# Objective
- Alternative to and builds on top of #16284.
- Fixes#15849.
## Solution
- Rename component `StateScoped` to `DespawnOnExitState`.
- Rename system `clear_state_scoped_entities` to
`despawn_entities_on_exit_state`.
- Add `DespawnOnEnterState` and `despawn_entities_on_enter_state` which
is the `OnEnter` equivalent.
> [!NOTE]
> Compared to #16284, the main change is that I did the rename in such a
way as to keep the terms `OnExit` and `OnEnter` together. In my own
game, I was adding `VisibleOnEnterState` and `HiddenOnExitState` and
when naming those, I kept the `OnExit` and `OnEnter` together. When I
checked #16284 it stood out to me that the naming was a bit awkward.
Putting the `State` in the middle and breaking up `OnEnter` and `OnExit`
also breaks searching for those terms.
## Open questions
1. Should we split `enable_state_scoped_entities` into two functions,
one for the `OnEnter` and one for the `OnExit`? I personally have zero
need thus far for the `OnEnter` version, so I'd be interested in not
having this enabled unless I ask for it.
2. If yes to 1., should we follow my lead in my `Visibility` state
components (see below) and name these
`app.enable_despawn_entities_on_enter_state()` and
`app.enable_despawn_entities_on_exit_state()`, which IMO says what it
does on the tin?
## Testing
Ran all changed examples.
## Side note: `VisibleOnEnterState` and `HiddenOnExitState`
For reference to anyone else and to help with the open questions, I'm
including the code I wrote for controlling entity visibility when a
state is entered/exited.
<details>
<summary>visibility.rs</summary>
```rust
use bevy_app::prelude::*;
use bevy_ecs::prelude::*;
use bevy_reflect::prelude::*;
use bevy_render::prelude::*;
use bevy_state::{prelude::*, state::StateTransitionSteps};
use tracing::*;
pub trait AppExtStates {
fn enable_visible_entities_on_enter_state<S: States>(&mut self) -> &mut Self;
fn enable_hidden_entities_on_exit_state<S: States>(&mut self) -> &mut Self;
}
impl AppExtStates for App {
fn enable_visible_entities_on_enter_state<S: States>(&mut self) -> &mut Self {
self.main_mut()
.enable_visible_entities_on_enter_state::<S>();
self
}
fn enable_hidden_entities_on_exit_state<S: States>(&mut self) -> &mut Self {
self.main_mut().enable_hidden_entities_on_exit_state::<S>();
self
}
}
impl AppExtStates for SubApp {
fn enable_visible_entities_on_enter_state<S: States>(&mut self) -> &mut Self {
if !self
.world()
.contains_resource::<Events<StateTransitionEvent<S>>>()
{
let name = core::any::type_name::<S>();
warn!("Visible entities on enter state are enabled for state `{}`, but the state isn't installed in the app!", name);
}
// We work with [`StateTransition`] in set
// [`StateTransitionSteps::ExitSchedules`] as opposed to [`OnExit`],
// because [`OnExit`] only runs for one specific variant of the state.
self.add_systems(
StateTransition,
update_to_visible_on_enter_state::<S>.in_set(StateTransitionSteps::ExitSchedules),
)
}
fn enable_hidden_entities_on_exit_state<S: States>(&mut self) -> &mut Self {
if !self
.world()
.contains_resource::<Events<StateTransitionEvent<S>>>()
{
let name = core::any::type_name::<S>();
warn!("Hidden entities on exit state are enabled for state `{}`, but the state isn't installed in the app!", name);
}
// We work with [`StateTransition`] in set
// [`StateTransitionSteps::ExitSchedules`] as opposed to [`OnExit`],
// because [`OnExit`] only runs for one specific variant of the state.
self.add_systems(
StateTransition,
update_to_hidden_on_exit_state::<S>.in_set(StateTransitionSteps::ExitSchedules),
)
}
}
#[derive(Clone, Component, Debug, Reflect)]
#[reflect(Component, Debug)]
pub struct VisibleOnEnterState<S: States>(pub S);
#[derive(Clone, Component, Debug, Reflect)]
#[reflect(Component, Debug)]
pub struct HiddenOnExitState<S: States>(pub S);
/// Makes entities marked with [`VisibleOnEnterState<S>`] visible when the state
/// `S` is entered.
pub fn update_to_visible_on_enter_state<S: States>(
mut transitions: EventReader<StateTransitionEvent<S>>,
mut query: Query<(&VisibleOnEnterState<S>, &mut Visibility)>,
) {
// We use the latest event, because state machine internals generate at most
// 1 transition event (per type) each frame. No event means no change
// happened and we skip iterating all entities.
let Some(transition) = transitions.read().last() else {
return;
};
if transition.entered == transition.exited {
return;
}
let Some(entered) = &transition.entered else {
return;
};
for (binding, mut visibility) in query.iter_mut() {
if binding.0 == *entered {
visibility.set_if_neq(Visibility::Visible);
}
}
}
/// Makes entities marked with [`HiddenOnExitState<S>`] invisible when the state
/// `S` is exited.
pub fn update_to_hidden_on_exit_state<S: States>(
mut transitions: EventReader<StateTransitionEvent<S>>,
mut query: Query<(&HiddenOnExitState<S>, &mut Visibility)>,
) {
// We use the latest event, because state machine internals generate at most
// 1 transition event (per type) each frame. No event means no change
// happened and we skip iterating all entities.
let Some(transition) = transitions.read().last() else {
return;
};
if transition.entered == transition.exited {
return;
}
let Some(exited) = &transition.exited else {
return;
};
for (binding, mut visibility) in query.iter_mut() {
if binding.0 == *exited {
visibility.set_if_neq(Visibility::Hidden);
}
}
}
```
</details>
---------
Co-authored-by: Benjamin Brienen <Benjamin.Brienen@outlook.com>
Co-authored-by: Ben Frankel <ben.frankel7@gmail.com>
# Objective
Contributes to #18741 and #18453.
## Solution
Deprecate `SimpleExecutor`. If users run into migration issues, we can
backtrack. Otherwise, we follow this up with #18741
We can't easily deprecate the module too because of
[this](https://github.com/rust-lang/rust/issues/47238).
## Testing
CI
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Cyrill Schenkel <cyrill.schenkel@gmail.com>
# Objective
- bevy removed `Observe` type parameters in #15151 ,it enables merging
`Observer` and `ObserverState ` into a single component. with this
consolidation ,we can improve efficiency while reducing boilerplate.
## Solution
- remove `ObserverState `and merge it into `Observer`
## Testing
40%~60% performance win due to removal of redundant look up.
This also improves ergonomics when using dynamic observer
```rust
// previously
world.spawn(ObserverState {
// SAFETY: we registered `event_a` above and it matches the type of EventA
descriptor: unsafe { ObserverDescriptor::default().with_events(vec![event_a]) },
runner: |mut world, _trigger, _ptr, _propagate| {
world.resource_mut::<Order>().observed("event_a");
},
..Default::default()
});
// now
let observe = unsafe {
Observer::with_dynamic_runner(|mut world, _trigger, _ptr, _propagate| {
world.resource_mut::<Order>().observed("event_a");
})
.with_event(event_a)
};
world.spawn(observe);
```
# Objective
Based on and closes#18054, this PR builds on #18035 and #18147 to
remove:
- `Commands::insert_or_spawn_batch`
- `Entities::alloc_at_without_replacement`
- `Entities::alloc_at`
- `entity::AllocAtWithoutReplacement`
- `World::insert_or_spawn_batch`
- `World::insert_or_spawn_batch_with_caller`
## Testing
Just removing unused, deprecated code, so no new tests. Note that as of
writing, #18035 is still under testing and review.
## Future Work
Per
[this](https://github.com/bevyengine/bevy/issues/18054#issuecomment-2689088899)
comment on #18054, there may be additional performance improvements
possible to the entity allocator now that `alloc_at` no longer is
supported. At a glance, I don't see anything obvious to improve, but it
may be worth further investigation in the future.
---------
Co-authored-by: JaySpruce <jsprucebruce@gmail.com>
# Objective
Stop using `ArchetypeComponentId` in the executor. These IDs will grow
even more quickly with relations, and the size may start to degrade
performance.
## Solution
Have systems expose their `FilteredAccessSet<ComponentId>`, and have the
executor use that to determine which systems conflict. This can be
determined statically, so determine all conflicts during initialization
and only perform bit tests when running.
## Testing
I ran many_foxes and didn't see any performance changes. It's probably
worth testing this with a wider range of realistic schedules to see
whether the reduced concurrency has a cost in practice, but I don't know
what sort of test cases to use.
## Migration Guide
The schedule will now prevent systems from running in parallel if there
*could* be an archetype that they conflict on, even if there aren't
actually any. For example, these systems will now conflict even if no
entity has both `Player` and `Enemy` components:
```rust
fn player_system(query: Query<(&mut Transform, &Player)>) {}
fn enemy_system(query: Query<(&mut Transform, &Enemy)>) {}
```
To allow them to run in parallel, use `Without` filters, just as you
would to allow both queries in a single system:
```rust
// Either one of these changes alone would be enough
fn player_system(query: Query<(&mut Transform, &Player), Without<Enemy>>) {}
fn enemy_system(query: Query<(&mut Transform, &Enemy), Without<Player>>) {}
```
# Objective
Prevent using exclusive systems as observers. Allowing them is unsound,
because observers are only expected to have `DeferredWorld` access, and
the observer infrastructure will keep pointers that are invalidated by
the creation of `&mut World`.
See
https://github.com/bevyengine/bevy/actions/runs/14778342801/job/41491517847?pr=19011
for a MIRI failure in a recent PR caused by an exclusive system being
used as an observer in a test.
## Solution
Have `Observer::new` panic if `System::is_exclusive()` is true. Document
that method, and methods that call it, as panicking.
(It should be possible to express this in the type system so that the
calls won't even compile, but I did not want to attempt that.)
## Testing
Added a unit test that calls `World::add_observer` with an exclusive
system.
# Objective
The default should be `OverflowClipBox::PaddingBox` not
`OverflowClipBox::ContentBox`
`padding-box` is the default in CSS.
## Solution
Set the default to `PaddingBox`.
## Testing
Compare the `overflow` UI example on main vs with this PR. You should
see that on main the outline around the inner node gets clipped. With
this PR by default clipping starts at the inner edge of the border (the
`padding-box`) and the outlines are visible.
Fixes#18934
# Objective
This PR begins integrating the new releate-content drafting process
(https://github.com/bevyengine/bevy/pull/18427) into our GitHub
workflows. It's similar to what we had before: Messages are posted to
PRs tagged with `M-Needs-Release-Note` or `M-Needs-Migration-Guide`
asking them to add the required material and linking to the
instructions. These messages do not trigger if the PR already has
modified files in the `release-notes` or `migration-guides` directories
(respectively).
I have also re-arranged and content slightly (to remove the need for a
directory with the current version number), tweaked the language, and
switched the templates to use the [standard markdown frontmatter
format](https://jekyllrb.com/docs/front-matter/).
## Reviewer Questions
+ Do we want to add a CI rule actually requiring tagged PRs to
create/modify files in the correct directories, or is the message prompt
enough?
+ Do we want to add a CI rule to lint the metadata, for example to
enforce that the PR number is included in the files it modifies?
