Appendix B: API Glossary

All Bevy, Rust standard library, and third-party APIs referenced across this book, organized by category. Each entry links to official documentation and notes the chapter where it first appears.

Bevy: Core ECS

API	Description	First Seen
`App`	Application builder and entry point	Ch 1
`Commands`	Deferred command queue for spawning/despawning entities	Ch 1
`Component`	Derive macro to mark a type as attachable to entities	Ch 1
`Plugin`	Trait for modular code organization	Ch 1
`Query<T>`	System parameter for reading/writing entity components	Ch 1
`Res<T>`	Immutable access to a global resource	Ch 1
`ResMut<T>`	Mutable access to a global resource	Ch 1
`Resource`	Derive macro for global singleton data	Ch 1
`Single<T>`	Query that expects exactly one matching entity	Ch 1
`Startup`	Schedule that runs systems once at launch	Ch 1
`Update`	Schedule that runs systems every frame	Ch 1
`With<T>`	Query filter requiring a component’s presence	Ch 1
`Changed<C>`	Filter for modified components	Ch 4
`Entity`	Unique identifier for an ECS entity	Ch 5
`OnEnter`	One-shot schedule on state entry	Ch 4
`OnExit`	One-shot schedule on state exit	Ch 4
`States`	Derive for state machine enums	Ch 4
`Without<T>`	Query filter excluding entities with a component	Ch 4
`in_state()`	Run-condition gating systems to a state	Ch 4
`.chain()`	Enforces sequential system execution	Ch 4
`.run_if()`	Conditional system execution	Ch 4

Bevy: Rendering

API	Description	First Seen
`Camera2d`	Marker component for 2D camera entities	Ch 1
`Color`	Color representation (multiple color spaces)	Ch 1
`Sprite`	2D image rendering component	Ch 1
`Text2d`	2D text rendering component	Ch 1
`TextColor`	Text color component	Ch 1
`TextFont`	Font configuration for text rendering	Ch 1
`TextureAtlas`	Sprite atlas frame selection	Ch 1
`TextureAtlasLayout`	Defines how a spritesheet is sliced	Ch 1
`Gizmos`	Immediate-mode debug shape drawing	Ch 4
`OrthographicProjection`	Camera projection for zoom control	Ch 5

Bevy: Transforms & Math

API	Description	First Seen
`Transform`	Position, rotation, and scale of an entity	Ch 1
`UVec2`	Unsigned integer 2D vector	Ch 1
`Vec2`	2D floating-point vector	Ch 1
`Vec3`	3D floating-point vector	Ch 1
`URect`	Unsigned integer rectangle	Ch 2
`GlobalTransform`	World-space transform (parent hierarchy)	Ch 5
`IVec2`	Signed integer 2D vector	Ch 4

Bevy: Assets

API	Description	First Seen
`AssetServer`	Loads and manages game assets	Ch 1
`Assets<T>`	Typed storage for loaded assets	Ch 1
`Handle<T>`	Reference-counted pointer to a loaded asset	Ch 1
`Asset`	Marks a type as a loadable Bevy asset	Ch 3
`TypePath`	Runtime type path info (required for `Asset`)	Ch 3

Bevy: Input

API	Description	First Seen
`ButtonInput<KeyCode>`	Keyboard state resource	Ch 1
`KeyCode`	Identifies a physical keyboard key	Ch 1

Bevy: Time

API	Description	First Seen
`Time`	Frame timing and delta time resource	Ch 1
`Timer`	Countdown or repeating timer	Ch 1
`TimerMode`	Once or Repeating timer behavior	Ch 1

Bevy: Plugins & Configuration

API	Description	First Seen
`AssetPlugin`	Configures asset loading paths	Ch 1
`ClearColor`	Global background color resource	Ch 1
`DefaultPlugins`	Standard plugin group	Ch 1
`ImagePlugin`	Configures image loading defaults	Ch 1
`Window`	Window configuration	Ch 1
`WindowPlugin`	Configures window creation	Ch 1
`WindowResolution`	Window size configuration	Ch 2
`MonitorSelection`	Which monitor for fullscreen	Ch 5
`WindowMode`	Fullscreen/windowed/borderless mode	Ch 5

Rust Standard Library

API	Description	First Seen
`Clone`	Deep-copy capability	Ch 1
`Copy`	Cheap bitwise duplication	Ch 1
`Debug`	Debug formatting (`{:?}`)	Ch 1
`Default`	Default value generation	Ch 1
`Deref`	Transparent wrapper delegation	Ch 1
`DerefMut`	Mutable wrapper delegation	Ch 1
`Eq`	Total equality	Ch 1
`Option<T>`	Optional value (`Some` or `None`)	Ch 1
`PartialEq`	Equality comparison (`==`)	Ch 1
`Result<T, E>`	Success or failure return type	Ch 1
`Vec<T>`	Growable heap-allocated array	Ch 1
`String`	Owned heap-allocated UTF-8 string	Ch 2
`HashMap<K, V>`	Key-value container with O(1) lookup	Ch 3
`Hash`	Enables use as HashMap key	Ch 3
`fmt::Display`	User-facing `{}` string formatting	Ch 5

serde

API	Description	First Seen
`Serialize`	Serialization to RON, JSON, etc.	Ch 3
`Deserialize`	Deserialization from RON, JSON, etc.	Ch 3

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