f33074116b
5 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Corvus
|
a312170749
|
Increase upper limit of children! (#18865)
# Objective Currently, `bevy_ecs`'s `children!` macro only supports spawning up to twelve children at once. Ideally there would be no limit. ## Solution `children!` is limited because `SpawnableList`, [the primary trait bound here](https://docs.rs/bevy/0.16.0-rc.5/bevy/ecs/hierarchy/struct.Children.html#method.spawn), uses the fake variadics pattern on tuples of up to twelve elements. However, since a tuple itself implements `SpawnableList`, we can simply nest tuples of entities when we run out of room. This PR achieves this using `macro_rules` macros with a bit of brute force, following [some discussion on Discord](https://discord.com/channels/691052431525675048/692572690833473578/1362174415458013314). If we create patterns for lists of up to eleven bundles, then use a repetition pattern to handle the rest, we can "special-case" the recursion into a nested tuple. In principle, this would permit an arbitrary number of children, but Rust's recursion limits will cut things short at around 1400 elements by default. Of course, it's generally not a good idea to stick that many bundles in a single invocation, but it might be worth mentioning in the docs. ## Implementation notes ### Why are cases 0-11 expanded by hand? We could make use of a tertiary macro: ```rs macro_rules! recursive_spawn { // so that this... ($a:expr, $b:expr) => { ( $crate::spawn::Spawn($a), $crate::spawn::Spawn($b), ) }; // becomes this... ($a:expr, $b:expr) => { $crate::spawn_tuple!($a, $b) }; } ``` But I already feel a little bad exporting `recursive_spawn`. I'd really like to avoid exposing more internals, even if they are annotated with `#[doc(hidden)]`. If I had to guess, I'd say it'll also make the expansion a tiny bit slower. ### Do we really need to handle up to twelve elements in the macro? The macro is a little long, but doing it this way maximizes the "flatness" of the types to be spawned. This should improve the codegen a bit and makes the macro output a little bit easier to look at. ## Future work The `related!` macro is essentially the same as `children!`, so if this direction is accepted, `related!` should receive the same treatment. I imagine we'd want to extract out the `recursive_spawn` macro into its own file since it can be used for both. If this should be tackled in this PR, let me know! ## Testing This change is fairly trivial, but I added a single test to verify that it compiles and nothing goes wrong once recursion starts happening. It's pretty easy to verify that the change works in practice -- just spawn over twelve entities as children at once! |
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|
Freyja-moth
|
714b4a43d6
|
Change with_related to work with a Bundle and added with_relationships method (#18699)
# Objective Fixes #18678 ## Solution Moved the current `with_related` method to `with_relationships` and added a new `with_related` that uses a bundle. I'm not entirely sold on the name just yet, if anyone has any ideas let me know. ## Testing I wasn't able to test these changes because it crashed my computer every time I tried (fun). But there don't seem to be any tests that use the old `with_related` method so it should be fine, hopefully ## Showcase ```rust commands.spawn_empty() .with_related::<Relationship>(Name::new("Related thingy")) .with_relationships(|rel| { rel.spawn(Name::new("Second related thingy")); }); ``` --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com> |
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|
krunchington
|
f1331069e7
|
Implement SpawnableList for Vec<Bundle> (#18259)
# Objective In updating examples to use the Improved Spawning API I got tripped up on being able to spawn children with a Vec. I eventually figured out that I could use `Children::spawn(SpawnIter(my_vec.into_iter()))` but thought there might be a more ergonomic way to approach it. After tinkering with it for a while I came up with the implementation here. It allows authors to use `Children::spawn(my_vec)` as an equivalent implementation. ## Solution - Implements `<R: Relationship, B: Bundle SpawnableList<R> for Vec<B>` - uses `alloc::vec::Vec` for compatibility with `no_std` (`std::Vec` also inherits implementations against the `alloc::vec::Vec` because std is a re-export of the alloc struct, thanks @bushrat011899 for the info on this!) ## Testing - Did you test these changes? If so, how? - Opened the examples before and after and verified the same behavior was observed. I did this on Ubuntu 24.04.2 LTS using `--features wayland`. - Are there any parts that need more testing? - Other OS's and features can't hurt, but this is such a small change it shouldn't be a problem. - How can other people (reviewers) test your changes? Is there anything specific they need to know? - Run the examples yourself with and without these changes. - If relevant, what platforms did you test these changes on, and are there any important ones you can't test? - see above ## Showcase n/a ## Migration Guide - Optional: you may use the new API to spawn `Vec`s of `Bundle` instead of using the `SpawnIter` approach. |
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Eagster
|
246ce590e5
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Queued component registration (#18173)
# Objective This is an alternative to #17871 and #17701 for tracking issue #18155. This thanks to @maniwani for help with this design. The goal is to enable component ids to be reserved from multiple threads concurrently and with only `&World`. This contributes to assets as entities, read-only query and system parameter initialization, etc. ## What's wrong with #17871 ? In #17871, I used my proposed staging utilities to allow *fully* registering components from any thread concurrently with only `&Components`. However, if we want to pursue components as entities (which is desirable for a great many reasons. See [here](https://discord.com/channels/691052431525675048/692572690833473578/1346499196655505534) on discord), this staging isn't going to work. After all, if registering a component requires spawning an entity, and spawning an entity requires `&mut World`, it is impossible to register a component fully with only `&World`. ## Solution But what if we don't have to register it all the way? What if it's enough to just know the `ComponentId` it will have once it is registered and to queue it to be registered at a later time? Spoiler alert: That is all we need for these features. Here's the basic design: Queue a registration: 1. Check if it has already been registered. 2. Check if it has already been queued. 3. Reserve a `ComponentId`. 4. Queue the registration at that id. Direct (normal) registration: 1. Check if this registration has been queued. 2. If it has, use the queued registration instead. 3. Otherwise, proceed like normal. Appllying the queue: 1. Pop queued items off one by one. 2. Register them directly. One other change: The whole point of this design over #17871 is to facilitate coupling component registration with the World. To ensure that this would fully work with that, I went ahead and moved the `ComponentId` generator onto the world itself. That stemmed a couple of minor organizational changes (see migration guide). As we do components as entities, we will replace this generator with `Entities`, which lives on `World` too. Doing this move early let me verify the design and will reduce migration headaches in the future. If components as entities is as close as I think it is, I don't think splitting this up into different PRs is worth it. If it is not as close as it is, it might make sense to still do #17871 in the meantime (see the risks section). I'll leave it up to y'all what we end up doing though. ## Risks and Testing The biggest downside of this compared to #17871 is that now we have to deal with correct but invalid `ComponentId`s. They are invalid because the component still isn't registered, but they are correct because, once registered, the component will have exactly that id. However, the only time this becomes a problem is if some code violates safety rules by queuing a registration and using the returned id as if it was valid. As this is a new feature though, nothing in Bevy does this, so no new tests were added for it. When we do use it, I left detailed docs to help mitigate issues here, and we can test those usages. Ex: we will want some tests on using queries initialized from queued registrations. ## Migration Guide Component registration can now be queued with only `&World`. To facilitate this, a few APIs needed to be moved around. The following functions have moved from `Components` to `ComponentsRegistrator`: - `register_component` - `register_component_with_descriptor` - `register_resource_with_descriptor` - `register_non_send` - `register_resource` - `register_required_components_manual` Accordingly, functions in `Bundle` and `Component` now take `ComponentsRegistrator` instead of `Components`. You can obtain `ComponentsRegistrator` from the new `World::components_registrator`. You can obtain `ComponentsQueuedRegistrator` from the new `World::components_queue`, and use it to stage component registration if desired. # Open Question Can we verify that it is enough to queue registration with `&World`? I don't think it would be too difficult to package this up into a `Arc<MyComponentsManager>` type thing if we need to, but keeping this on `&World` certainly simplifies things. If we do need the `Arc`, we'll need to look into partitioning `Entities` for components as entities, so we can keep most of the allocation fast on `World` and only keep a smaller partition in the `Arc`. I'd love an SME on assets as entities to shed some light on this. --------- Co-authored-by: andriyDev <andriydzikh@gmail.com> |
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Carter Anderson
|
ea578415e1
|
Improved Spawn APIs and Bundle Effects (#17521)
## 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>
|