# Objective
Fixes#13917
## Solution
Changed `IntoSystemSetConfigs::chain_ignore_deferred`'s return type from
`SystemConfigs` to `SystemSetConfigs`
## Testing
Tried to run the `ecs_guide` example, where `chain` method is replaced
by `chain_ignore_deferred` method
---
# Objective
- Fix a typo in documentation for `Query::single_mut`
## Solution
- Change `item` to `items`
## Testing
- I built the documentation and it looked fine.
- Since this only affects a doc comment, no further testing should be
necessary.
---
## Changelog
> This section is optional. If this was a trivial fix, or has no
externally-visible impact, you can delete this section.
- Fixed a typo in the documentation for Query.
# Objective
While writing code for the `bevy_ecs` I noticed we were using a
unnecessarily stable sort to sort component ids
## Solution
- Sort component ids with a unstable sort
- Comb the bevy_ecs crate for any other obvious inefficiencies.
- Don't clone component vectors when inserting an archetype.
## Testing
I ran `cargo test -p bevy_ecs`. Everything else I leave to CI.
## Profiling
I measured about a 1% speed increase when spawning entities directly
into a world. Since the difference is so small (and might just be noise)
I didn't bother to figure out which of change if any made the biggest
difference.
<details>
<summary> Tracy data </summary>
Yellow is this PR. Red is the commit I branched from.
</details>
<details>
<summary>Methodology</summary>
I created a system that spawn a 1000 entities each with the same 30
components each frame, and then I measured it's run time. The unusually
high number of components was chosen because the standard library [will
use a insertion sort for slices under 20
elements](0de24a5177/library/core/src/slice/sort.rs (L1048-L1049)).
This holds for both stable and unstable sorts.
</details>
# Objective
- Provide an expressive way to register dynamic behavior in response to
ECS changes that is consistent with existing bevy types and traits as to
provide a smooth user experience.
- Provide a mechanism for immediate changes in response to events during
command application in order to facilitate improved query caching on the
path to relations.
## Solution
- A new fundamental ECS construct, the `Observer`; inspired by flec's
observers but adapted to better fit bevy's access patterns and rust's
type system.
---
## Examples
There are 3 main ways to register observers. The first is a "component
observer" that looks like this:
```rust
world.observe(|trigger: Trigger<OnAdd, Transform>, query: Query<&Transform>| {
let transform = query.get(trigger.entity()).unwrap();
});
```
The above code will spawn a new entity representing the observer that
will run it's callback whenever the `Transform` component is added to an
entity. This is a system-like function that supports dependency
injection for all the standard bevy types: `Query`, `Res`, `Commands`
etc. It also has a `Trigger` parameter that provides information about
the trigger such as the target entity, and the event being triggered.
Importantly these systems run during command application which is key
for their future use to keep ECS internals up to date. There are similar
events for `OnInsert` and `OnRemove`, and this will be expanded with
things such as `ArchetypeCreated`, `TableEmpty` etc. in follow up PRs.
Another way to register an observer is an "entity observer" that looks
like this:
```rust
world.entity_mut(entity).observe(|trigger: Trigger<Resize>| {
// ...
});
```
Entity observers run whenever an event of their type is triggered
targeting that specific entity. This type of observer will de-spawn
itself if the entity (or entities) it is observing is ever de-spawned so
as to not leave dangling observers.
Entity observers can also be spawned from deferred contexts such as
other observers, systems, or hooks using commands:
```rust
commands.entity(entity).observe(|trigger: Trigger<Resize>| {
// ...
});
```
Observers are not limited to in built event types, they can be used with
any type that implements `Event` (which has been extended to implement
Component). This means events can also carry data:
```rust
#[derive(Event)]
struct Resize { x: u32, y: u32 }
commands.entity(entity).observe(|trigger: Trigger<Resize>, query: Query<&mut Size>| {
let event = trigger.event();
// ...
});
// Will trigger the observer when commands are applied.
commands.trigger_targets(Resize { x: 10, y: 10 }, entity);
```
You can also trigger events that target more than one entity at a time:
```rust
commands.trigger_targets(Resize { x: 10, y: 10 }, [e1, e2]);
```
Additionally, Observers don't _need_ entity targets:
```rust
app.observe(|trigger: Trigger<Quit>| {
})
commands.trigger(Quit);
```
In these cases, `trigger.entity()` will be a placeholder.
Observers are actually just normal entities with an `ObserverState` and
`Observer` component! The `observe()` functions above are just shorthand
for:
```rust
world.spawn(Observer::new(|trigger: Trigger<Resize>| {});
```
This will spawn the `Observer` system and use an `on_add` hook to add
the `ObserverState` component.
Dynamic components and trigger types are also fully supported allowing
for runtime defined trigger types.
## Possible Follow-ups
1. Deprecate `RemovedComponents`, observers should fulfill all use cases
while being more flexible and performant.
2. Queries as entities: Swap queries to entities and begin using
observers listening to archetype creation triggers to keep their caches
in sync, this allows unification of `ObserverState` and `QueryState` as
well as unlocking several API improvements for `Query` and the
management of `QueryState`.
3. Trigger bubbling: For some UI use cases in particular users are
likely to want some form of bubbling for entity observers, this is
trivial to implement naively but ideally this includes an acceleration
structure to cache hierarchy traversals.
4. All kinds of other in-built trigger types.
5. Optimization; in order to not bloat the complexity of the PR I have
kept the implementation straightforward, there are several areas where
performance can be improved. The focus for this PR is to get the
behavior implemented and not incur a performance cost for users who
don't use observers.
I am leaving each of these to follow up PR's in order to keep each of
them reviewable as this already includes significant changes.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: MiniaczQ <xnetroidpl@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
As discovered in
https://github.com/Leafwing-Studios/leafwing-input-manager/issues/538,
there appears to be some real weirdness going on in how event updates
are processed between Bevy 0.13 and Bevy 0.14.
To identify the cause and prevent regression, I've added tests to
validate the intended behavior.
My initial suspicion was that this would be fixed by
https://github.com/bevyengine/bevy/pull/13762, but that doesn't seem to
be the case.
Instead, events appear to never be updated at all when using `bevy_app`
by itself. This is part of the problem resolved by
https://github.com/bevyengine/bevy/pull/11528, and introduced by
https://github.com/bevyengine/bevy/pull/10077.
After some investigation, it appears that `signal_event_update_system`
is never added using a bare-bones `App`, and so event updates are always
skipped.
This can be worked around by adding your own copy to a
later-in-the-frame schedule, but that's not a very good fix.
## Solution
Ensure that if we're not using a `FixedUpdate` schedule, events are
always updated every frame.
To do this, I've modified the logic of `event_update_condition` and
`event_update_system` to clearly and correctly differentiate between the
two cases: where we're waiting for a "you should update now" signal and
where we simply don't care.
To encode this, I've added the `ShouldUpdateEvents` enum, replacing a
simple `bool` in `EventRegistry`'s `needs_update` field.
Now, both tests pass as expected, without having to manually add a
system!
## Testing
I've written two parallel unit tests to cover the intended behavior:
1. Test that `iter_current_update_events` works as expected in
`bevy_ecs`.
2. Test that `iter_current_update_events` works as expected in
`bevy_app`
I've also added a test to verify that event updating works correctly in
the presence of a fixed main schedule, and a second test to verify that
fixed updating works at all to help future authors narrow down failures.
## Outstanding
- [x] figure out why the `bevy_app` version of this test fails but the
`bevy_ecs` version does not
- [x] figure out why `EventRegistry::run_updates` isn't working properly
- [x] figure out why `EventRegistry::run_updates` is never getting
called
- [x] figure out why `event_update_condition` is always returning false
- [x] figure out why `EventRegistry::needs_update` is always false
- [x] verify that the problem is a missing `signal_events_update_system`
---------
Co-authored-by: Mike <mike.hsu@gmail.com>
…izer (#13442)"
This reverts commit 5cfb063d4a.
- This PR broke bevy-trait-query, which needs to be able to write a
resource in init_state. See #13798 for more details.
- Note this doesn't fix everything as transmutes for bevy-trait-query
will still be broken,. But the current usage in that crate is UB, so we
need to find another solution.
# Objective
- Split the bevy_ecs::events module so it's easier to work with
## Solution
- Split the event.rs file across multiple files, made sure all tests
passed, and exports from the module were the same as previous
## Testing
- All automated tests pass.
Fixes#13758.
# Objective
Calling `update` on the main app already calls `clear_trackers`. Calling
it again in `SubApps::update` caused RemovedCompenet Events to be
cleared earlier than they should be.
## Solution
- Don't call clear_trackers an extra time.
## Testing
I manually tested the fix with this unit test:
```
#[cfg(test)]
mod test {
use crate::core::{FrameCount, FrameCountPlugin};
use crate::prelude::*;
#[test]
fn test_next_frame_removal() {
#[derive(Component)]
struct Foo;
#[derive(Resource)]
struct RemovedCount(usize);
let mut app = App::new();
app.add_plugins(FrameCountPlugin);
app.add_systems(Startup, |mut commands: Commands| {
for _ in 0..100 {
commands.spawn(Foo);
}
commands.insert_resource(RemovedCount(0));
});
app.add_systems(First, |counter: Res<FrameCount>| {
println!("Frame {}:", counter.0)
});
fn detector_system(
mut removals: RemovedComponents<Foo>,
foos: Query<Entity, With<Foo>>,
mut removed_c: ResMut<RemovedCount>,
) {
for e in removals.read() {
println!(" Detected removed Foo component for {e:?}");
removed_c.0 += 1;
}
let c = foos.iter().count();
println!(" Total Foos: {}", c);
assert_eq!(c + removed_c.0, 100);
}
fn deleter_system(foos: Query<Entity, With<Foo>>, mut commands: Commands) {
foos.iter().next().map(|e| {
commands.entity(e).remove::<Foo>();
});
}
app.add_systems(Update, (detector_system, deleter_system).chain());
app.update();
app.update();
app.update();
app.update();
}
}
```
# Objective
There were some issues with the `serialize` feature:
- `bevy_app` had a `serialize` feature and a dependency on `serde` even
there is no usage of serde at all inside `bevy_app`
- the `bevy_app/serialize` feature enabled `bevy_ecs/serde`, which is
strange
- `bevy_internal/serialize` did not enable `bevy_app/serialize` so there
was no way of serializing an Entity in bevy 0.14
## Solution
- Remove `serde` and `bevy_app/serialize`
- Add a `serialize` flag on `bevy_ecs` that enables `serde`
- ` bevy_internal/serialize` now enables `bevy_ecs/serialize`
# Objective
- My attempt at fulfilling #13629.
## Solution
Renames the `and_then` / `or_else` run condition methods to `and` /
`or`, respectively.
Extends the run conditions API to include a suite of binary logical
operators:
- `and`
- `or`
- `nand`
- `nor`
- `xor`
- `xnor`
## Testing
- Did you test these changes? If so, how?
- The test **run_condition_combinators** was extended to include the
added run condition combinators. A **double_counter** system was added
to test for combinators running on even count cycles.
- Are there any parts that need more testing?
- I'm not too sure how I feel about the "counter" style of testing but I
wanted to keep it consistent. If it's just a unit test I would prefer
simply to just assert `true` == _combinator output_ or `false` ==
_combinator output_ .
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- Nothing too specific. The added methods should be equivalent to the
logical operators they are analogous to (`&&` , `||`, `^`, `!`).
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
- Should not be relevant, I'm using Windows.
## Changelog
- What changed as a result of this PR?
- The run conditions API.
- If applicable, organize changes under "Added", "Changed", or "Fixed"
sub-headings
- Changed:
- `and_then` run condition combinator renamed to simply `and`
- `or_else` run condition combinator renamed to simply `or`
- Added:
- `nand` run condition combinator.
- `nor` run condition combinator.
- `xor` run condition combinator.
- `xnor` run condition combinator.
## Migration Guide
- The `and_then` run condition method has been replaced with the `and`
run condition method.
- The `or_else` run condition method has been replaced with the `or` run
condition method.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Andres O. Vela <andresovela@users.noreply.github.com>
# Objective
The `EntityCommands::despawn` method was previously changed from
panicking behavior to a warning, but the docs continue to state that it
panics.
## Solution
- Removed panic section, copied warning blurb from `World::despawn`
- Adds a similar warning blurb to
`DespawnRecursiveExt::despawn_recursive` and
`DespawnRecursiveExt::despawn_descendants`
# Objective
- Fixes#13703
## Solution
- Added `mappings` to the `EntityMapper` trait, which returns an
iterator over currently tracked `Entity` to `Entity` mappings.
- Added `DynEntityMapper` as an [object
safe](https://doc.rust-lang.org/reference/items/traits.html#object-safety)
alternative to `EntityMapper`.
- Added `assert_object_safe` as a helper for ensuring traits are object
safe.
## Testing
- Added new unit test `entity_mapper_iteration` which tests the
`SceneEntityMapper` implementation of `EntityMapper::mappings`.
- Added unit tests to ensure `DynEntityMapper`, `DynEq` and `DynHash`
are object safe.
- Passed CI on my Windows 10 development environment
---
## Changelog
- Added `mappings` to `EntityMapper` trait.
## Migration Guide
- If you are implementing `EntityMapper` yourself, you can use the below
as a stub implementation:
```rust
fn mappings(&self) -> impl Iterator<Item = (Entity, Entity)> {
unimplemented!()
}
```
- If you were using `EntityMapper` as a trait object (`dyn
EntityMapper`), instead use `dyn DynEntityMapper` and its associated
methods.
## Notes
- The original issue proposed returning a `Vec` from `EntityMapper`
instead of an `impl Iterator` to preserve its object safety. This is a
simpler option, but also forces an allocation where it isn't strictly
needed. I've opted for this split into `DynEntityMapper` and
`EntityMapper` as it's been done several times across Bevy already, and
provides maximum flexibility to users.
- `assert_object_safe` is an empty function, since the assertion
actually happens once you try to use a `dyn T` for some trait `T`. I
have still added this function to clearly document what object safety is
within Bevy, and to create a standard way to communicate that a given
trait must be object safe.
- Other traits should have tests added to ensure object safety, but I've
left those off to avoid cluttering this PR further.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Add slice based variants of existing `get_many_entities` functions on
`World`. This allows for a collection of entries to be looked up mutably
or immutably instead of requiring a compile time constant number.
## Solution
We just take slices and return Vectors.
the following functions have been added:
- `get_many_entities_dynamic`
- `get_many_entities_dynamic_mut`
- `get_many_entities_from_set_mut`
## Testing
- Doc tests, which pass when run through Miri
# Objective
- Fix#10958 by performing entity mapping on the entities inside of
resources.
## Solution
- Resources can reflect(MapEntitiesResource) and impl MapEntities to get
access to the mapper during the world insert of the scene.
## Testing
- A test resource_entity_map_maps_entities confirms the desired
behavior.
## Changelog
- Added reflect(MapEntitiesResource) for mapping entities on Resources
in a DynamicScene.
fixes 10958
# Objective
- Follow-up on some changes in #11498
- Unblock using `Identifier` to replace `ComponentId` internals.
## Solution
- Implement the same `Reflect` impls from `Entity` onto `Identifier` as
they share same/similar purposes,
## Testing
- No compile errors. Currently `Identifier` has no serialization impls,
so there's no need to test a serialization/deserialization roundtrip to
ensure correctness.
---
## Changelog
### Added
- Reflection implementations on `Identifier`.
# Objective
`SceneEntityMapper` seems like it could be generally useful.
## Solution
Allow end users to call `SceneEntityMapper::new` and
`SceneEntityMapper::finish`.
# Objective
Adds capability to clear all components on an entity without de-spawning
said entity.
## Testing
The function calls `remove_by_id` on every component in the entity
archetype - wasn't sure if it's worth going out of our way to create a
test for this considering `remove_by_id` is already unit tested.
---
## Changelog
Added `clear` function to `EntityWorldMut` which removes all components
on an entity.
## Migration Guide
N/A
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
In #13343, `WorldQuery::get_state` was constrained from `&World` as the
argument to `&Components`, but `WorldQuery::init_state` hasn't yet been
changed from `&mut World` to match.
Fixes#13358
## Solution
Create a wrapper around `&mut Components` and `&mut Storages` that can
be obtained from `&mut World` with a `component_initializer` method.
This new `ComponentInitializer` re-exposes the API on `&mut Components`
minus the `&mut Storages` parameter where it was present. For the
`&Components` API, it simply derefs to its `components` field.
## Changelog
### Added
The `World::component_initializer` method.
The `ComponentInitializer` struct that re-exposes `Components` API.
### Changed
`WorldQuery::init_state` now takes `&mut ComponentInitializer` instead
of `&mut World`.
## Migration Guide
Instead of passing `&mut World` to `WorldQuery::init_state` directly,
pass in a mutable reference to the struct returned from
`World::component_initializer`.
Currently, either an `EntityRef` or `EntityMut` is required in order to
reflect a component on an entity. This can, however, be generalized to
`FilteredEntityRef` and `FilteredEntityMut`, which are versions of
`EntityRef` and `EntityMut` that restrict the components that can be
accessed. This is useful because dynamic queries yield
`FilteredEntityRef` and `FilteredEntityMut` rows when iterated over.
This commit changes `ReflectComponent::contains()`,
`ReflectComponent::reflect()`, and `ReflectComponent::reflect_mut()` to
take an `Into<FilteredEntityRef>` (in the case of `contains()` and
`reflect()`) and `Into<FilteredEntityMut>` (in the case of
`reflect_mut()`). Fortunately, `EntityRef` and `EntityMut` already
implement the corresponding trait, so nothing else has to be done to the
public API. Note that in order to implement
`ReflectComponent::reflect_mut()` properly, an additional method
`FilteredEntityMut::into_mut()` was required, to match the one on
`EntityMut`.
I ran into this when attempting to implement `QUERY` in the Bevy Remote
Protocol when trying to iterate over rows of dynamic queries and fetch
the associated components without unsafe code. There were other
potential ways to work around this problem, but they required either
reimplementing the query logic myself instead of using regular Bevy
queries or storing entity IDs and then issuing another query to fetch
the associated `EntityRef`. Both of these seemed worse than just
improving the `reflect()` function.
## Migration Guide
* `ReflectComponent::contains`, `ReflectComponent::reflect`, and
`ReflectComponent::reflect_mut` now take `FilteredEntityRef` (in the
case of `contains()` and `reflect()`) and `FilteredEntityMut` (in the
case of `reflect_mut()`) parameters. `FilteredEntityRef` and
`FilteredEntityMut` have very similar APIs to `EntityRef` and
`EntityMut` respectively, but optionally restrict the components that
can be accessed.
# Objective
- `FilteredEntity{Ref,Mut}` various `get` methods never checked that the
given component was present on the entity, only the access allowed
reading/writing them, which is always the case when it is constructed
from a `EntityRef`/`EntityMut`/`EntityWorldMut` (and I guess can also
happen with queries containing `Option<T>` that get transmuted).
- In those cases the various `get` methods were calling
`debug_checked_unwrap` on `None`s, which is UB when debug assertions are
not enabled;
- The goal is thus to fix this soundness issue.
## Solution
- Don't call `debug_checked_unwrap` on those `None` and instead
`flatten` them.
## Testing
- This PR includes regression tests for each combination of
`FilteredEntityRef`/`FilteredEntityMut` and component
present/not-present. The two tests for the not-present cases fail on
`main` but success with this PR changes.
# Objective
- Prevent the case where a hook/observer is triggered but the source
entity/component no longer exists
## Solution
- Re-order command application such that all hooks/observers that are
notified will run before any have a chance to invalidate the result.
## Testing
Updated relevant tests in `bevy_ecs`, all other tests pass.
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Co-authored-by: Mike Hsu <mike.hsu@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
The current query iterators cannot be used in positions with a `Debug`
bound.
F.e. when they are packaged in `Result` in the error position, `expect`
cannot be called on them.
Required for `QueryManyIter::entities_all_unique` in #13477.
## Solution
Add simple `Debug` impls that print the query iterator names.
## Changelog
`QueryIter`, `QueryManyIter`, `QueryCombinationIter`, and
`QuerySortedIter` now implement `Debug`.
# Objective
While reviewing the other open hooks-related PRs, I found that the docs
on the `ComponentHooks` struct itself didn't give enough information
about how and why the feature could be used.
## Solution
1. Clean up the docs to add additional context.
2. Add a doc test demonstrating simple usage.
## Testing
The doc test passes locally.
---------
Co-authored-by: Alice Cecile <alice.i.cecil@gmail.com>
# Objective
- Implement a general purpose mechanism for building `SystemParam`.
- Unblock the usage of dynamic queries in regular systems.
## Solution
- Implement a `SystemBuilder` type.
## Examples
Here are some simple test cases for the builder:
```rust
fn local_system(local: Local<u64>) -> u64 {
*local
}
fn query_system(query: Query<()>) -> usize {
query.iter().count()
}
fn multi_param_system(a: Local<u64>, b: Local<u64>) -> u64 {
*a + *b + 1
}
#[test]
fn local_builder() {
let mut world = World::new();
let system = SystemBuilder::<()>::new(&mut world)
.builder::<Local<u64>>(|x| *x = 10)
.build(local_system);
let result = world.run_system_once(system);
assert_eq!(result, 10);
}
#[test]
fn query_builder() {
let mut world = World::new();
world.spawn(A);
world.spawn_empty();
let system = SystemBuilder::<()>::new(&mut world)
.builder::<Query<()>>(|query| {
query.with::<A>();
})
.build(query_system);
let result = world.run_system_once(system);
assert_eq!(result, 1);
}
#[test]
fn multi_param_builder() {
let mut world = World::new();
world.spawn(A);
world.spawn_empty();
let system = SystemBuilder::<()>::new(&mut world)
.param::<Local<u64>>()
.param::<Local<u64>>()
.build(multi_param_system);
let result = world.run_system_once(system);
assert_eq!(result, 1);
}
```
This will be expanded as this PR is iterated.
# Objective
Currently, a query iterator can be collected into a `Vec` and sorted,
but this can be quite unwieldy, especially when many `Component`s are
involved. The `itertools` crate helps somewhat, but the need to write a
closure over all of `QueryData`
can sometimes hurt ergonomics, anywhere from slightly to strongly. A key
extraction function only partially helps, as `sort_by_key` does not
allow returning non-`Copy` data. `sort_by` does not suffer from the
`Copy` restriction, but now the user has to write out a `cmp` function
over two `QueryData::Item`s when it could have just been handled by the
`Ord` impl for the key.
`sort` requires the entire `Iterator` Item to be `Ord`, which is rarely
usable without manual helper functionality. If the user wants to hide
away unused components with a `..` range, they need to track item tuple
order across their function. Mutable `QueryData` can also introduce
further complexity.
Additionally, sometimes users solely include `Component`s /`Entity` to
guarantee iteration order.
For a user to write a function to abstract away repeated sorts over
various `QueryData` types they use would require reaching for the
`all_tuples!` macro, and continue tracking tuple order afterwards.
Fixes https://github.com/bevyengine/bevy/issues/1470.
## Solution
Custom sort methods on `QueryIter`, which take a query lens as a generic
argument, like `transmute_lens` in `Query`.
This allows users to choose what part of their queries they pass to
their sort function calls, serving as a kind of "key extraction
function" before the sort call. F.e. allowing users to implement `Ord`
for a Component, then call `query.iter().sort::<OrdComponent>()`
This works independent of mutability in `QueryData`, `QueryData` tuple
order, or the underlying `iter/iter_mut` call.
Non-`Copy` components could also be used this way, an internal
`Arc<usize>` being an example.
If `Ord` impls on components do not suffice, other sort methods can be
used. Notably useful when combined with `EntityRef` or `EntityMut`.
Another boon from using underlying `transmute` functionality, is that
with the [allowed
transmutes](http://dev-docs.bevyengine.org/bevy/ecs/prelude/struct.Query.html#allowed-transmutes),
it is possible to sort a `Query` with `Entity` even if it wasn't
included in the original `Query`.
The additional generic parameter on the methods other than `sort` and
`sort_unstable` currently cannot be removed due to Rust limitations,
however their types can be inferred.
The new methods do not conflict with the `itertools` sort methods, as
those use the "sorted" prefix.
This is implemented barely touching existing code. That change to
existing code being that `QueryIter` now holds on to the reference to
`UnsafeWorldCell` that is used to initialize it.
A lens query is constructed with `Entity` attached at the end, sorted,
and turned into an iterator. The iterator maps away the lens query,
leaving only an iterator of `Entity`, which is used by `QuerySortedIter`
to retrieve the actual items.
`QuerySortedIter` resembles a combination of `QueryManyIter` and
`QueryIter`, but it uses an entity list that is guaranteed to contain
unique entities, and implements `ExactSizeIterator`,
`DoubleEndedIterator`, `FusedIterator` regardless of mutability or
filter kind (archetypal/non-archetypal).
The sort methods are not allowed to be called after `next`, and will
panic otherwise. This is checked using `QueryIterationCursor` state,
which is unique on initialization. Empty queries are an exception to
this, as they do not return any item in the first place.
That is because tracking how many iterations have already passed would
require regressing either normal query iteration a slight bit, or sorted
iteration by a lot. Besides, that would not be the intended use of these
methods.
## Testing
To ensure that `next` being called before `sort` results in a panic, I
added some tests. I also test that empty `QueryIter`s do not exhibit
this restriction.
The query sorts test checks for equivalence to the underlying sorts.
This change requires that `Query<(Entity, Entity)>` remains legal, if
that is not already guaranteed, which is also ensured by the
aforementioned test.
## Next Steps
Implement the set of sort methods for `QueryManyIter` as well.
- This will mostly work the same, other than needing to return a new
`QuerySortedManyIter` to account for iteration
over lists of entities that are not guaranteed to be unique. This new
query iterator will need a bit of internal restructuring
to allow for double-ended mutable iteration, while not regressing
read-only iteration.
The implementations for each pair of
- `sort`, `sort_unstable`,
- `sort_by`, sort_unstable_by,
- `sort_by_key,` `sort_by_cached_key`
are the same aside from the panic message and the sort call, so they
could be merged with an inner function.
That would require the use of higher-ranked trait bounds on
`WorldQuery::Item<'1>`, and is unclear to me whether it is currently
doable.
Iteration in QuerySortedIter might have space for improvement.
When sorting by `Entity`, an `(Entity, Entity)` lens `QueryData` is
constructed, is that worth remedying?
When table sorts are implemented, a fast path could be introduced to
these sort methods.
## Future Possibilities
Implementing `Ord` for EntityLocation might be useful.
Some papercuts in ergonomics can be improved by future Rust features:
- The additional generic parameter aside from the query lens can be
removed once this feature is stable:
`Fn -> impl Trait` (`impl Trait` in `Fn` trait return position)
- With type parameter defaults, the query lens generic can be defaulted
to `QueryData::Item`, allowing the sort methods
to look and behave like `slice::sort` when no query lens is specified.
- With TAIT, the iterator generic on `QuerySortedIter` and thus the huge
visible `impl Iterator` type in the sort function
signatures can be removed.
- With specialization, the bound on `L` could be relaxed to `QueryData`
when the underlying iterator is mutable.
## Changelog
Added `sort`, `sort_unstable`, `sort_by`, `sort_unstable_by`,
`sort_by_key`, `sort_by_cached_key` to `QueryIter`.
# Objective
- Fixes#12377
## Solution
Added simple `#[diagnostic::on_unimplemented(...)]` attributes to some
critical public traits providing a more approachable initial error
message. Where appropriate, a `note` is added indicating that a `derive`
macro is available.
## Examples
<details>
<summary>Examples hidden for brevity</summary>
Below is a collection of examples showing the new error messages
produced by this change. In general, messages will start with a more
Bevy-centric error message (e.g., _`MyComponent` is not a `Component`_),
and a note directing the user to an available derive macro where
appropriate.
### Missing `#[derive(Resource)]`
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
struct MyResource;
fn main() {
App::new()
.insert_resource(MyResource)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `MyResource` is not a `Resource`
--> examples/app/empty.rs:7:26
|
7 | .insert_resource(MyResource)
| --------------- ^^^^^^^^^^ invalid `Resource`
| |
| required by a bound introduced by this call
|
= help: the trait `Resource` is not implemented for `MyResource`
= note: consider annotating `MyResource` with `#[derive(Resource)]`
= help: the following other types implement trait `Resource`:
AccessibilityRequested
ManageAccessibilityUpdates
bevy::bevy_a11y::Focus
DiagnosticsStore
FrameCount
bevy::prelude::State<S>
SystemInfo
bevy::prelude::Axis<T>
and 141 others
note: required by a bound in `bevy::prelude::App::insert_resource`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:419:31
|
419 | pub fn insert_resource<R: Resource>(&mut self, resource: R) -> &mut Self {
| ^^^^^^^^ required by this bound in `App::insert_resource`
```
</details>
### Putting A `QueryData` in a `QueryFilter` Slot
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
#[derive(Component)]
struct A;
#[derive(Component)]
struct B;
fn my_system(_query: Query<&A, &B>) {}
fn main() {
App::new()
.add_systems(Update, my_system)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `&B` is not a valid `Query` filter
--> examples/app/empty.rs:9:22
|
9 | fn my_system(_query: Query<&A, &B>) {}
| ^^^^^^^^^^^^^ invalid `Query` filter
|
= help: the trait `QueryFilter` is not implemented for `&B`
= help: the following other types implement trait `QueryFilter`:
With<T>
Without<T>
bevy::prelude::Or<()>
bevy::prelude::Or<(F0,)>
bevy::prelude::Or<(F0, F1)>
bevy::prelude::Or<(F0, F1, F2)>
bevy::prelude::Or<(F0, F1, F2, F3)>
bevy::prelude::Or<(F0, F1, F2, F3, F4)>
and 28 others
note: required by a bound in `bevy::prelude::Query`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_ecs\src\system\query.rs:349:51
|
349 | pub struct Query<'world, 'state, D: QueryData, F: QueryFilter = ()> {
| ^^^^^^^^^^^ required by this bound in `Query`
```
</details>
### Missing `#[derive(Component)]`
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
struct A;
fn my_system(mut commands: Commands) {
commands.spawn(A);
}
fn main() {
App::new()
.add_systems(Startup, my_system)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `A` is not a `Bundle`
--> examples/app/empty.rs:6:20
|
6 | commands.spawn(A);
| ----- ^ invalid `Bundle`
| |
| required by a bound introduced by this call
|
= help: the trait `bevy::prelude::Component` is not implemented for `A`, which is required by `A: Bundle`
= note: consider annotating `A` with `#[derive(Component)]` or `#[derive(Bundle)]`
= help: the following other types implement trait `Bundle`:
TransformBundle
SceneBundle
DynamicSceneBundle
AudioSourceBundle<Source>
SpriteBundle
SpriteSheetBundle
Text2dBundle
MaterialMesh2dBundle<M>
and 34 others
= note: required for `A` to implement `Bundle`
note: required by a bound in `bevy::prelude::Commands::<'w, 's>::spawn`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_ecs\src\system\commands\mod.rs:243:21
|
243 | pub fn spawn<T: Bundle>(&mut self, bundle: T) -> EntityCommands {
| ^^^^^^ required by this bound in `Commands::<'w, 's>::spawn`
```
</details>
### Missing `#[derive(Asset)]`
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
struct A;
fn main() {
App::new()
.init_asset::<A>()
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `A` is not an `Asset`
--> examples/app/empty.rs:7:23
|
7 | .init_asset::<A>()
| ---------- ^ invalid `Asset`
| |
| required by a bound introduced by this call
|
= help: the trait `Asset` is not implemented for `A`
= note: consider annotating `A` with `#[derive(Asset)]`
= help: the following other types implement trait `Asset`:
Font
AnimationGraph
DynamicScene
Scene
AudioSource
Pitch
bevy::bevy_gltf::Gltf
GltfNode
and 17 others
note: required by a bound in `init_asset`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_asset\src\lib.rs:307:22
|
307 | fn init_asset<A: Asset>(&mut self) -> &mut Self;
| ^^^^^ required by this bound in `AssetApp::init_asset`
```
</details>
### Mismatched Input and Output on System Piping
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
fn producer() -> u32 {
123
}
fn consumer(_: In<u16>) {}
fn main() {
App::new()
.add_systems(Update, producer.pipe(consumer))
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `fn(bevy::prelude::In<u16>) {consumer}` is not a valid system with input `u32` and output `_`
--> examples/app/empty.rs:11:44
|
11 | .add_systems(Update, producer.pipe(consumer))
| ---- ^^^^^^^^ invalid system
| |
| required by a bound introduced by this call
|
= help: the trait `bevy::prelude::IntoSystem<u32, _, _>` is not implemented for fn item `fn(bevy::prelude::In<u16>) {consumer}`
= note: expecting a system which consumes `u32` and produces `_`
note: required by a bound in `pipe`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_ecs\src\system\mod.rs:168:12
|
166 | fn pipe<B, Final, MarkerB>(self, system: B) -> PipeSystem<Self::System, B::System>
| ---- required by a bound in this associated function
167 | where
168 | B: IntoSystem<Out, Final, MarkerB>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `IntoSystem::pipe`
```
</details>
### Missing Reflection
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
#[derive(Component)]
struct MyComponent;
fn main() {
App::new()
.register_type::<MyComponent>()
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `MyComponent` does not provide type registration information
--> examples/app/empty.rs:8:26
|
8 | .register_type::<MyComponent>()
| ------------- ^^^^^^^^^^^ the trait `GetTypeRegistration` is not implemented for `MyComponent`
| |
| required by a bound introduced by this call
|
= note: consider annotating `MyComponent` with `#[derive(Reflect)]`
= help: the following other types implement trait `GetTypeRegistration`:
bool
char
isize
i8
i16
i32
i64
i128
and 443 others
note: required by a bound in `bevy::prelude::App::register_type`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:619:29
|
619 | pub fn register_type<T: bevy_reflect::GetTypeRegistration>(&mut self) -> &mut Self {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `App::register_type`
```
</details>
### Missing `#[derive(States)]` Implementation
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, Hash)]
enum AppState {
#[default]
Menu,
InGame {
paused: bool,
turbo: bool,
},
}
fn main() {
App::new()
.init_state::<AppState>()
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: the trait bound `AppState: FreelyMutableState` is not satisfied
--> examples/app/empty.rs:15:23
|
15 | .init_state::<AppState>()
| ---------- ^^^^^^^^ the trait `FreelyMutableState` is not implemented for `AppState`
| |
| required by a bound introduced by this call
|
= note: consider annotating `AppState` with `#[derive(States)]`
note: required by a bound in `bevy::prelude::App::init_state`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:282:26
|
282 | pub fn init_state<S: FreelyMutableState + FromWorld>(&mut self) -> &mut Self {
| ^^^^^^^^^^^^^^^^^^ required by this bound in `App::init_state`
```
</details>
### Adding a `System` with Unhandled Output
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
fn producer() -> u32 {
123
}
fn main() {
App::new()
.add_systems(Update, consumer)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `fn() -> u32 {producer}` does not describe a valid system configuration
--> examples/app/empty.rs:9:30
|
9 | .add_systems(Update, producer)
| ----------- ^^^^^^^^ invalid system configuration
| |
| required by a bound introduced by this call
|
= help: the trait `IntoSystem<(), (), _>` is not implemented for fn item `fn() -> u32 {producer}`, which is required by `fn() -> u32 {producer}: IntoSystemConfigs<_>`
= help: the following other types implement trait `IntoSystemConfigs<Marker>`:
<Box<(dyn bevy::prelude::System<In = (), Out = ()> + 'static)> as IntoSystemConfigs<()>>
<NodeConfigs<Box<(dyn bevy::prelude::System<In = (), Out = ()> + 'static)>> as IntoSystemConfigs<()>>
<(S0,) as IntoSystemConfigs<(SystemConfigTupleMarker, P0)>>
<(S0, S1) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1)>>
<(S0, S1, S2) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2)>>
<(S0, S1, S2, S3) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2, P3)>>
<(S0, S1, S2, S3, S4) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2, P3, P4)>>
<(S0, S1, S2, S3, S4, S5) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2, P3, P4, P5)>>
and 14 others
= note: required for `fn() -> u32 {producer}` to implement `IntoSystemConfigs<_>`
note: required by a bound in `bevy::prelude::App::add_systems`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:342:23
|
339 | pub fn add_systems<M>(
| ----------- required by a bound in this associated function
...
342 | systems: impl IntoSystemConfigs<M>,
| ^^^^^^^^^^^^^^^^^^^^ required by this bound in `App::add_systems`
```
</details>
</details>
## Testing
CI passed locally.
## Migration Guide
Upgrade to version 1.78 (or higher) of Rust.
## Future Work
- Currently, hints are not supported in this diagnostic. Ideally,
suggestions like _"consider using ..."_ would be in a hint rather than a
note, but that is the best option for now.
- System chaining and other `all_tuples!(...)`-based traits have bad
error messages due to the slightly different error message format.
---------
Co-authored-by: Jamie Ridding <Themayu@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
# Objective
Provides a `WorldQuery` implementation on `Mut<T>` that forwards to the
implementation on `&mut T`, and give users a way to opt-in to change
detection in auto-generated `QueryData::ReadOnly` types.
Fixes#13329.
## Solution
I implemented `WorldQuery` on `Mut<'w, T>` as a forwarding
implementation to `&mut T`, setting the `QueryData::ReadOnly` associated
type to `Ref<'w, T>`. This provides users the ability to explicitly
opt-in to change detection in the read-only forms of queries.
## Testing
A documentation test was added to `Mut` showcasing the new
functionality.
---
## Changelog
### Added
- Added an implementation of `WorldQuery` and `QueryData` on
`bevy_ecs::change_detection::Mut`.
# Objective
Passing `&World` in the `WorldQuery::get_state` method is unnecessary,
as all implementations of this method in the engine either only access
`Components` in `&World`, or do nothing with it.
It can introduce UB by necessitating the creation of a `&World` from a
`UnsafeWorldCell`.
This currently happens in `Query::transmute_lens`, which obtains a
`&World` from the internal `UnsafeWorldCell` solely to pass to
`get_state`. `Query::join` suffers from the same issue.
Other cases of UB come from allowing implementors of `WorldQuery` to
freely access `&World`, like in the `bevy-trait-query` crate, where a
[reference to a resource is
obtained](0c0e7dd646/src/lib.rs (L445))
inside of
[`get_state`](0c0e7dd646/src/one.rs (L245)),
potentially aliasing with a `ResMut` parameter in the same system.
`WorldQuery::init_state` currently requires `&mut World`, which doesn't
suffer from these issues.
But that too can be changed to receive a wrapper around `&mut
Components` and `&mut Storages` for consistency in a follow-up PR.
## Solution
Replace the `&World` parameter in `get_state` with `&Components`.
## Changelog
`WorldQuery::get_state` now takes `&Components` instead of `&World`.
The `transmute`, `transmute_filtered`, `join` and `join_filtered`
methods on `QueryState` now similarly take `&Components` instead of
`&World`.
## Migration Guide
Users of `WorldQuery::get_state` or `transmute`, `transmute_filtered`,
`join` and `join_filtered` methods on `QueryState` now need to pass
`&Components` instead of `&World`.
`&Components` can be trivially obtained from either `components` method
on `&World` or `UnsafeWorldCell`.
For implementors of `WorldQuery::get_state` that were accessing more
than the `Components` inside `&World` and its methods, this is no longer
allowed.
# Objective
As was pointed out in #13183, `bevy_mikktspace` is missing it's msrv
from it `Cargo.toml`. This promted me to check the msrv of every
`bevy_*` crate. Closes#13183.
## Solution
- Call `cargo check` with different rust versions on every bevy crate
until it doesn't complain.
- Write down the rust version `cargo check` started working.
## Testing
- Install `cargo-msrv`.
- Run `cargo msrv verify`.
- Rejoice.
---
## Changelog
Every published bevy crate now specifies a MSRV. If your rust toolchain
isn't at least version `1.77.0` You'll likely not be able to compile
most of bevy.
## Migration Guide
If your rust toolchain is bellow version`1.77.0, update.
# Objective
Extracts the state mechanisms into a new crate called "bevy_state".
This comes with a few goals:
- state wasn't really an inherent machinery of the ecs system, and so
keeping it within bevy_ecs felt forced
- by mixing it in with bevy_ecs, the maintainability of our more robust
state system was significantly compromised
moving state into a new crate makes it easier to encapsulate as it's own
feature, and easier to read and understand since it's no longer a
single, massive file.
## Solution
move the state-related elements from bevy_ecs to a new crate
## Testing
- Did you test these changes? If so, how? all the automated tests
migrated and passed, ran the pre-existing examples without changes to
validate.
---
## Migration Guide
Since bevy_state is now gated behind the `bevy_state` feature, projects
that use state but don't use the `default-features` will need to add
that feature flag.
Since it is no longer part of bevy_ecs, projects that use bevy_ecs
directly will need to manually pull in `bevy_state`, trigger the
StateTransition schedule, and handle any of the elements that bevy_app
currently sets up.
---------
Co-authored-by: Kristoffer Søholm <k.soeholm@gmail.com>
# Objective
fixes#13224
adds conversions for Vec3 and Vec4 since these appear so often
## Solution
added Covert trait (couldn't think of good name) for [f32; 4], [f32, 3],
Vec4, and Vec3 along with the symmetric implementation
## Changelog
added conversions between arrays and vector to colors and vice versa
#migration
LinearRgba appears to have already had implicit conversions for [f32;4]
and Vec4
# Objective
Fixes#12966
## Solution
Renaming multi_threaded feature to match snake case
## Migration Guide
Bevy feature multi-threaded should be refered to multi_threaded from now
on.
# Objective
- Follow-up of #13184 :)
- We use `ui_test` to test compiler errors for our custom macros.
- There are four crates related to compile fail tests
- `bevy_ecs_compile_fail_tests`, `bevy_macros_compile_fail_tests`, and
`bevy_reflect_compile_fail_tests`, which actually test the macros.
-
[`bevy_compile_test_utils`](64c1c65783/crates/bevy_compile_test_utils),
which provides helpers and common patterns for these tests.
- All of these crates reside within the `crates` directory.
- This can be confusing, especially for newcomers. All of the other
folders in `crates` are actual published libraries, except for these 4.
## Solution
- Move all compile fail tests to a `compile_fail` folder under their
corresponding crate.
- E.g. `crates/bevy_ecs_compile_fail_tests` would be moved to
`crates/bevy_ecs/compile_fail`.
- Move `bevy_compile_test_utils` to `tools/compile_fail_utils`.
There are a few benefits to this approach:
1. An internal testing detail is less intrusive (and confusing) for
those who just want to browse the public Bevy interface.
2. Follows a pre-existing approach of organizing related crates inside a
larger crate's folder.
- See `bevy_gizmos/macros` for an example.
4. Makes consistent the terms `compile_test`, `compile_fail`, and
`compile_fail_test` in code. It's all just `compile_fail` now, because
we are specifically testing the error messages on compiler failures.
- To be clear it can still be referred to by these terms in comments and
speech, just the names of the crates and the CI command are now
consistent.
## Testing
Run the compile fail CI command:
```shell
cargo run -p ci -- compile-fail
```
If it still passes, then my refactor was successful.
# Objective
Resolves#13185
## Solution
Move the following methods from `sub_app` to the `Schedules` resource,
and use them in the sub app:
- `add_systems`
- `configure_sets`
- `ignore_ambiguity`
Add an `entry(&mut self, label: impl ScheduleLabel) -> &mut Schedule`
method to the `Schedules` resource, which returns a mutable reference to
the schedule associated with the label, and creates one if it doesn't
already exist. (build on top of the `entry(..).or_insert_with(...)`
pattern in `HashMap`.
## Testing
- Did you test these changes? If so, how? Added 4 unit tests to the
`schedule.rs` - one that validates adding a system to an existing
schedule, one that validates adding a system to a new one, one that
validates configuring sets on an existing schedule, and one that
validates configuring sets on a new schedule.
- I didn't add tests for `entry` since the previous 4 tests use
functions that rely on it.
- I didn't test `ignore_ambiguity` since I didn't see examples of it's
use, and am not familiar enough with it to know how to set up a good
test for it. However, it relies on the `entry` method as well, so it
should work just like the other 2 methods.
## Summary/Description
This PR extends states to allow support for a wider variety of state
types and patterns, by providing 3 distinct types of state:
- Standard [`States`] can only be changed by manually setting the
[`NextState<S>`] resource. These states are the baseline on which the
other state types are built, and can be used on their own for many
simple patterns. See the [state
example](https://github.com/bevyengine/bevy/blob/latest/examples/ecs/state.rs)
for a simple use case - these are the states that existed so far in
Bevy.
- [`SubStates`] are children of other states - they can be changed
manually using [`NextState<S>`], but are removed from the [`World`] if
the source states aren't in the right state. See the [sub_states
example](https://github.com/lee-orr/bevy/blob/derived_state/examples/ecs/sub_states.rs)
for a simple use case based on the derive macro, or read the trait docs
for more complex scenarios.
- [`ComputedStates`] are fully derived from other states - they provide
a [`compute`](ComputedStates::compute) method that takes in the source
states and returns their derived value. They are particularly useful for
situations where a simplified view of the source states is necessary -
such as having an `InAMenu` computed state derived from a source state
that defines multiple distinct menus. See the [computed state
example](https://github.com/lee-orr/bevy/blob/derived_state/examples/ecs/computed_states.rscomputed_states.rs)
to see a sampling of uses for these states.
# Objective
This PR is another attempt at allowing Bevy to better handle complex
state objects in a manner that doesn't rely on strict equality. While my
previous attempts (https://github.com/bevyengine/bevy/pull/10088 and
https://github.com/bevyengine/bevy/pull/9957) relied on complex matching
capacities at the point of adding a system to application, this one
instead relies on deterministically deriving simple states from more
complex ones.
As a result, it does not require any special macros, nor does it change
any other interactions with the state system once you define and add
your derived state. It also maintains a degree of distinction between
`State` and just normal application state - your derivations have to end
up being discreet pre-determined values, meaning there is less of a
risk/temptation to place a significant amount of logic and data within a
given state.
### Addition - Sub States
closes#9942
After some conversation with Maintainers & SMEs, a significant concern
was that people might attempt to use this feature as if it were
sub-states, and find themselves unable to use it appropriately. Since
`ComputedState` is mainly a state matching feature, while `SubStates`
are more of a state mutation related feature - but one that is easy to
add with the help of the machinery introduced by `ComputedState`, it was
added here as well. The relevant discussion is here:
https://discord.com/channels/691052431525675048/1200556329803186316
## Solution
closes#11358
The solution is to create a new type of state - one implementing
`ComputedStates` - which is deterministically tied to one or more other
states. Implementors write a function to transform the source states
into the computed state, and it gets triggered whenever one of the
source states changes.
In addition, we added the `FreelyMutableState` trait , which is
implemented as part of the derive macro for `States`. This allows us to
limit use of `NextState<S>` to states that are actually mutable,
preventing mis-use of `ComputedStates`.
---
## Changelog
- Added `ComputedStates` trait
- Added `FreelyMutableState` trait
- Converted `NextState` resource to an Enum, with `Unchanged` and
`Pending`
- Added `App::add_computed_state::<S: ComputedStates>()`, to allow for
easily adding derived states to an App.
- Moved the `StateTransition` schedule label from `bevy_app` to
`bevy_ecs` - but maintained the export in `bevy_app` for continuity.
- Modified the process for updating states. Instead of just having an
`apply_state_transition` system that can be added anywhere, we now have
a multi-stage process that has to run within the `StateTransition`
label. First, all the state changes are calculated - manual transitions
rely on `apply_state_transition`, while computed transitions run their
computation process before both call `internal_apply_state_transition`
to apply the transition, send out the transition event, trigger
dependent states, and record which exit/transition/enter schedules need
to occur. Once all the states have been updated, the transition
schedules are called - first the exit schedules, then transition
schedules and finally enter schedules.
- Added `SubStates` trait
- Adjusted `apply_state_transition` to be a no-op if the `State<S>`
resource doesn't exist
## Migration Guide
If the user accessed the NextState resource's value directly or created
them from scratch they will need to adjust to use the new enum variants:
- if they created a `NextState(Some(S))` - they should now use
`NextState::Pending(S)`
- if they created a `NextState(None)` -they should now use
`NextState::Unchanged`
- if they matched on the `NextState` value, they would need to make the
adjustments above
If the user manually utilized `apply_state_transition`, they should
instead use systems that trigger the `StateTransition` schedule.
---
## Future Work
There is still some future potential work in the area, but I wanted to
keep these potential features and changes separate to keep the scope
here contained, and keep the core of it easy to understand and use.
However, I do want to note some of these things, both as inspiration to
others and an illustration of what this PR could unlock.
- `NextState::Remove` - Now that the `State` related mechanisms all
utilize options (#11417), it's fairly easy to add support for explicit
state removal. And while `ComputedStates` can add and remove themselves,
right now `FreelyMutableState`s can't be removed from within the state
system. While it existed originally in this PR, it is a different
question with a separate scope and usability concerns - so having it as
it's own future PR seems like the best approach. This feature currently
lives in a separate branch in my fork, and the differences between it
and this PR can be seen here: https://github.com/lee-orr/bevy/pull/5
- `NextState::ReEnter` - this would allow you to trigger exit & entry
systems for the current state type. We can potentially also add a
`NextState::ReEnterRecirsive` to also re-trigger any states that depend
on the current one.
- More mechanisms for `State` updates - This PR would finally make
states that aren't a set of exclusive Enums useful, and with that comes
the question of setting state more effectively. Right now, to update a
state you either need to fully create the new state, or include the
`Res<Option<State<S>>>` resource in your system, clone the state, mutate
it, and then use `NextState.set(my_mutated_state)` to make it the
pending next state. There are a few other potential methods that could
be implemented in future PRs:
- Inverse Compute States - these would essentially be compute states
that have an additional (manually defined) function that can be used to
nudge the source states so that they result in the computed states
having a given value. For example, you could use set the `IsPaused`
state, and it would attempt to pause or unpause the game by modifying
the `AppState` as needed.
- Closure-based state modification - this would involve adding a
`NextState.modify(f: impl Fn(Option<S> -> Option<S>)` method, and then
you can pass in closures or function pointers to adjust the state as
needed.
- Message-based state modification - this would involve either creating
states that can respond to specific messages, similar to Elm or Redux.
These could either use the `NextState` mechanism or the Event mechanism.
- ~`SubStates` - which are essentially a hybrid of computed and manual
states. In the simplest (and most likely) version, they would work by
having a computed element that determines whether the state should
exist, and if it should has the capacity to add a new version in, but
then any changes to it's content would be freely mutated.~ this feature
is now part of this PR. See above.
- Lastly, since states are getting more complex there might be value in
moving them out of `bevy_ecs` and into their own crate, or at least out
of the `schedule` module into a `states` module. #11087
As mentioned, all these future work elements are TBD and are explicitly
not part of this PR - I just wanted to provide them as potential
explorations for the future.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Marcel Champagne <voiceofmarcel@gmail.com>
Co-authored-by: MiniaczQ <xnetroidpl@gmail.com>
# Objective
I'm reading through the schedule code, which is somewhat lacking
documentation.
I've been adding some docstrings to help me understand the code; I feel
like some of them could be useful to also help others read this code.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
The `Events` containerr should be reflectable, in order to make dev
tools that examine its state more useful.
Fixes#13148.
## Solution
- Add a `Reflect` derive to `Events`, gated behind the `bevy_reflect`
feature
- Add `Reflect` to the contained types to make everything compile.
---------
Co-authored-by: Alice Cecile <alice.i.cecil@gmail.com>
# Objective
- `from_reflect_or_world` is an internal utilty used in the
implementations of `ReflectComponent` and `ReflectBundle` to create a
`T` given a `&dyn Reflect` by trying to use `FromReflect`, and if that
fails it falls back to `ReflectFromWorld`
- reflecting `FromWorld` is not intuitive though: often it is implicitly
implemented by deriving `Default` so people might not even be aware of
it.
- the panic messages mentioning `ReflectFromWorld` are not directly
correlated to what the user would have to do (reflect `FromWorld`)
## Solution
- Also check for `ReflectDefault` in addition to `ReflectFromWorld`.
- Change the panic messages to mention the reflected trait rather than
the `Reflect*` types.
---
## Changelog
- `ReflectComponent` and `ReflectBundle` no longer require `T:
FromReflect` but instead only `T: Reflect`.
- `ReflectComponent` and `ReflectBundle` will also work with types that
only reflected `Default` and not `FromWorld`.
## Migration Guide
- `ReflectBundle::insert` now requires an additional `&TypeRegistry`
parameter.
# Objective
- Better `SystemId` <-> `Entity` conversion.
## Solution
- Provide a method `SystemId::from_entity` to create a `SystemId<I, O>`
form an `Entity`. When users want to deal with the entities manually
they need a way to convert the `Entity` back to a `SystemId` to actually
run the system with `Commands` or `World`.
- Provide a method `SystemId::entity` that returns an `Entity` from
`SystemId`. The current `From` impl is not very discoverable as it does
not appear on the `SystemId` doc page.
- Remove old `From` impl.
## Migration Guide
```rust
let system_id = world.register_system(my_sys);
// old
let entity = Entity::from(system_id);
// new
let entity = system_id.entity();
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Closes#12958
## Solution
- Find all methods under `Query` that mention panicking, and add
`#[track_caller]` to them.
---
## Changelog
- Added `#[track_caller]` to `Query::many`, `Query::many_mut`,
`Query::transmute_lens`, and `Query::transmute_lens_filtered`.
## For reviewers
I'm unfamiliar with the depths of the `Query` struct. Please check
whether it makes since for the updated methods to have
`#[track_caller]`, and if I missed any!
