bevy-ecs-expert

Bevy ECS Expert

Overview

A guide to building high-performance game logic using Bevy's data-oriented ECS architecture. Learn how to structure systems, optimize queries, manage resources, and leverage parallel execution.

When to Use This Skill

• Use when developing games with the Bevy engine in Rust.
• Use when designing game systems that need to run in parallel.
• Use when optimizing game performance by minimizing cache misses.
• Use when refactoring object-oriented logic into data-oriented ECS patterns.

Step-by-Step Guide

1. Defining Components

Use simple structs for data. Derive Component and Reflect.

#[derive(Component, Reflect, Default)]
#[reflect(Component)]
struct Velocity {
    x: f32,
    y: f32,
}

#[derive(Component)]
struct Player;

2. Writing Systems

Systems are regular Rust functions that query components.

fn movement_system(
    time: Res<Time>,
    mut query: Query<(&mut Transform, &Velocity), With<Player>>,
) {
    for (mut transform, velocity) in &mut query {
        transform.translation.x += velocity.x * time.delta_seconds();
        transform.translation.y += velocity.y * time.delta_seconds();
    }
}

3. Managing Resources

Use Resource for global data (score, game state).

#[derive(Resource)]
struct GameState {
    score: u32,
}

fn score_system(mut game_state: ResMut<GameState>) {