# `vehicleSubSystems` — the engineering-screen subsystem cluster panels (reconstruction plan) > Status: **reconstruction UNDERWAY** (from-scratch). This is the largest single gauge item — not a > widget but the whole engineering-screen (MFD) subsystem-panel system. Full decomp captured in the > session scratchpad (`vss_full.txt` / `vss_sub.txt`, Ghidra headless of `BTL4OPT.EXE`); this doc is the > durable spec so the analysis survives across sessions. ## What it is The config primitive `vehicleSubSystems(qXXX0.pcc .. qXXX7.pcc)` (26 uses in `L4GAUGE.CFG`, one per vehicle init block after `MechInit;`) registers a **Make dispatcher** (`FUN_004cbaf0`, methodDescription @`0x51c080`, 8 `typeString` params = the 8 strip bitmaps). At cockpit-build time the Make walks the mech's subsystem roster (`entity+0x124` count / `+0x128` array, **skipping slot 0** = the controls mapper) and, for each subsystem, builds a **status cluster panel** onto one of 12 auxiliary MFD positions, dispatching on the subsystem's `classID` (`sub+4`): | classID | subsystem | child cluster | ctor | new size | id string | |---|---|---|---|---|---| | 0xBC3 | Sensor | `HeatSinkCluster` (looks up the `"HUD"` subsystem via `FindSubsystem`, `FUN_0041f98c`) | `FUN_004c8a6c` | 0xf0 | "SensorCluster" | | 0xBC6 | Myomers | `MyomerCluster` | `FUN_004c8df4` | 0xd8 | "MyomerCluster" | | 0xBC8 / 0xBD4 | Emitter / PPC | `EnergyWeaponCluster` | `FUN_004c93b0` | 0xf0 | "EnergyWeaponCluster" | | 0xBCD / 0xBD0 | Projectile / Missile | `BallisticWeaponCluster` | `FUN_004c9558` | 0x11c | "ProjWeaponCluster" | | 0xBCE | Gauss | — (error "Gauss rifle not yet supported") | — | — | — | | all others | | skip | | | | Type filter before dispatch: `FUN_0041a1a4(**(sub+0xc), "")` (an IsA/registry check) must pass. ## The per-group geometry table @`0x51bf34` (12 groups × 7 dwords, keyed by `sub[0x1dc]-1`) Each group = `{ X, Y, planeMask, subBit, mfdPortName, engPortName, planeIndex }`: ``` grp X Y planeMask subBit mfdPort engPort idx 1 0 240 0x1 0x2 mfd1 eng1 0 2 322 240 0x1 0x4 mfd1 eng1 0 3 0 28 0x1 0x8 mfd1 eng1 0 4 322 28 0x1 0x10 mfd1 eng1 1 5 0 240 0x20 0x40 mfd2 eng2 1 6 322 240 0x20 0x80 mfd2 eng2 1 7 0 28 0x20 0x100 mfd2 eng2 1 8 322 28 0x20 0x200 mfd2 eng2 2 9 0 240 0x400 0x800 mfd3 eng3 2 10 322 240 0x400 0x1000 mfd3 eng3 2 11 0 28 0x400 0x2000 mfd3 eng3 2 12 322 28 0x400 0x4000 mfd3 eng3 (self) ``` `mfdPort` → `renderer->GetGraphicsPort(name)` (the visible MFD surface); `engPort` (string) is the engineering-screen render port name passed to the cluster sub-gauges. ## Class family (all btl4gau2, all DECLARED in btl4gau2.hpp, NONE reconstructed pre-this-effort except `SeekVoltageGraph`) - **`SubsystemCluster`** base @`0x4c8140` (vt `0x51a020`) : `GraphicGauge` — builds ~11 sub-gauges (HorizTwoPartBar temp bar, CoolingLoop ×2, PowerSource ×2, BackgroundBitmap, OneOfSeveralInt modeLamp, GeneratorVoltage/ScalarBarGauge, OneOfSeveralStates stateLamp, VertTwoPartBar ×2, LeakGauge). dtor `0x4c87dc`, Execute `0x4c88e4`, draw-bg helper `0x4c89c4`, BecameActive-draw `0x4c8820`, TestInstance `0x4c8990`, ShowInstance `0x4c8a28`. Reads attributes InputVoltage/HeatSink/CurrentTemperature/ DegradationTemperature/FailureTemperature/CoolantMassLeakRate via `FUN_0041bfc0` (=`GetAttributeIndex` by name, returns `owner + idx - 1` or 0). - **`HeatSinkCluster`** @`0x4c8a6c` (vt `0x519fd4`) : SubsystemCluster — adds 4 fail TwoStates (btehfail/btepfail/btesfail) + a NumericDisplayScalar. Execute `0x4c8db0` scales `this[0x35]` by `_DAT_004c8df0` (=100.0). dtor `0x4c8d18`. - **`MyomerCluster`** @`0x4c8df4` (vt `0x519f88`) : SubsystemCluster — adds a SeekVoltageGraph ("EngrGraph", edestryd.pcc) + a seek-step OneOfSeveralInt (bteseek.pcc, `subsys+0x800`). Execute = base. dtor `0x4c8f54`. - **`WeaponCluster`** @`0x4c8fc4` (vt `0x519f38`) : SubsystemCluster — adds SegmentArc270 recharge dial (reads "PercentDone") + ConfigMapGauge. Make-time warns "WeaponCluster missing ". Execute `0x4c9290` toggles a warn lamp when `this[0x36] > _DAT_004c92e0`. DrawWarningLamp `0x4c932c`, BecameActive `0x4c9258`, dtor `0x4c91d4`, slot17 `0x4c92e4`. - **`EnergyWeaponCluster`** @`0x4c93b0` (vt `0x519ee8`) : WeaponCluster — adds SeekVoltageGraph (OutputVoltage) + seek-step OneOfSeveralInt (`subsys+0x3f0`). dtor `0x4c94dc`. - **`BallisticWeaponCluster`** @`0x4c9558` (vt `0x519e98`) : WeaponCluster — adds 2× NumericDisplayInteger (ammo, `link+0x180`), jam/fire TwoStates (btejam/btefire), NumericDisplayScalarTwoState, eject BitMapInverseWipeScalar (bteejtm, `subsys+0x3f8`), a GraphicsViewRecord erase tracker. Execute `0x4c9a38` tracks weaponAlarm==5 (Jammed, `subsys+0x364`) + the reload clock. dtor `0x4c9940`, BecameActive `0x4c99cc`, TestInstance `0x4c9adc`, slots `0x4c9b24`/`0x4c9b50`. ## Sub-gauge classes to reconstruct (btl4gau2, declared not defined) - **`AnimatedSubsystemLamp`** (CoolingLoop) @`0x4c70a4` (vt `0x51a174`) : OneOfSeveral + connection `FUN_004c3134` (vt `0x518ea8`, subsystem-state driven) at `+0x2b`. dtor `0x4c7134`. - **`AnimatedSourceLamp`** (PowerSource) @`0x4c7160` (vt `0x51a130`) : OneOfSeveral + connection `FUN_004c31ec` (vt `0x518e9c`) at `+0x2b`. dtor `0x4c71f0`. - **`ScalarBarGauge`** (GeneratorVoltage) @`0x4c721c` (vt `0x51a0e4`) : engine bar `FUN_00472ef0` (VertNormalSlider-ish) + connection `FUN_004c3288` (vt `0x518e90`) at `+0x2d`. 2nd ctor `0x4c72ac` (uses the engine `FUN_00474855` scalar-attr connection). dtor `0x4c733c`. - **`ConfigMapGauge`** @`0x4c6d80` (vt `0x51a1b8`) : GraphicGauge — 5 pcc names (btjoy/cm_off/cm_other/ cm_only/cm_both) interned into the warehouse; Execute `0x4c6f1c` reads the control-mapper state from `app->GetModeManager()` (`DAT_004efc94+0x3c`, group `0x1c0 + i*0x20`) and blits the matching frame. SetColor `0x4c6ee0` (writes `this+0x94`). dtor `0x4c6e54`. Engine primitives it calls (ALREADY in `munga_engine.lib`, callable — do NOT reconstruct): `TwoState` (`FUN_004739d8`, vt `0x4fb740`), `NumericDisplayScalar` (`0x470888`, vt `0x4fbb40`), `NumericDisplayInteger` (`0x470cfc`), `NumericDisplayScalarTwoState` (`0x473c94`), `BackgroundBitmap` (`0x471d00`), and the GaugeConnection ctors `FUN_00474855`/`FUN_004749de`. Already reconstructed: HorizTwoPartBar/VertTwoPartBar/OneOfSeveralInt/OneOfSeveralStates/BitMapInverseWipe(Scalar)/SegmentArc270/ SeekVoltageGraph. ## ⚠ THE BLOCKER — core `MechSubsystem` layout (Phase 2) The Make reads `subsystem[0x1dc]` (auxiliary-screen position, INT 1..12; 0/miss → the panel is skipped with "Auxiliary screen position = zero"), `[0x1e4]` (display label), `[0x1e0]` (damage-zone index), `[0x224]` (a name). Our reconstructed `MechSubsystem` ends at **0x114** — these are **unreconstructed base fields not populated from the resource parse**. So the panels render NOTHING until the core subsystem layout is extended + populated (from `MechSubsystem::CreateStreamedSubsystem` / the resource ctor `FUN_004ac644`) — a change to the WORKING combat/heat subsystem code (regression risk per the §10 systemic rules). The bytes exist in the allocation (subclass layouts are locked to binary offsets, so there is padding between 0x114 and the subclass fields); the task is to CARVE named fields out of that region + wire the resource parse, verifying combat/heat un-regressed. **This is the final, sign-off-gated step.** ## Phasing - **Phase 1 (SAFE, gated):** reconstruct the cluster family + the 4 sub-gauge classes + connections + the Make dispatcher + register in `BTL4MethodDescription[]`. Gauges only build under `BT_DEV_GAUGES`/pod; with `[0x1dc]` unpopulated the Make hits its skip path, so **combat is untouched**. Buildable + committable. - **Phase 2 (core-layout, sign-off):** extend + populate `MechSubsystem[0x1dc/0x1e0/0x1e4/0x224]` from the resource → the panels render live on mfd1/mfd2/mfd3. Verify combat/heat un-regressed.