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15 commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Christian Hughes
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c7ec456e50
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Support systems that take references as input (#15184)
# Objective - Fixes #14924 - Closes #9584 ## Solution - We introduce a new trait, `SystemInput`, that serves as a type function from the `'static` form of the input, to its lifetime'd version, similarly to `SystemParam` or `WorldQuery`. - System functions now take the lifetime'd wrapped version, `SystemInput::Param<'_>`, which prevents the issue presented in #14924 (i.e. `InRef<T>`). - Functions for running systems now take the lifetime'd unwrapped version, `SystemInput::Inner<'_>` (i.e. `&T`). - Due to the above change, system piping had to be re-implemented as a standalone type, rather than `CombinatorSystem` as it was previously. - Removes the `Trigger<'static, E, B>` transmute in observer runner code. ## Testing - All current tests pass. - Added additional tests and doc-tests. --- ## Showcase ```rust let mut world = World::new(); let mut value = 2; // Currently possible: fn square(In(input): In<usize>) -> usize { input * input } value = world.run_system_once_with(value, square); // Now possible: fn square_mut(InMut(input): InMut<usize>) { *input *= *input; } world.run_system_once_with(&mut value, square_mut); // Or: fn square_ref(InRef(input): InRef<usize>) -> usize { *input * *input } value = world.run_system_once_with(&value, square_ref); ``` ## Migration Guide - All current explicit usages of the following types must be changed in the way specified: - `SystemId<I, O>` to `SystemId<In<I>, O>` - `System<In = T>` to `System<In = In<T>>` - `IntoSystem<I, O, M>` to `IntoSystem<In<I>, O, M>` - `Condition<M, T>` to `Condition<M, In<T>>` - `In<Trigger<E, B>>` is no longer a valid input parameter type. Use `Trigger<E, B>` directly, instead. --------- Co-authored-by: Giacomo Stevanato <giaco.stevanato@gmail.com> |
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Gino Valente
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2b4180ca8f
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bevy_reflect: Function reflection terminology refactor (#14813)
# Objective One of the changes in #14704 made `DynamicFunction` effectively the same as `DynamicClosure<'static>`. This change meant that the de facto function type would likely be `DynamicClosure<'static>` instead of the intended `DynamicFunction`, since the former is much more flexible. We _could_ explore ways of making `DynamicFunction` implement `Copy` using some unsafe code, but it likely wouldn't be worth it. And users would likely still reach for the convenience of `DynamicClosure<'static>` over the copy-ability of `DynamicFunction`. The goal of this PR is to fix this confusion between the two types. ## Solution Firstly, the `DynamicFunction` type was removed. Again, it was no different than `DynamicClosure<'static>` so it wasn't a huge deal to remove. Secondly, `DynamicClosure<'env>` and `DynamicClosureMut<'env>` were renamed to `DynamicFunction<'env>` and `DynamicFunctionMut<'env>`, respectively. Yes, we still ultimately kept the naming of `DynamicFunction`, but changed its behavior to that of `DynamicClosure<'env>`. We need a term to refer to both functions and closures, and "function" was the best option. [Originally](https://discord.com/channels/691052431525675048/1002362493634629796/1274091992162242710), I was going to go with "callable" as the replacement term to encompass both functions and closures (e.g. `DynamciCallable<'env>`). However, it was [suggested](https://discord.com/channels/691052431525675048/1002362493634629796/1274653581777047625) by @SkiFire13 that the simpler "function" term could be used instead. While "callable" is perhaps the better umbrella term—being truly ambiguous over functions and closures— "function" is more familiar, used more often, easier to discover, and is subjectively just "better-sounding". ## Testing Most changes are purely swapping type names or updating documentation, but you can verify everything still works by running the following command: ``` cargo test --package bevy_reflect ``` |
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Gino Valente
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423285cf1c
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bevy_reflect: Store functions as DynamicClosure<'static> in FunctionRegistry (#14704)
# Objective #14098 added the `FunctionRegistry` for registering functions such that they can be retrieved by name and used dynamically. One thing we chose to leave out in that initial PR is support for closures. Why support closures? Mainly, we don't want to prohibit users from injecting environmental data into their registered functions. This allows these functions to not leak their internals to the public API. For example, let's say we're writing a library crate that allows users to register callbacks for certain actions. We want to perform some actions before invoking the user's callback so we can't just call it directly. We need a closure for this: ```rust registry.register("my_lib::onclick", move |event: ClickEvent| { // ...other work... user_onclick.call(event); // <-- Captured variable }); ``` We could have made our callback take a reference to the user's callback. This would remove the need for the closure, but it would change our desired API to place the burden of fetching the correct callback on the caller. ## Solution Modify the `FunctionRegistry` to store registered functions as `DynamicClosure<'static>` instead of `DynamicFunction` (now using `IntoClosure` instead of `IntoFunction`). Due to limitations in Rust and how function reflection works, `DynamicClosure<'static>` is functionally equivalent to `DynamicFunction`. And a normal function is considered a subset of closures (it's a closure that doesn't capture anything), so there shouldn't be any difference in usage: all functions that satisfy `IntoFunction` should satisfy `IntoClosure`. This means that the registration API introduced in #14098 should require little-to-no changes on anyone following `main`. ### Closures vs Functions One consideration here is whether we should keep closures and functions separate. This PR unifies them into `DynamicClosure<'static>`, but we can consider splitting them up. The reasons we might want to do so are: - Simplifies mental model and terminology (users don't have to understand that functions turn into closures) - If Rust ever improves its function model, we may be able to add additional guarantees to `DynamicFunction` that make it useful to separate the two - Adding support for generic functions may be less confusing for users since closures in Rust technically can't be generic The reasons behind this PR's unification approach are: - Reduces the number of methods needed on `FunctionRegistry` - Reduces the number of lookups a user may have to perform (i.e. "`get_function` or else `get_closure`") - Establishes `DynamicClosure<'static>` as the de facto dynamic callable (similar to how most APIs in Rust code tend to prefer `impl Fn() -> String` over `fn() -> String`) I'd love to hear feedback on this matter, and whether we should continue with this PR's approach or switch to a split model. ## Testing You can test locally by running: ``` cargo test --package bevy_reflect ``` --- ## Showcase Closures can now be registered into the `FunctionRegistry`: ```rust let punct = String::from("!!!"); registry.register_with_name("my_crate::punctuate", move |text: String| { format!("{}{}", text, punct) }); ``` |
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Gino Valente
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a0cc636ea3
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bevy_reflect: Anonymous function parsing (#14641)
# Objective ### TL;DR #14098 added the `FunctionRegistry` but had some last minute complications due to anonymous functions. It ended up going with a "required name" approach to ensure anonymous functions would always have a name. However, this approach isn't ideal for named functions since, by definition, they will always have a name. Therefore, this PR aims to modify function reflection such that we can make function registration easier for named functions, while still allowing anonymous functions to be registered as well. ### Context Function registration (#14098) ran into a little problem: anonymous functions. Anonymous functions, including function pointers, have very non-unique type names. For example, the anonymous function `|a: i32, b: i32| a + b` has the type name of `fn(i32, i32) -> i32`. This obviously means we'd conflict with another function like `|a: i32, b: i32| a - b`. The solution that #14098 landed on was to always require a name during function registration. The downside with this is that named functions (e.g. `fn add(a: i32, b: i32) -> i32 { a + b }`) had to redundantly provide a name. Additionally, manually constructed `DynamicFunction`s also ran into this ergonomics issue. I don't entirely know how the function registry will be used, but I have a strong suspicion that most of its registrations will either be named functions or manually constructed `DynamicFunction`s, with anonymous functions only being used here and there for quick prototyping or adding small functionality. Why then should the API prioritize the anonymous function use case by always requiring a name during registration? #### Telling Functions Apart Rust doesn't provide a lot of out-of-the-box tools for reflecting functions. One of the biggest hurdles in attempting to solve the problem outlined above would be to somehow tell the different kinds of functions apart. Let's briefly recap on the categories of functions in Rust: | Category | Example | | ------------------ | ----------------------------------------- | | Named function | `fn add(a: i32, b: i32) -> i32 { a + b }` | | Closure | `\|a: i32\| a + captured_variable` | | Anonymous function | `\|a: i32, b: i32\| a + b` | | Function pointer | `fn(i32, i32) -> i32` | My first thought was to try and differentiate these categories based on their size. However, we can see that this doesn't quite work: | Category | `size_of` | | ------------------ | --------- | | Named function | 0 | | Closure | 0+ | | Anonymous function | 0 | | Function pointer | 8 | Not only does this not tell anonymous functions from named ones, but it struggles with pretty much all of them. My second then was to differentiate based on type name: | Category | `type_name` | | ------------------ | ----------------------- | | Named function | `foo::bar::baz` | | Closure | `foo::bar::{{closure}}` | | Anonymous function | `fn() -> String` | | Function pointer | `fn() -> String` | This is much better. While it can't distinguish between function pointers and anonymous functions, this doesn't matter too much since we only care about whether we can _name_ the function. So why didn't we implement this in #14098? #### Relying on `type_name` While this solution was known about while working on #14098, it was left out from that PR due to it being potentially controversial. The [docs](https://doc.rust-lang.org/stable/std/any/fn.type_name.html) for `std::any::type_name` state: > The returned string must not be considered to be a unique identifier of a type as multiple types may map to the same type name. Similarly, there is no guarantee that all parts of a type will appear in the returned string: for example, lifetime specifiers are currently not included. In addition, the output may change between versions of the compiler. So that's it then? We can't use `type_name`? Well, this statement isn't so much a rule as it is a guideline. And Bevy is no stranger to bending the rules to make things work or to improve ergonomics. Remember that before `TypePath`, Bevy's scene system was entirely dependent on `type_name`. Not to mention that `type_name` is being used as a key into both the `TypeRegistry` and the `FunctionRegistry`. Bevy's practices aside, can we reliably use `type_name` for this? My answer would be "yes". Anonymous functions are anonymous. They have no name. There's nothing Rust could do to give them a name apart from generating a random string of characters. But remember that this is a diagnostic tool, it doesn't make sense to obfuscate the type by randomizing the output. So changing it to be anything other than what it is now is very unlikely. The only changes that I could potentially see happening are: 1. Closures replace `{{closure}}` with the name of their variable 2. Lifetimes are included in the output I don't think the first is likely to happen, but if it does then it actually works out in our favor: closures are now named! The second point is probably the likeliest. However, adding lifetimes doesn't mean we can't still rely on `type_name` to determine whether or not a function is named. So we should be okay in this case as well. ## Solution Parse the `type_name` of the function in the `TypedFunction` impl to determine if the function is named or anonymous. This once again makes `FunctionInfo::name` optional. For manual constructions of `DynamicFunction`, `FunctionInfo::named` or ``FunctionInfo::anonymous` can be used. The `FunctionRegistry` API has also been reworked to account for this change. `FunctionRegistry::register` no longer takes a name and instead takes it from the supplied function, returning a `FunctionRegistrationError::MissingName` error if the name is `None`. This also doubles as a replacement for the old `FunctionRegistry::register_dynamic` method, which has been removed. To handle anonymous functions, a `FunctionRegistry::register_with_name` method has been added. This works in the same way `FunctionRegistry::register` used to work before this PR. The overwriting methods have been updated in a similar manner, with modifications to `FunctionRegistry::overwrite_registration`, the removal of `FunctionRegistry::overwrite_registration_dynamic`, and the addition of `FunctionRegistry::overwrite_registration_with_name`. This PR also updates the methods on `App` in a similar way: `App::register_function` no longer requires a name argument and `App::register_function_with_name` has been added to handle anonymous functions (and eventually closures). ## Testing You can run the tests locally by running: ``` cargo test --package bevy_reflect --features functions ``` --- ## Internal Migration Guide > [!important] > Function reflection was introduced as part of the 0.15 dev cycle. This migration guide was written for developers relying on `main` during this cycle, and is not a breaking change coming from 0.14. > [!note] > This list is not exhaustive. It only contains some of the most important changes. `FunctionRegistry::register` no longer requires a name string for named functions. Anonymous functions, however, need to be registered using `FunctionRegistry::register_with_name`. ```rust // BEFORE registry .register(std::any::type_name_of_val(&foo), foo)? .register("bar", || println!("Hello world!")); // AFTER registry .register(foo)? .register_with_name("bar", || println!("Hello world!")); ``` `FunctionInfo::name` is now optional. Anonymous functions and closures will now have their name set to `None` by default. Additionally, `FunctionInfo::new` has been renamed to `FunctionInfo::named`. |
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Gino Valente
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df61117850
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bevy_reflect: Function registry (#14098)
# Objective #13152 added support for reflecting functions. Now, we need a way to register those functions such that they may be accessed anywhere within the ECS. ## Solution Added a `FunctionRegistry` type similar to `TypeRegistry`. This allows a function to be registered and retrieved by name. ```rust fn foo() -> i32 { 123 } let mut registry = FunctionRegistry::default(); registry.register("my_function", foo); let function = registry.get_mut("my_function").unwrap(); let value = function.call(ArgList::new()).unwrap().unwrap_owned(); assert_eq!(value.downcast_ref::<i32>(), Some(&123)); ``` Additionally, I added an `AppFunctionRegistry` resource which wraps a `FunctionRegistryArc`. Functions can be registered into this resource using `App::register_function` or by getting a mutable reference to the resource itself. ### Limitations #### `Send + Sync` In order to get this registry to work across threads, it needs to be `Send + Sync`. This means that `DynamicFunction` needs to be `Send + Sync`, which means that its internal function also needs to be `Send + Sync`. In most cases, this won't be an issue because standard Rust functions (the type most likely to be registered) are always `Send + Sync`. Additionally, closures tend to be `Send + Sync` as well, granted they don't capture any `!Send` or `!Sync` variables. This PR adds this `Send + Sync` requirement, but as mentioned above, it hopefully shouldn't be too big of an issue. #### Closures Unfortunately, closures can't be registered yet. This will likely be explored and added in a followup PR. ### Future Work Besides addressing the limitations listed above, another thing we could look into is improving the lookup of registered functions. One aspect is in the performance of hashing strings. The other is in the developer experience of having to call `std::any::type_name_of_val` to get the name of their function (assuming they didn't give it a custom name). ## Testing You can run the tests locally with: ``` cargo test --package bevy_reflect ``` --- ## Changelog - Added `FunctionRegistry` - Added `AppFunctionRegistry` (a `Resource` available from `bevy_ecs`) - Added `FunctionRegistryArc` - Added `FunctionRegistrationError` - Added `reflect_functions` feature to `bevy_ecs` and `bevy_app` - `FunctionInfo` is no longer `Default` - `DynamicFunction` now requires its wrapped function be `Send + Sync` ## Internal Migration Guide > [!important] > Function reflection was introduced as part of the 0.15 dev cycle. This migration guide was written for developers relying on `main` during this cycle, and is not a breaking change coming from 0.14. `DynamicFunction` (both those created manually and those created with `IntoFunction`), now require `Send + Sync`. All standard Rust functions should meet that requirement. Closures, on the other hand, may not if they capture any `!Send` or `!Sync` variables from its environment. |
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Sou1gh0st
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f51a306b30
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feat(bevy_app): expose an API to perform updates for a specific sub-app. (#14009)
# Objective - Fixes https://github.com/bevyengine/bevy/issues/14003 ## Solution - Expose an API to perform updates for a specific sub-app, so we can avoid mutable borrow the app twice. ## Testing - I have tested the API by modifying the code in the `many_lights` example with the following changes: ```rust impl Plugin for LogVisibleLights { fn build(&self, app: &mut App) { let Some(render_app) = app.get_sub_app_mut(RenderApp) else { return; }; render_app.add_systems(Render, print_visible_light_count.in_set(RenderSet::Prepare)); } fn finish(&self, app: &mut App) { app.update_sub_app_by_label(RenderApp); } } ``` --- ## Changelog - add the `update_sub_app_by_label` API to `App` and `SubApps`. --------- Co-authored-by: Jan Hohenheim <jan@hohenheim.ch> |
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Chris Juchem
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49661b99fe
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Remove extra call to clear_trackers (#13762)
Fixes #13758. # Objective Calling `update` on the main app already calls `clear_trackers`. Calling it again in `SubApps::update` caused RemovedCompenet Events to be cleared earlier than they should be. ## Solution - Don't call clear_trackers an extra time. ## Testing I manually tested the fix with this unit test: ``` #[cfg(test)] mod test { use crate::core::{FrameCount, FrameCountPlugin}; use crate::prelude::*; #[test] fn test_next_frame_removal() { #[derive(Component)] struct Foo; #[derive(Resource)] struct RemovedCount(usize); let mut app = App::new(); app.add_plugins(FrameCountPlugin); app.add_systems(Startup, |mut commands: Commands| { for _ in 0..100 { commands.spawn(Foo); } commands.insert_resource(RemovedCount(0)); }); app.add_systems(First, |counter: Res<FrameCount>| { println!("Frame {}:", counter.0) }); fn detector_system( mut removals: RemovedComponents<Foo>, foos: Query<Entity, With<Foo>>, mut removed_c: ResMut<RemovedCount>, ) { for e in removals.read() { println!(" Detected removed Foo component for {e:?}"); removed_c.0 += 1; } let c = foos.iter().count(); println!(" Total Foos: {}", c); assert_eq!(c + removed_c.0, 100); } fn deleter_system(foos: Query<Entity, With<Foo>>, mut commands: Commands) { foos.iter().next().map(|e| { commands.entity(e).remove::<Foo>(); }); } app.add_systems(Update, (detector_system, deleter_system).chain()); app.update(); app.update(); app.update(); app.update(); } } ``` |
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MiniaczQ
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25f7a29a2f
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Move state installation methods from bevy_app to bevy_state (#13637)
# Objective After separating `bevy_states`, state installation methods like `init_state` were kept in `bevy_app` under the `bevy_state` feature flag. This is problematic, because `bevy_state` is not a core module, `bevy_app` is, yet it depends on `bevy_state`. This causes practical problems like the inability to use `bevy_hierarchy` inside `bevy_state`, because of circular dependencies. ## Solution - `bevy_state` now has a `bevy_app` feature flag, which gates the new `AppStateExt` trait. All previous state installation methods were moved to this trait. It's implemented for both `SubApp` and `App`. ## Changelog - All state related app methods are now in `AppExtStates` trait in `bevy_state`. - Added `StatesPlugin` which is in `DefaultPlugins` when `bevy_state` is enabled. ## Migration Guide `App::init_state` is now provided by the `bevy_state::app::AppExtStates;` trait: import it if you need this method and are not blob-importing the `bevy` prelude. |
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MiniaczQ
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5cb4808026
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Simplify state transitions (#13616)
# Objective Prerequisite to #13579. Make state transition schedule running simpler. ## Solution - Remove `should_run_transition` which read the latest event and fake-fire an event for the startup transitions (e.g. startup `OnEnter()`). - Account for startup event, by actually emitting an event when adding states to `App`. - Replace `should_run_transition` with `last_transition`, which is a light wrapper over `EventReader::read().last()`. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> |
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Lee-Orr
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42ba9dfaea
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Separate state crate (#13216)
# Objective Extracts the state mechanisms into a new crate called "bevy_state". This comes with a few goals: - state wasn't really an inherent machinery of the ecs system, and so keeping it within bevy_ecs felt forced - by mixing it in with bevy_ecs, the maintainability of our more robust state system was significantly compromised moving state into a new crate makes it easier to encapsulate as it's own feature, and easier to read and understand since it's no longer a single, massive file. ## Solution move the state-related elements from bevy_ecs to a new crate ## Testing - Did you test these changes? If so, how? all the automated tests migrated and passed, ran the pre-existing examples without changes to validate. --- ## Migration Guide Since bevy_state is now gated behind the `bevy_state` feature, projects that use state but don't use the `default-features` will need to add that feature flag. Since it is no longer part of bevy_ecs, projects that use bevy_ecs directly will need to manually pull in `bevy_state`, trigger the StateTransition schedule, and handle any of the elements that bevy_app currently sets up. --------- Co-authored-by: Kristoffer Søholm <k.soeholm@gmail.com> |
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Lee-Orr
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b9455afd0c
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Schedule resource mutation (#13193)
# Objective Resolves #13185 ## Solution Move the following methods from `sub_app` to the `Schedules` resource, and use them in the sub app: - `add_systems` - `configure_sets` - `ignore_ambiguity` Add an `entry(&mut self, label: impl ScheduleLabel) -> &mut Schedule` method to the `Schedules` resource, which returns a mutable reference to the schedule associated with the label, and creates one if it doesn't already exist. (build on top of the `entry(..).or_insert_with(...)` pattern in `HashMap`. ## Testing - Did you test these changes? If so, how? Added 4 unit tests to the `schedule.rs` - one that validates adding a system to an existing schedule, one that validates adding a system to a new one, one that validates configuring sets on an existing schedule, and one that validates configuring sets on a new schedule. - I didn't add tests for `entry` since the previous 4 tests use functions that rely on it. - I didn't test `ignore_ambiguity` since I didn't see examples of it's use, and am not familiar enough with it to know how to set up a good test for it. However, it relies on the `entry` method as well, so it should work just like the other 2 methods. |
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Lee-Orr
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b8832dc862
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Computed State & Sub States (#11426)
## Summary/Description This PR extends states to allow support for a wider variety of state types and patterns, by providing 3 distinct types of state: - Standard [`States`] can only be changed by manually setting the [`NextState<S>`] resource. These states are the baseline on which the other state types are built, and can be used on their own for many simple patterns. See the [state example](https://github.com/bevyengine/bevy/blob/latest/examples/ecs/state.rs) for a simple use case - these are the states that existed so far in Bevy. - [`SubStates`] are children of other states - they can be changed manually using [`NextState<S>`], but are removed from the [`World`] if the source states aren't in the right state. See the [sub_states example](https://github.com/lee-orr/bevy/blob/derived_state/examples/ecs/sub_states.rs) for a simple use case based on the derive macro, or read the trait docs for more complex scenarios. - [`ComputedStates`] are fully derived from other states - they provide a [`compute`](ComputedStates::compute) method that takes in the source states and returns their derived value. They are particularly useful for situations where a simplified view of the source states is necessary - such as having an `InAMenu` computed state derived from a source state that defines multiple distinct menus. See the [computed state example](https://github.com/lee-orr/bevy/blob/derived_state/examples/ecs/computed_states.rscomputed_states.rs) to see a sampling of uses for these states. # Objective This PR is another attempt at allowing Bevy to better handle complex state objects in a manner that doesn't rely on strict equality. While my previous attempts (https://github.com/bevyengine/bevy/pull/10088 and https://github.com/bevyengine/bevy/pull/9957) relied on complex matching capacities at the point of adding a system to application, this one instead relies on deterministically deriving simple states from more complex ones. As a result, it does not require any special macros, nor does it change any other interactions with the state system once you define and add your derived state. It also maintains a degree of distinction between `State` and just normal application state - your derivations have to end up being discreet pre-determined values, meaning there is less of a risk/temptation to place a significant amount of logic and data within a given state. ### Addition - Sub States closes #9942 After some conversation with Maintainers & SMEs, a significant concern was that people might attempt to use this feature as if it were sub-states, and find themselves unable to use it appropriately. Since `ComputedState` is mainly a state matching feature, while `SubStates` are more of a state mutation related feature - but one that is easy to add with the help of the machinery introduced by `ComputedState`, it was added here as well. The relevant discussion is here: https://discord.com/channels/691052431525675048/1200556329803186316 ## Solution closes #11358 The solution is to create a new type of state - one implementing `ComputedStates` - which is deterministically tied to one or more other states. Implementors write a function to transform the source states into the computed state, and it gets triggered whenever one of the source states changes. In addition, we added the `FreelyMutableState` trait , which is implemented as part of the derive macro for `States`. This allows us to limit use of `NextState<S>` to states that are actually mutable, preventing mis-use of `ComputedStates`. --- ## Changelog - Added `ComputedStates` trait - Added `FreelyMutableState` trait - Converted `NextState` resource to an Enum, with `Unchanged` and `Pending` - Added `App::add_computed_state::<S: ComputedStates>()`, to allow for easily adding derived states to an App. - Moved the `StateTransition` schedule label from `bevy_app` to `bevy_ecs` - but maintained the export in `bevy_app` for continuity. - Modified the process for updating states. Instead of just having an `apply_state_transition` system that can be added anywhere, we now have a multi-stage process that has to run within the `StateTransition` label. First, all the state changes are calculated - manual transitions rely on `apply_state_transition`, while computed transitions run their computation process before both call `internal_apply_state_transition` to apply the transition, send out the transition event, trigger dependent states, and record which exit/transition/enter schedules need to occur. Once all the states have been updated, the transition schedules are called - first the exit schedules, then transition schedules and finally enter schedules. - Added `SubStates` trait - Adjusted `apply_state_transition` to be a no-op if the `State<S>` resource doesn't exist ## Migration Guide If the user accessed the NextState resource's value directly or created them from scratch they will need to adjust to use the new enum variants: - if they created a `NextState(Some(S))` - they should now use `NextState::Pending(S)` - if they created a `NextState(None)` -they should now use `NextState::Unchanged` - if they matched on the `NextState` value, they would need to make the adjustments above If the user manually utilized `apply_state_transition`, they should instead use systems that trigger the `StateTransition` schedule. --- ## Future Work There is still some future potential work in the area, but I wanted to keep these potential features and changes separate to keep the scope here contained, and keep the core of it easy to understand and use. However, I do want to note some of these things, both as inspiration to others and an illustration of what this PR could unlock. - `NextState::Remove` - Now that the `State` related mechanisms all utilize options (#11417), it's fairly easy to add support for explicit state removal. And while `ComputedStates` can add and remove themselves, right now `FreelyMutableState`s can't be removed from within the state system. While it existed originally in this PR, it is a different question with a separate scope and usability concerns - so having it as it's own future PR seems like the best approach. This feature currently lives in a separate branch in my fork, and the differences between it and this PR can be seen here: https://github.com/lee-orr/bevy/pull/5 - `NextState::ReEnter` - this would allow you to trigger exit & entry systems for the current state type. We can potentially also add a `NextState::ReEnterRecirsive` to also re-trigger any states that depend on the current one. - More mechanisms for `State` updates - This PR would finally make states that aren't a set of exclusive Enums useful, and with that comes the question of setting state more effectively. Right now, to update a state you either need to fully create the new state, or include the `Res<Option<State<S>>>` resource in your system, clone the state, mutate it, and then use `NextState.set(my_mutated_state)` to make it the pending next state. There are a few other potential methods that could be implemented in future PRs: - Inverse Compute States - these would essentially be compute states that have an additional (manually defined) function that can be used to nudge the source states so that they result in the computed states having a given value. For example, you could use set the `IsPaused` state, and it would attempt to pause or unpause the game by modifying the `AppState` as needed. - Closure-based state modification - this would involve adding a `NextState.modify(f: impl Fn(Option<S> -> Option<S>)` method, and then you can pass in closures or function pointers to adjust the state as needed. - Message-based state modification - this would involve either creating states that can respond to specific messages, similar to Elm or Redux. These could either use the `NextState` mechanism or the Event mechanism. - ~`SubStates` - which are essentially a hybrid of computed and manual states. In the simplest (and most likely) version, they would work by having a computed element that determines whether the state should exist, and if it should has the capacity to add a new version in, but then any changes to it's content would be freely mutated.~ this feature is now part of this PR. See above. - Lastly, since states are getting more complex there might be value in moving them out of `bevy_ecs` and into their own crate, or at least out of the `schedule` module into a `states` module. #11087 As mentioned, all these future work elements are TBD and are explicitly not part of this PR - I just wanted to provide them as potential explorations for the future. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Marcel Champagne <voiceofmarcel@gmail.com> Co-authored-by: MiniaczQ <xnetroidpl@gmail.com> |
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Charles Bournhonesque
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f73950767b
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Update App:is_plugin_added to work inside Plugin::finish and Plugin::clean (#12761)
# Objective I have been trying to check for the existing of some plugins via `App::is_plugin_added` to conditionally run some behaviour in the `Plugin::finish` part of my plugin, before realizing that the plugin registry is actually not available during this step. This is because the `App::is_plugin_added` using the plugin registry to check for previous registration. ## Solution - Switch the `App::is_plugin_added` to use the list of plugin names to check for previous registrations - Add a unit test showcasing that `App::is_plugin_added` works during `Plugin::finish` |
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James Liu
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ae9775c83b
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Optimize Event Updates (#12936)
# Objective Improve performance scalability when adding new event types to a Bevy app. Currently, just using Bevy in the default configuration, all apps spend upwards of 100+us in the `First` schedule, every app tick, evaluating if it should update events or not, even if events are not being used for that particular frame, and this scales with the number of Events registered in the app. ## Solution As `Events::update` is guaranteed `O(1)` by just checking if a resource's value, swapping two Vecs, and then clearing one of them, the actual cost of running `event_update_system` is *very* cheap. The overhead of doing system dependency injection, task scheduling ,and the multithreaded executor outweighs the cost of running the system by a large margin. Create an `EventRegistry` resource that keeps a number of function pointers that update each event. Replace the per-event type `event_update_system` with a singular exclusive system uses the `EventRegistry` to update all events instead. Update `SubApp::add_event` to use `EventRegistry` instead. ## Performance This speeds reduces the cost of the `First` schedule in both many_foxes and many_cubes by over 80%. Note this is with system spans on. The majority of this is now context-switching costs from launching `time_system`, which should be mostly eliminated with #12869.  The actual `event_update_system` is usually *very* short, using only a few microseconds on average.  --- ## Changelog TODO ## Migration Guide TODO --------- Co-authored-by: Josh Matthews <josh@joshmatthews.net> Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> |
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Cameron
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01649f13e2
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Refactor App and SubApp internals for better separation (#9202)
# 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>.` |