Function bevy_ecs::schedule::common_conditions::on_event
source · pub fn on_event<T: Event>(
) -> impl FnMut(EventReader<'_, '_, T>) -> bool + Clone
Expand description
Generates a Condition
-satisfying closure that returns true
if there are any new events of the given type since it was last called.
§Example
app.add_systems(
my_system.run_if(on_event::<MyEvent>()),
);
#[derive(Event)]
struct MyEvent;
fn my_system(mut counter: ResMut<Counter>) {
counter.0 += 1;
}
// No new `MyEvent` events have been push so `my_system` won't run
app.run(&mut world);
assert_eq!(world.resource::<Counter>().0, 0);
world.resource_mut::<Events<MyEvent>>().send(MyEvent);
// A `MyEvent` event has been pushed so `my_system` will run
app.run(&mut world);
assert_eq!(world.resource::<Counter>().0, 1);