@thi.ng/ecs
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Entity Component System based around typed arrays & sparse sets
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# 
[](https://www.npmjs.com/package/@thi.ng/ecs)
[](https://mastodon.thi.ng/@toxi)
> [!NOTE]
> This is one of 210 standalone projects, maintained as part
> of the [.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo
> and anti-framework.
>
> 🚀 Please help me to work full-time on these projects by [sponsoring me on
> GitHub](https://github.com/sponsors/postspectacular). Thank you! ❤️
- [About](#about)
- [Status](#status)
- [Installation](#installation)
- [Dependencies](#dependencies)
- [Usage examples](#usage-examples)
- [API](#api)
- [Basic usage](#basic-usage)
- [Authors](#authors)
- [License](#license)
## About
Entity Component System based around typed arrays & sparse sets.
- Entities are merely numeric identifiers
- Component types:
- Numeric / vectors are stored as typed array views with customizable striding
- arbitrary JS values are stored in vanilla JS arrays
- Component grouping w/ optional group ownership to allow re-ordering
components for optimized iteration
- Systems are plain functions
- Configurable caching of component views: LRU, Unbounded, Null (no-cache)
## Status
**ALPHA** - bleeding edge / work-in-progress
[Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Becs%5D+in%3Atitle)
## Installation
```bash
yarn add .ng/ecs
```
ESM import:
```ts
import * as ecs from "@thi.ng/ecs";
```
Browser ESM import:
```html
<script type="module" src="https://esm.run/@thi.ng/ecs"></script>
```
[JSDelivr documentation](https://www.jsdelivr.com/)
For Node.js REPL:
```js
const ecs = await import("@thi.ng/ecs");
```
Package sizes (brotli'd, pre-treeshake): ESM: 3.17 KB
## Dependencies
- [.ng/api](https://github.com/thi-ng/umbrella/tree/develop/packages/api)
- [.ng/associative](https://github.com/thi-ng/umbrella/tree/develop/packages/associative)
- [.ng/binary](https://github.com/thi-ng/umbrella/tree/develop/packages/binary)
- [.ng/checks](https://github.com/thi-ng/umbrella/tree/develop/packages/checks)
- [.ng/dcons](https://github.com/thi-ng/umbrella/tree/develop/packages/dcons)
- [.ng/errors](https://github.com/thi-ng/umbrella/tree/develop/packages/errors)
- [.ng/idgen](https://github.com/thi-ng/umbrella/tree/develop/packages/idgen)
- [.ng/logger](https://github.com/thi-ng/umbrella/tree/develop/packages/logger)
- [.ng/malloc](https://github.com/thi-ng/umbrella/tree/develop/packages/malloc)
- [.ng/transducers](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers)
Note: .ng/api is in _most_ cases a type-only import (not used at runtime)
## Usage examples
One project in this repo's
[/examples](https://github.com/thi-ng/umbrella/tree/develop/examples)
directory is using this package:
| Screenshot | Description | Live demo | Source |
|:--------------------------------------------------------------------------------------------------------------------|:---------------------------------------------|:----------------------------------------------|:---------------------------------------------------------------------------|
| <img src="https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/examples/soa-ecs-100k.png" width="240"/> | Entity Component System w/ 100k 3D particles | [Demo](https://demo.thi.ng/umbrella/soa-ecs/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/soa-ecs) |
## API
[Generated API docs](https://docs.thi.ng/umbrella/ecs/)
### Basic usage
```ts tangle:export/readme-1.ts
import { ECS } from "@thi.ng/ecs";
interface CompSpecs {
pos: Float32Array;
vel: Float32Array;
color: string;
}
// init ECS w/ given max number of entities
const ecs = new ECS<CompSpecs>({ capacity: 1000 });
// define components (and their memory layout)
const pos = ecs.defComponent({
id: "pos",
type: "f32",
size: 2,
})!;
const vel = ecs.defComponent({
id: "vel",
type: "f32",
size: 2,
stride: 4,
default: () => [Math.random() * 2 - 1, Math.random() * 2 - 1],
})!;
// this component stores string values (not mem-mapped)
const color = ecs.defComponent({
id: "color",
default: () => ["red", "green", "blue"][(Math.random() * 3) | 0],
})!;
// define group of given components
// the group will obtain ownership of all by default, meaning
// it is allowed to re-order entities to optimize iteration performance
const group = ecs.defGroup([pos, vel, color]);
// add entities and associate them w/ different components
// if a component is part of a group, the group will be notified/updated
// entities are just numeric IDs assigned using the ECS's internal ID generator
console.log(ecs.defEntity(["pos", "vel", "color"]));
// 0
console.log(ecs.defEntity([pos, vel]));
// 1
console.log(
ecs.defEntity({
pos: new Float32Array([1, 2]),
vel: new Float32Array([-1, 0]),
color: "orange",
})
);
// 2
// apply given function to each entity in the group
// note: entity (id=1) is NOT part of the group,
// since it doesn't have a `color` component...
group.forEach((x) => console.log(x));
// Note: The `color` and `vel`ocity of this first item are randomly assigned
// (see component default methods above)
// {
// id: 0,
// color: 'green',
// vel: Float32Array [ 0.16836269199848175, -0.36699679493904114 ],
// pos: Float32Array [ 0, 0 ]
// }
// {
// id: 2,
// color: "orange",
// vel: Float32Array(2) [ -1, 0 ],
// pos: Float32Array(2) [ 1, 2 ],
// }
```
## Authors
- [Karsten Schmidt](https://thi.ng)
If this project contributes to an academic publication, please cite it as:
```bibtex
{thing-ecs,
title = "@thi.ng/ecs",
author = "Karsten Schmidt",
note = "https://thi.ng/ecs",
year = 2019
}
```
## License
© 2019 - 2025 Karsten Schmidt // Apache License 2.0