rust bevy states

Rust Bevy States

Rust Bevy is an open-source game engine built in Rust. It provides a high-level API for building games and interactive applications. Bevy uses a state-based architecture, where the state of the game is managed using a combination of components and systems.

In Bevy, states are represented by components that are attached to entities. These components define the behavior and properties of the entities. For example, you can have a Player component that stores the position, velocity, and other relevant data for a player entity. By modifying the values of these components, you can change the state of the game.

To manage the state transitions and update logic, Bevy uses systems. Systems are functions that are executed every frame and can read and modify the state of the game. You can define your own systems and register them with Bevy to handle specific game logic.

Bevy provides a convenient way to define and manage states using its State and StateStage types. The State type represents a single state of the game, while the StateStage type allows you to define a sequence of states that the game can transition through.

Here's an example of how you can define and use states in Bevy:

use bevy::prelude::*;

struct MainMenuState;
struct GameState;
struct GameOverState;

fn main() {
    App::build()
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup.system())
        .add_state(MainMenuState)
        .add_state(GameState)
        .add_state(GameOverState)
        .run();
}

fn setup(commands: &mut Commands) {
    // Add entities and components here
}

fn main_menu_system(mut state: ResMut<State<MainMenuState>>) {
    // Handle main menu logic here
    if / some condition / {
        state.set(GameState).unwrap();
    }
}

fn game_system(mut state: ResMut<State<GameState>>) {
    // Handle game logic here
    if / some condition / {
        state.set(GameOverState).unwrap();
    }
}

fn game_over_system(mut state: ResMut<State<GameOverState>>) {
    // Handle game over logic here
    if / some condition / {
        state.set(MainMenuState).unwrap();
    }
}

In this example, we define three states: MainMenuState, GameState, and GameOverState. We register these states with Bevy using the add_state method. Each state has its own system that handles the logic specific to that state. The systems can transition between states by calling the set method on the State resource.

I hope this helps! Let me know if you have any further questions.