# Objective
- Contributes to #15460
- Reduce quantity and complexity of feature gates across Bevy
## Solution
- Used `target_has_atomic` configuration variable to automatically
detect impartial atomic support and automatically switch to
`portable-atomic` over the standard library on an as-required basis.
## Testing
- CI
## Notes
To explain the technique employed here, consider getting `Arc` either
from `alloc::sync` _or_ `portable-atomic-util`. First, we can inspect
the `alloc` crate to see that you only have access to `Arc` _if_
`target_has_atomic = "ptr"`. We add a target dependency for this
particular configuration _inverted_:
```toml
[target.'cfg(not(target_has_atomic = "ptr"))'.dependencies]
portable-atomic-util = { version = "0.2.4", default-features = false }
```
This ensures we only have the dependency when it is needed, and it is
entirely excluded from the dependency graph when it is not. Next, we
adjust our configuration flags to instead of checking for `feature =
"portable-atomic"` to instead check for `target_has_atomic = "ptr"`:
```rust
// `alloc` feature flag hidden for brevity
#[cfg(not(target_has_atomic = "ptr"))]
use portable_atomic_util as arc;
#[cfg(target_has_atomic = "ptr")]
use alloc::sync as arc;
pub use arc::{Arc, Weak};
```
The benefits of this technique are three-fold:
1. For platforms without full atomic support, the functionality is
enabled automatically.
2. For platforms with atomic support, the dependency is never included,
even if a feature was enabled using `--all-features` (for example)
3. The `portable-atomic` feature no longer needs to virally spread to
all user-facing crates, it's instead something handled within
`bevy_platform_support` (with some extras where other dependencies also
need their features enabled).
# Objective
- Fixes#17960
## Solution
- Followed the [edition upgrade
guide](https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html)
## Testing
- CI
---
## Summary of Changes
### Documentation Indentation
When using lists in documentation, proper indentation is now linted for.
This means subsequent lines within the same list item must start at the
same indentation level as the item.
```rust
/* Valid */
/// - Item 1
/// Run-on sentence.
/// - Item 2
struct Foo;
/* Invalid */
/// - Item 1
/// Run-on sentence.
/// - Item 2
struct Foo;
```
### Implicit `!` to `()` Conversion
`!` (the never return type, returned by `panic!`, etc.) no longer
implicitly converts to `()`. This is particularly painful for systems
with `todo!` or `panic!` statements, as they will no longer be functions
returning `()` (or `Result<()>`), making them invalid systems for
functions like `add_systems`. The ideal fix would be to accept functions
returning `!` (or rather, _not_ returning), but this is blocked on the
[stabilisation of the `!` type
itself](https://doc.rust-lang.org/std/primitive.never.html), which is
not done.
The "simple" fix would be to add an explicit `-> ()` to system
signatures (e.g., `|| { todo!() }` becomes `|| -> () { todo!() }`).
However, this is _also_ banned, as there is an existing lint which (IMO,
incorrectly) marks this as an unnecessary annotation.
So, the "fix" (read: workaround) is to put these kinds of `|| -> ! { ...
}` closuers into variables and give the variable an explicit type (e.g.,
`fn()`).
```rust
// Valid
let system: fn() = || todo!("Not implemented yet!");
app.add_systems(..., system);
// Invalid
app.add_systems(..., || todo!("Not implemented yet!"));
```
### Temporary Variable Lifetimes
The order in which temporary variables are dropped has changed. The
simple fix here is _usually_ to just assign temporaries to a named
variable before use.
### `gen` is a keyword
We can no longer use the name `gen` as it is reserved for a future
generator syntax. This involved replacing uses of the name `gen` with
`r#gen` (the raw-identifier syntax).
### Formatting has changed
Use statements have had the order of imports changed, causing a
substantial +/-3,000 diff when applied. For now, I have opted-out of
this change by amending `rustfmt.toml`
```toml
style_edition = "2021"
```
This preserves the original formatting for now, reducing the size of
this PR. It would be a simple followup to update this to 2024 and run
`cargo fmt`.
### New `use<>` Opt-Out Syntax
Lifetimes are now implicitly included in RPIT types. There was a handful
of instances where it needed to be added to satisfy the borrow checker,
but there may be more cases where it _should_ be added to avoid
breakages in user code.
### `MyUnitStruct { .. }` is an invalid pattern
Previously, you could match against unit structs (and unit enum
variants) with a `{ .. }` destructuring. This is no longer valid.
### Pretty much every use of `ref` and `mut` are gone
Pattern binding has changed to the point where these terms are largely
unused now. They still serve a purpose, but it is far more niche now.
### `iter::repeat(...).take(...)` is bad
New lint recommends using the more explicit `iter::repeat_n(..., ...)`
instead.
## Migration Guide
The lifetimes of functions using return-position impl-trait (RPIT) are
likely _more_ conservative than they had been previously. If you
encounter lifetime issues with such a function, please create an issue
to investigate the addition of `+ use<...>`.
## Notes
- Check the individual commits for a clearer breakdown for what
_actually_ changed.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
- Contributes to #15460
## Solution
- Switched `tracing` for `log` for the atomically challenged platforms
- Setup feature flags as required
- Added to `compile-check-no-std` CI task
## Testing
- CI
---
## Notes
- _Very_ easy one this time. Most of the changes here are just feature
definitions and documentation within the `Cargo.toml`
This adds support for one-to-many non-fragmenting relationships (with
planned paths for fragmenting and non-fragmenting many-to-many
relationships). "Non-fragmenting" means that entities with the same
relationship type, but different relationship targets, are not forced
into separate tables (which would cause "table fragmentation").
Functionally, this fills a similar niche as the current Parent/Children
system. The biggest differences are:
1. Relationships have simpler internals and significantly improved
performance and UX. Commands and specialized APIs are no longer
necessary to keep everything in sync. Just spawn entities with the
relationship components you want and everything "just works".
2. Relationships are generalized. Bevy can provide additional built in
relationships, and users can define their own.
**REQUEST TO REVIEWERS**: _please don't leave top level comments and
instead comment on specific lines of code. That way we can take
advantage of threaded discussions. Also dont leave comments simply
pointing out CI failures as I can read those just fine._
## Built on top of what we have
Relationships are implemented on top of the Bevy ECS features we already
have: components, immutability, and hooks. This makes them immediately
compatible with all of our existing (and future) APIs for querying,
spawning, removing, scenes, reflection, etc. The fewer specialized APIs
we need to build, maintain, and teach, the better.
## Why focus on one-to-many non-fragmenting first?
1. This allows us to improve Parent/Children relationships immediately,
in a way that is reasonably uncontroversial. Switching our hierarchy to
fragmenting relationships would have significant performance
implications. ~~Flecs is heavily considering a switch to non-fragmenting
relations after careful considerations of the performance tradeoffs.~~
_(Correction from @SanderMertens: Flecs is implementing non-fragmenting
storage specialized for asset hierarchies, where asset hierarchies are
many instances of small trees that have a well defined structure)_
2. Adding generalized one-to-many relationships is currently a priority
for the [Next Generation Scene / UI
effort](https://github.com/bevyengine/bevy/discussions/14437).
Specifically, we're interested in building reactions and observers on
top.
## The changes
This PR does the following:
1. Adds a generic one-to-many Relationship system
3. Ports the existing Parent/Children system to Relationships, which now
lives in `bevy_ecs::hierarchy`. The old `bevy_hierarchy` crate has been
removed.
4. Adds on_despawn component hooks
5. Relationships can opt-in to "despawn descendants" behavior, meaning
that the entire relationship hierarchy is despawned when
`entity.despawn()` is called. The built in Parent/Children hierarchies
enable this behavior, and `entity.despawn_recursive()` has been removed.
6. `world.spawn` now applies commands after spawning. This ensures that
relationship bookkeeping happens immediately and removes the need to
manually flush. This is in line with the equivalent behaviors recently
added to the other APIs (ex: insert).
7. Removes the ValidParentCheckPlugin (system-driven / poll based) in
favor of a `validate_parent_has_component` hook.
## Using Relationships
The `Relationship` trait looks like this:
```rust
pub trait Relationship: Component + Sized {
type RelationshipSources: RelationshipSources<Relationship = Self>;
fn get(&self) -> Entity;
fn from(entity: Entity) -> Self;
}
```
A relationship is a component that:
1. Is a simple wrapper over a "target" Entity.
2. Has a corresponding `RelationshipSources` component, which is a
simple wrapper over a collection of entities. Every "target entity"
targeted by a "source entity" with a `Relationship` has a
`RelationshipSources` component, which contains every "source entity"
that targets it.
For example, the `Parent` component (as it currently exists in Bevy) is
the `Relationship` component and the entity containing the Parent is the
"source entity". The entity _inside_ the `Parent(Entity)` component is
the "target entity". And that target entity has a `Children` component
(which implements `RelationshipSources`).
In practice, the Parent/Children relationship looks like this:
```rust
#[derive(Relationship)]
#[relationship(relationship_sources = Children)]
pub struct Parent(pub Entity);
#[derive(RelationshipSources)]
#[relationship_sources(relationship = Parent)]
pub struct Children(Vec<Entity>);
```
The Relationship and RelationshipSources derives automatically implement
Component with the relevant configuration (namely, the hooks necessary
to keep everything in sync).
The most direct way to add relationships is to spawn entities with
relationship components:
```rust
let a = world.spawn_empty().id();
let b = world.spawn(Parent(a)).id();
assert_eq!(world.entity(a).get::<Children>().unwrap(), &[b]);
```
There are also convenience APIs for spawning more than one entity with
the same relationship:
```rust
world.spawn_empty().with_related::<Children>(|s| {
s.spawn_empty();
s.spawn_empty();
})
```
The existing `with_children` API is now a simpler wrapper over
`with_related`. This makes this change largely non-breaking for existing
spawn patterns.
```rust
world.spawn_empty().with_children(|s| {
s.spawn_empty();
s.spawn_empty();
})
```
There are also other relationship APIs, such as `add_related` and
`despawn_related`.
## Automatic recursive despawn via the new on_despawn hook
`RelationshipSources` can opt-in to "despawn descendants" behavior,
which will despawn all related entities in the relationship hierarchy:
```rust
#[derive(RelationshipSources)]
#[relationship_sources(relationship = Parent, despawn_descendants)]
pub struct Children(Vec<Entity>);
```
This means that `entity.despawn_recursive()` is no longer required.
Instead, just use `entity.despawn()` and the relevant related entities
will also be despawned.
To despawn an entity _without_ despawning its parent/child descendants,
you should remove the `Children` component first, which will also remove
the related `Parent` components:
```rust
entity
.remove::<Children>()
.despawn()
```
This builds on the on_despawn hook introduced in this PR, which is fired
when an entity is despawned (before other hooks).
## Relationships are the source of truth
`Relationship` is the _single_ source of truth component.
`RelationshipSources` is merely a reflection of what all the
`Relationship` components say. By embracing this, we are able to
significantly improve the performance of the system as a whole. We can
rely on component lifecycles to protect us against duplicates, rather
than needing to scan at runtime to ensure entities don't already exist
(which results in quadratic runtime). A single source of truth gives us
constant-time inserts. This does mean that we cannot directly spawn
populated `Children` components (or directly add or remove entities from
those components). I personally think this is a worthwhile tradeoff,
both because it makes the performance much better _and_ because it means
theres exactly one way to do things (which is a philosophy we try to
employ for Bevy APIs).
As an aside: treating both sides of the relationship as "equivalent
source of truth relations" does enable building simple and flexible
many-to-many relationships. But this introduces an _inherent_ need to
scan (or hash) to protect against duplicates.
[`evergreen_relations`](https://github.com/EvergreenNest/evergreen_relations)
has a very nice implementation of the "symmetrical many-to-many"
approach. Unfortunately I think the performance issues inherent to that
approach make it a poor choice for Bevy's default relationship system.
## Followup Work
* Discuss renaming `Parent` to `ChildOf`. I refrained from doing that in
this PR to keep the diff reasonable, but I'm personally biased toward
this change (and using that naming pattern generally for relationships).
* [Improved spawning
ergonomics](https://github.com/bevyengine/bevy/discussions/16920)
* Consider adding relationship observers/triggers for "relationship
targets" whenever a source is added or removed. This would replace the
current "hierarchy events" system, which is unused upstream but may have
existing users downstream. I think triggers are the better fit for this
than a buffered event queue, and would prefer not to add that back.
* Fragmenting relations: My current idea hinges on the introduction of
"value components" (aka: components whose type _and_ value determines
their ComponentId, via something like Hashing / PartialEq). By labeling
a Relationship component such as `ChildOf(Entity)` as a "value
component", `ChildOf(e1)` and `ChildOf(e2)` would be considered
"different components". This makes the transition between fragmenting
and non-fragmenting a single flag, and everything else continues to work
as expected.
* Many-to-many support
* Non-fragmenting: We can expand Relationship to be a list of entities
instead of a single entity. I have largely already written the code for
this.
* Fragmenting: With the "value component" impl mentioned above, we get
many-to-many support "for free", as it would allow inserting multiple
copies of a Relationship component with different target entities.
Fixes#3742 (If this PR is merged, I think we should open more targeted
followup issues for the work above, with a fresh tracking issue free of
the large amount of less-directed historical context)
Fixes#17301Fixes#12235Fixes#15299Fixes#15308
## Migration Guide
* Replace `ChildBuilder` with `ChildSpawnerCommands`.
* Replace calls to `.set_parent(parent_id)` with
`.insert(Parent(parent_id))`.
* Replace calls to `.replace_children()` with `.remove::<Children>()`
followed by `.add_children()`. Note that you'll need to manually despawn
any children that are not carried over.
* Replace calls to `.despawn_recursive()` with `.despawn()`.
* Replace calls to `.despawn_descendants()` with
`.despawn_related::<Children>()`.
* If you have any calls to `.despawn()` which depend on the children
being preserved, you'll need to remove the `Children` component first.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
While directional navigation is helpful for UI in general for
accessibility reasons, it is *especially* valuable for a game engine,
where menus may be navigated primarily or exclusively through the use of
a game controller.
Thumb-stick powered cursor-based navigation can work as a fallback, but
is generally a pretty poor user experience. We can do better!
## Prior art
Within Bevy, https://github.com/nicopap/ui-navigation and
https://github.com/rparrett/bevy-alt-ui-navigation-lite exist to solve
this same problem. This isn't yet a complete replacement for that
ecosystem, but hopefully we'll be there for 0.16.
## Solution
UI navigation is complicated, and the right tradeoffs will vary based on
the project and even the individual scene.
We're starting with something simple and flexible, hooking into the
existing `InputFocus` resource, and storing a manually constructed graph
of entities to explore in a `DirectionalNavigationMap` resource. The
developer experience won't be great (so much wiring to do!), but the
tools are all there for a great user experience.
We could have chosen to represent these linkages via component-flavored
not-quite-relations. This would be useful for inspectors, and would give
us automatic cleanup when the entities were despawned, but seriously
complicates the developer experience when building and checking this
API. For now, we're doing a dumb "entity graph in a resource" thing and
`remove` helpers. Once relations are added, we can re-evaluate.
I've decided to use a `CompassOctant` as our key for the possible paths.
This should give users a reasonable amount of precise control without
being fiddly, and playing reasonably nicely with arrow-key navigation.
This design lets us store the set of entities that we're connected to as
a 8-byte array (yay Entity-niching). In theory, this is maybe nicer than
the double indirection of two hashmaps. but if this ends up being slow
we should create benchmarks.
To make this work more pleasant, I've added a few utilities to the
`CompassOctant` type: converting to and from usize, and adding a helper
to find the 180 degrees opposite direction. These have been mirrored
onto `CompassQuadrant` for consistency: they should be generally useful
for game logic.
## Future work
This is a relatively complex initiative! In the hopes of easing review
and avoiding merge conflicts, I've opted to split this work into
bite-sized chunks.
Before 0.16, I'd like to have:
- An example demonstrating gamepad and tab-based navigation in a
realistic game menu
- Helpers to convert axis-based inputs into compass quadrants / octants
- Tools to check the listed graph desiderata
- A helper to build a graph from a grid of entities
- A tool to automatically build a graph given a supplied UI layout
One day, it would be sweet if:
- We had an example demonstrating how to use focus navigation in a
non-UI scene to cycle between game objects
- Standard actions for tab-style and directional navigation with a
first-party bevy_actions integration
- We had a visual debugging tool to display these navigation graphs for
QC purposes
- There was a built-in way to go "up a level" by cancelling the current
action
- The navigation graph is built completely out of relations
## Testing
- tests for the new `CompassQuadrant` / `CompassOctant` methods
- tests for the new directional navigation module
---------
Co-authored-by: Rob Parrett <robparrett@gmail.com>
Bump version after release
This PR has been auto-generated
---------
Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
- Contributes to #11478
## Solution
- Made `bevy_utils::tracing` `doc(hidden)`
- Re-exported `tracing` from `bevy_log` for end-users
- Added `tracing` directly to crates that need it.
## Testing
- CI
---
## Migration Guide
If you were importing `tracing` via `bevy::utils::tracing`, instead use
`bevy::log::tracing`. Note that many items within `tracing` are also
directly re-exported from `bevy::log` as well, so you may only need
`bevy::log` for the most common items (e.g., `warn!`, `trace!`, etc.).
This also applies to the `log_once!` family of macros.
## Notes
- While this doesn't reduce the line-count in `bevy_utils`, it further
decouples the internal crates from `bevy_utils`, making its eventual
removal more feasible in the future.
- I have just imported `tracing` as we do for all dependencies. However,
a workspace dependency may be more appropriate for version management.
# Objective
Tab navigation can fail in all manner of ways. The current API
recognizes this, but merely logs a warning and returns `None`.
We should supply the actual reason for failure to the caller, so they
can handle it in whatever fashion they please (including logging a
warning!).
Swapping to a Result-oriented pattern is also a bit more idiomatic and
makes the code's control flow easier to follow.
## Solution
- Refactor the `tab_navigation` module to return a `Result` rather than
an `Option` from its key APIs.
- Move the logging to the provided prebuilt observer. This leaves the
default behavior largely unchanged, but allows for better user control.
- Make the case where no tab group was found for the currently focused
entity an error branch, but provide enough information that we can still
recover from it.
## Testing
The `tab_navigation` example continues to function as intended.
# Objective
The rust-versions are out of date.
Fixes#17008
## Solution
Update the values
Cherry-picked from #17006 in case it is controversial
## Testing
Validated locally and in #17006
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
This PR continues the work of `bevy_input_focus` by adding a pluggable
tab navigation framework.
As part of this work, `FocusKeyboardEvent` now propagates to the window
after exhausting all ancestors.
## Testing
Unit tests and manual tests.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
I was curious to use the newly created `bevy_input_focus`, but I found
some issues with it
- It was only implementing traits for `World`.
- Lack of tests
- `is_focus_within` logic was incorrect.
## Solution
This PR includes some improvements to the `bevy_input_focus` crate:
- Add new `IsFocusedHelper` that doesn't require access to `&World`. It
implements `IsFocused`
- Remove `IsFocused` impl for `DeferredWorld`. Since it already
implements `Deref<Target=World>` it was just duplication of code.
- impl `SetInputFocus` for `Commands`. There was no way to use
`SetFocusCommand` directly. This allows it.
- The `is_focus_within` logic has been fixed to check descendants.
Previously it was checking if any of the ancestors had focus which is
not correct according to the documentation.
- Added a bunch of unit tests to verify the logic of the crate.
## Testing
- Did you test these changes? If so, how? Yes, running newly added unit
tests.
---
# Objective
Define a framework for handling keyboard focus and bubbled keyboard
events, as discussed in #15374.
## Solution
Introduces a new crate, `bevy_input_focus`. This crate provides:
* A resource for tracking which entity has keyboard focus.
* Methods for getting and setting keyboard focus.
* Event definitions for triggering bubble-able keyboard input events to
the focused entity.
* A system for dispatching keyboard input events to the focused entity.
This crate does *not* provide any integration with UI widgets, or
provide functions for
tab navigation or gamepad-based focus navigation, as those are typically
application-specific.
## Testing
Most of the code has been copied from a different project, one that has
been well tested. However, most of what's in this module consists of
type definitions, with relatively small amounts of executable code. That
being said, I expect that there will be substantial bikeshedding on the
design, and I would prefer to hold off writing tests until after things
have settled.
I think that an example would be appropriate, however I'm waiting on a
few other pending changes to Bevy before doing so. In particular, I can
see a simple example with four buttons, with focus navigation between
them, and which can be triggered by the keyboard.
@alice-i-cecile
