Bevy 3D world building

When to use

Load this when placing meshes, lights, and colliders into a level. Scene spawn mechanics stay on bevy-asset-scenes. Physics bodies stay on bevy-physics-3d.

ECS shape

• Spawn: entities with transforms and render components. bevy_mesh provides a mesh format. Check the mesh docs for primitive constructors before writing them.
• Scenes: bevy_scene and bevy_gltf are features. Spawn details are on bevy-asset-scenes (AssetServer, scene spawn).
• Lights: place them using bevy-3d-lighting.
• Systems: level streaming is your state plus asset handles. No streaming type was opened.

Coming from Godot

Godot idea	Bevy idiom
Packed level	A scene asset spawned through bevy-asset-scenes
Kitbash props	Entities. No grid-map node.
Environment	Lights, DistanceFog, and camera. No world-environment node.

Scope

• Check the mesh docs.rs page for primitive helper names before writing them.
• CSG and terrain heightmaps are yours to build in ECS. Check the mesh module list before assuming a built-in type.
• Collider authoring belongs with bevy-physics-3d once you choose a physics solver.

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 on latest; 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 CSG, GridMap, or world-environment types. 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 latest branch.
• ECS - Component, systems, Query, Startup, Update, and .chain().
• Plugins - Plugin, DefaultPlugins, MinimalPlugins, and add_plugins.
• bevy::gltf - glTF asset loader module exists.
• bevy::mesh - Mesh module reference.

Related Skills

Prerequisites

• bevy-master - Hub and schedules.
• bevy-ecs-composition - Components and systems.
• bevy-asset-scenes - Scene spawn.
• bevy-3d-lighting - Lights.
• bevy-3d-materials - Surfaces.
• bevy-camera-systems - View.

Complements

• bevy-procedural-generation - Generated layouts.
• bevy-physics-3d - Simulated props. Solver still unpicked.
• godot-3d-world-building - Equivalent Godot skill.

Downstream / consumers

• None yet.

Master

• bevy-master - Bevy router.