Bevy Engine Tutorial: Your First Steps

Hey everyone! So, you’ve heard about the Bevy game engine , right? It’s this super cool, data-driven engine written in Rust that’s been gaining a ton of traction lately. If you’re looking to jump into game development with Rust and want a modern, efficient engine, Bevy is definitely worth checking out. This tutorial is all about getting you started with the Bevy engine, covering the absolute basics to get your first project up and running. We’ll go through setting up your environment, creating a new project, and then diving into the core concepts that make Bevy tick. Don’t worry if you’re new to Rust or game development; we’ll break everything down step by step. So, grab your favorite beverage, get comfy, and let’s dive into the exciting world of Bevy game development!

Setting Up Your Rust and Bevy Environment

Alright guys, the very first thing we need to do before we can start making awesome games with Bevy is to make sure our development environment is all set up. This means we need Rust installed on our machines. If you don’t have Rust yet, head over to the official Rust website ( rust-lang.org ) and follow their simple installation guide. It usually involves downloading and running a small script that sets everything up for you. Once Rust is installed, you’ll have access to the rustup tool, the Rust compiler ( rustc ), and the package manager ( cargo ). cargo is your best friend here, as it handles dependencies, builds, and running your projects. Now, to actually use Bevy, we need to add it as a dependency to our project. When we create a new Bevy project, cargo will help us manage this. We don’t need to install Bevy globally or anything like that. It’s managed on a per-project basis, which is super convenient. So, the main takeaway here is: ensure Rust is installed correctly. You can verify this by opening your terminal or command prompt and typing rustc --version and cargo --version . If you see version numbers for both, you’re golden! We’ll be using cargo extensively throughout this tutorial, so get familiar with it. It’s the backbone of Rust development, and Bevy leverages it fully for all its build and run commands. This initial setup is crucial, and getting it right ensures a smooth ride as we progress. We’re talking about a solid foundation here, so let’s make sure it’s built strong!

Creating Your First Bevy Project

Now that our environment is ready, let’s create our very first Bevy project. This is where the magic starts! Open up your terminal or command prompt and navigate to the directory where you want to create your game project. Once you’re in the right spot, we’ll use cargo to create a new project. Type the following command: cargo new my_bevy_game . This command will create a new directory named my_bevy_game with a basic Rust project structure inside. Now, we need to switch into that new directory: cd my_bevy_game . The next crucial step is to tell cargo that we want to use the Bevy engine. We do this by editing the Cargo.toml file, which is located at the root of your project directory. Open Cargo.toml in your favorite text editor. You’ll see some default content. We need to add Bevy as a dependency. Find the [dependencies] section and add the following line: bevy = "0.12" (or the latest stable version of Bevy you want to use – always check the official Bevy documentation for the most up-to-date version). You might also want to add some optional Bevy features, like bevy_rapier3d for physics or bevy_egui for UI, depending on your project needs. For now, let’s keep it simple. Save the Cargo.toml file. Now, to make sure everything is downloaded and compiled correctly, run cargo build . This command will download the Bevy crate and all its dependencies, and then compile your project. It might take a little while the first time, especially since Bevy can be quite a large dependency, but subsequent builds will be much faster. This step is vital because it ensures that all the necessary game engine components are fetched and ready to go. It’s like gathering all your tools before you start building something. So, be patient here, and once cargo build completes without errors, you’ve successfully set up your Bevy project! We’re one step closer to making a game, guys!

Understanding Bevy’s Core Concepts: ECS

Alright, let’s talk about the heart and soul of Bevy: its Entity-Component-System (ECS) architecture. You’ll hear this term thrown around a lot, and it’s fundamental to understanding how Bevy works. Don’t let the name intimidate you; it’s actually a really elegant way to structure game data and logic. Think of it like building with LEGOs. You have different types of pieces, and you combine them to create something cool. In Bevy’s ECS, we have three main concepts: Entities , Components , and Systems . Entities are basically just unique IDs, like a name tag for an object in your game. They don’t hold any data themselves, they’re just identifiers. You can think of them as the ‘things’ in your game – a player, an enemy, a bullet, a tree. Components are where the actual data lives. These are simple structs that hold pieces of data, like Position { x: f32, y: f32 } , Velocity { dx: f32, dy: f32 } , or Sprite { color: Color } . An entity can have multiple components attached to it, and these components define what that entity is and what it can do . For example, a player entity might have a Position component, a Velocity component, and a PlayerTag component (which is itself a component, often an empty struct used for identification). Systems are where the logic happens. They operate on entities that have specific combinations of components. A system is essentially a function that iterates over all entities that possess a given set of components and performs some logic. For instance, you might have a movement_system that takes entities with Position and Velocity components and updates their Position based on their Velocity . Bevy’s ECS is highly performant because it’s designed for data-parallelism. It organizes data in a way that allows the CPU to process it very efficiently, especially on modern multi-core processors. This is a huge advantage for game development, where performance is often critical. Understanding how to query for entities with specific components and how to make systems interact with that data is key to unlocking Bevy’s power. We’ll be using this extensively, so try to wrap your head around these three concepts: Entities are the ‘things’, Components are the ‘data’ they hold, and Systems are the ‘logic’ that acts upon them. It’s a powerful paradigm that leads to clean, maintainable, and high-performance game code. Keep this ECS mental model handy, guys, because it’s going to be our primary tool!## Writing Your First Bevy Code: A Simple Game Loop

Now that we’ve got a handle on Bevy’s ECS, let’s write some actual code and get something running in our project! We’ll aim to create a very basic application that demonstrates the game loop and how to add and modify components. Open up the src/main.rs file in your my_bevy_game directory. You’ll find some boilerplate code there. Let’s replace it with the following:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .run();
}

#[derive(Component)]
struct Person { name: String, age: u32 }

fn setup(mut commands: Commands) {
    commands.spawn(Person { name: "Alice".to_string(), age: 30 });
}

Let’s break this down, guys. use bevy::prelude::*; brings all the essential Bevy modules into scope. The main function is the entry point. App::new() creates a new Bevy application instance. .add_plugins(DefaultPlugins) is super important; it adds a collection of essential plugins that provide common game functionalities like rendering, window management, input handling, and more. You’ll almost always want to include DefaultPlugins . .add_systems(Startup, setup) tells Bevy to run our setup function once when the application starts up. Startup is a special schedule for initialization tasks. Finally, .run() starts the Bevy event loop and begins the game. Now, what’s this Person struct? We’ve derived Component on it, which means this struct can now be attached to an entity. It’s just a simple struct holding a name and age . The setup function is where we create our first entity. mut commands: Commands gives us access to a Commands struct, which is how we interact with the ECS world, like spawning entities. commands.spawn(Person { name: "Alice".to_string(), age: 30 }); creates a new entity and attaches our Person component to it. So, when you run cargo run , you won’t see anything visually yet, but you’ve successfully created an entity with a component! This is the fundamental building block. We’ve initialized an application, added essential plugins, defined a component, and spawned an entity with that component. It might seem small, but it’s a massive step! This is how you start populating your game world. We’re just getting warmed up, folks!

Adding a System to Query and Print Data

Okay, so we’ve spawned an entity with a Person component. But how do we see that data or do anything with it? That’s where another system comes in! We need a system that can find entities with the Person component and then do something with them, like print their details. Let’s modify our src/main.rs file:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, print_people_names) // Add this line
        .run();
}

#[derive(Component)]
struct Person { name: String, age: u32 }

fn setup(mut commands: Commands) {
    commands.spawn(Person { name: "Alice".to_string(), age: 30 });
    commands.spawn(Person { name: "Bob".to_string(), age: 25 });
    commands.spawn(Person { name: "Charlie".to_string(), age: 35 });
}

// New system to print names
fn print_people_names(people: Query<&Person>) {
    for person in people.iter() {
        println!("Name: {}, Age: {}", person.name, person.age);
    }
}

See that? We added .add_systems(Update, print_people_names) . The Update schedule runs every frame, making it the place for most game logic. Our new print_people_names function is our system. It takes a Query<&Person> as an argument. This is how systems interact with the ECS world. The Query lets us ask Bevy for all entities that have a Person component. people.iter() then gives us an iterator over all the Person components found. Inside the loop, we can access the name and age of each Person and print them. I also added a couple more Person entities in the setup function so we have more data to see. Now, when you run cargo run , you’ll see output in your terminal like this:

Name: Alice, Age: 30
Name: Bob, Age: 25
Name: Charlie, Age: 35

This output will repeat every frame because the print_people_names system runs in the Update schedule. It might seem a bit verbose for just printing, but this is the core mechanism! You define data in Components, add them to Entities, and then write Systems that query for those components to process the data. This is the foundation of nearly everything you’ll do in Bevy. Pretty neat, right guys? You’ve just written your first Bevy system that queries and processes data! We’re building some serious momentum here!

Spawning Entities with Multiple Components

So far, we’ve only attached one component, Person , to our entities. But the real power of ECS comes from combining multiple components to define more complex entities. Let’s say we want to represent an entity that has a position and a visual representation (a color for now). We’ll need two new components: Position and ColorComponent (note: Bevy uses Color for colors, but we often wrap it in a Component struct if we need to associate it with an entity directly, though Bevy provides built-in components like Sprite that handle this well). For simplicity, let’s use Bevy’s built-in Transform component for position and add a SpriteBundle which includes a Sprite (for the visual appearance) and a Transform .

Let’s create a new system to spawn a colored square that moves. First, we need to add a Transform component. Bevy provides a Transform component for every 2D and 3D entity, which handles position, rotation, and scale. We’ll also add a SpriteBundle which bundles a Sprite (defining the shape and color) and a Transform .

Modify your src/main.rs like so:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, move_square)
        .run();
}

#[derive(Component)]
struct Person { name: String, age: u32 }

// New component for movement
#[derive(Component)]
struct Velocity { x: f32, y: f32 }

fn setup(mut commands: Commands) {
    // Spawn the person entities as before
    commands.spawn(Person { name: "Alice".to_string(), age: 30 });
    commands.spawn(Person { name: "Bob".to_string(), age: 25 });

    // Spawn a colored square that can move
    commands.spawn(( // Tuple of components
        SpriteBundle {
            sprite: Sprite {
                color: Color::rgb(0.8, 0.7, 0.6),
                custom_size: Some(Vec2::new(50.0, 50.0)),
                ..default()
            },
            ..default()
        },
        Position { x: 0.0, y: 0.0 }, // Our custom Position component
        Velocity { x: 10.0, y: 5.0 }, // Our custom Velocity component
    ));
}

// System to move entities with Position and Velocity components
fn move_square(mut query: Query<(&mut Position, &Velocity)>, time: Res<Time>) {
    for (mut pos, vel) in query.iter_mut() {
        pos.x += vel.x * time.delta_seconds();
        pos.y += vel.y * time.delta_seconds();
        // println!("Square moved to: ({}, {})", pos.x, pos.y);
    }
}

// Define Position and Velocity components
#[derive(Component)]
struct Position { x: f32, y: f32 }

In the setup function, we’re now spawning a new entity. Notice the tuple (SpriteBundle { ... }, Position { ... }, Velocity { ... }) . This is how you attach multiple components to a single entity when spawning it. We’re giving it a SpriteBundle to make it visible (a 50x50 pixel square with a beige color), a Position component, and a Velocity component. We’ve also added a new Velocity component definition and a move_square system. This system queries for entities that have both a mutable Position component and a Velocity component. time: Res<Time> gives us access to the time since the last frame, allowing for frame-rate independent movement. Inside the loop, we update the pos.x and pos.y using the vel.x and vel.y and the delta_seconds . If you run cargo run now, you’ll see the Bevy window appear, and a beige square will start moving diagonally across the screen! It won’t be visible in the console output unless you uncomment the println! line, but it’s definitely moving in the game window. This demonstrates how you can combine different components to create entities with specific behaviors and how systems can modify these components over time. This is the essence of game development with Bevy, guys! We’re making things move!

Conclusion: Your Bevy Journey Begins!

And there you have it, folks! You’ve just taken your very first steps into the world of the Bevy game engine. We covered setting up your Rust environment, creating a new Bevy project using cargo , and, most importantly, we delved into the core concepts of Bevy’s Entity-Component-System (ECS) architecture. You learned how entities are just IDs, components hold the data, and systems contain the logic.

We then walked through writing actual Bevy code, from the main function and DefaultPlugins to spawning entities with single and multiple components. You saw how to define custom components like Person , Position , and Velocity , and how systems like print_people_names and move_square query and manipulate this data. If you ran cargo run , you should have seen a window with a beige square moving across it, proving your code is working!

This is just the tip of the iceberg, but understanding these fundamentals is crucial for building anything more complex. Bevy’s ECS is incredibly powerful and efficient, and as you continue your journey, you’ll discover how to leverage it for sophisticated game mechanics, UI, networking, and much more. Keep experimenting, keep learning, and don’t be afraid to dive into the Bevy documentation and community resources. The Bevy ecosystem is growing rapidly, and there are tons of helpful people and examples out there.

So, congratulations on getting your Bevy project up and running! You’ve built a solid foundation, and I can’t wait to see what amazing games you’ll create. Happy game developing, everyone!