bevy/crates/bevy_app
robtfm 3dc6a07d27
generic component propagation (#17575)
# Objective

add functionality to allow propagating components to children. requested
originally for `RenderLayers` but can be useful more generally.

## Solution

- add `HierarchyPropagatePlugin<C, F=()>` which schedules systems to
propagate components through entities matching `F`
- add `Propagate<C: Component + Clone + PartialEq>` which will cause `C`
to be added to all children
more niche features:
- add `PropagateStop<C>` which stops the propagation at this entity
- add `PropagateOver<C>` which allows the propagation to continue to
children, but doesn't add/remove/modify a `C` on this entity itself

## Testing

see tests inline

## Notes

- could happily be an out-of-repo plugin
- not sure where it lives: ideally it would be in `bevy_ecs` but it
requires a `Plugin` so I put it in `bevy_app`, doesn't really belong
there though.
- i'm not totally up-to-date on triggers and observers so possibly this
could be done more cleanly, would be very happy to take review comments
- perf: this is pretty cheap except for `update_reparented` which has to
check the parent of every moved entity. since the entirety is opt-in i
think it's acceptable but i could possibly use `(Changed<Children>,
With<Inherited<C>>)` instead if it's a concern
2025-06-06 00:02:02 +00:00
..
src generic component propagation (#17575) 2025-06-06 00:02:02 +00:00
Cargo.toml bevyengine.org -> bevy.org (#19503) 2025-06-05 23:09:28 +00:00
LICENSE-APACHE Cleanup publish process (#17728) 2025-02-09 17:46:19 +00:00
LICENSE-MIT Cleanup publish process (#17728) 2025-02-09 17:46:19 +00:00
README.md add and fix shields in Readmes (#9993) 2023-10-15 00:52:31 +00:00

Bevy App

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This crate is about everything concerning the highest-level, application layer of a Bevy app.