f481ccbb5f
The three sections recorded as undecoded are fixed-stride arrays and counts[0..2] are their record counts: 12, 96 and 48 bytes. Section 1's remainder is exactly 0 in 11/11 objects and section 2's exactly 96 in 11/11, which is what makes these strides rather than a coincidence of division. Section 0 is a point list: 13467 of 13467 records lie inside their object's own header bounding box. Section 2 is a plane list, 12 f32: four zeros, a unit normal (|n|=1 in 133573/133573), a signed distance, a point inside the bbox (133573/133573), and a trailing 1.0 (133573/133573). The decisive check is algebraic -- n.p + d must vanish for a real plane, and over all 133573 records the relative residual has a median of 2.29e-08 and a maximum of 2.15e-07. That is float round-off, not a fit. So a REGN object carries a point list and a plane list beside its uniform grid, which fits collision or region-boundary geometry and sits next to MCOL. Still open: section 1 (96 B, 60631 records), what queries the planes, the zeros at [0..3], and the constant 96-byte tail.
204 lines
8.8 KiB
Markdown
204 lines
8.8 KiB
Markdown
# `REGN` — a per-map spatial grid (and `MCOL` beside it)
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**Status: ✅ `CONFIRMED` for the header**, which self-checks on all 11 objects on
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the disc. ❔ the four data sections are undecoded. **New to this corpus** — no
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document mentioned `REGN`, `MCOL` or `hidden/MiscBin.pak` before 2026-08-24.
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## Where it is
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`hidden/MiscBin.pak` — 40 entries, **none** name-resolved, in three groups:
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| magic | count | sizes |
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|---|---|---|
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| `REGN` | **11** | 49 KB … 3.1 MB |
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| `MCOL` | **11** | 37 KB … 81 KB |
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| (other) | 18 | — |
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Eleven of each, which pairs them: one `REGN` and one `MCOL` per map. `MCOL` is
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untouched here; the name and the size range read like mesh collision.
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## The header, and why it is believable
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```
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0x00 char[4] 'REGN'
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0x04 u32 size of the data area (the POF0 table starts at 0x04-value + 16)
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0x10 f32[4] bbox min (x, y, z, 1.0)
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0x20 f32[4] bbox max (x, y, z, 1.0)
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0x30 f32[4] extent (max - min)
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0x40 f32[4] cell size
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0x50 u32[4] grid dimensions
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0x60 u16[6] six counts
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0x70 u32[4] four section offsets (the first is always 0x80)
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```
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**The check that makes this a decode rather than a guess** — over all 11 objects:
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* `extent == cell × dims` holds **11 of 11**, exactly;
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* `counts[3]` equals the **cell count**: `1000` on every 10×10×10 map and `125`
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on every 5×5×5 one.
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Two independent fields reproducing the grid is what rules out coincidence.
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## The three map sizes on the disc
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| half-extent | cell | dims | objects |
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|---|---|---|---|
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| 250 000 | 50 000 | 10×10×10 | 2 |
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| 50 000 | 10 000 | 10×10×10 | 6 |
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| 25 000 | 10 000 | 5×5×5 | 3 |
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So every map is a cube partitioned into 125 or 1 000 uniform cells — 10 km cells
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in a 100 km cube for the common case, and one pair of maps five times larger.
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## ✅ Section 3 is the cell index — and it self-checks 11/11
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The fourth section is a **one entry per cell** table of 8-byte records
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`(count, offset)`, immediately followed by the records those offsets point at:
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```
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index = offsets[3] .. offsets[3] + cells*8
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payload = align16(index end) ..
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record = 32 bytes (offsets step by 0x20)
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```
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Checked over all 11 objects: the lowest offset any cell refers to equals
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**`align16(offsets[3] + cells × 8)` — 11 of 11**. On the six 10×10×10 maps
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`cells × 8` is already 16-aligned and the payload butts straight up against the
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index; on the three 5×5×5 maps `125 × 8 = 1000` is not, and the payload starts
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8 bytes later, which is what makes the alignment rule visible rather than assumed.
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Two more invariants from the same sweep:
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* every occupied cell has count **exactly 1** — total items equals occupied cells
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on all 11 objects, so this is "one record per cell", not a bucket list;
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* **`counts[4] = occupied cells + 2`**, exactly, on all 11 (e.g. 997/995,
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880/878, 125/123). The `+2` is unexplained — two sentinels, or two cells
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counted differently.
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Most cells are occupied: 878–998 of 1 000, 123 of 125.
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## ✅ It is a serialised object graph with a `POF0` fixup table
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Every one of the 11 objects contains the tag **`POF0`**, always near the tail,
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and its position is exactly **`header[0x04] + 16`** — on **11 of 11**:
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```
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e993b93e header +0x04 = 0x0b100 POF0 at 45328 = 45312 + 16
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e4155d94 header +0x04 = 0x235d70 POF0 at 2317696 = 2317680 + 16
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… 11 of 11 identical relation
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```
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`POF0` is a **pointer-offset (fixup) table**: the file is a serialised C++ object
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graph, and the loader patches the recorded slots into real pointers. That
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explains a detail that would otherwise be odd — the "offsets" inside the cell
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index are absolute **file** offsets, because that is what a fixup table rewrites.
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So `header[0x04]` is the size of the data area, and everything past
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`header[0x04] + 16` is relocation bookkeeping rather than content.
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## 🔴 Two readings of the cell payload, both refuted by generalising
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Both came from the smallest object and both died the moment they were checked
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against the other ten — recorded because the temptation to keep them was real:
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* **"the `f32` at record `+0x1c` is the grid's bounding-sphere radius."** On
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`e993b93e` it is 86 689 against `√3 × 50 000 = 86 603`, a ratio of **1.001**.
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On the other ten the ratio runs **0.13 – 0.27**. Fitted to one sample.
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* **"a record's `(count, offset)` pairs point at leaf arrays of `count × 4`
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bytes."** True for the first record of `e993b93e`; across the objects the
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offset deltas fail that rule on **every** object checked (0 of 11 clean).
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What survives is only descriptive: the payload area is dominated by **float
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data** — the "strings" a printable-run scan finds are all byte patterns like
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`0x46`/`0x47` high bytes, i.e. medium-magnitude floats, not text.
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## ❔ The other three sections
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Their offsets scale with the object, and `counts[0..2]` scale with them —
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`(318, 1172, 2584)` for the 350 KB map against `(2936, 14967, 31155)` for the
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3.1 MB one, a roughly `1 : 4.5 : 10` ratio that holds across all eleven. The
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smallest object (49 KB) is nearly empty by comparison — `(8, 6, 18)` — which
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makes it the cheapest one to decode first.
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## Why this matters, stated without overclaiming
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A mission's enemy count **rises and falls** as waves arrive and are destroyed, so
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somewhere there is a scheduler with parameters — what spawns, where, and on what
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trigger. A per-map uniform grid indexed by cell is exactly the structure such a
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thing is indexed *by*.
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🔴 **But nothing here shows spawn parameters yet.** The header is a spatial
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partition and no more; the sections are unread. Treat this as the location of the
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world's spatial data, not as the wave table.
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## ✅ Update: `REGN` is a stage's **MapPath**
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The per-stage definition record (see
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[stage-definition-table.md](stage-definition-table.md)) has a field
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`MapPath = test.rgn`, and `name_hash("test.rgn") = 0x3506e972`, which is one of
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the `REGN` objects in `MiscBin.pak`. The sibling field `MapMesh = test.col`
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hashes to `0x2cf7eb47`, an `MCOL` object in the same pak.
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So `.rgn`/`REGN` is stage navigation/path data referenced by the stage record,
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and `.col`/`MCOL` is the stage collision mesh. This does not by itself validate
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either of the two refuted cell-payload readings recorded above, but it does
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explain why the payload looks like a grid of route data.
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## ✅ Sections 0, 1 and 2 have record strides — and section 2 is a PLANE list
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**2026-08-26.** The three sections the page called undecoded are fixed-stride
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record arrays, and `counts[0..2]` are their record counts. Dividing each
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section's byte span by its count over all 11 objects:
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| section | stride | evidence |
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| 0 | **12 bytes** | `count × 12` fits with a remainder of 0–12 in **11 / 11** |
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| 1 | **96 bytes** | `count × 96` fits with a remainder of **exactly 0 in 11 / 11** |
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| 2 | **48 bytes** | `count × 48` fits with a remainder of **exactly 96 in 11 / 11** |
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Section 1 landing on a zero remainder in every object, and section 2 on the same
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96-byte tail in every object, is what makes these strides rather than a
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coincidence of division.
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### ✅ Section 0 is a point list
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12 bytes is three `f32`. Over **13 467** records across all 11 objects, **every
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one lies inside that object's own header bounding box — 13 467 / 13 467 (100 %)**.
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Values land on the box corners (`±250 000`) and inside.
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### ✅ Section 2 is a plane list — 48 bytes, and the plane equation closes
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Read as twelve `f32`:
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[0..3] zero
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[4..6] unit normal |n| = 1 ± 0.02 in 133 573 / 133 573 (100 %)
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[7] signed distance d
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[8..10] a point on the plane, inside the bbox in 133 573 / 133 573 (100 %)
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[11] 1.0 exactly in 133 573 / 133 573 (100 %)
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**The check that makes this a decode**: for a genuine plane, `n·p + d` must be
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zero. Over all **133 573** records:
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|n·p + d| / scale : median 2.29e-08 p90 6.78e-08 max 2.15e-07
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That is float round-off, not a fit — the relation holds to the last bits of a
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32-bit float in **every record on the disc**. Three independent 100 % properties
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(unit normal, point in bbox, trailing 1.0) and an exact algebraic identity are
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well past what a wrong reading survives.
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So a `REGN` object carries, alongside its uniform grid, a **point list** and a
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**plane list** — which is the shape of collision or region-boundary geometry,
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and consistent with `MCOL` sitting beside it.
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### ❔ Still open
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* **Section 1** (96 bytes/record, 60 631 records disc-wide) is untouched. Its
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content is float-dominated with both large coordinates and mid-range values.
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96 bytes is 24 floats — a plausible shape for a 4×4 matrix plus extras, or for
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two 48-byte plane records, but nothing is measured.
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* **What the planes are for.** "Collision or region boundary" is a reading of the
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shape; nothing here shows what queries them.
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* The **zeros at `[0..3]`** of every plane record, and the constant `96`-byte
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tail after section 2, are unexplained.
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