# `.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**. Its own header is the screen's **element declaration table**, and
the elements themselves follow as children:

| 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 looping sprite animation (see below) |

### The bundle header — element declaration table

```
0x14  u32   entry count
0x20  entry[count], 60 bytes each:
        +0   char[28]  element name, NUL-padded ("pgp_ttrl_eff10.t32", "pgp_ttrl_btn10.rat")
        +28  u32       0            on every entry seen
        +32  u32       PARENT       element index, or 0xffffffff for "none"  ← see below
        +36  u32       0xffffffff   on every entry seen
        +40  u32       kind flags   0 for a plain sprite, 0x3002 for a button record,
                                    1 for an element that has a parent
        +44  u32       0xffffffff, but 0 on button records
        +48  u32       pivot X
        +52  u32       pivot Y
        +56  u32       0
```

**Corrected 2026-08-11:** this was previously written as "`+28` u32 ×4 flags" — it
is **five** words, and the second of them is not a flag.

**`+32` is a parent element index.** In the in-mission pause bundle,
`pgpeff02a.t32` carries `3` and element 3 is `pgpeff02.t32`; `pgpeff03a.t32`
carries `5` and element 5 is `pgpeff03.t32` — each `…a` variant naming its base
element. Verified on two independent language builds of that screen (4 links, no
out-of-range value anywhere in any bundle), and the tutorial bundle, which has no
`…a` variants, carries `0xffffffff` throughout.

The table lists **both** sprites and `.rat` records — it is the screen's element list.
`pgp_ttrl` declares 11: six `eff*`, `msg`, and four `.rat`s (`title`, `btn10..12`).

✅ **Verified:** for all 7 `.t32` entries the declared pivot is *exactly* half the decoded
texture's dimensions — `eff10` 408×120 → 204,60; `eff21` 428×360 → 214,180; `msg` 381×38 →
190,19; and so on, 7/7 with no mismatch (`tools/re-capture/ratc_decls.py`).

`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), and **tag-driven**: 4-char ASCII tags (`opt `,
`PRMD`, `end `) mark sections, so a record is a stream of blocks rather than a fixed struct.
A minimal record (a static button) is 165 bytes:

```
0x00  "RATC"                     magic — a RATC bundle reused as a data record
0x08  u32  payload size
0x14  u32  entry count           (loop1.rat: 3, matching its 3 sprite names)
0x18  u32  design width   = 1280
0x1c  u32  design height  = 720
0x20  char[16]                   the sprite this record places, e.g. "pgpbtn00.t32"
0x50  u32  pivot X               = texture width  / 2
0x54  u32  pivot Y               = texture height / 2
...
      ── placement block ──
      u32  scale X        = 100  (percent)
      u32  scale Y        = 100
      u32  tint           = 0xffffffff  (RGBA, white = untinted)
      u32  X                      ← top-left position
      u32  Y                      ←
      u32  time                   (keyframe records only)
...
      "opt " u32 len  char[len]   link to another record, e.g. "pgpbtn00f.rat"
```

- **X/Y is the sprite's top-left**, not its centre: compositing at these coordinates
  reproduces the screenshot, which drawing centred on them would not.
- **The pivot at 0x50/0x54 is half the texture size** — 4 of the 5 plain sprites match
  exactly (`pgpbtn00` 86×42 → 43,21; `pgpbtn05` 221×42 → 110,21; `pgptitle` 202×73 →
  101,36; `pgpbtn04` 172×43 → 86,22). It is a rotation/scale centre, not a draw offset.
- **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*. Focused records place their sprite
  42 px left and 8 px up of the base, because the focused art includes the selection ring
  that hangs off the left edge; their pivot is a constant (21,25) rather than half-size.
- `<screen>loop1.rat` is **not** a screen composition — it is a looping sprite animation:
  a 3-name table (`pgpeff34/35/36.t32`) plus ~30 keyframes all at one position.
- The small (380 B) top-level entries are **`PRMD` primitives**, not sprites: a colour and
  four explicit corner coordinates `(0,0) (1280,0) (0,720) (1280,720)` — the full-screen
  quad that dims the scene behind the pause menu — terminated by `end `.

### The records are language-independent

`pgpbtn00.rat` is **byte-identical** in the English and Japanese bundles. The layout is
authored once and only the `.t32` sprites are swapped, which has two consequences:

- The baked pivot belongs to *whichever build the record was authored from*, not to the
  sprite actually shipped beside it. That is why `pgpbtn01`'s pivot (113 → a 226 px wide
  texture) matches neither the English sprite (207) nor the Japanese one (148).
- The split is visible inside a single bundle: in the **English** tutorial build, every
  `.t32` declaration carries the correct English pivot (7/7), while the `.rat` declarations
  carry Japanese-derived ones (`btn10` → 43,21 = 86/2, the *Japanese* sprite). So the
  `.t32` table is regenerated per language and the `.rat` layer is inherited from the
  Japanese master.
- **Do not infer anything about a language from a texture size** — see the traps below.

## 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. **Absolute placement — the decisive test.** The *tutorial* build's records give
   546/288, 546/358, 546/428 and 540/119. Compositing its sprites at exactly those numbers,
   with no offset and no fitting, reproduces the screenshot (image above).
3. **Pivot.** 4 of 5 plain sprites carry exactly half their texture's dimensions at
   0x50/0x54 (above).

> A caution on step 2, because the first pass here got it subtly wrong: the screenshot is
> of the **tutorial** pause menu, so only the `pgp_ttrl_*` records can be checked against
> it. The in-mission records (X = 226) also map onto the same screenshot under a single
> constant offset — but that only works because both builds share the 70 px pitch, and it
> proves nothing. The in-mission coordinates remain **unverified**: confirming them needs a
> screenshot of a pause during an actual mission.

## It generalizes — the title screen

The same method run against `GP_TITLE.pak` reproduces the **main menu**, which is a
different screen with a different item count and a different pitch:

![main menu real vs rebuilt](captures/ui-layout/title-mainmenu-real-vs-rebuilt.png)

`ptbtn01..05.rat` give X = 542 for all five and Y = 162 / 242 / 322 / 402 / 482 — an
**80 px** pitch, where the pause menu used 70. Measured against the screenshot, the sprite
tops land at a constant **+46 px** for all five (one reads 45, a 1-px edge-detection
wobble), and 46 is exactly the 45 px of Xenia window chrome plus one. So the record's Y is
the sprite's top edge in the guest framebuffer, to the pixel, on a second screen.

`GP_TITLE.pak` also splits by sub-screen the way the pause pak splits by context:
`ptbtn00` alone (the `PRESS Ⓐ BUTTON` prompt), `ptbtn01..05` (main menu), `ptbtn11..13`
(the EXTRAS submenu), plus `pgloading_*` for the loading screen.

## 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 records being language-independent makes this worse:
  a record's baked pivot implies a texture width that matches *no* shipped sprite.)
- **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

- **Half of this gap is now closed.** The `eff*` / `deli*` / `msg` sprites have no
  `.rat` of their own, and `loop1.rat` is an animation, so the question was where the
  screen's draw list lives. **It is the bundle's own declaration table** (above): that
  table is not the child listing — the children are grouped by type (every `.t32`, then
  every `.rat`), while the declaration table names *elements*, in a plausible back-to-front
  order, and it is exactly the missing set that appears there. For the in-mission pause
  menu it lists 23: `eff11/12/10`, `eff02(+a)`, `eff03(+a)`, `eff01`, `title.rat`,
  `btn00/01/04/05.rat`, `msg`, `deli1…4`, `eff30…33`, `loop1.rat`. Note what it does
  **not** list: the focused button variants, which are reached through each base record's
  `opt ` link — so the table is the screen's element set, not a resource inventory.
- **And the position is there too — the gap is closed.** Immediately after the
  declaration table the bundle carries a **placement region, one group per element**:

  ```
  group header:  u32 element index      (0,1,2… — the correspondence is stated, not inferred)
                 u32 keyframe count
  then `count` keyframes, 40 bytes apart, each holding:
                 u32 scale X = 100      u32 scale Y = 100
                 u32 tint    = 0xffffffff
                 i32 X                  i32 Y            ← SIGNED
                 u32 time               u32 flags/terminator
  ```

  **Three things here are easy to get wrong, and were:**

  - **X and Y are signed.** Off-screen animation starts are negative — the Arsenal's
    weapon-list window begins at **X = −516**. Read as unsigned it is 4 294 966 780,
    which a naïve implementation would happily draw four billion pixels to the right.
  - **The trailing word is a time**, and a group is an **in → hold → out**
    animation. `prselect_win1` runs `t=4:−516 → 6:−71 → 7:81 → 8:127 → 23:134 →
    24:134 → 25:127 → 27:81 → 31:−71 → 1:−516`.
  - **So neither the first nor the last keyframe is where the element sits.** Both
    are off-screen for an animated element. The resting position is the
    **max-dwell** keyframe — the one with the longest gap to the next time — which
    for that window is **(127,155)…(134,155)**, matching where the list panel
    actually appears. `screen_layout.rs` reports that, not `final`.

  For the tutorial pause bundle this yields 11 groups for 11 elements, and every
  group's header index and count match the blocks actually present. The values are
  self-evidently right: the three menu buttons sit at X=546, **70 px apart**
  (288 / 358 / 428) — static, every keyframe identical, which is why their reading
  was unaffected by the first/last mistake above — the title at (540,119), the
  message at (451,545), and the `eff*` sprites carry multi-position fly-ins.

  **Cross-checked against the records themselves:** `pgp_ttrl_btn10.rat` places its
  sprite at **(546,288)** — identical to its inline group. So the inline region is
  the same placement data, and it covers the `eff*` / `deli*` / `msg` elements that
  have no record of their own.

  A screen is therefore fully reconstructible from its bundle alone: **element list
  and order** (declaration table) + **placement and animation** (this region) +
  sprites, with `opt ` supplying focused states.
- 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).

## It generalises: the ARSENAL screen, and how a multi-component screen composes

**2026-08-11.** [`examples/screen_layout.rs`](../../../crates/sylpheed-formats/examples/screen_layout.rs)
dumps a bundle's declaration table and placement region together. It reproduces
the tutorial pause menu exactly, and it reads the ARSENAL the same way
([capture](../captures/arsenal-main-screen-layout.txt)) — 23 elements that match
the running game:

- **Eight buttons** `prbtn1…8.rat` at **X=242**, Y `166, 220, 276, 331, 385, 441,
  496, 551` — evenly spaced, and eight is exactly what the screen's own config
  declares with `WEAPON_CATEGORIES = 8` (GUN, BEAM, LASER, MPM, ASM, B/R, CANNON,
  SPECIAL, the list photographed in the Arsenal).
- **`prexp3.t32` declared seven times** at X=726, 34 px apart (`381 … 585`) — the
  DATA SHEET's rows.
- `prexp1.t32` animates `(726,143) → (1286,143)`, sliding off the right edge, with
  `prexp1a.t32` **parented to it** (`parent = 13`).
- `prmsg.t32` at (151,645) — the description line along the bottom.

### Two things this adds

- **`kind = 0x4` marks a repeated instance.** `prexp3.t32` appears once with
  `kind 0x0` and then six more times with `0x4`, each with its own placement — the
  game repeats one row template rather than shipping seven sprites. So the element
  *name* is not a key; the declaration index is.
- **A screen is composed of named components.** The pause menu is one bundle, but
  `GP_HANGAR_ARSENAL.pak` holds **510** RATC entries because its screens are built
  from the `.prt` components its config names (`Menu = prmain_scr.prt`,
  `Select_Window = prselect_scr.prt`, `Detail_Window_Known = prselect_win3.prt`, …).
  Those resolve **under the config's own `PATH` prefix**: `prmain_scr.prt` is not
  present, `eng\prmain_scr.prt` is — the same `<lang>+<member>` convention the
  [movie table](../movie-subtitle-link.md) uses. A sub-component reads identically:
  `psselect_win1` declares 4 elements, three of them **parented to element 0**,
  which is the parent-index field doing real work on an independent pak.

### Validated against the running game, to ±2 px

The layout above is a static parse; this is the check that it predicts what the
game actually draws. Booting to the ARSENAL and detecting the eight teal category
chips by colour gives their row centres, against the eight `prbtn1…8.rat`
placements from `eng\prmain_scr.prt`:

```
placement Y   + pivotY(14) + chrome(45)   observed centre   diff
   166                225                      224          -1
   220                279                      278          -1
   276                335                      334          -1
   331                390                      388          -2
   385                444                      444          +0
   441                500                      498          -2
   496                555                      554          -1
   551                610                      608          -2
```

The spacings are the real signature: **54, 56, 55, 54, 56, 55, 55** predicted
against **54, 56, 54, 56, 54, 56, 54** observed — an irregular alternating pattern,
not a round number that could match by luck. The single free parameter is the
**45 px emulator window chrome** (title bar + menu bar), which is not part of the
game; the ±2 px residual is the centroid measurement, since a thresholded chip
centre is not exact.

This confirms three things at once: the **declaration table is the element set**,
the **placement region gives real screen coordinates**, and the **pivot composes
additively** — `pivotY = 14` is half the 28 px chip, so placement is the top-left
and pivot carries the centre offset, exactly as the record layout says.

**Not** confirmed by this: the max-dwell rule for *animated* elements. These eight
buttons are static (every keyframe identical), which is precisely why they make a
clean ruler. Validating the animation rule needs an element captured mid-slide.

Evidence: [`captures/arsenal-layout-validation.png`](../captures/arsenal-layout-validation.png).

## RATC nesting, measured

`INDEX` carried the bundle format as 🟡 "one level deep", which reads like a
parser limitation. It is not — **there is nothing deeper on the disc**:

- **2 859** top-level RATC bundles hold **18 002** children at depth 1 and
  **0** at depth 2, with **no** blob failing to parse.
- The children that are themselves RATC (the `.rat` layout records) are **leaf
  records**: they carry no child list and instead **reference their siblings by
  name** — the sprite they place and, via `opt `, their focused variant.
  **3 311** such leaves, every one embedding sibling names, and **10 144 of
  10 148** references resolve to a sibling of the same bundle.

That is the same by-name convention used one level up, where a screen's config
names `.prt` components, and one level up again, where the movie table names
`<lang>.pak+<member>`.

**The 4 unresolved references are a real defect on the disc**, not a parse gap:
`pmbase.rat` in `GP_STAGE_CLEAR.pak` (four language builds) places `pmbase.t32`,
and that sprite exists **nowhere** — not as a pak member, not as a child of those
bundles. It is the second such dangling asset found, after
[`SUBTITLE_S12B.tbl`](../movie-subtitle-link.md); a reimplementation should skip
a missing sprite rather than treat it as a decode failure.
