Files
BT412/context/decomp-reference.md
T
arcattackandClaude Opus 4.8 1cd57ade85 context-system: bootstrap the progressive-context expert knowledge base (foundation)
Adapt the spark-lesson / expert-seed.md progressive-context pattern to the bt411 port:
a thin router + context/*.md knowledge graph so the 2236-line CLAUDE.md's deep knowledge
loads on-demand instead of every session.

NON-DESTRUCTIVE foundation pass (live CLAUDE.md unchanged; proposed router is a draft):
- reference/glossary.yaml        -- ~45 terms (engine/formats/scene/reconstruction)
- context/decomp-reference.md    -- the quantitative hub: resource types, ClassID map,
                                    mech offsets, damage delivery, weapon constants, env gates, tools
- context/reconstruction-gotchas.md -- the 12 systemic bug classes (conventions/DO-NOT hub)
- context/bgf-format.md          -- geometry format + CONN/PCONN + LOD-sqrt3 + ramp shading
- context/gauges-hud.md          -- the gauge/MFD system (the just-completed wave)
- context/open-questions.md      -- deferred systems + get-from-Nick
- context/_ROUTER-DRAFT.md       -- the proposed slim CLAUDE.md (identity, protocols,
                                    quick-lookup, evidence tiers T0-T4, conventions, structure)
- phases/phase-01-context-restructure.md -- design + migration plan + status

docs/*.md ledgers stay as the DETAILED logs; context/*.md are the curated digests that
route into them. Remaining: ~10 topic files (project-overview, subsystems, combat-damage,
rendering, locomotion, wintesla-port, build-and-run, ...) then the CLAUDE.md swap.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-07 22:06:53 -05:00

170 lines
9.4 KiB
Markdown

---
id: decomp-reference
title: "Decomp Reference — resource types, ClassIDs, offsets, addresses, env gates"
status: established
source_sections: "CLAUDE.md §10c; game/reconstructed/CLASSMAP.md; reference/decomp/all/part_*.c"
related_topics: [subsystems, combat-damage, reconstruction-gotchas, build-and-run, gauges-hud]
key_terms: [ClassID, resource-type, subsystem-roster, BTL4OPT, factory]
open_questions:
- "0xBCE weapon family fully mapped? (GaussRifle : Emitter, FireWeapon is a no-op in this build)"
---
# Decomp Reference
The quantitative hub for the reconstruction: resource-type enum, ClassID map, mech struct
offsets, key `FUN_` addresses, and env gates. Cite a section here rather than re-deriving.
Everything is `[T1]` (decompiled + byte-verified) unless tagged otherwise. The living
source-of-truth is `reference/decomp/all/part_*.c`; the class map is
`game/reconstructed/CLASSMAP.md`.
---
## 1. Resource lookup
`ResourceFile::FindResourceDescription(name, type, index=-1)` (`FUN_00406ff8` = find-by-type-and-name;
`FUN_00407064` = `SearchList(resourceID, type)`). Lookup is **by NAME or by ID**. `Mech::ResolveAnimationClip(prefix,suffix)` builds a name and calls it.
⚠ A clip_id from `ResolveAnimationClip` is a **DIRECT resource ID**`FindResourceDescription(clip_id)`,
NOT `SearchList(clip_id, 16)` (which treats the arg as a LIST → walks garbage → AV). [T1]
### Resource type enum
| Type | Value | Holds |
|---|---|---|
| SkeletonStream | — | `.SKL` skeletons |
| DamageZoneStream | **0x14** | damage-zone records (Mech ctor reads count + array) |
| ModelList | **18** | model/mech names (`bhk1`, `madcat`, …) |
| AnimationResourceType | **16 (0x10)** | animation clips (lowercase: `blhrrl`=904, `blhrrr`=905, `blhwwli`=910, `blhrrli`=916) |
| damage-zone segment list | 0x14 | per-zone segment list |
| critical-subsystem segment | 0x1e | crit subsystem segments |
Animation clip names in `BTL4.RES` are **lowercase**. [T1]
---
## 2. ClassID map (subsystem factory)
Base 3000 = **0xBB8**. The factory switches on the resource ClassID; the `case <Name>ClassID`
LABELS are **systematically mislabeled** — trust the `// FUN_004xxxxx` ctor-address comment
reconciled via `CLASSMAP.md`, not the case label. [T1]
| ClassID | Real class | ctor @ | Notes |
|---|---|---|---|
| 0xBB9 | **Mech** | @004a2d48 (`Mech::Make`) | sizeof 0x854 (binary); reconstructed 0x638 |
| 0xBBD | **Condenser** | @4ae568 | valve; `case`="?" |
| 0xBBE | **AggregateHeatSink** (heat-sink BANK) | @4ae8d0 | GUID 0x50e590, sizeof 0x1E4; `case`=SensorClassID |
| 0xBC0 | **Reservoir** | @4af408 | `case`=Condenser |
| 0xBC1 | **Generator** | @4b… | power bus |
| 0xBC2 | **PoweredSubsystem** | @004b0f74 | sizeof 0x31C |
| 0xBC3 | **Sensor** | — | `case`=MyomersClassID |
| 0xBC4 | **Gyroscope** | @004b3778 | DEFERRED (NaN integrator; reverted to stub) |
| 0xBC5 | **Torso** | @004b6b0c | sizeof 0x280; `case`=SinkSource |
| 0xBC6 | **Myomers** | @4b8fec | `case`=Actuator; INERT un-stub |
| 0xBC8 | **Emitter** | @004b1d18 | sizeof 0x478; energy weapon |
| 0xBCB | **AmmoBin** | — | `case`=JumpJet; sizeof 0x22C |
| 0xBCD | **ProjectileWeapon** | @4bc3fc | sizeof 0x448 (`case`≠ this — see VDATA.h) |
| 0xBCE | **GaussRifle** | @4bdcb4 | : Emitter; FireWeapon is a **no-op** in this build |
| 0xBD0 | **MissileLauncher** | @4bcff0 | sizeof 0x44C |
| 0xBD3 | **SubsystemMessageManager** | — | DEFERRED (WAVE 8; the valve/message control hub @mech+0x190) |
| 0xBD4 | **PPC** (: Emitter) | — | same FireWeapon as Emitter; `factory calls it GaussRifle` |
| 0xBD6 | **HUD** | — | alloc 0x2a4; `case`=MechDisplay-ish |
| 0xBD8 | **Searchlight** | — | `case`=LegSubsystem |
| 0xBDC | **MechTech** | — | alloc 0x104 |
| 0xBDE | **ThermalSight** | — | `case`=MechDisplay |
Identify a class at runtime with `sub->GetClassID()` (== `sub+4`). [T1]
### Class hierarchy (the two branches that share only MechSubsystem)
- **Heat leaf:** `PoweredSubsystem : HeatSink : HeatableSubsystem : MechSubsystem` (Emitter/PPC/Sensor/Myomers/weapons chain here). [T1]
- **Watcher branch:** `Torso/Gyroscope/Searchlight/ThermalSight/HUD : PowerWatcher : HeatWatcher : MechSubsystem`; `AmmoBin : HeatWatcher`. Uses a 0xC connection + 0x54 alarm (NOT the 4/8-byte heat-leaf types). [T1]
---
## 3. Mech struct offsets (`Mech*`, binary layout)
Reconstructed access MUST use named members/accessors — these raw offsets are the BINARY's,
valid for reading the decomp, NOT for our compiled layout (see [[reconstruction-gotchas]]). [T1]
| Offset | Field | Notes |
|---|---|---|
| +0x11c / +0x120 | `damageZoneCount` / `damageZones[]` | inherited Entity; Mech ctor populates the array |
| +0x124 / +0x128 | `subsystemCount` / `subsystemArray[]` | the [[subsystem-roster]] (NOT the segment table) |
| +0x190 | `messageManager` | the 0xBD3 SubsystemMessageManager (damage guard / valve+message route source) |
| +0x260 / +0x26c | `localOrigin` = { Point3D linearPosition; Quaternion angularPosition } | ORIGIN.h:15; position@+0x100 in some subsystem views |
| +0x300 | segment table | skeleton `EntitySegment`s (muzzle sites, joints) |
| +0x37c | target world `Point3D` | aim source |
| +0x388 | target `Entity*` | HasActiveTarget() gate |
| +0x38c | targeted sub-zone (int) | -1 = whole |
| +0x42c | `shadowJointNode` (Joint*) | ShadowJointName @model+0xB4 |
| +0x438 | torso subsystem cache | HUD/mapper read it |
| +0x5b4 | HUD subsystem cache | (factory case 0xBD6 writes param_1[0x16d]) |
| +0x650 | `deathAnimationLatched` / crashed flag | |
| +0x7cc | `damageableSubsystems` chain | the condenser chain (GUID 0x50e4fc) RecomputeCondenserValves iterates |
`mech+0x100` (a subsystem-view of localOrigin.linearPosition): `.x@+0x100, .z@+0x108`. [T1]
---
## 4. Damage delivery
- `Entity::TakeDamageMessage(id, size, inflictingEntityID, zone, Damage&)``target->Dispatch(&msg)`.
- Base `Entity::TakeDamageMessageHandler` **IGNORES zone==-1** — send a VALID zone index (the Mech cylinder-lookup override for unaimed hits is not reconstructed). [T1]
- `class Damage { damageType(enum Collision/Ballistic/Explosive/Laser/Energy), damageAmount, damageForce, surfaceNormal, impactPoint, burstCount }`. [T1]
- Weapon effect id: **"explode" = 13** (`Explosion::Make`). [T2]
- `DestroyEntityMessage(id,size)` removes an entity — but a killed mech STAYS (a WRECK); death = a STATE transition (`SetGraphicState(DestroyedGraphicState)`), NOT removal. Issuing removal-on-death is the P5 teardown bug (do not). [T2]
---
## 5. Weapon fire-rate constants (recovered)
From the weapon `.SUB` records + the charge-curve `.data` constants (PE-parsed as x87 float10). [T1]
- `DischargeTime` = beam-on time. ER-medium laser (BLH) = **0.2 s**.
- `RechargeRate` = recharge time in **seconds exactly** (the two ln5 factors cancel): ER-S 1.0 / ER-M 2.0 / ER-L 4.0 / PPC 5.0.
- One BLH ER-M cycle = 0.2 + 2.0 = **2.2 s**; ~12 lasers staggered → aggregate ≈ 5/s.
- `WeaponRange` 500 (ER laser), `DamageAmount` 3.5, `PipColor` 1.0 0.0 0.0 (RED).
- Charge constants: `_DAT_004bb3c4`=1.0, `_DAT_004bb3b8`=1e-4, `_DAT_004bb3b4`=0.5; RatedVoltage (GENRATOR.SUB)=1e4; fire threshold `seekVoltage[rec]=0.8*RatedVoltage`.
---
## 6. Env-var gates (runtime; default OFF unless noted)
The authentic stack is DEFAULT-ON (`BTEnvOn`, mechrecon.hpp): `BT_GAIT_CUTOVER`, `BT_GAIT_SM`,
`BT_COLLISION`, `BT_REAL_CONTROLS` default ON — set `=0` to fall back. ⚠ Gates check
`getenv(name) != NULL`, so `BT_X=""` (empty) still ENABLES; use `Remove-Item Env:\BT_X`.
| Var | Effect |
|---|---|
| `BT_FORCE_THROTTLE` | auto-walk forward (no key) |
| `BT_SPAWN_ENEMY` | spawn a target mech 120u ahead along the spawn facing |
| `BT_FORCE_FIRE` | auto-fire on cooldown |
| `BT_ASSERT_TO_DEBUGGER` | route CRT asserts to the debugger, not a modal box |
| `BT_HEAPCHECK` | whole-heap validation on every alloc/free (O(n²) at mission load — SLOW) |
| `BT_PROBE_BGF=<name\|ALL>` | boot-time BGF loader probe, exits after |
| `BT_LOG=<file>` | per-instance log file (in content/) |
| `BT_GAUGE_ATTR_LOG` | `[attr] <binding> OK/NULL` per config binding |
| `BT_GAUGE_SKIP_LOG` | `[gskip] <primitive>` per unregistered gauge widget the parse skips |
| `BT_VALVE_LOG` | condenser valve flow distribution |
| `BT_SECTOR_LOG` | SectorDisplay Make/Execute |
| `BT_NET_TRACE` | `[net-tx]/[net-rx]/[net-upd]` MP tracing |
| `BT_DEV_GAUGES` | render the 6 pod MFD surfaces in a separate dev window |
Full render/locomotion gates (BT_RAMP, BT_MATPRI, BT_CULL, BT_SHADOW_*, BT_LODSEL, BT_ADDLOD,
BT_PUNCH, …) are catalogued in [[rendering]].
---
## 7. Tools
- `tools/disas2.py <VA> [len]` — capstone disassembly of BTL4OPT.EXE at a VA (recovers x87 math
Ghidra drops; folds known call targets + float constants). THE tool for any `FUN_` the
assert-anchored exporter didn't capture (e.g. `@0x4ae464` MoveValve, `@0x4ca07c` Execute).
- `tools/disas2.py`-style PE reads: `scratchpad/rdva.py` (4-byte VA read), `rdtbyte.py` (80-bit float10).
- `reference/ghidra_scripts/ExportBTSource.java` — the headless assert-anchored decompiler.
- `reference/ghidra_scripts/DecompVSS.java` — headless address-list decompiler (any skipped fn).
- `tools/btconsole.py` — the MP console emulator. `tools/mapscan.py`/`resscan.py` — content scanners.
---
## Key Relationships
- Feeds: [[subsystems]] (factory + ClassIDs), [[combat-damage]] (damage delivery), [[gauges-hud]] (attribute binding).
- Verified against: [[reconstruction-method]] (the decomp loop), [[reconstruction-gotchas]] (why raw offsets fail).