docs/bevy/examples/ecs/custom_executor.rs 1.3 K · 56 lines · raw · history

1 //! Demonstrates how to make a custom [`SystemExecutor`].
2
3 use bevy::{
4 ecs::{
5 error::{BevyError, ErrorContext},
6 schedule::{FixedBitSet, SystemExecutor, SystemSchedule},
7 },
8 prelude::*,
9 };
10
11 #[derive(Default)]
12 struct CustomExecutor;
13
14 impl SystemExecutor for CustomExecutor {
15 fn init(&mut self, _schedule: &SystemSchedule) {}
16
17 fn run(
18 &mut self,
19 schedule: &mut SystemSchedule,
20 world: &mut World,
21 _skip_systems: Option<&FixedBitSet>,
22 _error_handler: fn(BevyError, ErrorContext),
23 ) {
24 #[expect(unsafe_code, reason = "CustomExecutor's require unsafe")]
25 // SAFETY: `run` is a trait method on `System`
26 for entry in unsafe { schedule.systems_mut().iter_mut() } {
27 let _ = entry.run((), world);
28 }
29 }
30
31 fn set_apply_final_deferred(&mut self, _value: bool) {}
32 }
33
34 #[derive(Resource, Default)]
35 struct Counter(u32);
36
37 fn increment(mut counter: ResMut<Counter>) {
38 counter.0 += 1;
39 }
40
41 fn print_counter(counter: Res<Counter>) {
42 println!("Counter: {}", counter.0);
43 }
44
45 fn main() {
46 let mut world = World::new();
47 world.init_resource::<Counter>();
48
49 let mut schedule = Schedule::default();
50 schedule.set_executor(CustomExecutor);
51 schedule.add_systems((increment, print_counter).chain());
52
53 for _ in 0..5 {
54 schedule.run(&mut world);
55 }
56 }