https://github.com/technius/ecs-experiments

Experiments in writing entity-component-systems in Scala
https://github.com/technius/ecs-experiments

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Experiments in writing entity-component-systems in Scala

• Host: GitHub
• URL: https://github.com/technius/ecs-experiments
• Owner: Technius
• License: gpl-3.0
• Created: 2016-03-07T03:35:57.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2016-03-13T06:54:57.000Z (over 10 years ago)
• Last Synced: 2025-01-31T12:24:59.890Z (over 1 year ago)
• Language: Scala
• Size: 28.3 KB
• Stars: 2
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Entity-Component-System Experiments (in Scala)

This repository contains some plans for writing a game/simulation engine in

Scala based on entity-component-systems.

## Experiment List

In each experiment, an **entity** is defined as a collection of

`Component`s associated with an `Id`.

A **world** is a set of global rules.

### 1. Event Based

Inspired by Michael Shaw's

[Game Development in Scala talk](https://michaelshaw.github.io/game_talk/game.html#/).

The design of this ECS is based on the following ideas:

* The simulation is deterministic

* Everything is immutable

* Changes to entities are stored as immutable objects called `Event`s

  * Events are devided into `EntityEvent` and `WorldEvent`

    * An `EntityEvent` is applied to a specific entity entity

    * A `WorldEvent` is applied to the list of entities

  * An `EventHandler` applies the changes stored in events to the entities

* Systems are essentially `Seq[Entity] => (Seq[EntityEvent], Seq[WorldEvent])`

* During simulation, each system operates on the pre-simulation entity list to

  give events as output

* After the systems are run, the events are processed and the new entity list is

  returned

Principles:

* Events should have very little power

* Systems should be simple and composable

* Associative events are preferred

Benefits:

* Events that can be applied associately can be combined, making transfer of

  events take less bandwidth

* All systems can be run in parallel

* Separation of events into `EntityEvent` and `WorldEvent` limit side-effects

* Can easily undo and redo events

Disadvantages:

* Systems cannot depend on other systems easily

* Produces a lot of data to be garbage-collected

## License

The explanations and documentation are licensed under the

[CC BY 4.0](https://creativecommons.org/licenses/by/4.0/legalcode) license.

The code is licensed under the GPLv3 license. See LICENSE for more details.