ECS Wrapper

The AchEngine ECS module is a thin convenience layer over Unity Entities World, EntityManager, EntityCommandBuffer, Baker, and SystemBase.

When com.unity.entities is installed, the AchEngine.ECS assembly is enabled automatically.

using AchEngine.ECS;
using Unity.Entities;

When To Use It

Type	Purpose
AchSystemBase	Short helpers for CommandBuffer and Query usage in SystemBase
AchBaker<TAuthoring>	Add components or buffers to the primary entity with less boilerplate
IEcsWorld	Use ECS World and EntityManager from DI-backed services
EntityManagerExtensions	Remove repeated code with helpers such as TryGetComponent, SetOrAddComponent, and GetOrAddBuffer

Systems

Derive from AchSystemBase instead of SystemBase.

public struct Health : IComponentData
{
    public int Value;
}

public sealed partial class DamageSystem : AchSystemBase
{
    protected override void OnUpdate()
    {
        using var ecb = CreateCommandBuffer();

        foreach (var (health, entity) in
                 SystemAPI.Query<RefRW<Health>>().WithEntityAccess())
        {
            health.ValueRW.Value -= 1;

            if (health.ValueRO.Value <= 0)
            {
                ecb.Destroy(entity);
            }
        }

        ecb.Playback(EntityManager);
    }
}

EntityManager Extensions

The module adds convenience methods to the existing EntityManager.

EntityManager.SetOrAddComponent(entity, new Health { Value = 100 });

if (EntityManager.TryGetComponent<Health>(entity, out var health))
{
    UnityEngine.Debug.Log(health.Value);
}

EntityManager.RemoveComponentIfExists<Health>(entity);

Bakers

Derive from AchBaker<T> instead of Baker<T> to shorten primary entity authoring code.

using AchEngine.ECS;
using Unity.Entities;
using UnityEngine;

public class CharacterAuthoring : MonoBehaviour
{
    public int Health = 100;
}

public class CharacterBaker : AchBaker<CharacterAuthoring>
{
    public override void Bake(CharacterAuthoring authoring)
    {
        AddComponentToPrimary(new Health { Value = authoring.Health });
    }
}

DI

Add AchEngineEcsInstaller to the AchEngineScope Installers list to inject IEcsWorld into services.

using AchEngine.ECS;
using Unity.Entities;

public class SpawnService
{
    private readonly IEcsWorld _ecs;

    public SpawnService(IEcsWorld ecs)
    {
        _ecs = ecs;
    }

    public Entity Spawn(Entity prefab)
    {
        return _ecs.Instantiate(prefab);
    }
}

If World Name is empty, AchEngineEcsInstaller uses World.DefaultGameObjectInjectionWorld. If a name is provided, it registers the World with that exact name.