Best way to detect if a component has been added or removed?

Context:

I try to implement our weapon system of a networked shooter with ecs. Right now I have a weapon entity, and use several components to define its state, when it receives input:

state components eg:
Burst
Reload
Swap

This works great so far. What I struggle with is the syncing over the network. I get the input only on the server and I'd like to send a message with the component data as soon as one of the components gets added or removed.

Question:

Is there another way than creating AddedBurst / RemovedBurst components for all three state components respectively and adding / removing them by the systems that originally added / removed the state components?
This seems like way too much adding/removing components, distributes the responsibility for syncing to multiple systems and is a lot of code to write.

 

You can use generics: Added<T>, Changed<T>, Removed<T>.

For example:

Code (CSharp):

1. public struct Added<T> : IComponentData where T : struct, IComponentData {
2.     public T value;
3. }

Code (CSharp):

1. entityManager.AddComponentData(entity, new Added<T> { value = new T() });
2. endFrameBuffer.RemoveComponent<Added<T>>(entity);

"endFrameBuffer" is EndFrameBarrier's CommandBuffer. This way, "Added<T>" will get automatically removed at the end frame.

If you want to centralize all the syncing into one system, you can use a dedicated ComponentData to track old values of other CDs. Sample code:

Code (CSharp):

1. public class SyncSystem : ComponentSystem {
2.  
3.     ...
4.  
5.     protected override void OnUpdate() {
6.         ...
7.         oldValuesCompData.HealthValue = Process<Health>(entity, id, oldValuesCompData.HealthValue);
8.         oldValuesCompData.ManaValue = Process<Mana>(entity, id, oldValuesCompData.ManaValue);
9.         ...
10.     }
11.  
12.     protected T Process<T>(Entity entity, ushort id, T oldValue)
13.         where T : struct, IComponentData, INetworkCompData<T> {
14.         if (EntityManager.HasComponent<T>(entity)) {
15.             var comp = EntityManager.GetComponentData<T>(entity);
16.             var changed = !comp.Same(oldValue);
17.             if (changed)
18.                 SendToAllPlayers<T>(new DataPacket<T> { id = id, on = true, value = comp });
19.             return comp;
20.         } else {
21.             SendToAllPlayers<T>(new DataPacket<T> { id = id, on = false, value = oldValue });
22.         }
23.         return oldValue;
24.     }
25.  
26.     protected void SendToAllPlayers<T>(DataPacket<T> packet) {
27.         ...
28.     }
29.  
30. }
31.  
32. [System.Serializable]
33. public struct Health : IComponentData, INetworkCompData<Health> {
34.     public int value;
35.     public int max;
36.  
37.     public bool Same(Health other) {
38.         return this.value == other.value && this.max == other.max;
39.     }
40.  
41.     public void Serialize(NetDataWriter writer) {
42.         writer.Put((ushort)value);
43.         writer.Put((ushort)max);
44.     }
45.  
46.     public void Deserialize(NetDataReader reader) {
47.         value = reader.GetUShort();
48.         max = reader.GetUShort();
49.     }
50. }