CorgECS 1.1.0

CorgECS

A lightweight, simple and concise E/C library for C#. This library is as simple as possible to reduce the difficulty with working with ECS-style frameworks for games.

Entities

Entities hold components. You can add a component to an entity by calling the AddComponent method.

World world = new World();
Entity testEntity = world.CreateEntity();
testEntity.AddComponent(new TestComponent());

Components

Components store data and provide functionality to entities when a signal is raised against the parent entity.

Components must implement the Initialise() method. This is called when the component is added to an entity, and allows for it to start listening to signals.

public class TestComponent : Component
{

	private int componentData = 0;

	public override void Initialise()
	{
		RegisterSignal<TestSignal>(HandleSignal);
	}

	private void HandleSignal(TestSignal raised)
	{
		// Do something with the signal
	}

}

When a TestSignal is raised against an entity that has the TestComponent added, HandleSignal inside of the TestComponent will be called.

Signals

Signals are ways of communicating changes within the world to entities. Typically signals represent events that may be listened to, but don't necessarilly need to be handled.

Signals can store data, which can be used to send messages to components.

There are 2 types of signals:

• Asynchronous Signals (Fire and forget)
• Response Signals (Yield a response)

Asynchronous Signals

Asynchronous signals represent an event occuring which may be listened to by a component. Creating a new signal is as simple as creating a class which is a subtype of the signal class.

public class ExampleSignal : Signal
{

	public int ExampleData { get; }

	public ExampleSignal(int value)
	{
		ExampleData = value;
	}

}

Signals can be raised against an entity by calling Entity.Raise().

World world = new World();
Entity exampleEntity = world.CreateEntity();
// Add a component to the entity which listens for the Example signal here.
exampleEntity.Raise(new ExampleSignal(5));

Response Signals

Response signals are signals which can return a response. Any signal handlers that listen to a reponse signal can return no value.

Here is an example of a response signal which returns an integer value.

public class ResponseSignal : Signal<int>
{ /* Insert signal data here */ }

public class TestComponent : Component
{

	public override void Initialise()
	{
		RegisterSignal<ResponseSignal, int>(HandleSignal);
	}

	private SignalResponse<int> HandleSignal(TestSignal raised)
	{
		// Do something with the signal
		// Return a value
		return new SignalResponse<int>(10);
	}

}

World world = new World();
Entity testEntity = world.CreateEntity();
testEntity.AddComponent(new TestComponent());
SignalResult<int> result = testEntity.Raise<ResponseSignal, int>(new ResponseSignal());

Unfortunately, when registering signals for response types you must specify the return value as a generic constraint. This is due to generics being unable to determine the type of the return value despite it being defined in the signal class itself. It would be possible to modify the code so that it only requires the return type, however this could get confusing. If you have any idea of a workaround of this, please open a PR or contact me on discord.

Entity Systems

Entity systems allow for tracking components and sharing states between different components easilly.

You can fetch a singleton EntitySystem by calling World.GetEntitySystem().

World world = new World();
world.GetEntitySystem<ExampleSystem>();

Components can join an entity system by calling EntitySystem.JoinSystem(). This will cause the entity system to begin tracking the entity, so that it can be queried later.

/// We are required to specify the type of components that we want to track.
/// This could just be Component if we want to track any component type.
public class TestSystem : EntitySystem<TestComponent>
{ }

class TestComponent : Component
{

	public override void Initialise()
	{
		World.GetEntitySystem<TestSystem>()
			.JoinSystem(this);
	}

}

We can now get the entity system from anywhere in the code and execute queries across all components that are being tracked.