arcattackandClaude Fable 5
60ed54e008
Colleague: you fire without a lock, at "nothing." Double-checked the binary: - The weapon fire path is DOUBLY gated on mech+0x388 != 0: EmitterSimulation (FUN_004baa88:7689) only calls FireWeapon with a target, and FireWeapon (FUN_004bace8:7727) wraps its whole body -- including beamFlag(+0x46c)=1 -- in the same check. So no target => no beam, literally (cannot fire into truly empty space). [T1] - BUT a capstone scan of the entire CODE section finds 11 READS of +0x388 and ZERO direct stores: the target is written INDIRECTLY (a message/selector), i.e. AUTO-acquired -- there is no manual lock to fire. The spinning-ring LOCK (HudSimulation 5619-5634) is a separate, stricter state. So the colleague is right that no lock is needed; my port was wrong to gate firing on a pinpoint boresight-on-hull pick. Fix: mech+0x388 = the enemy whenever it is ALIVE (auto-target); firing needs only that. A pinpoint hull hit upgrades the shot to aimed-zone damage + the lock ring; off-hull with the enemy present, the beam converges on centre mass (body hits). Third correction from over-reading the RP-shared Reticle struct (after sticky-lock and mouse-cursor). Verified: BT_AIM="0.5 0.2" (off-hull) -> fires + lands damage (was 0 before); BT_AIM="0 0" (centred) -> HOT-aimed zone hits. KB swept; checkctx CLEAN. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
311 lines
26 KiB
Markdown
311 lines
26 KiB
Markdown
---
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id: combat-damage
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title: "Combat & Damage — targeting, firing, damage zones, death"
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status: established
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source_sections: "PROGRESS_LOG.md §10c; docs/HARD_PROBLEMS.md (P5)"
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related_topics: [subsystems, decomp-reference, reconstruction-gotchas, locomotion, rendering]
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key_terms: [damage-zone, TakeDamage, viewpoint-entity, master, replicant]
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open_questions:
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- "Per-impact aim (cylinder lookup); collision damage application; DeathShutdown + collapse anim"
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---
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# Combat & Damage
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The drive→target→fire→damage→destroy loop. Full detail: `docs/PROGRESS_LOG.md §10c`; the death/
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teardown forensics: `docs/HARD_PROBLEMS.md` (P5).
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## No AI — BT is PvP-only (verified, not a recovery gap)
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The mission system is NETWORKED and BT never had NPCs/AI. Every mech is driven by a `BTPlayer` (or a
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`BTCameraDirector` spectator). The BT registry knows only Mech/Projectile/Missile/BTPlayer/BTTeam; no
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Bot/Brain/AI class exists; `BTL4OPT.EXE` has no AI strings. `Crusher/Blocker/Runner` are RED PLANET
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classes, NOT BT. ⇒ a solo mission has no enemy by design; `BT_SPAWN_ENEMY` is a TEST DUMMY
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(uncontrolled Mech). The authentic opponent path is [[multiplayer]]. [T1]
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## Entity spawn + the per-mech gate
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`Mech::Make(MakeMessage*)` (`FUN_004a2d48`) allocs `sizeof(Mech)` + runs the ctor; the base Entity
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ctor self-registers it (renders + ticks). `Mech::PerformAndWatch` runs for EVERY mech → gate
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player-only logic on `this == application->GetViewpointEntity()` (else a spawned enemy is driven by
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player input). [T1]
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## Targeting (mech offsets, [[decomp-reference]] §3)
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`mech+0x37c` = target world Point3D; `mech+0x388` = target `Entity*` (the `HasActiveTarget()` gate);
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`mech+0x38c` = targeted sub-zone (−1=whole). Weapons cache hasTarget/targetPoint/muzzlePoint,
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refreshed each frame. [T1]
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**The AUTHENTIC acquisition model (recovered 2026-07-08; corrected 2026-07-08, task #39):** THERE
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IS NO FREE-AIM MOUSE CURSOR. The pod had a stick whose yaw drove the **torso twist**
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(`MechControlsMapper` writes `HUD::SetFreeAimSlew(stick_x)` → cockpit+0x28C, gated on the torso's
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horizontal-twist being enabled — `mechmppr.cpp:735/762`, hud.hpp:167 [T1]); the crosshair marks
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where the **torso guns boresight** relative to the body-mounted view. You aim by **steering the
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mech / twisting the torso**, not by moving a cursor. The engine `Reticle` struct
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(`engine/MUNGA/RETICLE.h`) carries `reticlePosition`, `pickPointingOn`, `rayIntersection`,
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`targetEntity`, `targetDamageZone` — a general struct shared with Red Planet — but in BT
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`reticlePosition`/HotBoxVector (@mech-HUD+0x1FC) is **COMPUTED by HudSimulation** from the mech
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pose quaternion (`FUN_0040954c` quat→euler of mech+0x10C) + the target geometry, and **zeroed to
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centre when there is no target** (part_013.c:5680, `FUN_00408440(...,&DAT_004e0f74)` [T1]) — it is
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NOT a free-floating cursor. The pick then hits whatever the guns point at; that entity + its
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DAMAGE ZONE become the target (`0x37c` rayIntersection, `0x388` targetEntity, `0x38c`
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targetDamageZone → aimed-zone damage). Fixed-torso mechs (the BLH: `TorsoHorizontalEnabled=0`)
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boresight dead-ahead — the crosshair sits centred and you point the whole mech. Once locked,
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`Emitter::FireWeapon` converges with NO aim/arc test (part_013.c:7758). `MechWeapon::
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UpdateTargetState` (`FUN_004b9bdc` [T1]): `targetWithinRange = dist < (1 − hostZoneDamage) ×
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weaponRange`. The 0x388 WRITER (the per-frame reticle→mech copy) is in an un-exported decomp gap.
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**Port status: RECONSTRUCTED + runtime-verified (tasks #36/#39, 2026-07-08) [T2].** The chain:
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the crosshair = **torso boresight** (`BTTwistToReticleX(torsoTwist)`, L4VIDEO — tan(twist)
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projected through the live per-axis projection; **0 = dead-centre on the fixed-torso BLH**;
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`BT_AIM="x y"` pins it for headless tests) → `BTGetAimRay` (the ACTIVE eye publishes pos+LookAtRH
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basis via `BTSetAimCamera`, the render loop publishes proj._11/_22 + backbuffer dims) →
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`Mech::PickRayHit` (world ray → local frame → `BoundingBox::HitBy` slab test vs the collision
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template's ExtentBox → world hit point).
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**FIRING NEEDS A TARGET BUT NOT A MANUAL LOCK / PINPOINT AIM (task #40, binary-verified [T1]).**
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The weapon fire path is DOUBLY gated on `mech+0x388 != 0`: `Emitter::EmitterSimulation`
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(`FUN_004baa88` :7689) only calls FireWeapon with a target, AND `Emitter::FireWeapon`
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(`FUN_004bace8` :7727) wraps its ENTIRE body (incl. `beamFlag`=+0x46c=1 :7749) in the same check —
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so **no target ⇒ no beam, ever** (you cannot fire into truly empty space). BUT a capstone scan of
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the whole CODE section finds **11 reads of `+0x388` and ZERO direct stores** — the target is
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written INDIRECTLY (a message/selector via a `this`-pointer), i.e. the game **AUTO-ACQUIRES** the
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target for you; there is no manual "lock to fire." The spinning-ring **LOCK** (HudSimulation
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5619-5634) is a SEPARATE, stricter state layered on top (host-zone < 0.75 damage AND targeted-zone
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< 1.0). **Port model:** `mech+0x388` = the enemy whenever it is ALIVE (`!IsMechDestroyed()`) — the
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pod's auto-target — so firing works freely with the enemy merely present, NO pinpoint needed
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(verified: `BT_AIM="0.5 0.2"` off-hull → fires + lands damage; before this fix off-hull dealt 0).
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A pinpoint hull hit (`PickRayHit` → `hotTarget`) UPGRADES the shot: `mech+0x37c` = the picked hull
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point → STEP-6 resolves the zone under the crosshair (aimed fire; center-aim → head-band zone 13),
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and lights the lock ring. Off-hull, `0x37c` = the target's centre mass (body hits, near-centre
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zone). (⚠ THREE earlier cuts were wrong and are corrected: a STICKY designation — locked forever;
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a MOUSE cursor slew — a free cursor the pod never had; and a PINPOINT-required fire gate — you had
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to boresight the hull exactly to fire at all. All from over-reading the RP-shared `Reticle` struct;
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removed.) The HUD draws the aim group at the boresight ([0x9a] translate), the designator hotbox at
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the target's projected point (subB9 hot / subB8 designated, `BTProjectHotBox`/`BTProjectToReticle`),
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and the edge arrows when off-screen/behind. `BT_FIRE_ARC` is now an EXPLICIT OPT-IN presentation clamp (unset = authentic
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no-arc). The old hardwired lock, the ±30°-default cone, and the projectile path's gEnemyMech
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fallback are all REMOVED. LMB fires lasers / RMB missiles (with SPACE/CTRL). ⚠ A view-selection
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bug was fixed en route: every
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renderable rebuild stomped `mCamera` back to the chase eye (btl4vid `mViewInside` now persists
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the chosen view — the aim camera feed and the V toggle both depend on it).
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## Firing arc + muzzles
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There is NO firing-arc field in the binary (`Emitter::FireWeapon` fires whenever HasActiveTarget) —
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the 1995 game got away with it because it was **cockpit-only** (a beam behind you is off-camera). The
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port's external camera exposes it, so the arc is gated on the **torso twist range**
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(`Torso::GetHorizontalReach`, 0 for the twist-disabled Blackhawk) + a base aim tolerance
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(`BT_FIRE_ARC`, a labeled PORT presentation param). Beams fire from the mech's real gun-port SITE
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segments (siterugunport etc.) resolved via `GetSegment(name)→segmentToEntity×localToWorld`. [T2]
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## Weapon fire is a PORT reconstruction (the dpl_* beam layer is unported)
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`Emitter::FireWeapon` builds a muzzle→target beam but the `dpl_*` beam renderable was never ported →
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the beam is drawn by `BTPushBeam`/`BTDrawBeams` (L4VIDEO — an additive quad / the real `ermlaser.bgf`
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tube with the scrolling `bexp` grit). Fire rate is decoded-exact (DischargeTime 0.2 + RechargeRate 2.2
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per ER-M laser; [[decomp-reference]] §5). Flying projectiles (LRM/autocannon) are also a PORT
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reconstruction (`BTPushProjectile` — the 2007 Entity is too small for the binary's raw integrator
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offsets). [T2]
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## Damage delivery + the real damage model
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`Entity::TakeDamageMessage(id, size, inflictingEntityID, zone, Damage&)` → `target->Dispatch`.
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**Base handler IGNORES zone==−1** (`Entity::TakeDamageMessageHandler`, ENTITY.cpp:878 — returns on
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`damageZone==−1`; the message carries `invalidDamageZone = damageZone<0` + `damageData.impactPoint`).
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The Mech override that resolves an unaimed hit's zone from the impact point (the **cylinder hit-location
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model**, **STEP 6**) is now **RECONSTRUCTED + runtime-verified [T2]** — see "STEP 6 COMPLETE" below.
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(Historical: it used to be unreconstructed, meanwhile aiming a valid zone.) **Investigated 2026-07 (durable):** the earlier-cited addresses `FUN_004a0230`/`FUN_0049ed0c` do
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NOT exist — the real pieces are: the **CylinderDamageZoneTable** = a list of 0x30-byte cylinder entries
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(entry ctor `FUN_0049e740`) loaded from resource type **0x1d** by the mech's cylinder-table NAME; the
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table ctor is `FUN_0049ea48` (vtable 0x50bd84, alloc 0x2c, cached at `Mech[0x111]`=byte 0x444) — the recon
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DOES build it (mislabeled `StandingAnimation`, mech.cpp:1221) but with an EMPTY name → 0 entries → the
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lookup is a no-op. **Fully reversed (2026-07):** the table is a passive nested-list **height × angle grid** — 3 container
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classes: TABLE (0x2c, ctor `FUN_0049ea48` / dtor `0x49eadc`, vtable 0x50bd84, `this[3]`=mech,
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`this[4]`=row list, `this[10]`=row count) → ROWS by HEIGHT (0x30, ctor `FUN_0049e740` / dtor `0x49e814`,
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vtable 0x50bd90, `this[3]`=RotateWithTorso flag, `this[4]`=torso (mech+0x438), `this[5]`=cell list,
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`this[0xb]`=cell count, cell key `i·(2π/count)` — `_DAT_0049e810`=**6.2831855=2π**) → CELLS by ANGLE
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(0x2c, ctor `FUN_0049deb0` / dtor `0x49df80`, vtable 0x50bd9c, `this[4]`=a refcounted zone-dict filled
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by `FUN_0049e5e4`, count-prefixed {int→int} entries) → zone ref(s).
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**⚠ CORRECTION (2026-07, verified from decomp): the lookup is NOT "entirely in the unexported handler"
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— it is EXPORTED pseudocode [T1].** Two functions:
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- `FUN_0049eb54` (@0049eb54, TABLE-level, `void(table, float* worldImpactPoint)` — Ghidra mistypes the
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return; it tail-returns the found cell): (1) transform world impact → **mech-local** via
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`FUN_00408bf8`+`FUN_00408440` reading the mech's transform at `mech+0xd0`; (2) **HEIGHT→row**:
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`mechHeight = *(*(mech+0x2ec)+0xc)`; clamp `local.y` to `[0,mechHeight]`;
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`rowIndex = clamp(floor(rowCount·y/mechHeight), 0, rowCount-1)`; `row = rowList.Find(&rowIndex)`
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(int key, list method vtable+0xc); (3) **ANGLE**: if `|local.z|>eps && |local.x|>eps`,
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`angle = atan2(local.z, local.x)` (`FUN_004dc8ec`=atan2, confirmed via `s_atan2`), wrap `<0 → +2π`;
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else degenerate `angle = FUN_00408050()·2π`; then call `FUN_0049e678(row, angle)`.
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- `FUN_0049e678` (@0049e678, ROW-level angle→cell): if `RotateWithTorso` (row+0xc), `angle += torso facing
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(*(torso+0x1d8))` and wrap into `[0,2π)`; `cellIndex = floor(cellCount·angle/2π)`; reconstruct the exact
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float key `(cellIndex+1)·2π/cellCount` (cells stored under `i·(2π/count)`, i=1..count);
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`cell = cellList.Find(&key)` (float key, list method vtable+0xc).
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Constants: `_DAT_0049e810 = _DAT_0049e72c = _DAT_0049ed08 = 2π`; `_DAT_0049e734 = 1/(2π)`;
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`_DAT_0049e730 = _DAT_0049ed00 = 0.0`; `_DAT_0049ed04 = eps`; `DAT_004e0f80/84/88 = (0,0,0)`.
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**Within-cell selection (fully recovered `FUN_0049de14` + disasm):** the cell → a **cumulative
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hit-distribution**; `zone = FUN_0049de14(cell)` rolls `random()` (`FUN_00408050` = `(1/RAND_MAX)·engineRand`,
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uniform [0,1)) and returns the **first entry whose threshold > roll** (entries sorted ascending) — classic
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BattleTech dice hit-scatter. The tiny glue `FUN_0049ed0c(table,worldPt) = FUN_0049de14(FUN_0049eb54(...))`;
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the real **`Mech::TakeDamageMessageHandler`** (disasm @0x4a037a, two call sites 0x4a038c/0x4a04b9) is:
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`if (msg->invalidDamageZone /*msg+0x28*/) { msg->damageZone /*+0x24*/ = FUN_0049ed0c(mech[0x111]/*+0x444*/,
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&msg->damageData.impactPoint /*+0x4c*/); msg->invalidDamageZone = 0; }` then the base
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`damageZones[zone]->TakeDamage`.
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**STREAM FORMAT — BYTE-VERIFIED against the real type-29 `.RES` bytes (EXACT consumption, 18 tables) [T1]:**
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```
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Table { i32 rowCount; Row[rowCount] }
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Row { i32 rotateWithTorso; i32 cellCount; Cell[cellCount] }
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Cell { i32 nameLen; char name[nameLen]; u8 0x00; i32 entryCount; Entry[entryCount] }
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Entry { f32 cumulativeThreshold; i32 zoneIndex } // zoneIndex → damageZones[]
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```
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Real sample (`ava1`, 7 rows × 8 cells): rows 0-2 `rotateWithTorso=0` (feet/legs — fixed to chassis),
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rows 3-6 `=1` (upper body — rotates with torso twist); a foot cell = `{0.5→16, 0.8→10, 1.0→5}`. The table
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is found by the mech's **type-0x14 DamageZoneStream NAME** (`ResourceDescription::resourceName`) →
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`ResourceFile::FindResourceDescription(name, DamageLookupTableStreamResourceType/*29*/)`.
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So STEP 6 remaining = (6b) fix the name-load (current `ResourceFindByName` is a NO-OP template stub → empty
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name → 0 rows); (6c) make the table functional + `ResolveHit→zone`; (6d) register the
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`Mech::TakeDamageMessageHandler` override + verify. **Nothing is guessed — geometry, roll, handler, and byte
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format are all verified.**
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## The classes ALREADY EXIST — `game/reconstructed/dmgtable.cpp` (2026-07 discovery)
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The three container classes are **already reconstructed** in `dmgtable.cpp`/`.hpp` (in the build):
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`DamageLookupTable` (layers=height) → `PieSlice` (slices=angle, `SelectSlice`) → `DamageZonePercentTable`
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(leaf, `SelectZone`=the roll, `ReadEntries`=stream parse). It **independently confirms this RE exactly**.
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BUT it is a **NON-FUNCTIONAL SKELETON** — it was written to capture the algorithm SHAPE and was never wired
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or run, so it has real runtime bugs the never-executed path hid:
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1. Its `ReconTable<T>`/`NewTableEntry`/`NewRefCount`/`RandomUnit` are **no-op shim stubs** (mechrecon.hpp —
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`Insert(){}`, `Lookup()→0`) → the table stays empty + lookups return null. Must be backed by REAL storage
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(safe: `ReconTable` is used ONLY in dmgtable). Direct 0-based vector indexing is faithful (the binary's
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float-key `Find((i+1)·span)` ≡ `slices[i]`).
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2. `DamageZonePercentTable::ReadEntries` **skips the cell name-string** (`FUN_00402948` = `[i32 len][len+1
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bytes: chars+NUL]`) that precedes the entry count → must read+discard it first or the parse misaligns.
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3. `PieSlice` ctor reads `rotateWithTorso` into the wrong member (`owner`), leaving the `rotateWithTorso`
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flag `SelectSlice` tests uninitialised; must read into `rotateWithTorso` + set `owner=param`.
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4. `PieSlice::SelectSlice` looks up `slices` by an `int index` but they're keyed by the `float` angle
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(dissolves once storage is a direct-indexed vector).
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5. `DamageLookupTable::ResolveHit` returns `void` — drops `SelectSlice`, never chains `SelectZone`; must
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return `int` (the zone), matching the glue `FUN_0049ed0c = SelectZone(ResolveHit(...))`.
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6. `Mech::WorldToLocal` / `TorsoOrientationSource` are DECLARED (mech.hpp) but UNDEFINED (never linked
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because dmgtable is never called); the height (`mech+0x2ec`=`[0xbb]`, the collision cylinder, `+0xc`=height)
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+ torso heading (`torso+0x1d8`) need NAMED accessors (databinding trap — no raw offset reads).
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So 6c = back the classes with real storage + fix bugs 2-5 + implement the 3 accessors; 6d = wire the mech
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ctor (real name-load, replacing the mislabeled `StandingAnimation` stub @mech.cpp:1221) + the handler override.
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## ✅ STEP 6 COMPLETE (2026-07-08) [T2]
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Built + runtime-verified. Changes:
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- **`dmgtable.cpp`/`.hpp`** — the 3 classes now use real `std::vector` storage (were no-op `ReconTable`
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shims); `DamageZonePercentTable::ReadEntries` consumes the leading cell name-string (`[i32 len][len+1]`);
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`PieSlice` ctor reads `rotateWithTorso` into the right member; `SelectSlice` direct-indexes;
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`DamageLookupTable::ResolveHit` now returns the zone (chains `SelectSlice`→`SelectZone`). Stream type is
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the real `MemoryStream` (`ReadBytes`).
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- **`mech.cpp` ctor** — replaced the empty-name stub with the real load: `FindResourceDescription(dzRes->
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resourceName, DamageLookupTableStreamResourceType/*0x1d*/)` → `DynamicMemoryStream` → `new DamageLookupTable`
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cached in the **named member `Mech::damageLookupTable`** (binary `this[0x111]`/byte 0x444; was mislabeled
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`ammoExpended` in the offset map); `~Mech` `delete`s it. ⚠ It was ORIGINALLY "cached" at `Wword(0x111)` —
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the absorber bank — which stores NOTHING, so the whole unaimed path was inert until 2026-07-08 (the
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"can't kill the enemy" bug). See [[reconstruction-gotchas]] §2. [T2]
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- **`Mech::TakeDamageMessageHandler`** override registered (`MESSAGE_ENTRY(Mech, TakeDamage)`, overlays
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Entity's by ID): on `invalidDamageZone`, `msg->damageZone = table->ResolveHit(msg->damageData.impactPoint)`,
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clear the flag, then base-route. Aimed hits pass straight through.
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- **Named accessors (no databinding-trap raw reads):** `Mech::WorldToLocal` (`localToWorld.MultiplyByInverse`),
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`CylinderReferenceHeight` (`standingTemplateMaxY` = `collisionTemplate->maxY` = the binary `mech+0x2ec[+0xc]`),
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`TorsoHeading` (via the `BTGetTorsoTwist` bridge in `torso.cpp` → `Torso::CurrentTwist` = torso+0x1d8;
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torso.hpp can't be `#include`d into mech.cpp — subsystem-stub collision).
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- **Runtime verify (2026-07-08, POST-Wword-fix — the earlier "verified" claim was PARTIAL: the handler
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wiring was live but the table cache was inert):** with `BT_AUTOFIRE=1 BT_AUTODRIVE=0.5 BT_SPAWN_ENEMY=1`,
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the full chain runs end-to-end: `[cyl] unaimed hit → zone N` resolves across **19 distinct zones**
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(front-facing zones 0/6/17/15/4 dominate for head-on fire, as the geometry predicts), structure climbs
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gradually per hit, the enemy dies after **14** hits (not 1) via the authentic cascade, 4+ zones reach
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`DestroyedGraphicState`, and the destroyed segment meshes visibly swap (RemakeEntity). Env gates
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`BT_CYL_LOG=1`, `BT_AUTOFIRE`/`BT_AUTODRIVE` (dev force-inputs, mech4.cpp). [T2]
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- **Fire path now UNAIMED (2026-07-08):** both bring-up hit paths (the SHOT block + the projectile
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impact, mech4.cpp) dispatch `zone=−1` + a world impact point (beam entry point = enemy origin shifted
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~3u toward the shooter at muzzle height; the projectile uses its own impact position) → the cylinder
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resolves the struck EXTERIOR zone. The old code aimed the internal VITAL zone directly →
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invisible 1-shot kills (internal zones are soft; the binary never aims them — they die only via the
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destruction cascade `RecurseSegmentTable`/`SendSubsystemDamage`). On kill the wreck STAYS TARGETED
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(`gEnemyMech` is NOT nulled) so beams keep terminating on it — nulling it made every later beam a
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"free" ray that visibly passed through the wreck; scoring latches off via `gEnemyDestroyed`. [T2]
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`Mech__DamageZone::TakeDamage` → engine armor model (`damageLevel
|
||
+= damageAmount*damageScale[type]`) → 1.0 = zone destroyed → death. The Mech ctor populates the
|
||
inherited `damageZones[]` from the DamageZoneStream (type 0x14) resource. `class Damage{ damageType
|
||
(Collision/Ballistic/Explosive/Laser/Energy), damageAmount, damageForce, surfaceNormal, impactPoint,
|
||
burstCount }`. Verified: `structure` climbs, vital zone destroyed → `*** TARGET DESTROYED ***`. [T2]
|
||
Two non-field fixes were needed: **message-handler chaining** (an unchained set drops TakeDamage
|
||
silently) + **entity validity** (`SetValidFlag()` on a manually-spawned entity) — see
|
||
[[reconstruction-gotchas]] §9. [T2]
|
||
|
||
## Death — the wreck STAYS (P5 CLOSED)
|
||
A killed mech does NOT disappear — BT death is a STATE transition
|
||
(`SetGraphicState(DestroyedGraphicState)` + death anim + effect/splash), the mech becomes a persistent
|
||
WRECK (RP analog: `VTV::DeathShutdown`). **NEVER issue `DestroyEntityMessage` on death** — the
|
||
teardown crash was an artifact of forcing a removal the original never does. The actual bug was ONE
|
||
thing: an EXPLICIT `JointedMover::~JointedMover()` in the reconstructed `~Mech` ran the whole base-dtor
|
||
chain TWICE (the dtor-epilogue rule, [[reconstruction-gotchas]] §7) → a double-free of `collisionLists`
|
||
+ the segment table. Removing it fixed BOTH the death-row crash AND app-exit crashes. [T2]
|
||
|
||
## Death SEQUENCE reconstruction — the map (2026-07-08)
|
||
Full decomp map of the death path. Two tiers:
|
||
**EXPORTED (reconstructable) [T1 read]:**
|
||
- `Mech::AdvanceLegAnimation` (`FUN_004a5028`) / `AdvanceBodyAnimation` (`FUN_004a5678`) — the **fall-anim
|
||
latch**: `movementMode` (mech+0x40) **5/6/7/8** = the four fall directions → animation-TABLE slots
|
||
**0x1c-0x1f** (`table[i]` at `mech+0x5cc+i*4`; `SetLegAnimation`/`SetBodyAnimation` =
|
||
`FUN_004a7fc4`/`FUN_004a800c` @part_012.c:13557/13570), one-shot via `deathAnimationLatched` (mech+0x650).
|
||
Already reconstructed (mech2.cpp:550-557/817-822).
|
||
✅ **RESOLVED (2026-07-08, task #32): the fall latch is a VESTIGE — BT 4.11 has NO collapse animation.**
|
||
[T1] Four convergent proofs: (1) the clip-table loader `FUN_004a80d4` (@part_012.c:13604) fills slots
|
||
0x00-0x1b + 0x20 (the `bmp` knockdown) by name and RETURNS — slots 0x1c-0x1f are never written; (2) the
|
||
offsets `mech+0x63c..0x648` appear in NO exported function at all; (3) BTL4.RES ships **27 clip codes
|
||
per mech** (`swr wwl wwr wsl wsr wrl wrr rrl rrr rwl rwr bmp bbl bbr bsl bsr sbl sbr ggl ggr gsl gsr
|
||
wgl wgr sqd squ trn` + `*i` variants) — no death/fall clip; (4) firing the latch would bind the
|
||
zero-initialised slot = **resource id 0 = a StaticAudioStream** as keyframes (garbage) — dead code in a
|
||
shipped arcade build. The authentic BT death modes are the FREEZE modes: `IsDestroyed()` ==
|
||
(`movementMode` 2 || 9), locomotion zeroed by `FUN_004ab1c8`. `UpdateDeathState` (mech4.cpp) settles
|
||
straight to 9 (never 5-8, which would trip the garbage latch).
|
||
- ✅ **The DEATH VISUAL is the WRECK-HULK SWAP, not a fall (2026-07-08) [T1].** The authentic chain:
|
||
death fires the victim's per-mech **death ModelList** (`blhdead`/`lokdead`/`owndead`/`thrdead` =
|
||
.RES ids 22-25; + `trkdead`/`bigdead`/`meddead` 32-34 for icons), whose authored video objects
|
||
dispatch (verified live from resource 22): **effect 104** = the burning-WRECK script + **1007**
|
||
(dnboom big explosion) + **1001** (ddthsmk rubble smoke plume) + a 3/4/5/15 damage-smoke burst.
|
||
The 1996 `ExplosionScripts` **case 4** (part_008.c:2663, LIVE — the "disabled" warning is case 6/
|
||
effect 106) loads the destroyed hulk + `flamesml/flamebig.bgf` flames with sweep-flicker and a slow
|
||
settle. Every mech ships its hulk (`BLHDBR/MADDBR/LOKDBR/VULDBR/AVADBR/OWNDBR/SNDDBR/THRDBR` +
|
||
`GENDBR` generic + `LDBR/MDBR/RAPDBR/STIDBR`); the 1996 script hardcodes `thrdbr.bgf` (dev
|
||
shortcut). **RECONSTRUCTED**: `BTL4VideoRenderer::SwapToWreck` (btl4vid.cpp) — kill →
|
||
`blhdead` Explosion → effect 104 → hide every segment mesh + hang the victim's own
|
||
`<prefix>dbr.bgf` on the tree root (gendbr fallback; pending-swap if death precedes tree build).
|
||
Mesh flames + the settle motion are noted follow-ups; burning reads via 1001/1007 + the wreck-smoke
|
||
re-arm. Verified: `[BTrender] wreck swap: victim -> 'blhdbr.bgf'`. [T2]
|
||
- `Mech::IsDestroyed()` (`FUN_0049fb54`) = `movementMode==2||9` (reconstructed as `IsDisabled`, btstubs.cpp);
|
||
`FUN_004ab1c8` freezes locomotion (zeros mech+0x298) when destroyed.
|
||
- **`MechDeathHandler`** (ctor `FUN_0042a984` + Performance `FUN_0042aa2c`, cached mech+0x850 / `mech[0x214]`) —
|
||
the **per-subsystem destroyed-skin + explosion engine**. Each tick walks the damage subsystems
|
||
(mech+0x120[mech+0x11c]); as a subsystem's damage crosses a descriptor-table threshold (`FUN_0042a5f4`
|
||
detects the crossing, `FUN_0042a664` looks up the state) it applies the `GraphicState` ("Destroyed" = enum 1,
|
||
parsed @part_003.c:9099) to the subsystem graphic (`sub+0xd4`) AND dispatches an effect-creation message
|
||
(`FUN_0043663c`→`FUN_004364e4` to the effect mgr `app+0x38`). **Fully exported but a no-op STUB** in the
|
||
recon (mech.cpp:221). Gamedata `DeathSplashDamage`/`Radius`/`Effect` load into a descriptor @ +0x74/78/7c
|
||
(`FUN_004a2da8`). Destroyed-skin variant set (`destroyed`, `destroyeds`…`destroyedd`) @part_003.c:5720.
|
||
**NOT EXPORTED (master-perf gap 0x4a9770-0x4ab188 + the un-exported TakeDamage) [T4]:**
|
||
- The `movementMode` WRITER (sets 5-8 then 2/9 on death) + the fall-direction (5/6/7/8) selection.
|
||
- The `Mech::DeathShutdown` roster loop (RP `VTV::DeathShutdown` analog — loop subsystems calling the
|
||
`Subsystem::DeathShutdown(int)` vtable slot; the base is an empty virtual, SUBSYSTM.h:166).
|
||
- The whole-mech `DeathEffect`/`DeathSplash` radius dispatch + the `graphicAlarm.SetLevel(9)` call site (the
|
||
recon already raises the alarm in mechdmg.cpp:426/586).
|
||
**The problem:** the orchestration lives in the per-frame Simulate that the **bring-up drive override
|
||
bypasses** (btstubs.cpp:116-119), so the death consumer must be reconstructed from its exported consumers +
|
||
the RP analog and wired into the active path (mech4.cpp `PerformAndWatch`).
|
||
|
||
### ✅ Death-STATE core DONE (2026-07-08) [T2]
|
||
`Mech::UpdateDeathState()` + `IsMechDestroyed()` (mech4.cpp) reconstruct the un-exported death branch from
|
||
its exported consumers + the RP analog, called for EVERY mech early in `PerformAndWatch`: on `graphicAlarm
|
||
>= 9` it (1) sets `movementMode = 5` → the collapse clip's latch in `AdvanceBodyAnimation` (fall direction
|
||
5-8 un-exported → 5 [T3]); (2) loops the roster calling `Subsystem::DeathShutdown(1)` (RP `VTV::DeathShutdown`
|
||
analog; base is a no-op virtual, a SHUTDOWN not teardown → safe, wreck STAYS); (3) next frame settles to
|
||
`movementMode = 9` → `IsDisabled` → locomotion frozen. The drive's lone `movementMode = 1` write (mech4.cpp
|
||
~1309) is guarded on `!IsMechDestroyed` so the death state isn't clobbered. **Runtime-verified** (forced kill):
|
||
`[death] … collapse + subsystem shutdown` → `[death] … settled -> disabled (IsDisabled=1, frozen wreck)`,
|
||
mech frozen in place (pos unchanged), subsystem tick + renderer keep running, **no crash, wreck stays**.
|
||
Env gate `BT_DEATH_LOG=1`.
|
||
**Deferred (honest):** (a) the visible **collapse ANIMATION** may not latch through the active path — the
|
||
gait SM showed `state=0` post-death (the clip trigger via `AdvanceBodyAnimation` needs the death `movementMode`
|
||
to reach its latch; and spawned NON-player mechs don't advance their body anim at all). (b) **`MechDeathHandler`**
|
||
(the exported per-subsystem destroyed-skin + explosion engine, `FUN_0042a984`/`FUN_0042aa2c`) is still the
|
||
no-op stub → no death explosions/skin-swaps yet. (c) the whole-mech **DeathSplash** radius damage (un-exported).
|
||
|
||
## Key Relationships
|
||
- Weapons/roster: [[subsystems]]. Aim source: [[locomotion]] (drive/facing). Effects: [[rendering]].
|
||
- P5 forensics: `docs/HARD_PROBLEMS.md`. Data: [[decomp-reference]] §4-5.
|