Entity Component System in GO

Description

What is Entity Component System?

Entity-component system (ECS) is an architectural pattern that follows Composition over inheritance principle

Why ECS?

ECS allows greater flexibility in defining entities where every object in a game's scene is an entity (e.g. enemies, bullets, vehicles, etc.). Every Entity consists of one or more components which add additional behavior or functionality. Therefore, the behavior of an entity can be changed at runtime by adding or removing components. This eliminates the ambiguity problems of deep and wide inheritance hierarchies that are difficult to understand, maintain and extend.

Main concepts

Entity

The entity is a general purpose object. Usually, it only consists of a unique id. They "tag every coarse gameobject as a separate item". Implementations typically use a plain integer for this.

Component

The raw data for one aspect of the object, and how it interacts with the world. "Labels the Entity as possessing this particular aspect". Implementations typically use Structs, Classes, or Associative Arrays.

System

"Each System runs continuously (as though each System had its own private thread) and performs global actions on every Entity that possesses a Component of the same aspect as that System."

Project details

This project includes proof of concept ECS example project. The project sets up Go Dev environment using vagrant.

ECS Example folder details

EntityComponentSystem   
    | -- ecs
            | -- component.go
            | -- entitymanager.go   
   
    | -- run
            | -- main.go
   
    | -- subsystems
                | -- cleanup.go
                | -- fallback.go
                | -- movement.go
                | -- render.go
                | -- system.go
   
    | -- wireup
            | -- Initialize.go

ecs

Contains core of ECS. component.go has components info and entitymanager.go manages "entities" and "components". Basically entitymanager.go acts as the Datastore and management of ECS.

run

run main.go to start the project

subsystems

subsystems implement System interface from system.go. subsystems run on seperate go routines.

wireup

Creates new entities, adds components and starts the susbsystems.

Installation requirements

• Install VirtualBox and Vagrant
• Clone this repo

Commands

Start:

$ vagrant up

This does the following:

• Installs Git
• Downloads Go version 1.8.3 and installs it

SSH into the server

$ vagrant ssh

Check Go version- This should display the version of go installed.

$ go version

cd into project run directory

$ cd ECS-GO/src/EntityComponentSystem/run/

run the project

$ go run main.go

Reference:

Wiki Article

Understanding ECS

Implementing ECS

Nice post on implementing ECS in games