How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/thedivergentai/game-design-agentic-skills --skill bevy-tweeningBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Bevy tweening
When to use
Load this when a value should ease over time. A tween player is yours to build in ECS from elapsed time.
ECS shape
- Feature:
bevy_curveis described as mathematical curves, not a tween player. - Components: a tween would be your own start, end, and elapsed fields until a player type is opened.
- Systems: step elapsed time on
Updateor the fixed clock (Fixedon bevy::time, already used by character movement). - Animation: property animation over a clip is
AnimationClipon bevy-animation. That is a clip, not a one-shot UI tween.
Coming from Godot
| Godot idea | Bevy idiom |
|---|---|
| Property tween | Either your elapsed component or an AnimationClip. No Tween type was opened. |
| Sequence | Chain systems or clip order. No sequence asset was opened. |
| Callback on finish | An AnimationEvent exists for clips. Check the animation docs for a tween callback type before writing one. |
Scope
- Check the
bevy::curvemodule for curve sample methods before writing them. - No tween crate was chosen.
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 Tween node. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
- No named tween crate as the chosen solution. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
- No Godot types in Bevy code. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
- No invented APIs or unnamed third-party crates as the chosen solver. 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 - API reference and Cargo feature list.
- Assets - Official asset catalog. No third-party crate was selected.
- Examples - Example tree on the
latestbranch. - ECS -
Component, systems,Query,Startup,Update, and.chain(). - Plugins -
Plugin,DefaultPlugins,MinimalPlugins, andadd_plugins. - bevy::curve - Curve trait module reference.
Related Skills
Prerequisites
- bevy-master - Hub and schedules.
- bevy-ecs-composition - Components and systems.
- bevy-animation - Clip-based property animation.
- bevy-master - Fixed clock name.
Complements
- godot-tweening - Equivalent Godot skill.
Downstream / consumers
- None yet.
Master
- bevy-master - Bevy router.
