# Objective
In #17905 we swapped to a named field on `ChildOf` to help resolve
variable naming ambiguity of child vs parent (ex: `child_of.parent`
clearly reads as "I am accessing the parent of the child_of
relationship", whereas `child_of.0` is less clear).
Unfortunately this has the side effect of making initialization less
ideal. `ChildOf { parent }` reads just as well as `ChildOf(parent)`, but
`ChildOf { parent: root }` doesn't read nearly as well as
`ChildOf(root)`.
## Solution
Move back to `ChildOf(pub Entity)` but add a `child_of.parent()`
function and use it for all accesses. The downside here is that users
are no longer "forced" to access the parent field with `parent`
nomenclature, but I think this strikes the right balance.
Take a look at the diff. I think the results provide strong evidence for
this change. Initialization has the benefit of reading much better _and_
of taking up significantly less space, as many lines go from 3 to 1, and
we're cutting out a bunch of syntax in some cases.
Sadly I do think this should land in 0.16 as the cost of doing this
_after_ the relationships migration is high.
# Objective
- Optimize static scene performance by marking unchanged subtrees.
-
[bef0209](bef0209de1)
fixes#18255 and #18363.
- Closes#18365
- Includes change from #18321
## Solution
- Mark hierarchy subtrees with dirty bits to avoid transform propagation
where not needed
- This causes a performance regression when spawning many entities, or
when the scene is entirely dynamic.
- This results in massive speedups for largely static scenes.
- In the future we could allow the user to change this behavior, or add
some threshold based on how dynamic the scene is?
## Testing
- Caldera Hotel scene
# Objective
- Optimize static scene performance by marking unchanged subtrees.
## Solution
- Mark hierarchy subtrees with dirty bits to avoid transform propagation
where not needed
- This causes a performance regression when spawning many entities, or
when the scene is entirely dynamic.
- This results in massive speedups for largely static scenes.
- In the future we could allow the user to change this behavior, or add
some threshold based on how dynamic the scene is?
## Testing
- Caldera Hotel scene
# Objective
There are currently three ways to access the parent stored on a ChildOf
relationship:
1. `child_of.parent` (field accessor)
2. `child_of.get()` (get function)
3. `**child_of` (Deref impl)
I will assert that we should only have one (the field accessor), and
that the existence of the other implementations causes confusion and
legibility issues. The deref approach is heinous, and `child_of.get()`
is significantly less clear than `child_of.parent`.
## Solution
Remove `impl Deref for ChildOf` and `ChildOf::get`.
The one "downside" I'm seeing is that:
```rust
entity.get::<ChildOf>().map(ChildOf::get)
```
Becomes this:
```rust
entity.get::<ChildOf>().map(|c| c.parent)
```
I strongly believe that this is worth the increased clarity and
consistency. I'm also not really a huge fan of the "pass function
pointer to map" syntax. I think most people don't think this way about
maps. They think in terms of a function that takes the item in the
Option and returns the result of some action on it.
## Migration Guide
```rust
// Before
**child_of
// After
child_of.parent
// Before
child_of.get()
// After
child_of.parent
// Before
entity.get::<ChildOf>().map(ChildOf::get)
// After
entity.get::<ChildOf>().map(|c| c.parent)
```
# Objective
fixes#17896
## Solution
Change ChildOf ( Entity ) to ChildOf { parent: Entity }
by doing this we also allow users to use named structs for relationship
derives, When you have more than 1 field in a struct with named fields
the macro will look for a field with the attribute #[relationship] and
all of the other fields should implement the Default trait. Unnamed
fields are still supported.
When u have a unnamed struct with more than one field the macro will
fail.
Do we want to support something like this ?
```rust
#[derive(Component)]
#[relationship_target(relationship = ChildOf)]
pub struct Children (#[relationship] Entity, u8);
```
I could add this, it but doesn't seem nice.
## Testing
crates/bevy_ecs - cargo test
## Showcase
```rust
use bevy_ecs::component::Component;
use bevy_ecs::entity::Entity;
#[derive(Component)]
#[relationship(relationship_target = Children)]
pub struct ChildOf {
#[relationship]
pub parent: Entity,
internal: u8,
};
#[derive(Component)]
#[relationship_target(relationship = ChildOf)]
pub struct Children {
children: Vec<Entity>
};
```
---------
Co-authored-by: Tim Overbeek <oorbecktim@Tims-MacBook-Pro.local>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-042.client.nl.eduvpn.org>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-059.client.nl.eduvpn.org>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-054.client.nl.eduvpn.org>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-027.client.nl.eduvpn.org>
# 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
- Make transform propagation faster.
## Solution
- Work sharing worker threads
- Parallel tree traversal excluding leaves
- Second cache friendly wide pass over all leaves
- 3-10x faster than main
## Testing
- Tracy
- Caldera hotel is showing 3-7x faster on my M4 Max. Timing for bevy's
existing transform system shifts wildly run to run, so I don't know that
I would advertise a particular number. But this implementation is faster
in a... statistically significant way.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: François Mockers <mockersf@gmail.com>
## Objective
A major critique of Bevy at the moment is how boilerplatey it is to
compose (and read) entity hierarchies:
```rust
commands
.spawn(Foo)
.with_children(|p| {
p.spawn(Bar).with_children(|p| {
p.spawn(Baz);
});
p.spawn(Bar).with_children(|p| {
p.spawn(Baz);
});
});
```
There is also currently no good way to statically define and return an
entity hierarchy from a function. Instead, people often do this
"internally" with a Commands function that returns nothing, making it
impossible to spawn the hierarchy in other cases (direct World spawns,
ChildSpawner, etc).
Additionally, because this style of API results in creating the
hierarchy bits _after_ the initial spawn of a bundle, it causes ECS
archetype changes (and often expensive table moves).
Because children are initialized after the fact, we also can't count
them to pre-allocate space. This means each time a child inserts itself,
it has a high chance of overflowing the currently allocated capacity in
the `RelationshipTarget` collection, causing literal worst-case
reallocations.
We can do better!
## Solution
The Bundle trait has been extended to support an optional
`BundleEffect`. This is applied directly to World immediately _after_
the Bundle has fully inserted. Note that this is
[intentionally](https://github.com/bevyengine/bevy/discussions/16920)
_not done via a deferred Command_, which would require repeatedly
copying each remaining subtree of the hierarchy to a new command as we
walk down the tree (_not_ good performance).
This allows us to implement the new `SpawnRelated` trait for all
`RelationshipTarget` impls, which looks like this in practice:
```rust
world.spawn((
Foo,
Children::spawn((
Spawn((
Bar,
Children::spawn(Spawn(Baz)),
)),
Spawn((
Bar,
Children::spawn(Spawn(Baz)),
)),
))
))
```
`Children::spawn` returns `SpawnRelatedBundle<Children, L:
SpawnableList>`, which is a `Bundle` that inserts `Children`
(preallocated to the size of the `SpawnableList::size_hint()`).
`Spawn<B: Bundle>(pub B)` implements `SpawnableList` with a size of 1.
`SpawnableList` is also implemented for tuples of `SpawnableList` (same
general pattern as the Bundle impl).
There are currently three built-in `SpawnableList` implementations:
```rust
world.spawn((
Foo,
Children::spawn((
Spawn(Name::new("Child1")),
SpawnIter(["Child2", "Child3"].into_iter().map(Name::new),
SpawnWith(|parent: &mut ChildSpawner| {
parent.spawn(Name::new("Child4"));
parent.spawn(Name::new("Child5"));
})
)),
))
```
We get the benefits of "structured init", but we have nice flexibility
where it is required!
Some readers' first instinct might be to try to remove the need for the
`Spawn` wrapper. This is impossible in the Rust type system, as a tuple
of "child Bundles to be spawned" and a "tuple of Components to be added
via a single Bundle" is ambiguous in the Rust type system. There are two
ways to resolve that ambiguity:
1. By adding support for variadics to the Rust type system (removing the
need for nested bundles). This is out of scope for this PR :)
2. Using wrapper types to resolve the ambiguity (this is what I did in
this PR).
For the single-entity spawn cases, `Children::spawn_one` does also
exist, which removes the need for the wrapper:
```rust
world.spawn((
Foo,
Children::spawn_one(Bar),
))
```
## This works for all Relationships
This API isn't just for `Children` / `ChildOf` relationships. It works
for any relationship type, and they can be mixed and matched!
```rust
world.spawn((
Foo,
Observers::spawn((
Spawn(Observer::new(|trigger: Trigger<FuseLit>| {})),
Spawn(Observer::new(|trigger: Trigger<Exploded>| {})),
)),
OwnerOf::spawn(Spawn(Bar))
Children::spawn(Spawn(Baz))
))
```
## Macros
While `Spawn` is necessary to satisfy the type system, we _can_ remove
the need to express it via macros. The example above can be expressed
more succinctly using the new `children![X]` macro, which internally
produces `Children::spawn(Spawn(X))`:
```rust
world.spawn((
Foo,
children![
(
Bar,
children![Baz],
),
(
Bar,
children![Baz],
),
]
))
```
There is also a `related!` macro, which is a generic version of the
`children!` macro that supports any relationship type:
```rust
world.spawn((
Foo,
related!(Children[
(
Bar,
related!(Children[Baz]),
),
(
Bar,
related!(Children[Baz]),
),
])
))
```
## Returning Hierarchies from Functions
Thanks to these changes, the following pattern is now possible:
```rust
fn button(text: &str, color: Color) -> impl Bundle {
(
Node {
width: Val::Px(300.),
height: Val::Px(100.),
..default()
},
BackgroundColor(color),
children![
Text::new(text),
]
)
}
fn ui() -> impl Bundle {
(
Node {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
..default(),
},
children![
button("hello", BLUE),
button("world", RED),
]
)
}
// spawn from a system
fn system(mut commands: Commands) {
commands.spawn(ui());
}
// spawn directly on World
world.spawn(ui());
```
## Additional Changes and Notes
* `Bundle::from_components` has been split out into
`BundleFromComponents::from_components`, enabling us to implement
`Bundle` for types that cannot be "taken" from the ECS (such as the new
`SpawnRelatedBundle`).
* The `NoBundleEffect` trait (which implements `BundleEffect`) is
implemented for empty tuples (and tuples of empty tuples), which allows
us to constrain APIs to only accept bundles that do not have effects.
This is critical because the current batch spawn APIs cannot efficiently
apply BundleEffects in their current form (as doing so in-place could
invalidate the cached raw pointers). We could consider allocating a
buffer of the effects to be applied later, but that does have
performance implications that could offset the balance and value of the
batched APIs (and would likely require some refactors to the underlying
code). I've decided to be conservative here. We can consider relaxing
that requirement on those APIs later, but that should be done in a
followup imo.
* I've ported a few examples to illustrate real-world usage. I think in
a followup we should port all examples to the `children!` form whenever
possible (and for cases that require things like SpawnIter, use the raw
APIs).
* Some may ask "why not use the `Relationship` to spawn (ex:
`ChildOf::spawn(Foo)`) instead of the `RelationshipTarget` (ex:
`Children::spawn(Spawn(Foo))`)?". That _would_ allow us to remove the
`Spawn` wrapper. I've explicitly chosen to disallow this pattern.
`Bundle::Effect` has the ability to create _significant_ weirdness.
Things in `Bundle` position look like components. For example
`world.spawn((Foo, ChildOf::spawn(Bar)))` _looks and reads_ like Foo is
a child of Bar. `ChildOf` is in Foo's "component position" but it is not
a component on Foo. This is a huge problem. Now that `Bundle::Effect`
exists, we should be _very_ principled about keeping the "weird and
unintuitive behavior" to a minimum. Things that read like components
_should be the components they appear to be".
## Remaining Work
* The macros are currently trivially implemented using macro_rules and
are currently limited to the max tuple length. They will require a
proc_macro implementation to work around the tuple length limit.
## Next Steps
* Port the remaining examples to use `children!` where possible and raw
`Spawn` / `SpawnIter` / `SpawnWith` where the flexibility of the raw API
is required.
## Migration Guide
Existing spawn patterns will continue to work as expected.
Manual Bundle implementations now require a `BundleEffect` associated
type. Exisiting bundles would have no bundle effect, so use `()`.
Additionally `Bundle::from_components` has been moved to the new
`BundleFromComponents` trait.
```rust
// Before
unsafe impl Bundle for X {
unsafe fn from_components<T, F>(ctx: &mut T, func: &mut F) -> Self {
}
/* remaining bundle impl here */
}
// After
unsafe impl Bundle for X {
type Effect = ();
/* remaining bundle impl here */
}
unsafe impl BundleFromComponents for X {
unsafe fn from_components<T, F>(ctx: &mut T, func: &mut F) -> Self {
}
}
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Co-authored-by: Emerson Coskey <emerson@coskey.dev>
Fixes#17412
## Objective
`Parent` uses the "has a X" naming convention. There is increasing
sentiment that we should use the "is a X" naming convention for
relationships (following #17398). This leaves `Children` as-is because
there is prevailing sentiment that `Children` is clearer than `ParentOf`
in many cases (especially when treating it like a collection).
This renames `Parent` to `ChildOf`.
This is just the implementation PR. To discuss the path forward, do so
in #17412.
## Migration Guide
- The `Parent` component has been renamed to `ChildOf`.
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>
# Background
In `no_std` compatible crates, there is often an `std` feature which
will allow access to the standard library. Currently, with the `std`
feature _enabled_, the
[`std::prelude`](https://doc.rust-lang.org/std/prelude/index.html) is
implicitly imported in all modules. With the feature _disabled_, instead
the [`core::prelude`](https://doc.rust-lang.org/core/prelude/index.html)
is implicitly imported. This creates a subtle and pervasive issue where
`alloc` items _may_ be implicitly included (if `std` is enabled), or
must be explicitly included (if `std` is not enabled).
# Objective
- Make the implicit imports for `no_std` crates consistent regardless of
what features are/not enabled.
## Solution
- Replace the `cfg_attr` "double negative" `no_std` attribute with
conditional compilation to _include_ `std` as an external crate.
```rust
// Before
#![cfg_attr(not(feature = "std"), no_std)]
// After
#![no_std]
#[cfg(feature = "std")]
extern crate std;
```
- Fix imports that are currently broken but are only now visible with
the above fix.
## Testing
- CI
## Notes
I had previously used the "double negative" version of `no_std` based on
general consensus that it was "cleaner" within the Rust embedded
community. However, this implicit prelude issue likely was considered
when forming this consensus. I believe the reason why is the items most
affected by this issue are provided by the `alloc` crate, which is
rarely used within embedded but extensively used within Bevy.
# Objective
- Contributes to #15460
## Solution
- Added the following features:
- `std` (default)
- `alloc` (default)
- `bevy_reflect` (default)
- `libm`
## Testing
- CI
## Notes
- `alloc` feature added to allow using this crate in `no_alloc`
environments.
- `bevy_reflect` was previously always enabled when `bevy-support` was
enabled, which isn't how most other crates handle reflection. I've
brought this in line with how most crates gate `bevy_reflect`.
The first step in the migration to required components! This PR removes
`GlobalTransform` from all user-facing code, since it's now added
automatically wherever `Transform` is used.
## Testing
- None of the examples I tested were broken, and I assume breaking
transforms in any way would be visible *everywhere*
---
## Changelog
- Make `Transform` require `GlobalTransform`
~~- Remove `GlobalTransform` from all engine bundles~~
- Remove in-engine insertions of GlobalTransform and TransformBundle
- Deprecate `TransformBundle`
- update docs to reflect changes
## Migration Guide
Replace all insertions of `GlobalTransform` and/or `TransformBundle`
with `Transform` alone.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Tim <JustTheCoolDude@gmail.com>
# 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
> Rust 1.81 released the #[expect(...)] attribute, which works like
#[allow(...)] but throws a warning if the lint isn't raised. This is
preferred to #[allow(...)] because it tells us when it can be removed.
- Adopts the parts of #15118 that are complete, and updates the branch
so it can be merged.
- There were a few conflicts, let me know if I misjudged any of 'em.
Alice's
[recommendation](https://github.com/bevyengine/bevy/issues/15059#issuecomment-2349263900)
seems well-taken, let's do this crate by crate now that @BD103 has done
the lion's share of this!
(Relates to, but doesn't yet completely finish #15059.)
Crates this _doesn't_ cover:
- bevy_input
- bevy_gilrs
- bevy_window
- bevy_winit
- bevy_state
- bevy_render
- bevy_picking
- bevy_core_pipeline
- bevy_sprite
- bevy_text
- bevy_pbr
- bevy_ui
- bevy_gltf
- bevy_gizmos
- bevy_dev_tools
- bevy_internal
- bevy_dylib
---------
Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
Co-authored-by: Ben Frankel <ben.frankel7@gmail.com>
Co-authored-by: Antony <antony.m.3012@gmail.com>
# Objective
- Makes naming between add_child and add_children more consistent
- Fixes#15101
## Solution
renamed push_children to add_children
## Testing
- Did you test these changes? If so, how?
Ran tests + grep search for any instance of `push_child`
- Are there any parts that need more testing?
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
ran tests on WSL2
---
## 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
rename any use of `push_children()` to the updated `add_children()`
# Objective
Fixes a performance issue when you have 1000s of entities in a bevy
hierarchy without transforms.
This was prominently happening in `bevy_ecs_tilemap`.
## Solution
Filter out entities that don't have a global transform.
## Testing
CI
We should test some other way...
## Migration Guide
- To avoid surprising performance pitfalls, `Transform` /
`GlobalTransform` propagation is no longer performed down through
hierarchies where intermediate parent are missing a `GlobalTransform`.
To restore the previous behavior, add `GlobalTransform::default` to
intermediate entities.
# Objective
- Optimize the `propagate_recursive` function in the transform system to
reduce CPU usage.
- Addresses performance bottleneck in transform propagation, especially
for scenes with complex hierarchies.
## Solution
- Avoided unnecessary cloning of `global_transform` when creating the
tuple in the `propagate_recursive` function.
- Used `as_ref()` method on `Mut<GlobalTransform>` when passing it to
the recursive call, avoiding an extra dereference.
- These changes significantly reduced the CPU usage of this function
from 4.91% to 1.16% of self function time.
## Testing
- Performance testing was conducted using the Hotspot GUI tool,
comparing CPU usage before and after the changes.
- `cargo run --release --example many_foxes`
- Tested on Fedora Linux.
---
## Showcase
Here are the PERF GUI results showing the improvement in CPU usage:
### Before
### After
As we can see, the CPU usage for the `propagate_recursive` function has
been reduced from 4.91% to 1.16%, resulting in a significant performance
improvement.
## Migration Guide
This change does not introduce any breaking changes. Users of the Bevy
engine will automatically benefit from this performance improvement
without needing to modify their code.
# Objective
The `BuildChildren` and `BuildWorldChildren` traits are mostly
identical, so I decided to try and merge them. I'm not sure of the
history, maybe they were added before GATs existed.
## Solution
- Add an associated type to `BuildChildren` which reflects the prior
differences between the `BuildChildren` and `BuildWorldChildren` traits.
- Add `ChildBuild` trait that is the bounds for
`BuildChildren::Builder`, with impls for `ChildBuilder` and
`WorldChildBuilder`.
- Remove `BuildWorldChildren` trait and replace it with an impl of
`BuildChildren` for `EntityWorldMut`.
## Testing
I ran several of the examples that use entity hierarchies, mainly UI.
---
## Changelog
n/a
## Migration Guide
n/a
# Objective
Part of https://github.com/bevyengine/bevy/issues/13529
Helps https://github.com/bevyengine/bevy/pull/13533
Splitting up `bevy_transform` makes it easier to selectively include or
exclude parts of it in such a way that it's possible to include only a
small part with a small dependency tree.
## Solution
Make the crate more modular.
---------
Signed-off-by: Torstein Grindvik <torstein.grindvik@muybridge.com>
Co-authored-by: Torstein Grindvik <torstein.grindvik@muybridge.com>
# Objective
- There are several redundant imports in the tests and examples that are
not caught by CI because additional flags need to be passed.
## Solution
- Run `cargo check --workspace --tests` and `cargo check --workspace
--examples`, then fix all warnings.
- Add `test-check` to CI, which will be run in the check-compiles job.
This should catch future warnings for tests. Examples are already
checked, but I'm not yet sure why they weren't caught.
## Discussion
- Should the `--tests` and `--examples` flags be added to CI, so this is
caught in the future?
- If so, #12818 will need to be merged first. It was also a warning
raised by checking the examples, but I chose to split off into a
separate PR.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
This is a necessary precursor to #9122 (this was split from that PR to
reduce the amount of code to review all at once).
Moving `!Send` resource ownership to `App` will make it unambiguously
`!Send`. `SubApp` must be `Send`, so it can't wrap `App`.
## Solution
Refactor `App` and `SubApp` to not have a recursive relationship. Since
`SubApp` no longer wraps `App`, once `!Send` resources are moved out of
`World` and into `App`, `SubApp` will become unambiguously `Send`.
There could be less code duplication between `App` and `SubApp`, but
that would break `App` method chaining.
## Changelog
- `SubApp` no longer wraps `App`.
- `App` fields are no longer publicly accessible.
- `App` can no longer be converted into a `SubApp`.
- Various methods now return references to a `SubApp` instead of an
`App`.
## Migration Guide
- To construct a sub-app, use `SubApp::new()`. `App` can no longer
convert into `SubApp`.
- If you implemented a trait for `App`, you may want to implement it for
`SubApp` as well.
- If you're accessing `app.world` directly, you now have to use
`app.world()` and `app.world_mut()`.
- `App::sub_app` now returns `&SubApp`.
- `App::sub_app_mut` now returns `&mut SubApp`.
- `App::get_sub_app` now returns `Option<&SubApp>.`
- `App::get_sub_app_mut` now returns `Option<&mut SubApp>.`
# Objective
Resolves#3824. `unsafe` code should be the exception, not the norm in
Rust. It's obviously needed for various use cases as it's interfacing
with platforms and essentially running the borrow checker at runtime in
the ECS, but the touted benefits of Bevy is that we are able to heavily
leverage Rust's safety, and we should be holding ourselves accountable
to that by minimizing our unsafe footprint.
## Solution
Deny `unsafe_code` workspace wide. Add explicit exceptions for the
following crates, and forbid it in almost all of the others.
* bevy_ecs - Obvious given how much unsafe is needed to achieve
performant results
* bevy_ptr - Works with raw pointers, even more low level than bevy_ecs.
* bevy_render - due to needing to integrate with wgpu
* bevy_window - due to needing to integrate with raw_window_handle
* bevy_utils - Several unsafe utilities used by bevy_ecs. Ideally moved
into bevy_ecs instead of made publicly usable.
* bevy_reflect - Required for the unsafe type casting it's doing.
* bevy_transform - for the parallel transform propagation
* bevy_gizmos - For the SystemParam impls it has.
* bevy_assets - To support reflection. Might not be required, not 100%
sure yet.
* bevy_mikktspace - due to being a conversion from a C library. Pending
safe rewrite.
* bevy_dynamic_plugin - Inherently unsafe due to the dynamic loading
nature.
Several uses of unsafe were rewritten, as they did not need to be using
them:
* bevy_text - a case of `Option::unchecked` could be rewritten as a
normal for loop and match instead of an iterator.
* bevy_color - the Pod/Zeroable implementations were replaceable with
bytemuck's derive macros.
# Objective
Fixes https://github.com/bevyengine/bevy/issues/11628
## Migration Guide
`Command` and `CommandQueue` have migrated from `bevy_ecs::system` to
`bevy_ecs::world`, so `use bevy_ecs::world::{Command, CommandQueue};`
when necessary.
# Objective
Reduce code duplication and improve APIs of Bevy's [global
taskpools](https://github.com/bevyengine/bevy/blob/main/crates/bevy_tasks/src/usages.rs).
## Solution
- As all three of the global taskpools have identical implementations
and only differ in their identifiers, this PR moves the implementation
into a macro to reduce code duplication.
- The `init` method is renamed to `get_or_init` to more accurately
reflect what it really does.
- Add a new `try_get` method that just returns `None` when the pool is
uninitialized, to complement the other getter methods.
- Minor documentation improvements to accompany the above changes.
---
## Changelog
- Added a new `try_get` method to the global TaskPools
- The global TaskPools' `init` method has been renamed to `get_or_init`
for clarity
- Documentation improvements
## Migration Guide
- Uses of `ComputeTaskPool::init`, `AsyncComputeTaskPool::init` and
`IoTaskPool::init` should be changed to `::get_or_init`.
# Objective
Rename RemovedComponents::iter/iter_with_id to read/read_with_id to make
it clear that it consume the data
Fixes#9755.
(It's my first pull request, if i've made any mistake, please let me
know)
## Solution
Refactor RemovedComponents::iter/iter_with_id to read/read_with_id
## Changelog
Refactor RemovedComponents::iter/iter_with_id to read/read_with_id
Deprecate RemovedComponents::iter/iter_with_id
Remove IntoIterator implementation
Update removal_detection example accordingly
---
## Migration Guide
Rename calls of RemovedComponents::iter/iter_with_id to
read/read_with_id
Replace IntoIterator iteration (&mut <RemovedComponents>) with .read()
---------
Co-authored-by: denshi_ika <mojang2824@gmail.com>
# Objective
- Move schedule name into `Schedule` to allow the schedule name to be
used for errors and tracing in Schedule methods
- Fixes#9510
## Solution
- Move label onto `Schedule` and adjust api's on `World` and `Schedule`
to not pass explicit label where it makes sense to.
- add name to errors and tracing.
- `Schedule::new` now takes a label so either add the label or use
`Schedule::default` which uses a default label. `default` is mostly used
in doc examples and tests.
---
## Changelog
- move label onto `Schedule` to improve error message and logging for
schedules.
## Migration Guide
`Schedule::new` and `App::add_schedule`
```rust
// old
let schedule = Schedule::new();
app.add_schedule(MyLabel, schedule);
// new
let schedule = Schedule::new(MyLabel);
app.add_schedule(schedule);
```
if you aren't using a label and are using the schedule struct directly
you can use the default constructor.
```rust
// old
let schedule = Schedule::new();
schedule.run(world);
// new
let schedule = Schedule::default();
schedule.run(world);
```
`Schedules:insert`
```rust
// old
let schedule = Schedule::new();
schedules.insert(MyLabel, schedule);
// new
let schedule = Schedule::new(MyLabel);
schedules.insert(schedule);
```
`World::add_schedule`
```rust
// old
let schedule = Schedule::new();
world.add_schedule(MyLabel, schedule);
// new
let schedule = Schedule::new(MyLabel);
world.add_schedule(schedule);
```
# Objective
`sync_simple_transforms` only checks for removed parents and doesn't
filter for `Without<Parent>`, so it overwrites the `GlobalTransform` of
non-orphan entities that were orphaned and then reparented since the
last update.
Introduced by #7264
## Solution
Filter for `Without<Parent>`.
Fixes#9517, #9492
## Changelog
`sync_simple_transforms`:
* Added a `Without<Parent>` filter to the orphaned entities query.
# Objective
The `QueryParIter::for_each_mut` function is required when doing
parallel iteration with mutable queries.
This results in an unfortunate stutter:
`query.par_iter_mut().par_for_each_mut()` ('mut' is repeated).
## Solution
- Make `for_each` compatible with mutable queries, and deprecate
`for_each_mut`. In order to prevent `for_each` from being called
multiple times in parallel, we take ownership of the QueryParIter.
---
## Changelog
- `QueryParIter::for_each` is now compatible with mutable queries.
`for_each_mut` has been deprecated as it is now redundant.
## Migration Guide
The method `QueryParIter::for_each_mut` has been deprecated and is no
longer functional. Use `for_each` instead, which now supports mutable
queries.
```rust
// Before:
query.par_iter_mut().for_each_mut(|x| ...);
// After:
query.par_iter_mut().for_each(|x| ...);
```
The method `QueryParIter::for_each` now takes ownership of the
`QueryParIter`, rather than taking a shared reference.
```rust
// Before:
let par_iter = my_query.par_iter().batching_strategy(my_batching_strategy);
par_iter.for_each(|x| {
// ...Do stuff with x...
par_iter.for_each(|y| {
// ...Do nested stuff with y...
});
});
// After:
my_query.par_iter().batching_strategy(my_batching_strategy).for_each(|x| {
// ...Do stuff with x...
my_query.par_iter().batching_strategy(my_batching_strategy).for_each(|y| {
// ...Do nested stuff with y...
});
});
```
# Objective
`GlobalTransform` after insertion will be updated only on `Transform` or
hierarchy change.
Fixes#9075
## Solution
Update `GlobalTransform` after insertion too.
---
## Changelog
- `GlobalTransform` is now updated not only on `Transform` or hierarchy
change, but also on insertion.
# Objective
- Fix#7263
This has nothing to do with #7024. This is for the case where the
user opted to **not** keep the same global transform on update.
## Solution
- Add a `RemovedComponent<Parent>` to `propagate_transforms`
- Add a `RemovedComponent<Parent>` and `Local<Vec<Entity>>` to
`sync_simple_transforms`
- Add test to make sure all of this works.
### Performance note
This should only incur a cost in cases where a parent is removed.
A minimal overhead (one look up in the `removed_components`
sparse set) per root entities without children which transform didn't
change. A `Vec` the size of the largest number of entities removed
with a `Parent` component in a single frame, and a binary search on
a `Vec` per root entities.
It could slow up considerably in situations where a lot of entities are
orphaned consistently during every frame, since
`sync_simple_transforms` is not parallel. But in this situation,
it is likely that the overhead of archetype updates overwhelms
everything.
---
## Changelog
- Fix the `GlobalTransform` not getting updated when `Parent` is removed
## Migration Guide
- If you called `bevy_transform::systems::sync_simple_transforms` and
`bevy_transform::systems::propagate_transforms` (which is not
re-exported by bevy) you need to account for the additional
`RemovedComponents<Parent>` parameter.
---------
Co-authored-by: vyb <vyb@users.noreply.github.com>
Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
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
Fixes#3184. Fixes#6640. Fixes#4798. Using `Query::par_for_each(_mut)` currently requires a `batch_size` parameter, which affects how it chunks up large archetypes and tables into smaller chunks to run in parallel. Tuning this value is difficult, as the performance characteristics entirely depends on the state of the `World` it's being run on. Typically, users will just use a flat constant and just tune it by hand until it performs well in some benchmarks. However, this is both error prone and risks overfitting the tuning on that benchmark.
This PR proposes a naive automatic batch-size computation based on the current state of the `World`.
## Background
`Query::par_for_each(_mut)` schedules a new Task for every archetype or table that it matches. Archetypes/tables larger than the batch size are chunked into smaller tasks. Assuming every entity matched by the query has an identical workload, this makes the worst case scenario involve using a batch size equal to the size of the largest matched archetype or table. Conversely, a batch size of `max {archetype, table} size / thread count * COUNT_PER_THREAD` is likely the sweetspot where the overhead of scheduling tasks is minimized, at least not without grouping small archetypes/tables together.
There is also likely a strict minimum batch size below which the overhead of scheduling these tasks is heavier than running the entire thing single-threaded.
## Solution
- [x] Remove the `batch_size` from `Query(State)::par_for_each` and friends.
- [x] Add a check to compute `batch_size = max {archeytpe/table} size / thread count * COUNT_PER_THREAD`
- [x] ~~Panic if thread count is 0.~~ Defer to `for_each` if the thread count is 1 or less.
- [x] Early return if there is no matched table/archetype.
- [x] Add override option for users have queries that strongly violate the initial assumption that all iterated entities have an equal workload.
---
## Changelog
Changed: `Query::par_for_each(_mut)` has been changed to `Query::par_iter(_mut)` and will now automatically try to produce a batch size for callers based on the current `World` state.
## Migration Guide
The `batch_size` parameter for `Query(State)::par_for_each(_mut)` has been removed. These calls will automatically compute a batch size for you. Remove these parameters from all calls to these functions.
Before:
```rust
fn parallel_system(query: Query<&MyComponent>) {
query.par_for_each(32, |comp| {
...
});
}
```
After:
```rust
fn parallel_system(query: Query<&MyComponent>) {
query.par_iter().for_each(|comp| {
...
});
}
```
Co-authored-by: Arnav Choubey <56453634+x-52@users.noreply.github.com>
Co-authored-by: Robert Swain <robert.swain@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Corey Farwell <coreyf@rwell.org>
Co-authored-by: Aevyrie <aevyrie@gmail.com>
# Objective
Fix#4647. If any child is changed, or even reordered, `Changed<Children>` is true, which causes transform propagation to propagate changes to all siblings of a changed child, even if they don't need to be.
## Solution
As `Parent` and `Children` are updated in tandem in hierarchy commands after #4800. `Changed<Parent>` is true on the child when `Changed<Children>` is true on the parent. However, unlike checking children, checking `Changed<Parent>` is only localized to the current entity and will not force propagation to the siblings.
Also took the opportunity to change propagation to use `Query::iter_many` instead of repeated `Query::get` calls. Should cut a bit of the overhead out of propagation. This means we won't panic when there isn't a `Parent` on the child, just skip over it.
The tests from #4608 still pass, so the change detection here still works just fine under this approach.
# Objective
Fixes#4697. Hierarchical propagation of properties, currently only Transform -> GlobalTransform, can be a very expensive operation. Transform propagation is a strict dependency for anything positioned in world-space. In large worlds, this can take quite a bit of time, so limiting it to a single thread can result in poor CPU utilization as it bottlenecks the rest of the frame's systems.
## Solution
- Move transforms without a parent or a child (free-floating (Global)Transform) entities into a separate parallel system.
- Chunk the hierarchy based on the root entities and process it in parallel with `Query::par_for_each_mut`.
- Utilize the hierarchy's specific properties introduced in #4717 to allow for safe use of `Query::get_unchecked` on multiple threads. Assuming each child is unique in the hierarchy, it is impossible to have an aliased `&mut GlobalTransform` so long as we verify that the parent for a child is the same one propagated from.
---
## Changelog
Removed: `transform_propagate_system` is no longer `pub`.
# Objective
Fix#6453.
## Solution
Use the solution mentioned in the issue by catching the unwind and dropping the error. Wrap the `executor.try_tick` calls with `std::catch::unwind`.
Ideally this would be moved outside of the hot loop, but the mut ref to the `spawned` future is not `UnwindSafe`.
This PR only addresses the bug, we can address the perf issues (should there be any) later.
# Objective
Right now, the `TaskPool` implementation allows panics to permanently kill worker threads upon panicking. This is currently non-recoverable without using a `std::panic::catch_unwind` in every scheduled task. This is poor ergonomics and even poorer developer experience. This is exacerbated by #2250 as these threads are global and cannot be replaced after initialization.
Removes the need for temporary fixes like #4998. Fixes#4996. Fixes#6081. Fixes#5285. Fixes#5054. Supersedes #2307.
## Solution
The current solution is to wrap `Executor::run` in `TaskPool` with a `catch_unwind`, and discarding the potential panic. This was taken straight from [smol](404c7bcc0a/src/spawn.rs (L44))'s current implementation. ~~However, this is not entirely ideal as:~~
- ~~the signaled to the awaiting task. We would need to change `Task<T>` to use `async_task::FallibleTask` internally, and even then it doesn't signal *why* it panicked, just that it did.~~ (See below).
- ~~no error is logged of any kind~~ (See below)
- ~~it's unclear if it drops other tasks in the executor~~ (it does not)
- ~~This allows the ECS parallel executor to keep chugging even though a system's task has been dropped. This inevitably leads to deadlock in the executor.~~ Assuming we don't catch the unwind in ParallelExecutor, this will naturally kill the main thread.
### Alternatives
A final solution likely will incorporate elements of any or all of the following.
#### ~~Log and Ignore~~
~~Log the panic, drop the task, keep chugging. This only addresses the discoverability of the panic. The process will continue to run, probably deadlocking the executor. tokio's detatched tasks operate in this fashion.~~
Panics already do this by default, even when caught by `catch_unwind`.
#### ~~`catch_unwind` in `ParallelExecutor`~~
~~Add another layer catching system-level panics into the `ParallelExecutor`. How the executor continues when a core dependency of many systems fails to run is up for debate.~~
`async_task::Task` bubbles up panics already, this will transitively push panics all the way to the main thread.
#### ~~Emulate/Copy `tokio::JoinHandle` with `Task<T>`~~
~~`tokio::JoinHandle<T>` bubbles up the panic from the underlying task when awaited. This can be transitively applied across other APIs that also use `Task<T>` like `Query::par_for_each` and `TaskPool::scope`, bubbling up the panic until it's either caught or it reaches the main thread.~~
`async_task::Task` bubbles up panics already, this will transitively push panics all the way to the main thread.
#### Abort on Panic
The nuclear option. Log the error, abort the entire process on any thread in the task pool panicking. Definitely avoids any additional infrastructure for passing the panic around, and might actually lead to more efficient code as any unwinding is optimized out. However gives the developer zero options for dealing with the issue, a seemingly poor choice for debuggability, and prevents graceful shutdown of the process. Potentially an option for handling very low-level task management (a la #4740). Roughly takes the shape of:
```rust
struct AbortOnPanic;
impl Drop for AbortOnPanic {
fn drop(&mut self) {
abort!();
}
}
let guard = AbortOnPanic;
// Run task
std::mem::forget(AbortOnPanic);
```
---
## Changelog
Changed: `bevy_tasks::TaskPool`'s threads will no longer terminate permanently when a task scheduled onto them panics.
Changed: `bevy_tasks::Task` and`bevy_tasks::Scope` will propagate panics in the spawned tasks/scopes to the parent thread.
# Objective
- Fix#5285
## Solution
- Put the panicking system in a single threaded stage during the test
- This way only the main thread will panic, which is handled by `cargo test`
# 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`.
