fd308571c4
# Objective - Shorten paths by removing unnecessary prefixes ## Solution - Remove the prefixes from many paths which do not need them. Finding the paths was done automatically using built-in refactoring tools in Jetbrains RustRover.
60 lines
1.8 KiB
Rust
60 lines
1.8 KiB
Rust
//! Demonstrates the use of "one-shot systems", which run once when triggered.
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//!
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//! These can be useful to help structure your logic in a push-based fashion,
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//! reducing the overhead of running extremely rarely run systems
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//! and improving schedule flexibility.
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//!
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//! See the [`World::run_system`](World::run_system) or
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//! [`World::run_system_once`](World#method.run_system_once_with)
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//! docs for more details.
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use bevy::{
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ecs::system::{RunSystemOnce, SystemId},
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prelude::*,
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};
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fn main() {
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App::new()
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.add_systems(Startup, (count_entities, setup))
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.add_systems(PostUpdate, count_entities)
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.add_systems(Update, evaluate_callbacks)
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.run();
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}
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// Any ordinary system can be run via commands.run_system or world.run_system.
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fn count_entities(all_entities: Query<()>) {
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dbg!(all_entities.iter().count());
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}
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#[derive(Component)]
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struct Callback(SystemId);
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#[derive(Component)]
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struct Triggered;
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fn setup(world: &mut World) {
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let button_pressed_id = world.register_system(button_pressed);
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world.spawn((Callback(button_pressed_id), Triggered));
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// This entity does not have a Triggered component, so its callback won't run.
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let slider_toggled_id = world.register_system(slider_toggled);
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world.spawn(Callback(slider_toggled_id));
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world.run_system_once(count_entities);
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}
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fn button_pressed() {
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println!("A button was pressed!");
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}
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fn slider_toggled() {
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println!("A slider was toggled!");
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}
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/// Runs the systems associated with each `Callback` component if the entity also has a Triggered component.
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///
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/// This could be done in an exclusive system rather than using `Commands` if preferred.
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fn evaluate_callbacks(query: Query<&Callback, With<Triggered>>, mut commands: Commands) {
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for callback in query.iter() {
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commands.run_system(callback.0);
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}
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}
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