Shared HUD and menus

ferravex_render::ui::Ui renders compact screen-space overlays on the same native OpenGL and browser WebGL2 stream as the world. It queues solid/gradient panels, bitmap text and buttons, applies nested rectangular clips, and preserves paint order. It does not change the caller's camera, lighting, material, depth or shader state. Strike uses it for labels, diagnostics, roster and Play/Resume; Neon Swarm uses it for its HUD and Start/Resume/Restart menus; Orchard Guard uses it for build, upgrade, wave and restart buttons. Existing immediate helpers remain compatible.

use ferravex_render::ui::{Ui, UiRect, Viewport, TextStyle, ButtonStyle};
let mut ui = Ui::new(); // Keep this instance across frames.
let viewport = Viewport::fit([1280., 720.], [1280., 720.], [0.; 4]).unwrap();
ui.begin(viewport);
ui.text_fmt(UiRect { min: [24., 20.], size: [220., 24.] },
    TextStyle::default(), format_args!("Health {}", 100)).unwrap();
ui.button(1, UiRect { min: [24., 60.], size: [180., 44.] },
    "Resume", true, ButtonStyle::default()).unwrap();
ui.finish(true); // Layout first, then process the current input journal once.
ui.paint();
if ui.activated(1) { /* resume */ }

Use logical display pixels, not framebuffer/device pixels. Viewport::fit letterboxes a design size inside the available screen, with left/top/right/bottom safe-area insets. The caller supplies OS safe areas; automatic mobile insets remain a native-host concern. unproject rejects letterbox space and half-open outer edges. Renderer-independent Anchors and slots support anchored/stretch rectangles and allocation-free equal row/column layouts. Neon and Orchard share their existing design-space viewport with world rendering; Strike keeps its responsive screen-space HUD.

Stable numeric IDs preserve capture and focus across frame rebuilds. Tab/right/ down advance focus; Shift+Tab/left/up go backward; Enter activates. Selected-pad D-pad/A uses finish_with_gamepad(enabled, player.settings().gamepad). finish_player(&mut player, enabled) also accepts the profile’s remapped global confirm action; the three adopting games use this adapter. Gameplay overlays can set_auto_focus(false) to require an explicit focus choice before accepting, so Orchard’s A button can still select a plot until its HUD receives focus. Navigation is edge based, without held-key repeat. Hotplugged held A is suppressed for the connection frame. Event-time mouse positions preserve fast same-frame drag cancellation. Mouse and touch require press and release on the same enabled, visible widget. One pointer owns capture; another mouse/finger cannot steal or release it. Removed, disabled, fully clipped, cancelled, unfocused or overflowed input cancels capture. Disabled widgets occlude clicks underneath. The F2 controls editor blocks menu input. Navigation and Enter have fixed host bindings in addition to a profile’s remapped confirm action. Gameplay action rebinding remains in PlayerInput. Space remains available to games such as Orchard's wave shortcut.

Call modal(blocker_id) before adding modal buttons to remove lower controls from interaction. Add its covering panel after lower draw commands. IDs must be unique within the current interaction scope, including the blocker. A nonfocusable blocker absorbs outside presses without activating another button. Rebuild/finish/paint a UI once per render frame. Keep game actions behind an appropriate input context; UI is not a simulation scheduler.

The original 5×7 font is drawn as horizontal bit runs, reducing geometry compared with one rectangle per lit pixel. Text supports alignment, shrinking to fit, explicit newlines, character wrapping, clipping and an optional shadow. UTF-8 boundaries are preserved; unsupported characters render ?. It does not provide complex-script shaping, rich text, editable fields, localization or a screen-reader bridge. The DOM F2 editor remains the browser's accessible controls interface.

Each Ui preallocates 1024 commands/widgets and a 32 KiB text arena. A frame admits at most 196608 estimated vertices and 16 clip levels; oversized or invalid commands return UiError without partially registering a button or retaining formatted text. text_fmt writes directly into the arena. Actual glyph geometry is clipped before submission. Renderer stream buffers may grow on initial/worst-case use; reused UI buffers do not grow during a frame. Each Ui owns 213504 bytes (about 209 KiB) of command, text and widget capacity on this 64-bit host, in addition to the renderer stream. Use fewer instances rather than one instance per entity. No textures, external fonts, layout libraries or third-party packages are required.