sailing/src/main.rs

use bevy::prelude::*;

#[derive(Component)]
struct EntityPhysics {
    x: f32,
    y: f32,
    speed: f32,
    heading: f32,
}

fn main() {
    let mut app = App::new();

    app.add_plugins(DefaultPlugins)
        .add_systems(Startup, (hello_world, camera_setup, sprite_setup).chain())
        .add_systems(Update, (handle_keys, player_physics).chain());

    app.run();
}

fn hello_world() {
    println!("Hello, world!");
}

fn camera_setup(mut clear_color: ResMut<ClearColor>, mut commands: Commands) {
    *clear_color = ClearColor(Color::WHITE);

    commands.spawn(Camera2d);
}

fn sprite_setup(assets: Res<AssetServer>, mut commands: Commands) {
    let sprite_handle = assets.load("sprite-0001.png");

    commands.spawn((
        Sprite {
            image: sprite_handle,
            ..default()
        },
        EntityPhysics {
            x: 0.,
            y: 0.,
            speed: 0.,
            heading: 0.,
        },
    ));
}

fn handle_keys(mut q_player: Query<&mut EntityPhysics>, keys: Res<ButtonInput<KeyCode>>) {
    if keys.just_pressed(KeyCode::KeyQ) {
        info!("Quit.");
    }

    let Ok(mut player) = q_player.single_mut() else {
        return;
    };

    if keys.just_pressed(KeyCode::ArrowUp) {
        player.speed += 0.1;
    }

    if keys.just_pressed(KeyCode::ArrowRight) {
        player.heading += 0.1;
    }

    if keys.just_pressed(KeyCode::ArrowLeft) {
        player.heading -= 0.1;
    }
}

fn player_physics(mut q_player: Query<(&mut EntityPhysics, &mut Transform)>) {
    let Ok((mut physics, mut transform)) = q_player.single_mut() else {
        return;
    };

    let x_speed = physics.heading.sin() * physics.speed;
    let y_speed = physics.heading.cos() * physics.speed;

    physics.x += x_speed;
    physics.y += y_speed;

    transform.translation = Vec3 {
        x: physics.x as f32,
        y: physics.y as f32,
        z: 0.,
    };

    transform.rotation = Quat::from_axis_angle(
        Vec3 {
            x: 0.,
            y: 0.,
            z: -1.,
        },
        physics.heading,
    );
}