Como usar
- Copie o comando e verifique o pacote antes de instalar no seu ambiente de agente.
- Consulte no original as ferramentas, credenciais e ambientes necessários.
- Descreva os dados de entrada e a entrega esperada; confira a saída com as fontes.
npx skills add https://github.com/thedivergentai/game-design-agentic-skills --skill bevy-events-messagingAntes de começar
- A instalação não inclui assinatura de modelo, franquia API ou acesso aos seus arquivos.
- Estrelas e instalações indicam atividade, não um teste independente de qualidade ou segurança.
Documento original do Skill
Renderizado do repositório de origem, preservando títulos, exemplos, código, tabelas, links e imagens.
Bevy events and messaging
When to use
Load this when one system should notice that something happened without storing that fact on every entity. Pick the mechanism from the pages below. Do not invent a third channel.
ECS shape
- Messages (pull).
bevy::ecs::message0.20.0 defines theMessagetrait as a buffered message for pull-based handling.MessageWriterwrites.MessageReaderreads and tracks what it already saw.Messagesholds what occurred within the last twoMessages::updatecalls.message_update_systemcallsMessages::updateon registered messages.signal_message_update_systemsignals that update afterFixedUpdatesystems. Check theAppdocs for message registration helpers before writing a method name. - Events (push). The
Eventtrait page: deriveEvent, add an observer, trigger. The sample usesWorld::triggerandworld.add_observerwithOn<Speak>.Commands::triggeris also named. Observers run immediately inside the trigger call.Event::Triggerdefaults toGlobalTriggerfor derived events. - Observers.
bevy::ecs::observer: anObserveris a component that holds a system.Onis the system parameter that processes the event.EntityEventis the page's pointer for events that target one entity. Check that trait page for method names before writing them. - State transitions.
bevy::statedocumentsStateTransitionEvent<S>when stateSchanges. That type lives with states. See bevy-state-machines.
Coming from Godot
| Godot idea | Bevy idiom |
|---|---|
| Something happened; readers poll later | A Message plus MessageWriter / MessageReader |
| Something happened; listeners run now | An Event plus an Observer (On<...>) and trigger |
| Notice on one entity | EntityEvent. Check the trait page for methods before writing them. |
| Global signal singleton | Not this. Use a message type or a global event |
Scope
- Check the
Appdocs for methods that register a message type before writing them. - Check the observer module for
EntityEventmethods, entity-targeted trigger helpers, and observer run-condition helpers beyond the module index names. - Check the message docs for ordering between
message_update_systemand gameplay systems beyond theFixedUpdatesignal function name.
Expert Knowledge Delta
Target: Bevy 0.20+.
Core ECS types: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. See bevy-events-messaging for their APIs. Systems run in parallel unless .chain() orders the ones that conflict.
Who owns state
| Piece | Owner | Who may mutate | Schedule |
|---|---|---|---|
| Data on one entity | Component | One system via Query | Update or FixedMain |
| One value for the whole app | Resource | One system | Startup to insert, then the schedule that reads it |
| Spawn | Commands | The spawning system | Startup for the initial world; later schedules for runtime spawn |
| Order that must not race | .chain() | The chained systems only | Same schedule |
| Plugin boundary | Plugin | build registers systems and resources | Before the app runs |
Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.
Decision
| If you need | Do this | Do not |
|---|---|---|
| Per-entity data | Component + Query | A Godot node script |
| App-wide config or clock | Resource | Copy the value onto every entity |
| Stable simulation step | FixedMain and the Fixed clock | Tie simulation to raw frame Update |
| Startup spawn | Commands in Startup | Spawn from a render system |
| Cross-system notice that is not shared state | Message or observer slot in bevy-events-messaging | A new event type invented in this file |
| An API outside the documented set | Check the official docs first | A made-up crate or API |
Load references/ecs-ownership.md for the ownership table.
NEVER
- Do not pin
/0.20.0/in docs URLs. WHY: links stay onlatest; the 0.20 target is stated once in prose. - Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless
.chain()orders them. - Do not invent a physics, navigation, networking, or XR crate here. WHY: this skill only names documented Bevy crates and modules.
- No Godot signal types or a signal bus autoload. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
- No invented message-registration or trigger methods. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
- No third-party crates. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
Reference
docs.rs links use the unversioned latest permalink. The library pin on bevy-master stays 0.20.0.
Official Documentation
- Migration guides - Unversioned hop index.
- bevy crate - Unversioned API index.
- bevy::ecs::message -
Message,MessageWriter,MessageReader,Messages,message_update_system. - Event -
Event,On,World::trigger,Commands::trigger,add_observer. - bevy::ecs::observer -
ObserverandOn. - Examples - Example tree on the
latestbranch.
Related Skills
Prerequisites
- bevy-master - ECS ownership before adding a notice channel.
- bevy-ecs-composition - Systems that write or read the notice.
Complements
- bevy-state-machines -
StateTransitionEventfor app-wide state changes. - godot-signal-architecture - Equivalent Godot skill. Do not import Godot types.
Downstream / consumers
- Gameplay skills cover combat, abilities, and similar loops.
Master
- bevy-master - Bevy router.
