bevy_ratatui_render

Bevy inside the terminal!

Uses bevy headless rendering, ratatui, and ratatui_image to print the rendered output of your bevy application to the terminal using unicode halfblocks.

examples/cube.rs, bevy many_foxes example, sponza test scene

Use bevy_ratatui for setting ratatui up and receiving terminal events (keyboard, focus, mouse, paste, resize) inside bevy.

getting started

cargo add bevy_ratatui_render bevy_ratatui

fn main() {
    App::new()
        .add_plugins((
            // disable WinitPlugin as it panics in environments without a display server
            // disable LogPlugin as it interferes with terminal output.
            DefaultPlugins.build()
                .disable::<WinitPlugin>()
                .disable::<LogPlugin>(),

            // create windowless loop and set its frame rate
            ScheduleRunnerPlugin::run_loop(Duration::from_secs_f64(1. / 60.)),

            // set up the Ratatui context and forward input events
            RatatuiPlugins::default(),

            // connect a bevy camera target to a ratatui widget
            RatatuiRenderPlugin::new("main", (256, 256)),
        ))
        .add_systems(Startup, setup_scene_system)
        .add_systems(Update, draw_scene_system.map(error))
        .run();
}

fn setup_scene_system(
    mut commands: Commands,
    ratatui_render: Res<RatatuiRenderContext>,
) {
    // spawn objects into your scene, and your camera

    ...

    commands.spawn((
        Camera3d::default(),
        Camera {
            target: ratatui_render.target("main").unwrap(),
            ..default()
        },
    ));
}

fn draw_scene_system(
    mut ratatui: ResMut<RatatuiContext>,
    ratatui_render: Res<RatatuiRenderContext>,
) -> io::Result<()> {
    ratatui.draw(|frame| {
        frame.render_widget(ratatui_render.widget("main").unwrap(), frame.size());
    })?;

    Ok(())
}

As shown above, RatatuiRenderPlugin makes a RatatuiRenderContext resource available that has two primary methods:

• target(id): Provides a bevy RenderTarget that can be set as the target of a normal bevy camera.
• widget(id): Provides a ratatui widget that prints the latest render made to the corresponding camera, as unicode half-blocks.

There is a convenience function if you do not need access to the ratatui draw loop and just would like the render to print to the full terminal (for the above example, use this instead of adding the draw_scene_system):

RatatuiRenderPlugin::new("main", (256, 256)).print_full_terminal()

There is another convenience function for autoresizing the render texture to match the terminal dimensions, during startup and when the terminal is resized:

RatatuiRenderPlugin::new("main", (1, 1)).autoresize()

To customize how the texture dimensions are calculated from the terminal dimensions, provide a callback to autoresize_conversion_fn:

RatatuiRenderPlugin::new("main", (1, 1))
    .autoresize()
    .autoresize_conversion_fn(|(width, height)| (width * 4, height * 3))

multiple renders

RatatuiRenderPlugin can be added to bevy multiple times. To access the correct render, use the same string id you passed into RatatuiRenderPlugin::new(id, dimensions) to call the target(id) and widget(id) methods on the RatatuiRenderContext resource.

supported terminals

Printing to terminal relies on the terminal supporting 24-bit color. I've personally tested and confirmed that the following terminals display correctly:

• Alacritty
• Kitty
• iTerm
• WezTerm

...but any terminal with 24-bit color support should work fine, if its performance is adequate.

compatibility

bevy	bevy_ratatui_render
0.15	0.7
0.14	0.6
0.13	0.4

credits

• Headless rendering code adapted from bevy's headless_render example (@bugsweeper, @alice-i-cecile, @mockersf).
• bevy's many_foxes example used for example gif.
• bevy_sponza_scene used for example gif.