N46: seldom_state

Author: Seldom-SE

content/news/046/index.md

@@ -75,6 +75,46 @@ If needed, a section can be split into subsections with a "------" delimiter.
 
 ## Library Updates
 
+### [seldom_state]
+
+[seldom_state] is a Bevy plugin that adds a `StateMachine` component that you
+can add to your entities. The state machine will change the entity's components
+based on states, triggers, and transitions that you define. It's useful
+for player controllers, animations, simple AI, etc.
+
+This month, [seldom_state] 0.6 was released:
+
+- Triggers don't need to be registered!
+- `StateMachine::new(MachineState)` has been replaced with
+`StateMachine::default()`, and you must insert the initial state manually
+- `MachineState` requires `Component` now instead of `Bundle`
+- `MachineState` and `Trigger` no longer require `Reflect`
+- `StateMachine`'s 
+`trans_builder(Trigger, Fn(&Trigger::Ok) -> Option<MyNextState>)` is now
+`trans_builder(Trigger, Fn(&MyCurrentState, Trigger::Ok) -> Option<MyNextState>)`,
+so you can take information from the current state when building the next!
+- `StateMachine` no longer tracks the current state, so you may add and remove
+state components manually, as long as it's still in one state. Manual state
+changes won't trigger `on_enter` etc events. States that aren't used in any
+transitions can be registered manually with `StateMachine::with_state`, else it
+will think it isn't in a state and panic.
+- Replaced `StateMachine`'s `insert_on_enter(Bundle)` and `remove_on_exit()`
+with the more versatile `on_enter(Fn(&mut EntityCommands))`,
+`on_exit(Fn(&mut EntityCommands))`, `command_on_enter(Command)`, and
+`command_on_exit(Command)`
+- `Trigger`s may be combined with combinators `not`, `and`, and `or`
+- Transitions have priority in the order they are added
+- `Trigger::trigger` accepts `ReadOnlySystemParam` instead of `&SystemParam`, so
+you can use `EventReader`, `Local`, etc in your triggers!
+- Added an `EventTrigger<E>` that triggers on an event
+- `StateMachine::set_trans_logging` sets whether to log state transitions for
+debugging
+
+Thanks to [Sera] for coauthoring this update!
+
+[seldom_state]: https://github.com/Seldom-SE/seldom_state
+[Sera]: https://github.com/deifactor
+
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