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re: measure the XBG7 declined set, and close off the descriptor shortcut

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"A few multi-stream / quantized bodies remain" declined understates it. Across
all 166 resource3d containers: 6294 XBG7 resources, 5480 decoded (87.1%), 814
declined, in 31 of 166 containers. By name the declined set is 492 e* (enemy
craft), 142 f*, 73 n*, 23 eff*, plus *_dead destroyed variants -- not hero
bodies.

Also recorded as a dead end, so nobody repeats it: the descriptor's third word
looks like (streams << 16) | format -- decoded g001..g003 carry 0x00010001 while
declined t170/t180 carry 0x00020004 -- but histogramming it disc-wide puts
decoded AND declined at every value (0x00010001 alone: 4479 decoded, 328
declined). Its low half tracks sub-mesh count. Decodability is not declared in
the descriptor; it is whether the unit-normal anchor scan can locate vb0, which
the code already tests. 229 declined resources carry the most common word[2] with
under 1 KB of data, i.e. small meshes with too little signal to anchor rather
than exotic formats.

No decode gained this iteration; the gap is now quantified and one attractive
wrong turn is closed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Claude (auto-RE)
2026-08-11 23:03:58 +00:00
parent d9c69c566c
commit 5b8b5e0ab1
2 changed files with 38 additions and 1 deletions
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docs/re/structures/xbg7-mesh.md
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@@ -252,3 +252,40 @@ mission* (where `DeltaSaber` renders) would hand over its exact declaration dire
validated so a stray trailing marker ends the chain. Result: **all 19 previously-declined weapons
decode** (`wep_81` 460 t missile w/ tail fins; `wep_30_hangar` 334 t). DeltaSaber unchanged (its
body IS the largest marker → same pivot). 7/7 disc tests green, stage quality audit unchanged.
## The declined set, measured (2026-08-11)
The module note said "a few multi-stream / quantized bodies remain" declined.
Measured across all 166 `hidden/resource3d/*.xpr`:
- **6 294 XBG7 resources, 5 480 decoded (87.1 %), 814 declined**, in **31 of 166**
containers. Worst: `Stage_S09` 64/380, `Stage_S06` 58/324, `ptc_pack` 57/136.
- The declined set is **not** "a few hero bodies". By name prefix it is **492
`e*`** (enemy craft), **142 `f*`**, **73 `n*`**, **23 `eff*`**, plus destroyed
variants (`_rou_f402_dead`, `_rou_f302_base_dead`) and one weapon
(`_rou_e011_wep04`).
### A shortcut that does not work
The resource descriptor's third word looked like a format/stream flag — decoded
`g001…g003` carry `0x00010001` while declined `t170`/`t180` carry `0x00020004`,
which reads temptingly as `(streams << 16) | format`. **It is not that.**
Histogramming it over the whole disc puts decoded *and* declined resources at
every value:
```
word[2] decoded declined
0x00010001 4479 328
0x00010002 126 27
0x00010003 120 112
0x00010004 142 84
… … …
```
Its low half runs 1…0x52 and tracks sub-mesh count, not vertex format. **So
decodability is not declared in the descriptor** — it is a property of whether
the unit-normal anchor scan can locate `vb0`, which is exactly what the current
code already tests. Anyone attacking this should not spend time on the
descriptor: 229 of the declined resources even carry the *most* common
`0x00010001` with under 1 KB of data, i.e. they are small meshes the scan has too
little signal to anchor, not exotic formats.