arcattackandClaude Opus 4.8
c0a0ec5e69
Investigation (workflow) found the searchlight-driven fog swap never worked in the ORIGINAL 1995 binary either -- it's a latent bug, not a port regression: SearchlightSimulation (@004b841c) reads requestedOn@0x1E0 (never written) while ToggleLamp (@004b860c) toggles commandedOn@0x1DC; no bridge exists, so lightState @0x1D8 is perpetually 0 (lamp never lights). The self-consistent sibling ThermalSight reads the field it toggles (0x1DC) -- the tell. The port reproduces the bug faithfully (searchlight.cpp:189). Additionally the port never constructs PullFogRenderable, so even absent the bug the swap wouldn't fire. Decision: LEAVE AS-IS + document (faithful to the buggy original); the port keeps the static lights-ON fog= values. A working swap would DEVIATE from the shipped binary (repair the sim to read commandedOn + construct PullFogRenderable at the btl4vid MakeMechRenderables inside pass + a toggle input) -- fully scoped in the KB if ever wanted. No code change this commit. Documented in rendering.md (fog section), open-questions.md (deferred subsystems), subsystems.md (Searchlight). Core per-map/time/weather fog (task #63) is unaffected. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
109 lines
7.9 KiB
Markdown
109 lines
7.9 KiB
Markdown
---
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id: subsystems
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title: "Subsystems — the factory + the reconstruction waves"
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status: established
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source_sections: "PROGRESS_LOG.md §10d; docs/SUBSYS_PLAN.md; docs/VEHICLE_SUBSYSTEMS.md; docs/RESOURCE_AUDIT.md"
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related_topics: [decomp-reference, reconstruction-gotchas, combat-damage, gauges-hud]
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key_terms: [subsystem, factory, ClassID, subsystem-roster, PoweredSubsystem, bridge]
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open_questions:
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- "Myomers coupling (gates on owning-player @mech+0x190); 0xBD3 damage-hub untangle (WAVE 8)"
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---
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# Subsystems
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The mech's components (heat/power/weapons/sensor/gyro/torso/myomers/…), built by the Mech-ctor
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factory. Full per-family plan: `docs/SUBSYS_PLAN.md`; the engineering-cluster panels:
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`docs/VEHICLE_SUBSYSTEMS.md`; the layout audit: `docs/RESOURCE_AUDIT.md`. ClassID map:
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[[decomp-reference]] §2.
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## The factory
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The Mech ctor switches on the resource ClassID to build each subsystem into the [[subsystem-roster]]
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(`subsystemArray@0x128`). **The `case <Name>ClassID` LABELS are systematically MISLABELED** — the
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real class is the `// FUN_004xxxxx` ctor-address comment reconciled via `CLASSMAP.md`, not the case
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name (e.g. 0xBBE case="Sensor" is actually AggregateHeatSink). Each real class is wired via a
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`Create<Class>Subsystem(Mech*,int,void*)` **bridge** in the class's own `.cpp` (do NOT `#include` the
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real subsystem headers into mech.cpp — the local stubs collide). Keep the alloc SIZE + special-cache.
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[T2]
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## Class hierarchy (two branches, shared only at MechSubsystem)
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- **Heat leaf:** `PoweredSubsystem : HeatSink : HeatableSubsystem : MechSubsystem`. Emitter/PPC/
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Sensor/Myomers/ProjectileWeapon/MissileLauncher/GaussRifle chain here. Uses 0xC `SubsystemConnection`
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+ 0x54 `GaugeAlarm54` (alarm level at +0x14). [T1]
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- **Watcher branch:** `Torso/Gyroscope/Searchlight/ThermalSight/HUD : PowerWatcher : HeatWatcher :
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MechSubsystem`; `AmmoBin : HeatWatcher`. Uses a 0xC `WatchedConnection` + 0x54 `WatcherGaugeAlarm`. [T1]
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Making a base byte-exact GROWS every subclass — they must be re-based TOGETHER in one build, each
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`static_assert`-locked (the P7 alarm-unification: HeatSink 0x1D0 → PoweredSubsystem 0x31C → MechWeapon
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0x3F0 → Emitter 0x478). [T2]
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## Reconstruction waves (state: ALL 20 factory cases wired to real classes — 0xBD3 = the real SubsystemMessageManager since task #7, 2026-07-11; the mapper lives in roster slot 0)
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- **WAVE 1** — HeatableSubsystem re-based onto MechSubsystem (de-shadow cascade).
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- **WAVE 2** — heat family (Condenser/AggregateHeatSink/Reservoir) + HUD + MechTech (un-swap).
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- **WAVE 3** — power bus (Generator/PoweredSubsystem) + Emitter/PPC fire-path (end-to-end fire; heat
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conducts to the central sink via the linked-sink roster).
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- **WAVE 4** — standalone readouts: Sensor/Searchlight/ThermalSight/AmmoBin (de-shim, gate fixes).
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- ⚠ **Searchlight has an ORIGINAL latent bug [T1, task #63]:** `SearchlightSimulation` (@004b841c)
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reads `requestedOn`@0x1E0 (never written) while `ToggleLamp` (@004b860c) toggles `commandedOn`@0x1DC
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— no bridge, so `lightState`@0x1D8 is perpetually 0 (lamp never lights). Present in the 1995 binary
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(sibling ThermalSight reads the field it toggles, 0x1DC); the port reproduces it faithfully. Left
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as-is by decision; it makes the searchlight→fog swap inert. See [[open-questions]] + [[rendering]] fog.
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- **WAVE 5** — Torso (aim twist/elevation; joint-I/O reconstructed; the BLH record disables torso →
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faithfully no visible twist).
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- **WAVE 6** — Myomers (mover-coupled; structural un-stub is INERT — no live mover/heat coupling).
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- **WAVE 7** — projectile/missile weapons (byte-exact; flying projectiles are a PORT reconstruction —
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the 2007 Entity is 0x1BC vs the binary's 0x300, so raw base-offset reads fail).
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- **TASK #56 (2026-07-11)** — Gyroscope LIVE byte-exact (ctor @004b3778, sizeof 0x3D0 locked;
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integrators + `FUN_004b2980` damage fan-out; joint dispatch from the Mech performance tail
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@0x4aaf74/83; `BT_GYRO_LOG`/`BT_GYRO_TRACE`) — see [[cockpit-view]].
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- **DEFERRED** — SubsystemMessageManager 0xBD3 (WAVE 8 — a
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**damage/explosion consolidation hub** cached to `Mech[0x10d]`=0x434; recon MISLABELS the slot
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`controlsMapper` + the drive squats there while the real mapper is roster slot 0, so wiring it needs
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an untangle. NOT the valve/advanced-damage gate — that's the owning **BTPlayer** @mech+0x190, see
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[[combat-damage]]/[[open-questions]]). [T2]
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## The watcher electrical chain (task #57, 2026-07-13 — the torso power gate)
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The Watcher branch is POWERED indirectly: a watcher WATCHES another roster subsystem and mirrors
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its electrical state. The full chain, byte-verified [T1]:
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- **Data:** the model entry `WatchedSubsystem=<name>` → segment index **+2** at resource+0xE4
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(`HeatWatcher::CreateStreamedSubsystem` @004aec54); the ctor @004aeb40 stores it at
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watcher+0x128 (`watchedSubsystem`).
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- **Bind (factory post-roster loop 1):** vtable slot 14 (+0x38) — `@004aee2c` (HeatWatcher) /
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`@004b1a40` (PowerWatcher/Torso override, byte-identical); **Ghidra missed both function
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starts** (recovered from raw bytes; the vtables.tsv rows have GAPS where the exporter skipped
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slots — dump the exe bytes at vtable+slot*4 when a slot looks missing). Master-gated
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(`(owner->simulationFlags & 0xC)==0 && (flags & 0x100)`); binds `watchedLink(+0x114).Add(
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owner->roster[+0x128][watchedSubsystem])`. Port: `BTWatcherWatchedIndex`/`BTWatcherBindTarget`
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bridges (heatfamily_reslice.cpp) called from the mech.cpp factory loop.
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- **Tick:** `@004b181c` = the REAL `PowerWatcher` Performance (PTR @0050f5fc → 004b181c) =
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`UpdateWatch()`: heat mirror (FUN_004aeac4) + `watchdogAlarm.SetLevel(watched->electrical
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level @+0x278)` + brownout downgrade to 1 when `gen->outputVoltage(+0x1DC) <= minVoltage(+0x180)
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× gen->ratedVoltage(+0x1D8)`. The Torso sims (@004b5cf0/@004b65f8) call it first-line.
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(`@004b1804` is slot-10 **ResetToInitialState**, NOT the Simulation — old recon mislabel, fixed.)
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- **MinVoltageScale = 0.01** — a 10-byte x87 literal at 0x4b1924 (`0a d7 a3 70 3d 0a d7 a3 f8 3f`);
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the port had 1.0f, making minVoltage 100× too big → the brownout latched every watchdog at 1.
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- **PowerWatcher::GetClassDerivations chains HeatWatcher** (real base) — the old HeatableSubsystem
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stand-in broke `IsDerivedFrom(HeatWatcher)` for Torso/Searchlight/ThermalSight and silently
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skipped them in the connect pass.
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- **Effect:** `Torso::ElectricalStateLevel()==Ready(4)` un-gates `effectiveTwistRate` — the MadCat
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torso twists at its authored 50°/s (±140° limits, roster 17 watching 15 → generator @10000V);
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the BLH is authentically fixed (`horizontalEnabled=0`, limits ±0.01°). [T2 live-verified]
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- **STILL DEAD:** factory loops 2-4 (heatable/weapon/damageable capability rosters) go through the
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`SubProxy` stub whose `IsDerivedFrom` returns 0 — they add NOTHING. See [[open-questions]].
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## The four systemic checks (every subsystem)
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See [[reconstruction-gotchas]]: (1) shadowing (re-declared engine-base fields), (2) the `Wword` trap,
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(3) message-handler chaining, (4) entity validity. Plus resource-struct layout (must mirror the class
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hierarchy, byte-exact — the RESOURCE_AUDIT found 8 bugs) and object-layout (alias/phantom/interior
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fields). A `+0x128`-style owner offset is the ROSTER, not the segment table (the heat-link type
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confusion that caused a heap-corruption via OOB `ConductHeat` writes). [T2]
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## Engineering cluster panels (`vehicleSubSystems`)
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Not a widget — a per-subsystem FACTORY (`FUN_004cbaf0`) building a status CLUSTER onto one of 12 aux
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MFD positions, dispatching on classID → HeatSinkCluster/MyomerCluster/EnergyWeaponCluster/
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BallisticWeaponCluster. Reads `PoweredSubsystem::auxScreenNumber/Placement/Label` (res +0x104/8/C) via
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the `BTGetSubsystemAuxScreen` bridge. See `docs/VEHICLE_SUBSYSTEMS.md` + [[gauges-hud]]. [T2]
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## Key Relationships
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- Data: [[decomp-reference]] (ClassIDs/hierarchy). Bugs: [[reconstruction-gotchas]].
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- Feeds: [[combat-damage]] (weapons/damage), [[gauges-hud]] (attribute state).
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- Plan: `docs/SUBSYS_PLAN.md`.
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