mirror of
https://github.com/bevyengine/bevy
synced 2024-12-23 11:33:06 +00:00
b724a0f586
# Objective - Remove all the `.system()` possible. - Check for remaining missing cases. ## Solution - Remove all `.system()`, fix compile errors - 32 calls to `.system()` remains, mostly internals, the few others should be removed after #2446
67 lines
2.5 KiB
Rust
67 lines
2.5 KiB
Rust
use bevy_ecs::{event::Events, prelude::*};
|
|
|
|
// In this example a system sends a custom event with a 50/50 chance during any frame.
|
|
// If an event was send, it will be printed by the console in a receiving system.
|
|
fn main() {
|
|
// Create a new empty world and add the event as a resource
|
|
let mut world = World::new();
|
|
world.insert_resource(Events::<MyEvent>::default());
|
|
|
|
// Create a schedule and a stage
|
|
let mut schedule = Schedule::default();
|
|
|
|
// Events need to be updated in every frame. This update should happen before we use
|
|
// the events. To guarantee this, we can let the update run in an earlier stage than our logic.
|
|
// Here we will use a stage called "first" that will always run it's systems before the Stage
|
|
// called "second". In "first" we update the events and in "second" we run our systems
|
|
// sending and receiving events.
|
|
let mut first = SystemStage::parallel();
|
|
first.add_system(Events::<MyEvent>::update_system);
|
|
schedule.add_stage("first", first);
|
|
|
|
// Add systems sending and receiving events to a "second" Stage
|
|
let mut second = SystemStage::parallel();
|
|
second.add_system(sending_system.label(EventSystem::Sending));
|
|
second.add_system(receiving_system.after(EventSystem::Sending));
|
|
|
|
// Run the "second" Stage after the "first" Stage, so our Events always get updated before we use them
|
|
schedule.add_stage_after("first", "second", second);
|
|
|
|
// Simulate 10 frames of our world
|
|
for iteration in 1..=10 {
|
|
println!("Simulating frame {}/10", iteration);
|
|
schedule.run(&mut world);
|
|
}
|
|
}
|
|
|
|
// System label to enforce a run order of our systems
|
|
#[derive(SystemLabel, Debug, Clone, PartialEq, Eq, Hash)]
|
|
enum EventSystem {
|
|
Sending,
|
|
}
|
|
|
|
// This is our event that we will send and receive in systems
|
|
#[derive(Debug)]
|
|
struct MyEvent {
|
|
pub message: String,
|
|
pub random_value: f32,
|
|
}
|
|
|
|
// In every frame we will send an event with a 50/50 chance
|
|
fn sending_system(mut event_writer: EventWriter<MyEvent>) {
|
|
let random_value: f32 = rand::random();
|
|
if random_value > 0.5 {
|
|
event_writer.send(MyEvent {
|
|
message: "A random event with value > 0.5".to_string(),
|
|
random_value,
|
|
});
|
|
}
|
|
}
|
|
|
|
// This system listens for events of the type MyEvent
|
|
// If an event is received it will be printed to the console
|
|
fn receiving_system(mut event_reader: EventReader<MyEvent>) {
|
|
for my_event in event_reader.iter() {
|
|
println!(" Received: {:?}", *my_event);
|
|
}
|
|
}
|