# `.rat` — the UI element layout / animation record

**Status:** ✅ `CONFIRMED` for placement (2026-07-28). The retail UI can be
**reassembled from the disc**: the tutorial PAUSE menu rebuilds pixel-accurately from its
sprites placed at the coordinates in their `.rat` records — no fitting, no manual nudging.

![real vs rebuilt](captures/ui-layout/pause-tutorial-real-vs-rebuilt.png)

*Left: the running game (Canary screenshot). Right: rebuilt from `GP_PAUSE_MENU.pak` alone.
The remaining differences are the animated frame/glow sprites (`*eff*`) that were not
placed, and the live 3D background.*

## Screen composition

The UI is **one pak per screen** — `GP_TITLE`, `GP_PAUSE_MENU`, `GP_READY_ROOM`,
`GP_SAVE_LOAD`, `GP_MISSION_SELECT`, `GP_OPTIONS`, `GP_SYSTEM`, `GP_TUTORIAL`,
`GP_STAGE_CLEAR`, `GP_MOVIE_THEATER`, `GP_DEBRIEFING_PILOTLOG`, `GP_LEADERBOARD`,
`GP_MISSION_LOG`, `GP_BUNK`, `GP_DIALOG`, `GP_GAMEOVER`, `GP_CHALLENGE`,
`GP_HANGAR_ARSENAL`.

Inside a screen pak, each top-level [RATC](../INDEX.md) bundle is **one (context × language)
build of that screen**, and its children come in pairs:

| child | what it is |
|---|---|
| `<name>.t32` | the sprite ([T8aD](texture-color-k8888.md)) |
| `<name>.rat` | that sprite's **layout record** (this document) |
| `<screen>loop1.rat` | a screen-level record (larger; not yet decoded) |

`GP_PAUSE_MENU.pak`'s six bundles are `{in-mission, tutorial} × {English, Japanese}`, with
the two in-mission builds each present twice at identical size. The purpose of that
duplicate is **NEEDS-HUMAN** (resolution or aspect variant?), and where the other four
shipped languages live is likewise unresolved — this pak holds only EN and JP.

Naming is transparent: `pgp` = pause screen, `pgp_ttrl_` = its tutorial context, `btnNN` =
menu item, `btnNNf` = that item's **focused** sprite, `eff*` = frame/glow decoration,
`deli*` = the item divider, `title`, `msg`.

## Record layout

Big-endian u32 throughout (Xbox 360). A minimal record (a static button) is 165 bytes:

```
0x00  "RATC"                     magic — a RATC bundle reused as a data record
0x08  u32  payload size
0x18  u32  design width   = 1280
0x1c  u32  design height  = 720
0x20  char[]                     the sprite this record places, e.g. "pgpbtn00.t32"
...
      ── placement block ──
      u32  scale X        = 100  (percent)
      u32  scale Y        = 100
      u32  tint           = 0xffffffff  (RGBA, white = untinted)
      u32  X                      ← position
      u32  Y                      ←
      u32  time                   (keyframe records only)
...
      "opt " u32 len  char[len]   link to another record, e.g. "pgpbtn00f.rat"
```

- **Animated elements are a keyframe list.** `pgptitle.rat` (752 B) is the same placement
  block repeated with a varying trailing `time` field — the PAUSE title's fly-in.
- **`opt `** carries a length-prefixed record name. On `pgpbtn00.rat` it points at
  `pgpbtn00f.rat`, i.e. *normal state → focused state*.
- Two fields (at 0x50/0x54 in the button records) vary per button and are **not identified**.

## Evidence

Positions were read out of the records and checked against a screenshot of the running
game, twice, in that order — the records were never fitted to the picture.

1. **Differential.** Across `pgpbtn00/01/04/05.rat`, exactly one field varies and it steps
   `268 → 338 → 408 → 478` — a constant 70 px pitch — while the field before it is 226 in
   all four. A vertical menu: constant X, evenly spaced Y.
2. **Against the game.** The three visible items measured at screenshot y-centres
   346.0 / 415.5 / 485.5 — spacing 70.0 and 70.0, and a *single* constant offset maps all
   three onto 268 / 338 / 408 to within 0.5 px.
3. **Absolute placement.** The tutorial build's records give 546/288, 546/358, 546/428 and
   540/119, which are framebuffer coordinates directly: compositing the sprites there
   reproduces the screenshot (image above).

## Two traps this caught

Both were mistakes made during this analysis, caught by comparing against the real game —
recording them because a static-only reading would have shipped them:

- **Texture width does not identify a language.** English `RESUME` (166 px) and Japanese
  `再開` (86 px) differ hugely, but Japanese `通信ログ` (148 px) is within a few px of an
  English label. The first language assignment made here was wrong; rendering the sprites
  is the only reliable check.
- **The in-mission and tutorial pause menus are different sprite sets, not one set
  re-packed.** In-mission is `RESUME / RADIO LOG / OPTIONS / BACK TO TITLE` (4 items,
  `pgpbtnNN`); the tutorial is `RESUME / OPTIONS / BACK TO MENU` (3 items,
  `pgp_ttrl_btn1N`). Matching the 3-item screenshot against the 4-item set suggests a
  runtime slot-packing rule that does not exist.

## Next

- `<screen>loop1.rat` (1320 B) is the screen-level record — decoding it should give the
  draw order and the `eff*`/`deli*` placements that are missing from the rebuild above.
- The same method should now unroll the other screens directly; `GP_HANGAR_ARSENAL.pak`
  (789 T8aD + 510 RATC) is the big one, and the ARSENAL `DATA SHEET` panel documented in
  [weapon-datasheet-runtime.md](../weapon-datasheet-runtime.md) is a ready-made oracle for it.
- Tooling: `crates/sylpheed-formats/examples/ui_screen.rs` (inventory a screen pak, carve a
  named RATC child), `sylpheed-cli pak textures` (decode every sprite).
