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re: REGN is a tetrahedral navigation mesh — the cell→geometry link, decoded

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Found the reader. It is the deserialiser, not a consumer, and it answers the
question twice: the fixup base is chunk+0x10 (82465198 addi r3,r31,16), so
every offset previously recorded was read 16 bytes early — which is why twenty
correlation tests sat at chance — and the POF0 table names every pointer word
in the file.

Six sections, not four. cell {count,item*} → item {n@+0x10, refs*@+0x14} →
array of pointers into section 1 → a 96-byte tetrahedron. Section 2 is a face:
plane, its three vertices, the two tetrahedra either side (0xFFFF = hull) and
their face slots.

All 11 objects: face passes through exactly 3 of its tet's 4 vertices in
253 722/253 722 (random control 0.07–2.2 %); portal cost == face-centroid
distance in 380 460/380 460; sphere reaches its cell 98.7–100 % vs 18–28 %
with transposed axes.

Refuted and kept: 'REGN'/'MCOL' are never built as constants in the executable
(0x474E occurs zero times in 1.87 M instructions), so no magic-dispatch site
exists; and "zero portal-pair float marks a hull edge" shows no lift at all.
Still open: the runtime consumer of the grid, the second portal float, and the
four flag bytes at tetrahedron +0x54.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PMRJjbxLqZtsb5Vb7KunPE
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Sylpheed RE agent
2026-08-26 07:53:13 +00:00
parent 0d51cdb403
commit b9643c63f6
3 changed files with 316 additions and 6 deletions
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docs/re/BACKLOG.md
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@@ -359,6 +359,27 @@ search cannot find a *schedule*.
index-shaped field in the cell payload has been followed into all three
sections and checked for spatial agreement against controls — nothing above
chance. Settling it needs the PE code that reads `REGN`, not more correlation.
✅✅ **2026-08-26 — SETTLED, and `REGN` is a tetrahedral navigation mesh.** The
reader is the deserialiser `sub_82465110`/`sub_82465138`/`sub_82465200`, and it
gives the answer twice over: the fixup base is **`chunk + 0x10`**
(`82465198 addi r3, r31, 16`), so **every offset above was read 16 bytes
early** — which is why twenty correlation tests returned chance — and the
`POF0` table is an exact list of which words are pointers, so the pointer
graph needs no guessing. There are **six** sections, not four. A cell holds
`{count, item*}`; the item holds `{n @+0x10, refs* @+0x14}`; `refs` is an
array of pointers into section 1, which is a **96-byte tetrahedron**
(bounding sphere, 4 vertex indices, 4 face indices, 6 face-pair portal costs).
Section 2 is a **face**: plane + its 3 vertices + the two tetrahedra either
side (`0xFFFF` = hull) + their face slots. Checks, all 11 objects: each face
passes through exactly 3 of its tetrahedron's 4 vertices in **253 722/253 722**
(random control 0.07–2.2 %); portal cost == face-centroid distance in
**380 460/380 460**; a listed tetrahedron's sphere reaches its cell in
98.7–100 % against 18–28 % for transposed axes. 🔴 Also recorded: **`'REGN'`
and `'MCOL'` are never built as constants in the executable** — `0x474E`
occurs zero times in 1.87 M instructions — so no magic-dispatch site exists.
❔ Still open: the runtime *consumer* of the grid, the second float of each
portal pair, and the 4 flag bytes at tetrahedron `+0x54`. Tool:
`tools/re-capture/regn_decode.py`.
See [`structures/regn-map-grid.md`](structures/regn-map-grid.md).
* 🔴 **`hidden/DefTables.pak` is NOT it** (checked 2026-08-24). The three
unnamed schemas are more **model/render** tables in the same vocabulary as the