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Bevy Asset Scenes
Docs-first stub for Bevy assets and scene spawning. Godot counterpart: godot-scene-management. Not a full port. Keywords: Bevy, AssetServer, Handle, Scene, bsn, spawn_scene.
Archived 2026-10-23 · Source updated 2026-10-11 · License: LGPL-3.0. Check the original repository for the latest version.
SKILL.md instructions
# Bevy asset scenes (docs-first stub) Not a full port. Levels are assets plus a `Scene` you spawn. They are not a packed Godot scene tree. ## When to use Load this when content comes from disk or a scene description should spawn entities. `bevy::asset` and `bevy::scene` on docs.rs `latest` (0.20.0) are the sources. ## ECS shape - **Assets:** `AssetServer` is the resource that loads from disk. `AssetServer::load` returns a `Handle` and does not reload while a strong handle still exists. Loaded data lives in `Assets<T>`. `AssetServer::is_loaded_with_dependencies` is true when the asset and its dependencies are ready. `LoadState` is the status type named on that page. - **Handles:** strong handles are reference counted. Dropping the last strong handle removes the asset. Weak handles do not keep it alive. `Assets::add` inserts a procedural asset and does not deduplicate. - **Hot reload:** the `file_watcher` Cargo feature, and `AssetPlugin`'s `watch_for_changes_override` field, are the toggles named on the asset index. - **Scenes:** `bevy::scene` describes a `Scene` (entity, components, children, assets), built with the `bsn!` macro. `World::spawn_scene` and `Commands::spawn_scene` spawn immediately and error if asset dependencies are not loaded. `World::queue_spawn_scene` and `Commands::queue_spawn_scene` wait, then spawn in the `SpawnScene` schedule between `Update` and `PostUpdate`. - **Hierarchy in a scene:** `Children [ ... ]` inside `bsn!`. Separate sibling entities with `--`. `#Name` assigns a `Name` inside that macro's scope. ## Godot idea to Bevy idiom | Idea | Bevy idiom (idea only) | | --- | --- | | Load a file | `AssetServer::load` → `Handle` | | Wait until ready | `is_loaded_with_dependencies` before a state change | | Instance a packed scene | `spawn_scene` or `queue_spawn_scene` around a `Scene` | | Child nodes in that scene | `Children` inside `bsn!` | | Change one entity's mesh | Swap the `Handle` on the component that stores it | ## Gaps - `.bsn` asset files are described as future on the scene page. Do not invent a file loader for them. - A `DynamicScene` type was not on docs.rs `latest` (the struct URL 404'd on 2026-10-11). Do not cite it. - Scene change as "free the old level, then spawn the next" is a design note. No level-switch API was opened. - Custom `AssetLoader` registration (`App::register_asset_loader`) was named, not opened as a worked example. ## Expert Knowledge Delta Library target in prose: **Bevy 0.20.0**. Lattice URLs stay unversioned. Opened canon only: `Component`, `Resource`, `Query`, `Commands`, `Startup`, `Update`, `Fixed` / `FixedMain` (`bevy::time`), `.chain()`, `Plugin`, `DefaultPlugins`, `MinimalPlugins`. Messages and observers are an ownership slot. This file does not invent their struct 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 this skill did not open | A Gaps row | A fabricated crate (solver, navmesh module, net, XR) | Load `references/a-gate-notes.md` for the same table plus the gap rule. ## NEVER - Do not put `/0.20.0/` in lattice URLs. WHY: permalinks stay on `latest`. The 0.20.0 pin belongs in prose once. - 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: those rows are gaps, blocked, or revisit. - No Godot packed-scene, node, or resource-loader types. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No scene format this file did not open. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No third-party scene crates. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No Creation Station content. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No umbrella skill over Godot and Bevy. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - Do not mark this row `ported`. It is `docs_mapped`. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. ## Reference docs.rs links use the unversioned `latest` permalink. The library pin on bevy-master stays **0.20.0**. ### Official Documentation - [Migration guides](https://bevy.org/learn/migration-guides/introduction/) - Unversioned hop index. - [bevy crate](https://docs.rs/bevy/latest/bevy/) - Unversioned API index. - [bevy::asset](https://docs.rs/bevy/latest/bevy/asset/index.html) - `AssetServer`, `Handle`, `Assets<T>`, load state, hot reload. - [bevy::scene](https://docs.rs/bevy/latest/bevy/scene/index.html) - `Scene`, `bsn!`, `spawn_scene`, `queue_spawn_scene`, `SpawnScene`. - [Assets](https://bevy.org/assets/) - Official asset catalog. - [Examples](https://github.com/bevyengine/bevy/tree/latest/examples#examples) - Example tree on the `latest` branch. ### Related Skills #### Prerequisites - [bevy-master](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-master/SKILL.md) - Who owns which piece of state. - [bevy-project-foundations](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-project-foundations/SKILL.md) - Cargo features, including asset watcher flags. - [bevy-state-machines](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-state-machines/SKILL.md) - The asset page points at app states for load gates. #### Complements - [bevy-audio-systems](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-audio-systems/SKILL.md) - Clips loaded through `AssetServer`. - [bevy-save-load](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-save-load/SKILL.md) - Player saves are a separate gap from scene spawn. - [godot-scene-management](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/godot-scene-management/SKILL.md) - Godot counterpart. Source idea only. #### Downstream / consumers - [bevy-camera-systems](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-camera-systems/SKILL.md) - Camera entities a scene may spawn. #### Master - [bevy-master](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-master/SKILL.md) - Bevy router.