# ECSx
[](https://hex.pm/packages/ecsx)
[](https://github.com/APB9785/ECSx/blob/master/LICENSE)
[](https://hexdocs.pm/ecsx)
ECSx is an Entity-Component-System (ECS) framework for Elixir. ECS is an architecture for building real-time games and simulations, wherein data about Entities is stored in small fragments called Components, which are then read and updated by Systems.
## Setup
- Add `:ecsx` to the list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:ecsx, "~> 0.5"}
]
end
```
- Run `mix deps.get`
- Run `mix ecsx.setup`
## Upgrading
While ECSx is pre-v1.0, minor version updates will contain breaking changes. If you are upgrading an application from ECSx 0.4.x or earlier, please refer to our [upgrade guide](upgrade_guide.html).
## Tutorial Project
[Building a ship combat engine with ECSx in a Phoenix app](https://hexdocs.pm/ecsx/initial_setup.html)
Note: This tutorial project is a work-in-progress
## Usage
### Entities and Components
Everything in your application is an Entity, but in ECS you won't work with these Entities directly - instead you will work with the individual attributes that an Entity might have. These attributes are given to an Entity by creating a Component, which holds, at minimum, the Entity's unique ID, but also can store a value. For example:
- You're running a 2-dimensional simulation of cars on a highway
- Each car gets its own `entity_id` e.g. `123`
- If the car with ID `123` is blue, we give it a `Color` Component with value `"blue"`
- If the same car is moving west at 60mph, we might model this with a `Direction` Component with value `"west"` and a `Speed` Component with value `60`
- The car would also have Components such as `XCoordinate` and `YCoordinate` to locate it on the map
### Systems
Once your Entities are modeled using Components, you'll create Systems to operate on them. For example:
- Entities with `Speed` Components should have their locations regularly updated according to the speed and direction
- We can create a `Move` System which reads the `Speed` and `Direction` Components, calculates how far the car has moved since the last server tick, and updates the Entity's `XCoordinate` and/or `YCoordinate` Component accordingly.
- The System will run every tick, only considering Entities which have a `Speed` Component
### Generators
ECSx comes with generators to quickly create new Components or Systems:
- `mix ecsx.gen.component`
- `mix ecsx.gen.system`
### Manager
Every ECSx application requires a Manager module, where valid Component types and Systems are declared, as well as the setup to spawn world objects before any players join. This module is created for you during `mix ecsx.setup` and will be automatically updated by the other generators.
It is especially important to consider the order of your Systems list. The manager will run each System one at a time, in order.
### Persistence
Components are not persisted by default. To persist an entity, use the `persist: true` option when adding the component. The default adapter for persistence is the [ECSx.Persistence.FileAdapter](lib/ecsx/persistence/file_adapter.ex), which stores the components in a binary file. The adapter can be changed using the `persistence_adapter` application variable:
```elixir
config :ecsx,
...
persistence_adapter: ...
```
Currently available Persistence Adapters (see links for installation/configuration instructions):
- [ECSx.Persistence.Ecto](https://github.com/ecsx-framework/ecsx_persistence_ecto)
## License
Copyright (C) 2022 Andrew P Berrien
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the [GNU General Public License](https://www.gnu.org/licenses/gpl.html) for more details.
