bevy_scriptum/examples/lua/side_effects.rs

use bevy::{app::AppExit, ecs::event::ManualEventReader, prelude::*};
use bevy_scriptum::prelude::*;
use bevy_scriptum::runtimes::lua::prelude::*;

fn main() {
    App::new()
        // This is just needed for headless console app, not needed for a regular bevy game
        // that uses a winit window
        .set_runner(move |mut app: App| {
            let mut app_exit_event_reader = ManualEventReader::<AppExit>::default();
            loop {
                if let Some(app_exit_events) = app.world.get_resource_mut::<Events<AppExit>>() {
                    if app_exit_event_reader
                        .read(&app_exit_events)
                        .last()
                        .is_some()
                    {
                        break;
                    }
                }
                app.update();
            }
        })
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, startup)
        .add_systems(Update, print_entity_names_and_quit)
        .add_scripting::<LuaRuntime>(|runtime| {
            runtime.add_function(String::from("spawn_entity"), spawn_entity);
        })
        .run();
}

fn spawn_entity(mut commands: Commands) {
    commands.spawn(Name::new("SpawnedEntity"));
}

fn startup(mut commands: Commands, assets_server: Res<AssetServer>) {
    commands.spawn((Script::<LuaScript>::new(
        assets_server.load("examples/lua/side_effects.lua"),
    ),));
}

fn print_entity_names_and_quit(query: Query<&Name>, mut exit: EventWriter<AppExit>) {
    if !query.is_empty() {
        for e in &query {
            println!("{}", e);
        }
        exit.send(AppExit);
    }
}