# Objective
Closes#19564.
The current `Event` trait looks like this:
```rust
pub trait Event: Send + Sync + 'static {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
The `Event` trait is used by both buffered events
(`EventReader`/`EventWriter`) and observer events. If they are observer
events, they can optionally be targeted at specific `Entity`s or
`ComponentId`s, and can even be propagated to other entities.
However, there has long been a desire to split the trait semantically
for a variety of reasons, see #14843, #14272, and #16031 for discussion.
Some reasons include:
- It's very uncommon to use a single event type as both a buffered event
and targeted observer event. They are used differently and tend to have
distinct semantics.
- A common footgun is using buffered events with observers or event
readers with observer events, as there is no type-level error that
prevents this kind of misuse.
- #19440 made `Trigger::target` return an `Option<Entity>`. This
*seriously* hurts ergonomics for the general case of entity observers,
as you need to `.unwrap()` each time. If we could statically determine
whether the event is expected to have an entity target, this would be
unnecessary.
There's really two main ways that we can categorize events: push vs.
pull (i.e. "observer event" vs. "buffered event") and global vs.
targeted:
| | Push | Pull |
| ------------ | --------------- | --------------------------- |
| **Global** | Global observer | `EventReader`/`EventWriter` |
| **Targeted** | Entity observer | - |
There are many ways to approach this, each with their tradeoffs.
Ultimately, we kind of want to split events both ways:
- A type-level distinction between observer events and buffered events,
to prevent people from using the wrong kind of event in APIs
- A statically designated entity target for observer events to avoid
accidentally using untargeted events for targeted APIs
This PR achieves these goals by splitting event traits into `Event`,
`EntityEvent`, and `BufferedEvent`, with `Event` being the shared trait
implemented by all events.
## `Event`, `EntityEvent`, and `BufferedEvent`
`Event` is now a very simple trait shared by all events.
```rust
pub trait Event: Send + Sync + 'static {
// Required for observer APIs
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
You can call `trigger` for *any* event, and use a global observer for
listening to the event.
```rust
#[derive(Event)]
struct Speak {
message: String,
}
// ...
app.add_observer(|trigger: On<Speak>| {
println!("{}", trigger.message);
});
// ...
commands.trigger(Speak {
message: "Y'all like these reworked events?".to_string(),
});
```
To allow an event to be targeted at entities and even propagated
further, you can additionally implement the `EntityEvent` trait:
```rust
pub trait EntityEvent: Event {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
}
```
This lets you call `trigger_targets`, and to use targeted observer APIs
like `EntityCommands::observe`:
```rust
#[derive(Event, EntityEvent)]
#[entity_event(traversal = &'static ChildOf, auto_propagate)]
struct Damage {
amount: f32,
}
// ...
let enemy = commands.spawn((Enemy, Health(100.0))).id();
// Spawn some armor as a child of the enemy entity.
// When the armor takes damage, it will bubble the event up to the enemy.
let armor_piece = commands
.spawn((ArmorPiece, Health(25.0), ChildOf(enemy)))
.observe(|trigger: On<Damage>, mut query: Query<&mut Health>| {
// Note: `On::target` only exists because this is an `EntityEvent`.
let mut health = query.get(trigger.target()).unwrap();
health.0 -= trigger.amount();
});
commands.trigger_targets(Damage { amount: 10.0 }, armor_piece);
```
> [!NOTE]
> You *can* still also trigger an `EntityEvent` without targets using
`trigger`. We probably *could* make this an either-or thing, but I'm not
sure that's actually desirable.
To allow an event to be used with the buffered API, you can implement
`BufferedEvent`:
```rust
pub trait BufferedEvent: Event {}
```
The event can then be used with `EventReader`/`EventWriter`:
```rust
#[derive(Event, BufferedEvent)]
struct Message(String);
fn write_hello(mut writer: EventWriter<Message>) {
writer.write(Message("I hope these examples are alright".to_string()));
}
fn read_messages(mut reader: EventReader<Message>) {
// Process all buffered events of type `Message`.
for Message(message) in reader.read() {
println!("{message}");
}
}
```
In summary:
- Need a basic event you can trigger and observe? Derive `Event`!
- Need the event to be targeted at an entity? Derive `EntityEvent`!
- Need the event to be buffered and support the
`EventReader`/`EventWriter` API? Derive `BufferedEvent`!
## Alternatives
I'll now cover some of the alternative approaches I have considered and
briefly explored. I made this section collapsible since it ended up
being quite long :P
<details>
<summary>Expand this to see alternatives</summary>
### 1. Unified `Event` Trait
One option is not to have *three* separate traits (`Event`,
`EntityEvent`, `BufferedEvent`), and to instead just use associated
constants on `Event` to determine whether an event supports targeting
and buffering or not:
```rust
pub trait Event: Send + Sync + 'static {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
const TARGETED: bool = false;
const BUFFERED: bool = false;
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
Methods can then use bounds like `where E: Event<TARGETED = true>` or
`where E: Event<BUFFERED = true>` to limit APIs to specific kinds of
events.
This would keep everything under one `Event` trait, but I don't think
it's necessarily a good idea. It makes APIs harder to read, and docs
can't easily refer to specific types of events. You can also create
weird invariants: what if you specify `TARGETED = false`, but have
`Traversal` and/or `AUTO_PROPAGATE` enabled?
### 2. `Event` and `Trigger`
Another option is to only split the traits between buffered events and
observer events, since that is the main thing people have been asking
for, and they have the largest API difference.
If we did this, I think we would need to make the terms *clearly*
separate. We can't really use `Event` and `BufferedEvent` as the names,
since it would be strange that `BufferedEvent` doesn't implement
`Event`. Something like `ObserverEvent` and `BufferedEvent` could work,
but it'd be more verbose.
For this approach, I would instead keep `Event` for the current
`EventReader`/`EventWriter` API, and call the observer event a
`Trigger`, since the "trigger" terminology is already used in the
observer context within Bevy (both as a noun and a verb). This is also
what a long [bikeshed on
Discord](https://discord.com/channels/691052431525675048/749335865876021248/1298057661878898791)
seemed to land on at the end of last year.
```rust
// For `EventReader`/`EventWriter`
pub trait Event: Send + Sync + 'static {}
// For observers
pub trait Trigger: Send + Sync + 'static {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
const TARGETED: bool = false;
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
The problem is that "event" is just a really good term for something
that "happens". Observers are rapidly becoming the more prominent API,
so it'd be weird to give them the `Trigger` name and leave the good
`Event` name for the less common API.
So, even though a split like this seems neat on the surface, I think it
ultimately wouldn't really work. We want to keep the `Event` name for
observer events, and there is no good alternative for the buffered
variant. (`Message` was suggested, but saying stuff like "sends a
collision message" is weird.)
### 3. `GlobalEvent` + `TargetedEvent`
What if instead of focusing on the buffered vs. observed split, we
*only* make a distinction between global and targeted events?
```rust
// A shared event trait to allow global observers to work
pub trait Event: Send + Sync + 'static {
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
// For buffered events and non-targeted observer events
pub trait GlobalEvent: Event {}
// For targeted observer events
pub trait TargetedEvent: Event {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
}
```
This is actually the first approach I implemented, and it has the neat
characteristic that you can only use non-targeted APIs like `trigger`
with a `GlobalEvent` and targeted APIs like `trigger_targets` with a
`TargetedEvent`. You have full control over whether the entity should or
should not have a target, as they are fully distinct at the type-level.
However, there's a few problems:
- There is no type-level indication of whether a `GlobalEvent` supports
buffered events or just non-targeted observer events
- An `Event` on its own does literally nothing, it's just a shared trait
required to make global observers accept both non-targeted and targeted
events
- If an event is both a `GlobalEvent` and `TargetedEvent`, global
observers again have ambiguity on whether an event has a target or not,
undermining some of the benefits
- The names are not ideal
### 4. `Event` and `EntityEvent`
We can fix some of the problems of Alternative 3 by accepting that
targeted events can also be used in non-targeted contexts, and simply
having the `Event` and `EntityEvent` traits:
```rust
// For buffered events and non-targeted observer events
pub trait Event: Send + Sync + 'static {
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
// For targeted observer events
pub trait EntityEvent: Event {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
}
```
This is essentially identical to this PR, just without a dedicated
`BufferedEvent`. The remaining major "problem" is that there is still
zero type-level indication of whether an `Event` event *actually*
supports the buffered API. This leads us to the solution proposed in
this PR, using `Event`, `EntityEvent`, and `BufferedEvent`.
</details>
## Conclusion
The `Event` + `EntityEvent` + `BufferedEvent` split proposed in this PR
aims to solve all the common problems with Bevy's current event model
while keeping the "weirdness" factor minimal. It splits in terms of both
the push vs. pull *and* global vs. targeted aspects, while maintaining a
shared concept for an "event".
### Why I Like This
- The term "event" remains as a single concept for all the different
kinds of events in Bevy.
- Despite all event types being "events", they use fundamentally
different APIs. Instead of assuming that you can use an event type with
any pattern (when only one is typically supported), you explicitly opt
in to each one with dedicated traits.
- Using separate traits for each type of event helps with documentation
and clearer function signatures.
- I can safely make assumptions on expected usage.
- If I see that an event is an `EntityEvent`, I can assume that I can
use `observe` on it and get targeted events.
- If I see that an event is a `BufferedEvent`, I can assume that I can
use `EventReader` to read events.
- If I see both `EntityEvent` and `BufferedEvent`, I can assume that
both APIs are supported.
In summary: This allows for a unified concept for events, while limiting
the different ways to use them with opt-in traits. No more guess-work
involved when using APIs.
### Problems?
- Because `BufferedEvent` implements `Event` (for more consistent
semantics etc.), you can still use all buffered events for non-targeted
observers. I think this is fine/good. The important part is that if you
see that an event implements `BufferedEvent`, you know that the
`EventReader`/`EventWriter` API should be supported. Whether it *also*
supports other APIs is secondary.
- I currently only support `trigger_targets` for an `EntityEvent`.
However, you can technically target components too, without targeting
any entities. I consider that such a niche and advanced use case that
it's not a huge problem to only support it for `EntityEvent`s, but we
could also split `trigger_targets` into `trigger_entities` and
`trigger_components` if we wanted to (or implement components as
entities :P).
- You can still trigger an `EntityEvent` *without* targets. I consider
this correct, since `Event` implements the non-targeted behavior, and
it'd be weird if implementing another trait *removed* behavior. However,
it does mean that global observers for entity events can technically
return `Entity::PLACEHOLDER` again (since I got rid of the
`Option<Entity>` added in #19440 for ergonomics). I think that's enough
of an edge case that it's not a huge problem, but it is worth keeping in
mind.
- ~~Deriving both `EntityEvent` and `BufferedEvent` for the same type
currently duplicates the `Event` implementation, so you instead need to
manually implement one of them.~~ Changed to always requiring `Event` to
be derived.
## Related Work
There are plans to implement multi-event support for observers,
especially for UI contexts. [Cart's
example](https://github.com/bevyengine/bevy/issues/14649#issuecomment-2960402508)
API looked like this:
```rust
// Truncated for brevity
trigger: Trigger<(
OnAdd<Pressed>,
OnRemove<Pressed>,
OnAdd<InteractionDisabled>,
OnRemove<InteractionDisabled>,
OnInsert<Hovered>,
)>,
```
I believe this shouldn't be in conflict with this PR. If anything, this
PR might *help* achieve the multi-event pattern for entity observers
with fewer footguns: by statically enforcing that all of these events
are `EntityEvent`s in the context of `EntityCommands::observe`, we can
avoid misuse or weird cases where *some* events inside the trigger are
targeted while others are not.
# Objective
Fix some grammatical errors: it's -> its
Not the most useful commit in the world, but I saw a couple of these and
decided to fix the lot.
## Solution
-
## Testing
-
# Objective
Fixes a part of #14274.
Bevy has an incredibly inconsistent naming convention for its system
sets, both internally and across the ecosystem.
<img alt="System sets in Bevy"
src="https://github.com/user-attachments/assets/d16e2027-793f-4ba4-9cc9-e780b14a5a1b"
width="450" />
*Names of public system set types in Bevy*
Most Bevy types use a naming of `FooSystem` or just `Foo`, but there are
also a few `FooSystems` and `FooSet` types. In ecosystem crates on the
other hand, `FooSet` is perhaps the most commonly used name in general.
Conventions being so wildly inconsistent can make it harder for users to
pick names for their own types, to search for system sets on docs.rs, or
to even discern which types *are* system sets.
To reign in the inconsistency a bit and help unify the ecosystem, it
would be good to establish a common recommended naming convention for
system sets in Bevy itself, similar to how plugins are commonly suffixed
with `Plugin` (ex: `TimePlugin`). By adopting a consistent naming
convention in first-party Bevy, we can softly nudge ecosystem crates to
follow suit (for types where it makes sense to do so).
Choosing a naming convention is also relevant now, as the [`bevy_cli`
recently adopted
lints](https://github.com/TheBevyFlock/bevy_cli/pull/345) to enforce
naming for plugins and system sets, and the recommended naming used for
system sets is still a bit open.
## Which Name To Use?
Now the contentious part: what naming convention should we actually
adopt?
This was discussed on the Bevy Discord at the end of last year, starting
[here](<https://discord.com/channels/691052431525675048/692572690833473578/1310659954683936789>).
`FooSet` and `FooSystems` were the clear favorites, with `FooSet` very
narrowly winning an unofficial poll. However, it seems to me like the
consensus was broadly moving towards `FooSystems` at the end and after
the poll, with Cart
([source](https://discord.com/channels/691052431525675048/692572690833473578/1311140204974706708))
and later Alice
([source](https://discord.com/channels/691052431525675048/692572690833473578/1311092530732859533))
and also me being in favor of it.
Let's do a quick pros and cons list! Of course these are just what I
thought of, so take it with a grain of salt.
`FooSet`:
- Pro: Nice and short!
- Pro: Used by many ecosystem crates.
- Pro: The `Set` suffix comes directly from the trait name `SystemSet`.
- Pro: Pairs nicely with existing APIs like `in_set` and
`configure_sets`.
- Con: `Set` by itself doesn't actually indicate that it's related to
systems *at all*, apart from the implemented trait. A set of what?
- Con: Is `FooSet` a set of `Foo`s or a system set related to `Foo`? Ex:
`ContactSet`, `MeshSet`, `EnemySet`...
`FooSystems`:
- Pro: Very clearly indicates that the type represents a collection of
systems. The actual core concept, system(s), is in the name.
- Pro: Parallels nicely with `FooPlugins` for plugin groups.
- Pro: Low risk of conflicts with other names or misunderstandings about
what the type is.
- Pro: In most cases, reads *very* nicely and clearly. Ex:
`PhysicsSystems` and `AnimationSystems` as opposed to `PhysicsSet` and
`AnimationSet`.
- Pro: Easy to search for on docs.rs.
- Con: Usually results in longer names.
- Con: Not yet as widely used.
Really the big problem with `FooSet` is that it doesn't actually
describe what it is. It describes what *kind of thing* it is (a set of
something), but not *what it is a set of*, unless you know the type or
check its docs or implemented traits. `FooSystems` on the other hand is
much more self-descriptive in this regard, at the cost of being a bit
longer to type.
Ultimately, in some ways it comes down to preference and how you think
of system sets. Personally, I was originally in favor of `FooSet`, but
have been increasingly on the side of `FooSystems`, especially after
seeing what the new names would actually look like in Avian and now
Bevy. I prefer it because it usually reads better, is much more clearly
related to groups of systems than `FooSet`, and overall *feels* more
correct and natural to me in the long term.
For these reasons, and because Alice and Cart also seemed to share a
preference for it when it was previously being discussed, I propose that
we adopt a `FooSystems` naming convention where applicable.
## Solution
Rename Bevy's system set types to use a consistent `FooSet` naming where
applicable.
- `AccessibilitySystem` → `AccessibilitySystems`
- `GizmoRenderSystem` → `GizmoRenderSystems`
- `PickSet` → `PickingSystems`
- `RunFixedMainLoopSystem` → `RunFixedMainLoopSystems`
- `TransformSystem` → `TransformSystems`
- `RemoteSet` → `RemoteSystems`
- `RenderSet` → `RenderSystems`
- `SpriteSystem` → `SpriteSystems`
- `StateTransitionSteps` → `StateTransitionSystems`
- `RenderUiSystem` → `RenderUiSystems`
- `UiSystem` → `UiSystems`
- `Animation` → `AnimationSystems`
- `AssetEvents` → `AssetEventSystems`
- `TrackAssets` → `AssetTrackingSystems`
- `UpdateGizmoMeshes` → `GizmoMeshSystems`
- `InputSystem` → `InputSystems`
- `InputFocusSet` → `InputFocusSystems`
- `ExtractMaterialsSet` → `MaterialExtractionSystems`
- `ExtractMeshesSet` → `MeshExtractionSystems`
- `RumbleSystem` → `RumbleSystems`
- `CameraUpdateSystem` → `CameraUpdateSystems`
- `ExtractAssetsSet` → `AssetExtractionSystems`
- `Update2dText` → `Text2dUpdateSystems`
- `TimeSystem` → `TimeSystems`
- `AudioPlaySet` → `AudioPlaybackSystems`
- `SendEvents` → `EventSenderSystems`
- `EventUpdates` → `EventUpdateSystems`
A lot of the names got slightly longer, but they are also a lot more
consistent, and in my opinion the majority of them read much better. For
a few of the names I took the liberty of rewording things a bit;
definitely open to any further naming improvements.
There are still also cases where the `FooSystems` naming doesn't really
make sense, and those I left alone. This primarily includes system sets
like `Interned<dyn SystemSet>`, `EnterSchedules<S>`, `ExitSchedules<S>`,
or `TransitionSchedules<S>`, where the type has some special purpose and
semantics.
## Todo
- [x] Should I keep all the old names as deprecated type aliases? I can
do this, but to avoid wasting work I'd prefer to first reach consensus
on whether these renames are even desired.
- [x] Migration guide
- [x] Release notes
# Objective
A small typo was found on `bevy_ecs/examples/event.rs`.
I know it's very minor but I'd think fixing it would still help others
in the long run.
## Solution
Fix the typo.
## Testing
I don't think this is necessary.
# Objective
- Prevent usage of `println!`, `eprintln!` and the like because they
require `std`
- Fixes#17446
## Solution
- Enable the `print_stdout` and `print_stderr` clippy lints
- Replace all `println!` and `eprintln!` occurrences with `log::*` where
applicable or alternatively ignore the warnings
## Testing
- Run `cargo clippy --workspace` to ensure that there are no warnings
relating to printing to `stdout` or `stderr`
Fixes#17856.
## Migration Guide
- `EventWriter::send` has been renamed to `EventWriter::write`.
- `EventWriter::send_batch` has been renamed to
`EventWriter::write_batch`.
- `EventWriter::send_default` has been renamed to
`EventWriter::write_default`.
---------
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
Fixes https://github.com/bevyengine/bevy/issues/17111
## Solution
Move `#![warn(clippy::allow_attributes,
clippy::allow_attributes_without_reason)]` to the workspace `Cargo.toml`
## Testing
Lots of CI testing, and local testing too.
---------
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
# Objective
Fixes#16104
## Solution
I removed all instances of `:?` and put them back one by one where it
caused an error.
I removed some bevy_utils helper functions that were only used in 2
places and don't add value. See: #11478
## Testing
CI should catch the mistakes
## Migration Guide
`bevy::utils::{dbg,info,warn,error}` were removed. Use
`bevy::utils::tracing::{debug,info,warn,error}` instead.
---------
Co-authored-by: SpecificProtagonist <vincentjunge@posteo.net>
# Objective
- Fixes#6370
- Closes#6581
## Solution
- Added the following lints to the workspace:
- `std_instead_of_core`
- `std_instead_of_alloc`
- `alloc_instead_of_core`
- Used `cargo +nightly fmt` with [item level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Item%5C%3A)
to split all `use` statements into single items.
- Used `cargo clippy --workspace --all-targets --all-features --fix
--allow-dirty` to _attempt_ to resolve the new linting issues, and
intervened where the lint was unable to resolve the issue automatically
(usually due to needing an `extern crate alloc;` statement in a crate
root).
- Manually removed certain uses of `std` where negative feature gating
prevented `--all-features` from finding the offending uses.
- Used `cargo +nightly fmt` with [crate level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Crate%5C%3A)
to re-merge all `use` statements matching Bevy's previous styling.
- Manually fixed cases where the `fmt` tool could not re-merge `use`
statements due to conditional compilation attributes.
## Testing
- Ran CI locally
## Migration Guide
The MSRV is now 1.81. Please update to this version or higher.
## Notes
- This is a _massive_ change to try and push through, which is why I've
outlined the semi-automatic steps I used to create this PR, in case this
fails and someone else tries again in the future.
- Making this change has no impact on user code, but does mean Bevy
contributors will be warned to use `core` and `alloc` instead of `std`
where possible.
- This lint is a critical first step towards investigating `no_std`
options for Bevy.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
Improve performance scalability when adding new event types to a Bevy
app. Currently, just using Bevy in the default configuration, all apps
spend upwards of 100+us in the `First` schedule, every app tick,
evaluating if it should update events or not, even if events are not
being used for that particular frame, and this scales with the number of
Events registered in the app.
## Solution
As `Events::update` is guaranteed `O(1)` by just checking if a
resource's value, swapping two Vecs, and then clearing one of them, the
actual cost of running `event_update_system` is *very* cheap. The
overhead of doing system dependency injection, task scheduling ,and the
multithreaded executor outweighs the cost of running the system by a
large margin.
Create an `EventRegistry` resource that keeps a number of function
pointers that update each event. Replace the per-event type
`event_update_system` with a singular exclusive system uses the
`EventRegistry` to update all events instead. Update `SubApp::add_event`
to use `EventRegistry` instead.
## Performance
This speeds reduces the cost of the `First` schedule in both many_foxes
and many_cubes by over 80%. Note this is with system spans on. The
majority of this is now context-switching costs from launching
`time_system`, which should be mostly eliminated with #12869.
The actual `event_update_system` is usually *very* short, using only a
few microseconds on average.
---
## Changelog
TODO
## Migration Guide
TODO
---------
Co-authored-by: Josh Matthews <josh@joshmatthews.net>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Currently the `missing_docs` lint is allowed-by-default and enabled at
crate level when their documentations is complete (see #3492).
This PR proposes to inverse this logic by making `missing_docs`
warn-by-default and mark crates with imcomplete docs allowed.
## Solution
Makes `missing_docs` warn at workspace level and allowed at crate level
when the docs is imcomplete.
# Objective
Scheduling low cost systems has significant overhead due to task pool
contention and the extra machinery to schedule and run them. Event
update systems are the prime example of a low cost system, requiring a
guaranteed O(1) operation, and there are a *lot* of them.
## Solution
Add a run condition to every event system so they only run when there is
an event in either of it's two internal Vecs.
---
## Changelog
Changed: Event update systems will not run if there are no events to
process.
## Migration Guide
`Events<T>::update_system` has been split off from the the type and can
be found at `bevy_ecs::event::event_update_system`.
---------
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
# Objective
- The current `EventReader::iter` has been determined to cause confusion
among new Bevy users. It was suggested by @JoJoJet to rename the method
to better clarify its usage.
- Solves #9624
## Solution
- Rename `EventReader::iter` to `EventReader::read`.
- Rename `EventReader::iter_with_id` to `EventReader::read_with_id`.
- Rename `ManualEventReader::iter` to `ManualEventReader::read`.
- Rename `ManualEventReader::iter_with_id` to
`ManualEventReader::read_with_id`.
---
## Changelog
- `EventReader::iter` has been renamed to `EventReader::read`.
- `EventReader::iter_with_id` has been renamed to
`EventReader::read_with_id`.
- `ManualEventReader::iter` has been renamed to
`ManualEventReader::read`.
- `ManualEventReader::iter_with_id` has been renamed to
`ManualEventReader::read_with_id`.
- Deprecated `EventReader::iter`
- Deprecated `EventReader::iter_with_id`
- Deprecated `ManualEventReader::iter`
- Deprecated `ManualEventReader::iter_with_id`
## Migration Guide
- Existing usages of `EventReader::iter` and `EventReader::iter_with_id`
will have to be changed to `EventReader::read` and
`EventReader::read_with_id` respectively.
- Existing usages of `ManualEventReader::iter` and
`ManualEventReader::iter_with_id` will have to be changed to
`ManualEventReader::read` and `ManualEventReader::read_with_id`
respectively.
# Objective
Be consistent with `Resource`s and `Components` and have `Event` types
be more self-documenting.
Although not susceptible to accidentally using a function instead of a
value due to `Event`s only being initialized by their type, much of the
same reasoning for removing the blanket impl on `Resource` also applies
here.
* Not immediately obvious if a type is intended to be an event
* Prevent invisible conflicts if the same third-party or primitive types
are used as events
* Allows for further extensions (e.g. opt-in warning for missed events)
## Solution
Remove the blanket impl for the `Event` trait. Add a derive macro for
it.
---
## Changelog
- `Event` is no longer implemented for all applicable types. Add the
`#[derive(Event)]` macro for events.
## Migration Guide
* Add the `#[derive(Event)]` macro for events. Third-party types used as
events should be wrapped in a newtype.
# Objective
Documentation should no longer be using pre-stageless terminology to
avoid confusion.
## Solution
- update all docs referring to stages to instead refer to sets/schedules
where appropriate
- also mention `apply_system_buffers` for anything system-buffer-related
that previously referred to buffers being applied "at the end of a
stage"
Huge thanks to @maniwani, @devil-ira, @hymm, @cart, @superdump and @jakobhellermann for the help with this PR.
# Objective
- Followup #6587.
- Minimal integration for the Stageless Scheduling RFC: https://github.com/bevyengine/rfcs/pull/45
## Solution
- [x] Remove old scheduling module
- [x] Migrate new methods to no longer use extension methods
- [x] Fix compiler errors
- [x] Fix benchmarks
- [x] Fix examples
- [x] Fix docs
- [x] Fix tests
## Changelog
### Added
- a large number of methods on `App` to work with schedules ergonomically
- the `CoreSchedule` enum
- `App::add_extract_system` via the `RenderingAppExtension` trait extension method
- the private `prepare_view_uniforms` system now has a public system set for scheduling purposes, called `ViewSet::PrepareUniforms`
### Removed
- stages, and all code that mentions stages
- states have been dramatically simplified, and no longer use a stack
- `RunCriteriaLabel`
- `AsSystemLabel` trait
- `on_hierarchy_reports_enabled` run criteria (now just uses an ad hoc resource checking run condition)
- systems in `RenderSet/Stage::Extract` no longer warn when they do not read data from the main world
- `RunCriteriaLabel`
- `transform_propagate_system_set`: this was a nonstandard pattern that didn't actually provide enough control. The systems are already `pub`: the docs have been updated to ensure that the third-party usage is clear.
### Changed
- `System::default_labels` is now `System::default_system_sets`.
- `App::add_default_labels` is now `App::add_default_sets`
- `CoreStage` and `StartupStage` enums are now `CoreSet` and `StartupSet`
- `App::add_system_set` was renamed to `App::add_systems`
- The `StartupSchedule` label is now defined as part of the `CoreSchedules` enum
- `.label(SystemLabel)` is now referred to as `.in_set(SystemSet)`
- `SystemLabel` trait was replaced by `SystemSet`
- `SystemTypeIdLabel<T>` was replaced by `SystemSetType<T>`
- The `ReportHierarchyIssue` resource now has a public constructor (`new`), and implements `PartialEq`
- Fixed time steps now use a schedule (`CoreSchedule::FixedTimeStep`) rather than a run criteria.
- Adding rendering extraction systems now panics rather than silently failing if no subapp with the `RenderApp` label is found.
- the `calculate_bounds` system, with the `CalculateBounds` label, is now in `CoreSet::Update`, rather than in `CoreSet::PostUpdate` before commands are applied.
- `SceneSpawnerSystem` now runs under `CoreSet::Update`, rather than `CoreStage::PreUpdate.at_end()`.
- `bevy_pbr::add_clusters` is no longer an exclusive system
- the top level `bevy_ecs::schedule` module was replaced with `bevy_ecs::scheduling`
- `tick_global_task_pools_on_main_thread` is no longer run as an exclusive system. Instead, it has been replaced by `tick_global_task_pools`, which uses a `NonSend` resource to force running on the main thread.
## Migration Guide
- Calls to `.label(MyLabel)` should be replaced with `.in_set(MySet)`
- Stages have been removed. Replace these with system sets, and then add command flushes using the `apply_system_buffers` exclusive system where needed.
- The `CoreStage`, `StartupStage, `RenderStage` and `AssetStage` enums have been replaced with `CoreSet`, `StartupSet, `RenderSet` and `AssetSet`. The same scheduling guarantees have been preserved.
- Systems are no longer added to `CoreSet::Update` by default. Add systems manually if this behavior is needed, although you should consider adding your game logic systems to `CoreSchedule::FixedTimestep` instead for more reliable framerate-independent behavior.
- Similarly, startup systems are no longer part of `StartupSet::Startup` by default. In most cases, this won't matter to you.
- For example, `add_system_to_stage(CoreStage::PostUpdate, my_system)` should be replaced with
- `add_system(my_system.in_set(CoreSet::PostUpdate)`
- When testing systems or otherwise running them in a headless fashion, simply construct and run a schedule using `Schedule::new()` and `World::run_schedule` rather than constructing stages
- Run criteria have been renamed to run conditions. These can now be combined with each other and with states.
- Looping run criteria and state stacks have been removed. Use an exclusive system that runs a schedule if you need this level of control over system control flow.
- For app-level control flow over which schedules get run when (such as for rollback networking), create your own schedule and insert it under the `CoreSchedule::Outer` label.
- Fixed timesteps are now evaluated in a schedule, rather than controlled via run criteria. The `run_fixed_timestep` system runs this schedule between `CoreSet::First` and `CoreSet::PreUpdate` by default.
- Command flush points introduced by `AssetStage` have been removed. If you were relying on these, add them back manually.
- Adding extract systems is now typically done directly on the main app. Make sure the `RenderingAppExtension` trait is in scope, then call `app.add_extract_system(my_system)`.
- the `calculate_bounds` system, with the `CalculateBounds` label, is now in `CoreSet::Update`, rather than in `CoreSet::PostUpdate` before commands are applied. You may need to order your movement systems to occur before this system in order to avoid system order ambiguities in culling behavior.
- the `RenderLabel` `AppLabel` was renamed to `RenderApp` for clarity
- `App::add_state` now takes 0 arguments: the starting state is set based on the `Default` impl.
- Instead of creating `SystemSet` containers for systems that run in stages, simply use `.on_enter::<State::Variant>()` or its `on_exit` or `on_update` siblings.
- `SystemLabel` derives should be replaced with `SystemSet`. You will also need to add the `Debug`, `PartialEq`, `Eq`, and `Hash` traits to satisfy the new trait bounds.
- `with_run_criteria` has been renamed to `run_if`. Run criteria have been renamed to run conditions for clarity, and should now simply return a bool.
- States have been dramatically simplified: there is no longer a "state stack". To queue a transition to the next state, call `NextState::set`
## TODO
- [x] remove dead methods on App and World
- [x] add `App::add_system_to_schedule` and `App::add_systems_to_schedule`
- [x] avoid adding the default system set at inappropriate times
- [x] remove any accidental cycles in the default plugins schedule
- [x] migrate benchmarks
- [x] expose explicit labels for the built-in command flush points
- [x] migrate engine code
- [x] remove all mentions of stages from the docs
- [x] verify docs for States
- [x] fix uses of exclusive systems that use .end / .at_start / .before_commands
- [x] migrate RenderStage and AssetStage
- [x] migrate examples
- [x] ensure that transform propagation is exported in a sufficiently public way (the systems are already pub)
- [x] ensure that on_enter schedules are run at least once before the main app
- [x] re-enable opt-in to execution order ambiguities
- [x] revert change to `update_bounds` to ensure it runs in `PostUpdate`
- [x] test all examples
- [x] unbreak directional lights
- [x] unbreak shadows (see 3d_scene, 3d_shape, lighting, transparaency_3d examples)
- [x] game menu example shows loading screen and menu simultaneously
- [x] display settings menu is a blank screen
- [x] `without_winit` example panics
- [x] ensure all tests pass
- [x] SubApp doc test fails
- [x] runs_spawn_local tasks fails
- [x] [Fix panic_when_hierachy_cycle test hanging](https://github.com/alice-i-cecile/bevy/pull/120)
## Points of Difficulty and Controversy
**Reviewers, please give feedback on these and look closely**
1. Default sets, from the RFC, have been removed. These added a tremendous amount of implicit complexity and result in hard to debug scheduling errors. They're going to be tackled in the form of "base sets" by @cart in a followup.
2. The outer schedule controls which schedule is run when `App::update` is called.
3. I implemented `Label for `Box<dyn Label>` for our label types. This enables us to store schedule labels in concrete form, and then later run them. I ran into the same set of problems when working with one-shot systems. We've previously investigated this pattern in depth, and it does not appear to lead to extra indirection with nested boxes.
4. `SubApp::update` simply runs the default schedule once. This sucks, but this whole API is incomplete and this was the minimal changeset.
5. `time_system` and `tick_global_task_pools_on_main_thread` no longer use exclusive systems to attempt to force scheduling order
6. Implemetnation strategy for fixed timesteps
7. `AssetStage` was migrated to `AssetSet` without reintroducing command flush points. These did not appear to be used, and it's nice to remove these bottlenecks.
8. Migration of `bevy_render/lib.rs` and pipelined rendering. The logic here is unusually tricky, as we have complex scheduling requirements.
## Future Work (ideally before 0.10)
- Rename schedule_v3 module to schedule or scheduling
- Add a derive macro to states, and likely a `EnumIter` trait of some form
- Figure out what exactly to do with the "systems added should basically work by default" problem
- Improve ergonomics for working with fixed timesteps and states
- Polish FixedTime API to match Time
- Rebase and merge #7415
- Resolve all internal ambiguities (blocked on better tools, especially #7442)
- Add "base sets" to replace the removed default sets.
# Objective
- fix new clippy lints before they get stable and break CI
## Solution
- run `clippy --fix` to auto-fix machine-applicable lints
- silence `clippy::should_implement_trait` for `fn HandleId::default<T: Asset>`
## Changes
- always prefer `format!("{inline}")` over `format!("{}", not_inline)`
- prefer `Box::default` (or `Box::<T>::default` if necessary) over `Box::new(T::default())`
# Objective
Now that we can consolidate Bundles and Components under a single insert (thanks to #2975 and #6039), almost 100% of world spawns now look like `world.spawn().insert((Some, Tuple, Here))`. Spawning an entity without any components is an extremely uncommon pattern, so it makes sense to give spawn the "first class" ergonomic api. This consolidated api should be made consistent across all spawn apis (such as World and Commands).
## Solution
All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input:
```rust
// before:
commands
.spawn()
.insert((A, B, C));
world
.spawn()
.insert((A, B, C);
// after
commands.spawn((A, B, C));
world.spawn((A, B, C));
```
All existing instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api. A new `spawn_empty` has been added, replacing the old `spawn` api.
By allowing `world.spawn(some_bundle)` to replace `world.spawn().insert(some_bundle)`, this opened the door to removing the initial entity allocation in the "empty" archetype / table done in `spawn()` (and subsequent move to the actual archetype in `.insert(some_bundle)`).
This improves spawn performance by over 10%:
To take this measurement, I added a new `world_spawn` benchmark.
Unfortunately, optimizing `Commands::spawn` is slightly less trivial, as Commands expose the Entity id of spawned entities prior to actually spawning. Doing the optimization would (naively) require assurances that the `spawn(some_bundle)` command is applied before all other commands involving the entity (which would not necessarily be true, if memory serves). Optimizing `Commands::spawn` this way does feel possible, but it will require careful thought (and maybe some additional checks), which deserves its own PR. For now, it has the same performance characteristics of the current `Commands::spawn_bundle` on main.
**Note that 99% of this PR is simple renames and refactors. The only code that needs careful scrutiny is the new `World::spawn()` impl, which is relatively straightforward, but it has some new unsafe code (which re-uses battle tested BundlerSpawner code path).**
---
## Changelog
- All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input
- All instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api
- World and Commands now have `spawn_empty()`, which is equivalent to the old `spawn()` behavior.
## Migration Guide
```rust
// Old (0.8):
commands
.spawn()
.insert_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
commands.spawn_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
let entity = commands.spawn().id();
// New (0.9)
let entity = commands.spawn_empty().id();
// Old (0.8)
let entity = world.spawn().id();
// New (0.9)
let entity = world.spawn_empty();
```
# Objective
Take advantage of the "impl Bundle for Component" changes in #2975 / add the follow up changes discussed there.
## Solution
- Change `insert` and `remove` to accept a Bundle instead of a Component (for both Commands and World)
- Deprecate `insert_bundle`, `remove_bundle`, and `remove_bundle_intersection`
- Add `remove_intersection`
---
## Changelog
- Change `insert` and `remove` now accept a Bundle instead of a Component (for both Commands and World)
- `insert_bundle` and `remove_bundle` are deprecated
## Migration Guide
Replace `insert_bundle` with `insert`:
```rust
// Old (0.8)
commands.spawn().insert_bundle(SomeBundle::default());
// New (0.9)
commands.spawn().insert(SomeBundle::default());
```
Replace `remove_bundle` with `remove`:
```rust
// Old (0.8)
commands.entity(some_entity).remove_bundle::<SomeBundle>();
// New (0.9)
commands.entity(some_entity).remove::<SomeBundle>();
```
Replace `remove_bundle_intersection` with `remove_intersection`:
```rust
// Old (0.8)
world.entity_mut(some_entity).remove_bundle_intersection::<SomeBundle>();
// New (0.9)
world.entity_mut(some_entity).remove_intersection::<SomeBundle>();
```
Consider consolidating as many operations as possible to improve ergonomics and cut down on archetype moves:
```rust
// Old (0.8)
commands.spawn()
.insert_bundle(SomeBundle::default())
.insert(SomeComponent);
// New (0.9) - Option 1
commands.spawn().insert((
SomeBundle::default(),
SomeComponent,
))
// New (0.9) - Option 2
commands.spawn_bundle((
SomeBundle::default(),
SomeComponent,
))
```
## Next Steps
Consider changing `spawn` to accept a bundle and deprecate `spawn_bundle`.
*This PR description is an edited copy of #5007, written by @alice-i-cecile.*
# Objective
Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds.
While ergonomic, this results in several drawbacks:
* it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource
* it is challenging to discover if a type is intended to be used as a resource
* we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component).
* dependencies can use the same Rust type as a resource in invisibly conflicting ways
* raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values
* we cannot capture a definitive list of possible resources to display to users in an editor
## Notes to reviewers
* Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits.
*ira: My commits are not as well organized :')*
* I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does.
* I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981.
## Changelog
`Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro.
## Migration Guide
Add `#[derive(Resource)]` to all types you are using as a resource.
If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics.
`ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing.
Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead.
Co-authored-by: Alice <alice.i.cecile@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: devil-ira <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Fixes#5362
## Solution
Add the attribute `#[label(ignore_fields)]` for `*Label` types.
```rust
#[derive(SystemLabel)]
pub enum MyLabel {
One,
// Previously this was not allowed since labels cannot contain data.
#[system_label(ignore_fields)]
Two(PhantomData<usize>),
}
```
## Notes
This label makes it possible for equality to behave differently depending on whether or not you are treating the type as a label. For example:
```rust
#[derive(SystemLabel, PartialEq, Eq)]
#[system_label(ignore_fields)]
pub struct Foo(usize);
```
If you compare it as a label, it will ignore the wrapped fields as the user requested. But if you compare it as a `Foo`, the derive will incorrectly compare the inner fields. I see a few solutions
1. Do nothing. This is technically intended behavior, but I think we should do our best to prevent footguns.
2. Generate impls of `PartialEq` and `Eq` along with the `#[derive(Label)]` macros. This is a breaking change as it requires all users to remove these derives from their types.
3. Only allow `PhantomData` to be used with `ignore_fields` -- seems needlessly prescriptive.
---
## Changelog
* Added the `ignore_fields` attribute to the derive macros for `*Label` types.
* Added an example showing off different forms of the derive macro.
<!--
## Migration Guide
> This section is optional. If there are no breaking changes, you can delete this section.
- If this PR is a breaking change (relative to the last release of Bevy), describe how a user might need to migrate their code to support these changes
- Simply adding new functionality is not a breaking change.
- Fixing behavior that was definitely a bug, rather than a questionable design choice is not a breaking change.
-->
Remove unnecessary calls to `iter()`/`iter_mut()`.
Mainly updates the use of queries in our code, docs, and examples.
```rust
// From
for _ in list.iter() {
for _ in list.iter_mut() {
// To
for _ in &list {
for _ in &mut list {
```
We already enable the pedantic lint [clippy::explicit_iter_loop](https://rust-lang.github.io/rust-clippy/stable/) inside of Bevy. However, this only warns for a few known types from the standard library.
## Note for reviewers
As you can see the additions and deletions are exactly equal.
Maybe give it a quick skim to check I didn't sneak in a crypto miner, but you don't have to torture yourself by reading every line.
I already experienced enough pain making this PR :)
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
- Since #4224, using labels which only refer to one system doesn't make sense.
## Solution
- Remove some of those.
## Future work
- We should remove the ability to use strings as system labels entirely. I haven't in this PR because there are tests which use this, and that's a lot of code to change.
- The only use cases for labels are either intra-crate, which use #4224, or inter-crate, which should either use #4224 or explicit types. Neither of those should use strings.
This implements the most minimal variant of #1843 - a derive for marker trait. This is a prerequisite to more complicated features like statically defined storage type or opt-out component reflection.
In order to make component struct's purpose explicit and avoid misuse, it must be annotated with `#[derive(Component)]` (manual impl is discouraged for compatibility). Right now this is just a marker trait, but in the future it might be expanded. Making this change early allows us to make further changes later without breaking backward compatibility for derive macro users.
This already prevents a lot of issues, like using bundles in `insert` calls. Primitive types are no longer valid components as well. This can be easily worked around by adding newtype wrappers and deriving `Component` for them.
One funny example of prevented bad code (from our own tests) is when an newtype struct or enum variant is used. Previously, it was possible to write `insert(Newtype)` instead of `insert(Newtype(value))`. That code compiled, because function pointers (in this case newtype struct constructor) implement `Send + Sync + 'static`, so we allowed them to be used as components. This is no longer the case and such invalid code will trigger a compile error.
Co-authored-by: = <=>
Co-authored-by: TheRawMeatball <therawmeatball@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- CI is failing again
- These failures result from https://github.com/rust-lang/rust/pull/85200
## Solution
- Fix the errors which result from this by using the given fields
- I also removed the now unused `Debug` impl.
I suspect that we shouldn't use -D warnings for nightly CI - ideally we'd get a discord webhook message into some (non-#github) dedicated channel on warnings.
But this does not implement that.
# Objective
- Remove all the `.system()` possible.
- Check for remaining missing cases.
## Solution
- Remove all `.system()`, fix compile errors
- 32 calls to `.system()` remains, mostly internals, the few others should be removed after #2446
[RENDERED](https://github.com/NiklasEi/bevy/blob/ecs_readme/crates/bevy_ecs/README.md)
Since I am trying to learn more about Bevy ECS at the moment, I thought this issue is a perfect fit.
This PR adds a readme to the `bevy_ecs` crate containing a minimal running example of stand alone `bevy_ecs`. Unique features like customizable component storage, Resources or change detection are introduced. For each of these features the readme links to an example in a newly created examples directory inside the `bevy_esc` crate.
Resolves#2008
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
