cu_bevymon

cu_bevymon is a Copper monitor frontend that renders the shared TUI monitor UI inside Bevy using bevy_ratatui.

By default, the Bevy windowed monitor uses bundled JetBrains Mono Nerd Font Mono TTF files so the Bevy rendering is much closer to the console monitor than the stock mono_8x13 backend.

It provides:

CuBevyMon: a CuMonitor implementation backed by the shared monitor model
CuBevyMonPlugin: a Bevy plugin that draws the monitor into a Bevy texture
CuBevyMonFontOptions: font sizing for the bundled windowed TUI renderer
CuBevyMonTexture and CuBevyMonPanel: the Bevy-backed monitor render surface
CuBevyMonSurfaceNode, CuBevyMonFocus, and CuBevyMonFocusBorder: helpers for click-to-focus split layouts
spawn_split_layout(...): the shared left/right split shell used by the current examples
CuBevyMonViewportSurface: a camera helper for syncing a 3D viewport to a Bevy UI panel

Design intent:

reuse the same Ratatui rendering as cu_consolemon
reuse the same shared LOG pane, including Copper live logs and optional stderr capture
integrate into existing Bevy sims like cu_rp_balancebot and cu_flight_controller
keep the rendering/backend split clean enough for later browser / wasm work

Recommended app structure:

keep Copper config backend-agnostic by pointing it at an app-local monitor alias
pick the actual monitor implementation in Rust with cfg(feature = "...")
let the Bevy host app decide layout and focus ownership

The existing flight-controller pattern is the recommended one:

// copperconfig.ron
(
    id: "monitor",
    type: "tasks::monitor::AppMonitor",
)

// src/tasks/monitor.rs
#[cfg(all(feature = "sim", not(feature = "firmware")))]
pub type AppMonitor = cu_bevymon::CuBevyMon;

#[cfg(all(feature = "terminal_sim", not(feature = "firmware")))]
pub type AppMonitor = cu_consolemon::CuConsoleMon;

#[cfg(any(feature = "firmware", not(feature = "sim")))]
pub type AppMonitor = cu_logmon::CuLogMon;

That keeps RON stable while the build target decides whether the app gets a Bevy panel, a terminal TUI, or a lighter real-target monitor.

Standard split-view pattern:

Keep your sim scene camera app-owned.
Recommended: render that camera to an offscreen RenderTarget::Image.
Add CuBevyMonPlugin::new(model) to the Bevy app.
Create a dedicated Camera2d for the split-shell UI.
Call spawn_split_layout(...) with the scene camera entity and the monitor texture handle.
Add app-specific overlays like loading cards, help panels, or OSD widgets as children of the returned sim_panel.
Gate sim-control systems on Res<CuBevyMonFocus> while cu_bevymon routes monitor events to cu_tuimon.

Shared shell sketch:

let layout = spawn_split_layout(
    &mut commands,
    monitor_texture.0.clone(),
    CuBevyMonSplitLayoutConfig::new(scene_camera).with_ui_camera(ui_camera),
);

commands.entity(layout.sim_panel).with_children(|panel| {
    panel.spawn((
        Node {
            position_type: PositionType::Absolute,
            bottom: Val::Px(5.0),
            right: Val::Px(5.0),
            ..default()
        },
        Pickable::IGNORE,
    ));
});

The cu_bevymon_demo, cu_rp_balancebot, and cu_flight_controller examples all use that shared split shell now. The main app-specific choice is how the left-side scene camera is produced.

Render strategy guidance:

Use the offscreen RenderTarget::Image + ViewportNode path when the sim already has its own UI overlays, picking, or camera behavior. This is the standardized path in the current examples.
CuBevyMonViewportSurface still exists for simpler panel-clipped window cameras, but it is now the lower-level escape hatch, not the primary documented pattern.

Input model:

window focus stays with Bevy
logical panel focus is tracked by CuBevyMonFocus
cu_bevymon translates Bevy events into backend-neutral cu_tuimon::MonitorUiEvent
monitor bindings live in cu_tuimon, not in the Bevy adapter

Font behavior:

the default bundled font set is JetBrains Mono Nerd Font Mono Light / SemiBold / LightItalic
the default bundled font size is 24 px
panel resize changes how many rows and columns fit; it does not change the glyph size
use CuBevyMonPlugin::with_font_size(...) or CuBevyMonPlugin::with_font_options(...) to tune the Bevy-side font size
use CuBevyMonPlugin::with_font_options(...) for full control
the bundled font bytes live under assets/fonts/
this improves glyph coverage for the powerline tabs, symbols, arrows, and box drawing used by cu_tuimon
OpenType feature selection like Kitty's +zero flag is not currently exposed through this backend

cu-bevymon 0.14.0

cu_bevymon