skesis

A high-performance Entity Component System for Rust.

[dependencies]
skesis = "0.1"

Quick Start

use skesis::World;

struct Position { x: f32, y: f32 }
struct Velocity { dx: f32, dy: f32 }

let mut world = World::new();

let entity = world.spawn_empty();
world.add_component(entity, Position { x: 0.0, y: 0.0 });
world.add_component(entity, Velocity { dx: 1.0, dy: 2.0 });

// Iterate matching entities
world.for_each_pair::<Position, Velocity>(|entity, pos, vel| {
    println!("{:?}: ({}, {})", entity, pos.x, pos.y);
});

// Tuple queries for 1-8 component types
for (entity, (pos, vel)) in world.query_tuple::<(&Position, &Velocity)>() {
    // ...
}

Features

Hybrid Storage

• Archetypes — contiguous typed columns (Vec<T>) grouped by component shape
• Sparse sets — register_sparse::<T>() for rare components (no archetype fragmentation)
• Entity generations — 64-bit IDs with index + generation for safe reuse

Queries

• Tuple queries — query_tuple::<(&A, &B, &C)>() for 1-8 component types
• Specialized queries — query_pair, for_each_pair, for_each_mut (optimized hot path)
• Query plans — precompiled archetype matches with prebound chunk pointers
• Without filter — query_pair_without::<A, B, Exclude>()
• Optional — query_with_optional::<T, Opt>()
• Toggle-aware — query_toggled, for_each_pair_toggled respect disabled components

Component Lifecycle

• add_component / remove_component — archetype transitions with cached edges
• set_component — write value + notify observers + bump change detection
• get_component_mut — silent hot-path mutation (zero overhead)
• disable_component / enable_component — toggle without archetype change

Observers

• on_add::<T>() — fires when a component is first added
• on_remove::<T>() — fires when a component is removed
• on_set::<T>() — fires on explicit set_component calls (not get_mut)

Relationships & Hierarchies

• Typed directed edges — add_relation::<ChildOf>(child, parent)
• Hierarchy sugar — add_child, remove_child, children, parent, is_root, is_leaf
• Recursive despawn — despawn_recursive::<ChildOf>(root) kills entire subtree
• Up traversal — find_up (component inheritance), ancestors, depth

Change Detection

• Anchor+delta model — zero write-path overhead
• Column-level version counter for fast "did anything change?" exit
• Per-entity byte-level diffing with AVX2 SIMD acceleration
• Per-reader snapshots for independent system change tracking
• ChangeHistory separated from World (serializable for networking/replay)

Systems & Scheduling

• Exclusive and parallel system functions
• .before(other_fn) / .after(other_fn) ordering with topological sort
• Declared access metadata for automatic conflict detection
• Deterministic parallel batching via Rayon

Serialization

• save_state() / load_state() — raw byte world snapshots
• Zero-copy, zero-serde overhead
• Perfect for save games, networking, and replay

Performance

Benchmarked against Bevy ECS 0.17 on identical workloads (1k entities):

Benchmark	Skesis	vs Bevy
has	1.7 us	1.6x faster
get_not_found	230 ns	8.2x faster
get_mut	3.9 us	2.0x faster
create_delete_empty	14.9 us	3.8x faster
remove_component	77.8 us	1.7x faster
query_pair_uncached	1.1 us	1.7x faster
query_optional	911 ns	1.4x faster

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.