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app_builder.rs
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app_builder.rs
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use crate::{
app::{App, AppExit},
plugin::Plugin,
CoreStage, PluginGroup, PluginGroupBuilder, StartupStage,
};
use bevy_ecs::{
component::{Component, ComponentDescriptor},
event::Events,
schedule::{
RunOnce, Schedule, Stage, StageLabel, State, SystemDescriptor, SystemSet, SystemStage,
},
system::{IntoExclusiveSystem, IntoSystem},
world::{FromWorld, World},
};
use bevy_utils::tracing::debug;
use std::{fmt::Debug, hash::Hash};
/// Configure [App]s using the builder pattern
pub struct AppBuilder {
pub app: App,
}
impl Default for AppBuilder {
fn default() -> Self {
let mut app_builder = AppBuilder {
app: App::default(),
};
#[cfg(feature = "bevy_reflect")]
app_builder.init_resource::<bevy_reflect::TypeRegistryArc>();
app_builder
.add_default_stages()
.add_event::<AppExit>()
.add_system_to_stage(CoreStage::Last, World::clear_trackers.exclusive_system());
#[cfg(feature = "bevy_ci_testing")]
{
crate::ci_testing::setup_app(&mut app_builder);
}
app_builder
}
}
impl AppBuilder {
pub fn empty() -> AppBuilder {
AppBuilder {
app: App::default(),
}
}
/// Start the application (through main runner)
///
/// Runs the application main loop.
///
/// Usually the main loop is handled by Bevy integrated plugins (`winit`), but
/// but one can also set the runner function through [`AppBuilder::set_runner`].
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// #
/// App::build()
/// // all required plugin insertions, systems, etc inserted here
/// // finally, call:
/// .run();
/// ```
pub fn run(&mut self) {
let app = std::mem::take(&mut self.app);
app.run();
}
pub fn world(&mut self) -> &World {
&self.app.world
}
pub fn world_mut(&mut self) -> &mut World {
&mut self.app.world
}
pub fn set_world(&mut self, world: World) -> &mut Self {
self.app.world = world;
self
}
pub fn add_stage<S: Stage>(&mut self, label: impl StageLabel, stage: S) -> &mut Self {
self.app.schedule.add_stage(label, stage);
self
}
pub fn add_stage_after<S: Stage>(
&mut self,
target: impl StageLabel,
label: impl StageLabel,
stage: S,
) -> &mut Self {
self.app.schedule.add_stage_after(target, label, stage);
self
}
pub fn add_stage_before<S: Stage>(
&mut self,
target: impl StageLabel,
label: impl StageLabel,
stage: S,
) -> &mut Self {
self.app.schedule.add_stage_before(target, label, stage);
self
}
pub fn add_startup_stage<S: Stage>(&mut self, label: impl StageLabel, stage: S) -> &mut Self {
self.app
.schedule
.stage(CoreStage::Startup, |schedule: &mut Schedule| {
schedule.add_stage(label, stage)
});
self
}
pub fn add_startup_stage_after<S: Stage>(
&mut self,
target: impl StageLabel,
label: impl StageLabel,
stage: S,
) -> &mut Self {
self.app
.schedule
.stage(CoreStage::Startup, |schedule: &mut Schedule| {
schedule.add_stage_after(target, label, stage)
});
self
}
pub fn add_startup_stage_before<S: Stage>(
&mut self,
target: impl StageLabel,
label: impl StageLabel,
stage: S,
) -> &mut Self {
self.app
.schedule
.stage(CoreStage::Startup, |schedule: &mut Schedule| {
schedule.add_stage_before(target, label, stage)
});
self
}
pub fn stage<T: Stage, F: FnOnce(&mut T) -> &mut T>(
&mut self,
label: impl StageLabel,
func: F,
) -> &mut Self {
self.app.schedule.stage(label, func);
self
}
/// Adds a system that runs every time `app.update()` is called by the runner
///
/// Systems are the main building block in the Bevy ECS app model. You can define
/// normal rust functions, and call `.system()` to make them be Bevy systems.
///
/// System functions can have parameters, through which one can query and
/// mutate Bevy ECS states.
/// See [The Bevy Book](https://bevyengine.org/learn/book/introduction/) for more information.
///
/// Systems are run in parallel, and the execution order is not deterministic.
/// If you want more fine-grained control for order, see [`AppBuilder::add_system_to_stage`].
///
/// For adding a system that runs only at app startup, see [`AppBuilder::add_startup_system`].
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// # use bevy_ecs::prelude::*;
/// #
/// fn my_system(_commands: Commands) {
/// println!("My system, triggered once per frame");
/// }
///
/// App::build()
/// .add_system(my_system.system());
/// ```
pub fn add_system(&mut self, system: impl Into<SystemDescriptor>) -> &mut Self {
self.add_system_to_stage(CoreStage::Update, system)
}
pub fn add_system_set(&mut self, system_set: SystemSet) -> &mut Self {
self.add_system_set_to_stage(CoreStage::Update, system_set)
}
pub fn add_system_to_stage(
&mut self,
stage_label: impl StageLabel,
system: impl Into<SystemDescriptor>,
) -> &mut Self {
self.app.schedule.add_system_to_stage(stage_label, system);
self
}
pub fn add_system_set_to_stage(
&mut self,
stage_label: impl StageLabel,
system_set: SystemSet,
) -> &mut Self {
self.app
.schedule
.add_system_set_to_stage(stage_label, system_set);
self
}
/// Adds a system that is run once at application startup
///
/// Startup systems run exactly once BEFORE all other systems. These are generally used for
/// app initialization code (ex: adding entities and resources).
///
/// * For adding a system that runs for every frame, see [`AppBuilder::add_system`].
/// * For adding a system to specific stage, see [`AppBuilder::add_system_to_stage`].
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// # use bevy_ecs::prelude::*;
/// #
/// fn my_startup_system(_commands: Commands) {
/// println!("My startup system");
/// }
///
/// App::build()
/// .add_startup_system(my_startup_system.system());
/// ```
pub fn add_startup_system(&mut self, system: impl Into<SystemDescriptor>) -> &mut Self {
self.add_startup_system_to_stage(StartupStage::Startup, system)
}
pub fn add_startup_system_to_stage(
&mut self,
stage_label: impl StageLabel,
system: impl Into<SystemDescriptor>,
) -> &mut Self {
self.app
.schedule
.stage(CoreStage::Startup, |schedule: &mut Schedule| {
schedule.add_system_to_stage(stage_label, system)
});
self
}
/// Adds a new [State] with the given `initial` value.
/// This inserts a new `State<T>` resource and adds a new "driver" to [CoreStage::Update].
/// Each stage that uses `State<T>` for system run criteria needs a driver. If you need to use
/// your state in a different stage, consider using [Self::add_state_to_stage] or manually
/// adding [State::get_driver] to additional stages you need it in.
pub fn add_state<T>(&mut self, initial: T) -> &mut Self
where
T: Component + Debug + Clone + Eq + Hash,
{
self.add_state_to_stage(CoreStage::Update, initial)
}
/// Adds a new [State] with the given `initial` value.
/// This inserts a new `State<T>` resource and adds a new "driver" to the given stage.
/// Each stage that uses `State<T>` for system run criteria needs a driver. If you need to use
/// your state in more than one stage, consider manually adding [State::get_driver] to the
/// stages you need it in.
pub fn add_state_to_stage<T>(&mut self, stage: impl StageLabel, initial: T) -> &mut Self
where
T: Component + Debug + Clone + Eq + Hash,
{
self.insert_resource(State::new(initial))
.add_system_set_to_stage(stage, State::<T>::get_driver())
}
pub fn add_default_stages(&mut self) -> &mut Self {
self.add_stage(CoreStage::First, SystemStage::parallel())
.add_stage(
CoreStage::Startup,
Schedule::default()
.with_run_criteria(RunOnce::default())
.with_stage(StartupStage::PreStartup, SystemStage::parallel())
.with_stage(StartupStage::Startup, SystemStage::parallel())
.with_stage(StartupStage::PostStartup, SystemStage::parallel()),
)
.add_stage(CoreStage::PreUpdate, SystemStage::parallel())
.add_stage(CoreStage::Update, SystemStage::parallel())
.add_stage(CoreStage::PostUpdate, SystemStage::parallel())
.add_stage(CoreStage::Last, SystemStage::parallel())
}
/// Setup the application to manage events of type `T`.
///
/// This is done by adding a `Resource` of type `Events::<T>`,
/// and inserting a `Events::<T>::update_system` system into `CoreStage::First`.
pub fn add_event<T>(&mut self) -> &mut Self
where
T: Component,
{
self.insert_resource(Events::<T>::default())
.add_system_to_stage(CoreStage::First, Events::<T>::update_system.system())
}
/// Inserts a resource to the current [App] and overwrites any resource previously added of the same type.
///
/// A resource in Bevy represents globally unique data. Resources must be added to Bevy Apps
/// before using them. This happens with [`AppBuilder::insert_resource`].
///
/// See also `init_resource` for resources that implement `Default` or [`FromResources`].
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// #
/// struct MyCounter {
/// counter: usize,
/// }
///
/// App::build()
/// .insert_resource(MyCounter { counter: 0 });
/// ```
pub fn insert_resource<T>(&mut self, resource: T) -> &mut Self
where
T: Component,
{
self.app.world.insert_resource(resource);
self
}
/// Inserts a non-send resource to the app
///
/// You usually want to use `insert_resource`, but there are some special cases when a resource must
/// be non-send.
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// #
/// struct MyCounter {
/// counter: usize,
/// }
///
/// App::build()
/// .insert_non_send_resource(MyCounter { counter: 0 });
/// ```
pub fn insert_non_send_resource<T>(&mut self, resource: T) -> &mut Self
where
T: 'static,
{
self.app.world.insert_non_send(resource);
self
}
/// Initialize a resource in the current [App], if it does not exist yet
///
/// Adds a resource that implements `Default` or [`FromResources`] trait.
/// If the resource already exists, `init_resource` does nothing.
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// #
/// struct MyCounter {
/// counter: usize,
/// }
///
/// impl Default for MyCounter {
/// fn default() -> MyCounter {
/// MyCounter {
/// counter: 100
/// }
/// }
/// }
///
/// App::build()
/// .init_resource::<MyCounter>();
/// ```
pub fn init_resource<R>(&mut self) -> &mut Self
where
R: FromWorld + Send + Sync + 'static,
{
// PERF: We could avoid double hashing here, since the `from_resources` call is guaranteed
// not to modify the map. However, we would need to be borrowing resources both
// mutably and immutably, so we would need to be extremely certain this is correct
if !self.world_mut().contains_resource::<R>() {
let resource = R::from_world(self.world_mut());
self.insert_resource(resource);
}
self
}
pub fn init_non_send_resource<R>(&mut self) -> &mut Self
where
R: FromWorld + 'static,
{
// See perf comment in init_resource
if self.app.world.get_non_send_resource::<R>().is_none() {
let resource = R::from_world(self.world_mut());
self.app.world.insert_non_send(resource);
}
self
}
/// Sets the main runner loop function for this Bevy App
///
/// Usually the main loop is handled by Bevy integrated plugins ([`WinitPlugin`]), but
/// in some cases one might wish to implement their own main loop.
///
/// This method sets the main loop function, overwriting a previous runner if any.
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// #
/// fn my_runner(mut app: App) {
/// loop {
/// println!("In main loop");
/// app.update();
/// }
/// }
///
/// App::build()
/// .set_runner(my_runner);
/// ```
pub fn set_runner(&mut self, run_fn: impl Fn(App) + 'static) -> &mut Self {
self.app.runner = Box::new(run_fn);
self
}
/// Adds a single plugin
///
/// One of Bevy's core principles is modularity. All Bevy engine features are implemented
/// as plugins. This includes internal features like the renderer.
///
/// Bevy also provides a few sets of default plugins. See [`AppBuilder::add_plugins`].
///
/// ## Example
/// ```
/// # use bevy_app::prelude::*;
/// #
/// App::build().add_plugin(bevy_log::LogPlugin::default());
/// ```
pub fn add_plugin<T>(&mut self, plugin: T) -> &mut Self
where
T: Plugin,
{
debug!("added plugin: {}", plugin.name());
plugin.build(self);
self
}
/// Adds a group of plugins
///
/// Bevy plugins can be grouped into a set of plugins. Bevy provides
/// built-in PluginGroups that provide core engine functionality.
///
/// The plugin groups available by default are [`DefaultPlugins`] and [`MinimalPlugins`].
///
/// ## Example
/// ```
/// # use bevy_app::{prelude::*, PluginGroupBuilder};
/// #
/// # // Dummy created to avoid using bevy_internal, which pulls in to many dependencies.
/// # struct MinimalPlugins;
/// # impl PluginGroup for MinimalPlugins {
/// # fn build(&mut self, group: &mut PluginGroupBuilder){;}
/// # }
/// #
/// App::build()
/// .add_plugins(MinimalPlugins);
/// ```
pub fn add_plugins<T: PluginGroup>(&mut self, mut group: T) -> &mut Self {
let mut plugin_group_builder = PluginGroupBuilder::default();
group.build(&mut plugin_group_builder);
plugin_group_builder.finish(self);
self
}
/// Adds a group of plugins with an initializer method
///
/// Can be used to add a group of plugins, where the group is modified
/// before insertion into Bevy application. For example, you can add
/// extra plugins at a specific place in the plugin group, or deactivate
/// specific plugins while keeping the rest.
///
/// ## Example
/// ```
/// # use bevy_app::{prelude::*, PluginGroupBuilder};
/// #
/// # // Dummies created to avoid using bevy_internal which pulls in to many dependencies.
/// # struct DefaultPlugins;
/// # impl PluginGroup for DefaultPlugins {
/// # fn build(&mut self, group: &mut PluginGroupBuilder){
/// # group.add(bevy_log::LogPlugin::default());
/// # }
/// # }
/// #
/// # struct MyOwnPlugin;
/// # impl Plugin for MyOwnPlugin {
/// # fn build(&self, app: &mut AppBuilder){;}
/// # }
/// #
/// App::build()
/// .add_plugins_with(DefaultPlugins, |group| {
/// group.add_before::<bevy_log::LogPlugin, _>(MyOwnPlugin)
/// });
/// ```
pub fn add_plugins_with<T, F>(&mut self, mut group: T, func: F) -> &mut Self
where
T: PluginGroup,
F: FnOnce(&mut PluginGroupBuilder) -> &mut PluginGroupBuilder,
{
let mut plugin_group_builder = PluginGroupBuilder::default();
group.build(&mut plugin_group_builder);
func(&mut plugin_group_builder);
plugin_group_builder.finish(self);
self
}
/// Registers a new component using the given [ComponentDescriptor]. Components do not need to
/// be manually registered. This just provides a way to override default configuration.
/// Attempting to register a component with a type that has already been used by [World]
/// will result in an error.
///
/// See [World::register_component]
pub fn register_component(&mut self, descriptor: ComponentDescriptor) -> &mut Self {
self.world_mut().register_component(descriptor).unwrap();
self
}
#[cfg(feature = "bevy_reflect")]
pub fn register_type<T: bevy_reflect::GetTypeRegistration>(&mut self) -> &mut Self {
{
let registry = self
.world_mut()
.get_resource_mut::<bevy_reflect::TypeRegistryArc>()
.unwrap();
registry.write().register::<T>();
}
self
}
}