# MECHMPPR.CPP / .HPP — reconstruction notes

`MechControlsMapper` (: Subsystem) is the mech's control-input subsystem,
installed at roster slot 0 via `Mech::SetMappingSubsystem`. It publishes the
control-input attributes (StickPosition..PilotArray, IDs 3–0x16) that the
streamed control mappings bind to, and — as of Phase 5.3 — interprets those raw
inputs into the locomotion/aim demands the mech drive consumes.

## Reconstructed

- The attribute table + AttributeIndex + shared-data statics (earlier wave).
- The ctor: primes the published inputs to neutral and (Phase 5.3) installs
  `InterpretControls` as the per-frame Performance.
- `InterpretControls(Scalar)` — the per-frame control interpretation
  (mechmppr.cpp @004afd10, authentic demand math):
  - throttle → forward speed: `speedDemand = topSpeed · throttle · fwdScale`
    (reverse thrust inverts and drops the forward scale). `topSpeed`/`walkSpeed`
    are read from the owner via `Mech::GetReverseStrideLength()/GetWalkStrideLength()`.
  - soft response: square the stick yaw (sign preserved), cube the pedals.
  - Basic mode: stick yaw = `turnDemand`; Standard/Veteran: pedals = `turnDemand`.
  - speed clamp while turning hard (`max_turn` ramps topSpeed → walkSpeed by
    |turnDemand|); VeteranMode has no clamp.
- Demand accessors `GetSpeedDemand()/GetTurnDemand()` (read by `Mech::Simulate`).
- `GetMech()` = `(Mech *)GetEntity()`.

The mapper ticks in the engine's `Entity::PerformAndWatch` roster walk (slot 0),
which runs BEFORE the mech's own Performance (`Simulation::PerformAndWatch` at
the tail), so the demands are same-frame — no input latency.

## DEV hook (headless verification)

`BT_FORCE_THROTTLE` / `BT_FORCE_TURN` override the pushed raw inputs (the RIO/
keyboard aren't present in the headless smoke test), so the demand math + mech
drive are exercisable without hardware. `BT_MECH_LOG` prints a 1 Hz `[mppr]`
demand trace. Verified: `throttle=1.0` → speedDemand=30; `throttle=0.3,turn=1.0`
→ the mech walks a circle; neutral → 0. See MECH.NOTES.md (Phase 5.3 inc 2).

## Torso aim wired (2026-07-21)

InterpretControls now routes the stick PITCH (`stick_y`, squared soft response)
into the torso weapon-elevation axis every control mode
(`Torso::SetAnalogElevationAxis`), and in Standard/Veteran the stick YAW into the
torso twist (`SetAnalogTwistAxis`); Basic keeps the stick yaw as the leg turn.
`Torso::TorsoSimulation` slews + clamps the elevation/twist (see TORSO.NOTES.md).
Verified: `BT_FORCE_ELEV=0.8` → torsoElev clamps at the authentic 20° limit.

## Look-button state machine wired (2026-07-21)

The five-state LOOK machine is live: `LookState` enum + `lookState`/
`previousLookState` members; each frame InterpretControls picks the state from
the look buttons (left/right/behind/down, priority in that order) and on a
CHANGE calls `Mech::CommitLookState(state)`, which re-aims the eyepoint from
the mech's authored look angles (see MECH.NOTES.md increment 6).
`BT_FORCE_LOOK=<1..4>` dev hook. Verified: look-behind commits yaw=π once and
the per-frame eyepoint compose carries it with the live elevation.

## Deferred (the free-aim / camera wave)

Still not reconstructed: the HUD free-aim slew (`HUD::SetFreeAimSlew`, the
Standard/Veteran torso-disabled path), the torso recenter command, and the
weapon-side half of the look commit (per-view fire enables + HUD pip group
mask — needs the MechWeapon viewFireEnable/rearFiring members). The
skeleton-joint application of the torso angles is deferred with the render
wave (TORSO.NOTES.md).