bevy/examples/ecs/event.rs
Carter Anderson 3a6f6de277
System Inputs, Outputs, Chaining, and Registration Ergo (#876)
System Inputs, Outputs, Chaining, and Registration Ergo
2020-11-16 18:18:00 -08:00

53 lines
1.3 KiB
Rust

use bevy::prelude::*;
/// This example creates a new event, a system that triggers the event once per second,
/// and a system that prints a message whenever the event is received.
fn main() {
App::build()
.add_plugins(DefaultPlugins)
.add_event::<MyEvent>()
.init_resource::<EventTriggerState>()
.add_system(event_trigger_system)
.add_system(event_listener_system)
.run();
}
struct MyEvent {
pub message: String,
}
struct EventTriggerState {
event_timer: Timer,
}
impl Default for EventTriggerState {
fn default() -> Self {
EventTriggerState {
event_timer: Timer::from_seconds(1.0, true),
}
}
}
// sends MyEvent every second
fn event_trigger_system(
time: Res<Time>,
mut state: ResMut<EventTriggerState>,
mut my_events: ResMut<Events<MyEvent>>,
) {
if state.event_timer.tick(time.delta_seconds).finished {
my_events.send(MyEvent {
message: "MyEvent just happened!".to_string(),
});
}
}
// prints events as they come in
fn event_listener_system(
mut my_event_reader: Local<EventReader<MyEvent>>,
my_events: Res<Events<MyEvent>>,
) {
for my_event in my_event_reader.iter(&my_events) {
println!("{}", my_event.message);
}
}