Summing up Health data among multiple Entities

I have a use case where an Organism is compromised of 8 entities, and each entity has it's own Health { float Amount; } component. But I would like to keep track of the total health of all 8 entities and having trouble figuring out a good way to do that. Any thoughts on this?

Here is my data layout:

• Entity1 [ Health, TotalHealth ]
• Entity2-8 [Health, TotalHealthRef ]

 

If you mean a total that automatically recalculated whenever data in an entity changes I think it is difficult, since ECS is based on update turns and nothing updates immediately.

Since total health is not a part of organism it should belong to a system, like TotalHealthCalculationSystem. Have it sum up the health and store in itself (system's code public fields) or its singleton entity that keeps summation of various things, or in each organism like you do but that's a lot of writes. Then all user of total health must have [UpdateAfter(typeof(TotalHealthCalculationSystem))] and all changes to the health must be before.

 

Can you give some details on what is the specific complication beyond simple summation?
Is damage propagated from the head to the children or the other way around or both?

I have a possibly similar scenario in my game which has to track the total fuel from a bunch of fuel barrels. In my case, changes are propagated in both directions.

 

^ Thanks Joachim. Going to give that a try.

The damage is propagated from the children to the head. Though do you need to propagate in both directions? I would think you just need to propagate from one of the two directions to keep data in sync.