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//! Legion aims to be a feature rich high performance ECS library for Rust game projects with minimal boilerplate. //! //! # Getting Started //! //! ```rust //! use legion::prelude::*; //! //! // Define our entity data types //! #[derive(Clone, Copy, Debug, PartialEq)] //! struct Position { //! x: f32, //! y: f32, //! } //! //! #[derive(Clone, Copy, Debug, PartialEq)] //! struct Velocity { //! dx: f32, //! dy: f32, //! } //! //! #[derive(Clone, Copy, Debug, PartialEq)] //! struct Model(usize); //! //! #[derive(Clone, Copy, Debug, PartialEq)] //! struct Static; //! //! // Create a world to store our entities //! let universe = Universe::new(); //! let mut world = universe.create_world(); //! //! // Create entities with `Position` and `Velocity` data //! world.insert( //! (), //! (0..999).map(|_| (Position { x: 0.0, y: 0.0 }, Velocity { dx: 0.0, dy: 0.0 })) //! ); //! //! // Create entities with `Position` data and a tagged with `Model` data and as `Static` //! // Tags are shared across many entities, and enable further batch processing and filtering use cases //! world.insert( //! (Model(5), Static), //! (0..999).map(|_| (Position { x: 0.0, y: 0.0 },)) //! ); //! //! // Create a query which finds all `Position` and `Velocity` components //! let mut query = <(Write<Position>, Read<Velocity>)>::query(); //! //! // Iterate through all entities that match the query in the world //! for (mut pos, vel) in query.iter_mut(&mut world) { //! pos.x += vel.dx; //! pos.y += vel.dy; //! } //! ``` //! //! ### Advanced Query Filters //! //! The query API can do much more than pull entity data out of the world. //! //! Additional data type filters: //! //! ```rust //! # use legion::prelude::*; //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Position { //! # x: f32, //! # y: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Velocity { //! # dx: f32, //! # dy: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Model(usize); //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Static; //! # let universe = Universe::new(); //! # let mut world = universe.create_world(); //! // It is possible to specify that entities must contain data beyond that being fetched //! let mut query = Read::<Position>::query() //! .filter(component::<Velocity>()); //! for position in query.iter(&mut world) { //! // these entities also have `Velocity` //! } //! ``` //! //! Filter boolean operations: //! //! ```rust //! # use legion::prelude::*; //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Position { //! # x: f32, //! # y: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Velocity { //! # dx: f32, //! # dy: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Model(usize); //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Static; //! # let universe = Universe::new(); //! # let mut world = universe.create_world(); //! // Filters can be combined with boolean operators //! let mut query = Read::<Position>::query() //! .filter(tag::<Static>() | !component::<Velocity>()); //! for position in query.iter(&mut world) { //! // these entities are also either marked as `Static`, or do *not* have a `Velocity` //! } //! ``` //! //! Filter by tag data value: //! //! ```rust //! # use legion::prelude::*; //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Position { //! # x: f32, //! # y: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Velocity { //! # dx: f32, //! # dy: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Model(usize); //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Static; //! # let universe = Universe::new(); //! # let mut world = universe.create_world(); //! // Filters can filter by specific tag values //! let mut query = Read::<Position>::query() //! .filter(tag_value(&Model(3))); //! for position in query.iter(&mut world) { //! // these entities all have tag value `Model(3)` //! } //! ``` //! //! Change detection: //! //! ```rust //! # use legion::prelude::*; //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Position { //! # x: f32, //! # y: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Velocity { //! # dx: f32, //! # dy: f32, //! # } //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Model(usize); //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Static; //! # let universe = Universe::new(); //! # let mut world = universe.create_world(); //! // Queries can perform coarse-grained change detection, rejecting entities who's data //! // has not changed since the last time the query was iterated. //! let mut query = <(Read<Position>, Tagged<Model>)>::query() //! .filter(changed::<Position>()); //! for (pos, model) in query.iter(&mut world) { //! // entities who have changed position //! } //! ``` //! //! ### Content Streaming //! //! Entities can be loaded and initialized in a background `World` on separate threads and then //! when ready, merged into the main `World` near instantaneously. //! //! ```rust //! # use legion::prelude::*; //! let universe = Universe::new(); //! let mut world_a = universe.create_world(); //! let mut world_b = universe.create_world(); //! //! // Move all entities from `world_b` into `world_a` //! // Entity IDs are guarenteed to be unique across worlds and will //! // remain unchanged across the merge. //! world_a.move_from(world_b); //! ``` //! //! ### Chunk Iteration //! //! Entity data is allocated in blocks called "chunks", each approximately containing 64KiB of data. //! The query API exposes each chunk via 'iter_chunk'. As all entities in a chunk are guarenteed to contain the same set of entity //! data and shared data values, it is possible to do batch processing via the chunk API. //! //! ```rust //! # use legion::prelude::*; //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Transform; //! # #[derive(Clone, Copy, Debug, PartialEq)] //! # struct Model(usize); //! # let universe = Universe::new(); //! # let mut world = universe.create_world(); //! fn render_instanced(model: &Model, transforms: &[Transform]) { //! // pass `transforms` pointer to graphics API to load into constant buffer //! // issue instanced draw call with model data and transforms //! } //! //! let mut query = Read::<Transform>::query() //! .filter(tag::<Model>()); //! //! for chunk in query.iter_chunks_mut(&mut world) { //! // get the chunk's model //! let model: &Model = chunk.tag().unwrap(); //! //! // get a (runtime borrow checked) slice of transforms //! let transforms = chunk.components::<Transform>().unwrap(); //! //! // give the model and transform slice to our renderer //! render_instanced(model, &transforms); //! } //! ``` //! //! # Feature Flags //! //! * `par-iter`: Enables parallel APIs on queries (enabled by default). //! * `par-schedule`: Configures system schedulers to try and run systems in parallel where possible (enabled by default). //! * `log`: Configures `tracing` to redirect events to the `log` crate. This is a convenience feature for applications //! that use `log` and do not wish to interact with `tracing`. #![allow(dead_code)] pub use legion_core::*; pub use legion_systems as systems; pub mod prelude { pub use legion_core::prelude::*; pub use legion_systems::prelude::*; }