Struct App 

pub struct App { /* private fields */ }

The main application container for ECS-based games.

App holds a World and a set of SystemStages organized by CoreStage. Systems are added to stages and executed in stage order.

Stage Execution Order

Stages run in CoreStage order: PreUpdate, Update, PostUpdate, PreRender, Render, PostRender.

Implementations

impl App

pub fn new_with_defaults() -> Self

Creates a new App with default stages and all DefaultPlugins applied.

pub fn new() -> Self

Creates a new App with default stages for each CoreStage variant.

pub fn add_plugin<P: Plugin>(&mut self, plugin: P) -> &mut Self

Adds a plugin to the app.

Each plugin type can only be added once. Duplicate additions are silently ignored.

Panics

Panics if the plugin declares dependencies that have not been added.

pub fn add_plugin_group<G: PluginGroup>(&mut self, group: G) -> &mut Self

Adds a plugin group to the app.

pub fn insert_non_send_resource<T: NonSendResource>( &mut self, resource: T, ) -> &mut Self

Inserts a non-send resource into the world.

pub fn add_system<S, Marker>( &mut self, stage: CoreStage, system: S, ) -> &mut Self

where S: IntoSystem<Marker>,

Adds a system to the specified stage.

pub fn insert_resource<R: Resource>(&mut self, resource: R) -> &mut Self

Inserts a resource into the world.

pub fn world(&self) -> &World

Returns an immutable reference to the world.

pub fn world_mut(&mut self) -> &mut World

Returns a mutable reference to the world.

pub fn run_once(&mut self)

Executes all stages once in order.

This runs every stage’s systems on the world, from PreUpdate through PostRender.

pub fn update(&mut self)

Executes all stages once, designed for per-frame use.

Currently identical to run_once. In the future, this may include frame-specific logic such as delta time updates.

pub fn register_set(&mut self, stage: CoreStage, name: &str) -> &mut Self

Registers a named system set in the specified stage.

pub fn add_system_to_set<S, Marker>( &mut self, stage: CoreStage, set_name: &str, system: S, ) -> &mut Self

where S: IntoSystem<Marker>,

Adds a system to a named set, returning its [SystemId].

The system is added to the stage and simultaneously placed in the named set.

pub fn configure_set( &mut self, stage: CoreStage, name: &str, config: SystemSetConfig, ) -> &mut Self

Configures ordering for a named set in the specified stage.

Trait Implementations

impl Debug for App

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for App

fn default() -> Self

Returns the “default value” for a type.