Component cloning

[ronniec95]

I'm new to ecs so perhaps a naive question

I'm loading some assets which become components for an entity. These are heavy data structures which take a while to load. I'm concerned that I have to clone them to make them part of an entity. Perhaps I'm doing something wrong

Example use case Run system A to load component type A. Create entities sing world.spawn_batch Run system B to load , component type B. Create entities using world.spawn_batch

Run system C, sometime later when user does something. Query for component A and B. Iterate over found entities and join components to create usable entity which has components A&B.

Problem: since query is by reference I have to clone component A & B which is expensive.

Is this the right design pattern? I don't really want clonable components.

[Ralith]

If you want components A and B to be on the same entity, why did you spawn separate entities for them to begin with?

[adamreichold]

(Figuring out why have to move the component values is the important but as an aside, you can always make expensive-to-clone types cheap-to-clone in Rust by wrapping them in Rc or Arc at the cost of another indirection and them becoming immutable.)

[ronniec95]

The extended example is more realistically

Create entity 1 with component A + state machine S1 (component) to manage the loading status Create entity 2 with component B + state machine S2 (component) to manage the loading status Create entity 3 with component C + state machine S3 (component) to manage the loading status

When the state of all of the entities are READY, I no longer care about the state machine component, or this entity. I then create my real entities which might be configured for example:-

Id, components

1. A B C
2. A C
3. A C
4. A B
5. A B

Edit: I think I've answered own question here by obviously needing clones of A, B and C. I also agree, RC/arc was an alternative.

I think I can use remove rather than despawn to delete the original entities

[ronniec95]

This is a design issue, not a issue with hecs