mirror of
https://github.com/bevyengine/bevy
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1260b7bcf1
# Objective
- Make it possible to react to arbitrary state changes
- this will be useful regardless of the other changes to states
currently being discussed
## Solution
- added `StateTransitionEvent<S>` struct
- previously, this would have been impossible:
```rs
#[derive(States, Eq, PartialEq, Hash, Copy, Clone, Default)]
enum MyState {
#[default]
Foo,
Bar(MySubState),
}
enum MySubState {
Spam,
Eggs,
}
app.add_system(Update, on_enter_bar);
fn on_enter_bar(trans: EventReader<StateTransition<MyState>>){
for (befoare, after) in trans.read() {
match before, after {
MyState::Foo, MyState::Bar(_) => info!("detected transition foo => bar");
_, _ => ();
}
}
}
```
---
## Changelog
- Added
- `StateTransitionEvent<S>` - Fired on state changes of `S`
## Migration Guide
N/A no breaking changes
---------
Co-authored-by: Federico Rinaldi <gisquerin@gmail.com>
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|---|---|---|
| .. | ||
| apply_deferred.rs | ||
| component_change_detection.rs | ||
| custom_query_param.rs | ||
| ecs_guide.rs | ||
| event.rs | ||
| fixed_timestep.rs | ||
| generic_system.rs | ||
| hierarchy.rs | ||
| iter_combinations.rs | ||
| nondeterministic_system_order.rs | ||
| one_shot_systems.rs | ||
| parallel_query.rs | ||
| removal_detection.rs | ||
| run_conditions.rs | ||
| startup_system.rs | ||
| state.rs | ||
| system_closure.rs | ||
| system_param.rs | ||
| system_piping.rs | ||