(); // wall and player are now drawn on screen

wall.sprite.visible = false;

world.update(); // only player is now drawn on screen

• Super simple example
• Game of life reimplemented

Documentation

Everything is documented in the code. It is small enough so you can read the documentation there.

You can also access documentation generated from code in doc/doc.md.

Tests

npm run test

Tests are available in the test folder. They are easy to read but boring, take a look if you want to understand better how it works.

License

This work is dual-licensed under Apache 2.0 and GPL 2.0 (or any later version). You can choose between one of them if you use this work.

SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later