cbd4abf0fc
# Objective - `apply_system_buffers` is an unhelpful name: it introduces a new internal-only concept - this is particularly rough for beginners as reasoning about how commands work is a critical stumbling block ## Solution - rename `apply_system_buffers` to the more descriptive `apply_deferred` - rename related fields, arguments and methods in the internals fo bevy_ecs for consistency - update the docs ## Changelog `apply_system_buffers` has been renamed to `apply_deferred`, to more clearly communicate its intent and relation to `Deferred` system parameters like `Commands`. ## Migration Guide - `apply_system_buffers` has been renamed to `apply_deferred` - the `apply_system_buffers` method on the `System` trait has been renamed to `apply_deferred` - the `is_apply_system_buffers` function has been replaced by `is_apply_deferred` - `Executor::set_apply_final_buffers` is now `Executor::set_apply_final_deferred` - `Schedule::apply_system_buffers` is now `Schedule::apply_deferred` --------- Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
62 lines
2.2 KiB
Rust
62 lines
2.2 KiB
Rust
//! This example shows how you can know when a [`Component`] has been removed, so you can react to it.
|
|
|
|
use bevy::prelude::*;
|
|
|
|
fn main() {
|
|
// Information regarding removed `Component`s is discarded at the end of each frame, so you need
|
|
// to react to the removal before the frame is over.
|
|
//
|
|
// Also, `Components` are removed via a `Command`, which are not applied immediately.
|
|
// So you need to react to the removal at some stage after `apply_deferred` has run,
|
|
// and the Component` is removed.
|
|
//
|
|
// With these constraints in mind we make sure to place the system that removes a `Component` in
|
|
// `CoreSet::Update', and the system that reacts on the removal in `CoreSet::PostUpdate`.
|
|
App::new()
|
|
.add_plugins(DefaultPlugins)
|
|
.add_systems(Startup, setup)
|
|
.add_systems(Update, remove_component)
|
|
.add_systems(PostUpdate, react_on_removal)
|
|
.run();
|
|
}
|
|
|
|
// This `Struct` is just used for convenience in this example. This is the `Component` we'll be
|
|
// giving to the `Entity` so we have a `Component` to remove in `remove_component()`.
|
|
#[derive(Component)]
|
|
struct MyComponent;
|
|
|
|
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
|
|
commands.spawn(Camera2dBundle::default());
|
|
commands.spawn((
|
|
SpriteBundle {
|
|
texture: asset_server.load("branding/icon.png"),
|
|
..default()
|
|
},
|
|
// Add the `Component`.
|
|
MyComponent,
|
|
));
|
|
}
|
|
|
|
fn remove_component(
|
|
time: Res<Time>,
|
|
mut commands: Commands,
|
|
query: Query<Entity, With<MyComponent>>,
|
|
) {
|
|
// After two seconds have passed the `Component` is removed.
|
|
if time.elapsed_seconds() > 2.0 {
|
|
if let Some(entity) = query.iter().next() {
|
|
commands.entity(entity).remove::<MyComponent>();
|
|
}
|
|
}
|
|
}
|
|
|
|
fn react_on_removal(mut removed: RemovedComponents<MyComponent>, mut query: Query<&mut Sprite>) {
|
|
// `RemovedComponents<T>::iter()` returns an iterator with the `Entity`s that had their
|
|
// `Component` `T` (in this case `MyComponent`) removed at some point earlier during the frame.
|
|
for entity in &mut removed {
|
|
if let Ok(mut sprite) = query.get_mut(entity) {
|
|
sprite.color.set_r(0.0);
|
|
}
|
|
}
|
|
}
|