Moving the system to Friflo

[cNoNim]

How i can translate System to Friflo ECS?

        private class DamageSystem : IEcsRunSystem
        {
            private readonly EcsWorld _world;
            private readonly EcsFilter _attackFilter;
            private readonly EcsFilter _filter;
            private readonly EcsPool<Attack<int>> _attackPool;
            private readonly EcsPool<Health> _healthPool;
            private readonly EcsPool<Damage> _damagePool;

            public DamageSystem(EcsWorld world)
            {
                _world = world;
                _attackFilter = world.Filter<Attack<int>>().End();
                _filter = world.Filter<Health>().Inc<Damage>().Exc<Dead>().End();
                _attackPool = world.GetPool<Attack<int>>();
                _healthPool = world.GetPool<Health>();
                _damagePool = world.GetPool<Damage>();
            }

            public void Run(IEcsSystems _)
            {
                foreach (var entity in _attackFilter)
                {
                    ref var attack = ref _attackPool.Get(entity);
                    if (attack.Ticks-- > 0)
                        continue;

                    var target = attack.Target;
                    var attackDamage = attack.Damage;

                    _world.DelEntity(entity);

                    if (!_filter.HasEntity(target))
                        continue;

                    ref var health = ref _healthPool.Get(target);
                    var damage = _damagePool.Get(target);
                    var totalDamage = attackDamage - damage.Defence;
                    health.Hp -= totalDamage;
                }
            }
        }

[cNoNim]

I'm trying to do something like:

        private class DamageSystem : QuerySystem<Comp<Attack<Entity>>>
        {
            public DamageSystem() =>
                Filter.WithoutAnyTags(Tags.Get<Tag<Dead>>());

            protected override void OnUpdate() =>
                Query.ForEachEntity((ref Comp<Attack<Entity>> attack, Entity entity) =>
                {
                    if (attack.V.Ticks-- > 0)
                        return;

                    CommandBuffer.DeleteEntity(entity.Id);

                    var target = attack.V.Target;
                    if (Query.Store.HasTag<Dead>(target))
                        return;

                    ref var health = ref Query.Store.Get<Health>(target, out var result);
                    if (!result)
                        return;

                    if (!Query.Store.TryGet(target, out Damage damage))
                        return;

                    var totalDamage = attack.V.Damage - damage.Defence;
                    health.Hp -= totalDamage;
                });
        }

[friflo]

hi @cNoNim

in general it looks ok. But I cannot verify it.
Too many missing types and extension methods.
See my comments:

private class DamageSystem : QuerySystem<Comp<Attack<Entity>>>  // Comp<>? Attack<>?
{
    public DamageSystem() =>
        Filter.WithoutAnyTags(Tags.Get<Tag<Dead>>());           // Tag? Dead?

    protected override void OnUpdate() =>
        Query.ForEachEntity((ref Comp<Attack<Entity>> attack, Entity entity) =>
        {
            if (attack.V.Ticks-- > 0)                           // attack.V.Ticks?
                return;

            CommandBuffer.DeleteEntity(entity.Id);

            var target = attack.V.Target;                       // attack.V.Target?
            if (Query.Store.HasTag<Dead>(target))               // HasTag<>()?
                return;

            ref var health = ref Query.Store.Get<Health>(target, out var result); // Get<>()?
            if (!result)
                return;

            if (!Query.Store.TryGet(target, out Damage damage)) // TryGet()? Damage?
                return;

            var totalDamage = attack.V.Damage - damage.Defence; // Attack<>? Damage?
            health.Hp -= totalDamage;
        });
}

[cNoNim]

Well, that's the question, there are no extension methods.
That's exactly what I'm asking, how to write this code correctly, because I haven't found anything similar.

[cNoNim]

I have an entity with an Attack component and a link to target entity. How can I check if there is a tag on the target and get data from it?

[friflo]

Understand.
Your initial example used a simple foreach.
So you can use query.Entites.

So something like.

  protected override void OnUpdate()
  {
      foreach (var entity in Query.Entities)
      {
          ref var attack = ref entity.GetComponent<Attack>();
          if (attack.Ticks-- > 0)
              continue;

          Entity target       = attack.Target;
          var    attackDamage = attack.Damage;

          entity.DeleteEntity();

          if (!_filter.HasEntity(target)) // not sure what this is. May remove?
              continue;

          ref var health  = ref target.GetComponent<Health>();
          var damage      = target.GetComponent<Damage>();
          var totalDamage = attackDamage - damage.Defence;
          health.Hp      -= totalDamage;
      }
  }

[cNoNim]

Filter check what target is alive (don't have Dead tag)

[cNoNim]

And thanks

[friflo]

That's exactly what I'm asking, how to write this code correctly, because I haven't found anything similar.

I added the foreach (var entity in Query.Entities) {...} as an example to README > Systems

I guess, this question is answered for now?

[cNoNim]

Final solution

            protected override void OnUpdate()
            {
                foreach (var entity in Query.Entities)
                {
                    ref var attack = ref entity.GetComponent<Comp<Attack<Entity>>>().V;
                    if (attack.Ticks-- > 0)
                        continue;

                    entity.DeleteEntity();

                    var target = attack.Target;
                    if (!target.Tags.Has<Tag<Dead>>())
                        continue;

                    ref var health = ref target.GetComponent<Comp<Health>>().V;
                    ref readonly var damage = ref target.GetComponent<Comp<Damage>>().V;
                    var totalDamage = attack.Damage - damage.Defence;
                    health.Hp -= totalDamage;
                }
            }

[friflo]

Hi,

only fyi.
Two days ago I started creating an ECS benchmark project and published it today.
ECS.CSharp.Benchmark - Common use-cases.

When I added Leopotam.EcsLite I instantaneously remembered this discussion.
Before I had no clue, which ECS was used in your initial example code.

[cNoNim]

Hi.

The initial is also a benchmark.

Benchmark 2048x1024 (Android)

Rank	Name	Average (µs)	Hash
1	Ecs.Net	939.30	2EC3131C
1	Entities SystemAPI	948.00	2EC3131C
1	Entities	951.00	2EC3131C
2	Entities Enableable	1073.80	2EC3131C
3	EcsLite	1299.10	2EC3131C
4	Friflo	1443.60	2EC3131C
5	DragonEcs	1476.30	2EC3131C
6	Morpeh	1516.10	2EC3131C

I removed some of the private frameworks from the results.
And while the benchmark is also private.
But if you are interested, I can provide an archive with sources.

The benchmark tests the interaction of the following systems:

var store = new EntityStore();
_root = new SystemRoot(store)
{
new SystemGroup("Spawn")
{
	new SpawnSystem(),
	new RespawnSystem(),
	new KillSystem()
},
new RenderSystem(Framebuffer),
new StateSpriteSystem<Tag<Spawn>>(SpriteMask.Spawn),
new StateSpriteSystem<Tag<Dead>>(SpriteMask.Grave),
new UnitSpriteSystem<Tag<Unit.NPC>>(SpriteMask.NPC),
new UnitSpriteSystem<Tag<Unit.Hero>>(SpriteMask.Hero),
new UnitSpriteSystem<Tag<Unit.Monster>>(SpriteMask.Monster),
new DamageSystem(),
new AttackSystem(),
new MovementSystem(),
new UpdateVelocitySystem(),
new UpdateDataSystem()
};

[friflo]

hi,
I added a note column. Can you confirm my notes?

|Name               | note @friflo | Correct?
|-------------------|------------- | --------
|Ecs.Net            | Flecs.NET?   |
|Entities SystemAPI | Unity?       |
|Entities           | Unity?       |
|Entities Enableable| Unity?       |
|EcsLite            | Sparse Set   |
|Friflo             | Archetype    |
|DragonEcs          | Sparse Set   |
|Morpeh             | Sparse Set   |

[friflo]

And yes, I am interested in the benchmark sources.
My Discord id: 354346834426331139

[cNoNim]

Ecs.Net it's private WIP framework based on archetypes. Note: statistics may not be entirely accurate because of WIP.
I thought Morpeh was based on archetypes.
And Entities it's Unity different approaches.