vwemirror/BT411
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

#110: the zone destruction cascade is LIVE -- an arm now takes its gun pod with it

Browse Source 
Lynx: "You can destroy an upper arm, and the gun pod is intact and can still
fire."  Conn Man's audit: three chassis, both arms, reproducible.  And the user
is right that this family was claimed fixed before: #86 gated fire on the
WEAPON's own destruction and was verified by destroying the weapon directly
(BT_KILL_SUBSYS) -- the field scenario was the ARM ZONE dying with the weapon
subsystem healthy, which that bench never reproduced.  Oracle's 693-night "I can
still fire destroyed energy weapons" was almost certainly this mechanism.

ROOT CAUSE -- a silent stub.  Mech__DamageZone::RecurseSegmentTable @0049cad4
was transcribed faithfully... against three local shim types whose iterators
unconditionally return NULL:
    struct SegmentIterator { DZRef *Next() { return 0; } };
    struct SegTableX       { SegmentRecord *operator[](int) { return 0; } };
The cascade fired on zone death (bench: 72 [cascade] lines), "descended", and
touched nothing.  Every line read correct; none of it did anything.

THE REAL WALK (decomp re-read, FUN_0049cad4): iterate the mech's segment table
(mech+0x300, vtbl+0x34 GetNth) to this zone's segment, then
    destroySiblingsOnDestruction (Wword 0x68): recurse every other zone on the
        SAME segment (seg+0xD0), setting graphic state 2 (Gone)
    descendOnDestruction (Wword 0x67): recurse every zone on every CHILD
        segment (seg+0xE8 -> child+0xD0) -- the arm takes the gun
The engine ALREADY HAS both structures: EntitySegment::damageZoneTable @0xD0 /
childIndexTable @0xE8 (TableOf is 0x18 -- byte-identical to the decomp offsets),
populated at stream time by JMOVER.cpp:373 [T0].  The stub was never necessary.
Implemented with the engine iterators via two new read accessors on
EntitySegment (SEGMENT.h); the binary's asymmetry is reproduced as-is (the
sibling loop checks graphic state != 1, the child loop does not; re-hits on a
1.0 zone re-run the cascade -- idempotent in effect).

VERIFIED (ava1, self-damage to one zone, autofire everything):
  dz_rarm -> [cascade] zone 9 -> zone 17; AFC100 + AmmoBinAFC100 + Condenser6
      ForceCriticalFailure'd; "[ammo] AFC100 -> NoAmmo (gate1): destroyed=1";
      torso LRM5/SRM2 keep firing (correct)
  dz_larm -> [cascade] zone 2 -> zone 6; PPC + Condenser4 force-failed;
      "[emitter] 'PPC' fire REFUSED (destroyed=1)" x4998 -- the emitter gate now
      logs refusals BY NAME (the FIRED line never named its weapon, which is how
      #86's verification gap survived)
  regression smoke: frame time 7.13/7.20ms, 0 asserts, 0 cascades in ordinary
      combat (they fire only on genuine zone deaths)

Authored data (now dumped under BT_DMG_LOG): descend=1 on exactly the four arm
zones (ava1: 2/6/9/17), destroySibs=0 everywhere -- so legs/torso behavior is
untouched by this change.

KB: combat-damage.md cascade section; reconstruction-gotchas #26 (the
silent-stub trap: a shim that returns EMPTY converts a reconstruction into
fiction that reads correct -- shims must Fail() loudly or log their emptiness).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Joe DiPrima
2026-08-02 08:26:53 -05:00
co-authored by Claude Opus 5
parent da70bd58b2
commit 06adaee523
6 changed files with 148 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files
game/reconstructed/mechdmg.cpp
+62 -19
View File
@@ -104,10 +104,11 @@ void BTGimpStompTrap(void *sim, unsigned cur, unsigned nw, void *ra)
static struct ReconClock { Scalar CurrentTick() { return 0; } } TheTime; // FUN_00414b60
static const Scalar TicksPerSecond = 1.0f; // DAT_0052140c
struct DZRef { int index; };
struct SegmentRecord { int siblings; int children; }; // mech segment-tree node
struct SegmentIterator { template<class A> SegmentIterator(const A &) {} DZRef *Next() { return 0; } };
struct SegTableX { SegmentRecord *operator[](int) { return 0; } }; // cast of EntitySegment::SegmentTable
// (#110: the DZRef/SegmentRecord/SegmentIterator/SegTableX stubs that lived here
// are GONE. They silently no-op'ed the whole destruction cascade walk --
// RecurseSegmentTable "descended" into nothing, so blowing an arm off never
// touched the gun pod hanging from it. The walk now uses the REAL engine
// segment tree; see RecurseSegmentTable below.)
// Subsystem facets the recovered code reaches that the engine Subsystem does
// not expose under these names (cast of Subsystem*).
@@ -283,7 +284,15 @@ Mech__DamageZone::Mech__DamageZone(
<< " scale={" << damageScale[0] << "," << damageScale[1] << ","
<< damageScale[2] << "," << damageScale[3] << "," << damageScale[4] << "}"
<< " leg=" << (int)(rightLeg || leftLeg)
<< " vital=" << (int)vitalDamageZone << std::endl;
<< " vital=" << (int)vitalDamageZone
// #110: the destruction-cascade authoring -- whether this zone's
// death descends the segment tree / takes its siblings, and how many
// critical subsystems it can fail. The arm chain lives or dies by
// these values.
<< " descend=" << (int)descendOnDestruction
<< " destroySibs=" << (int)destroySiblingsOnDestruction
<< " segIdx=" << segmentIndex
<< " crits=" << criticalSubsystemCount << std::endl;
//
// Critical-subsystem table.
@@ -805,8 +814,11 @@ void
}
else if (getenv("BT_DEATH_LOG"))
{
DEBUG_STREAM << "[deathfx] crit-subsys " << i << " damaged -> "
<< level << "\n" << std::flush;
DEBUG_STREAM << "[deathfx] crit-subsys " << i
<< " '" << (s->GetName() ? s->GetName() : "?") << "'"
<< " damaged -> " << level
<< " (pct=" << cs->damagePercentage
<< " used=" << cs->damagePercentageUsed << ")" << std::endl;
}
}
}
@@ -822,35 +834,66 @@ void
void
Mech__DamageZone::RecurseSegmentTable(Mech *my_mech)
{
if (getenv("BT_DEATH_LOG"))
DEBUG_STREAM << "[cascade] zone " << damageZoneIndex
<< " DESTROYED -> descend=" << (int)descendOnDestruction
<< " destroySibs=" << (int)destroySiblingsOnDestruction
<< " crits=" << criticalSubsystemCount << std::endl;
SendSubsystemDamage(); // FUN_0049c9a8
SetGraphicState(1); // slot 0xc
SegmentRecord *seg = ((SegTableX &)my_mech->segmentTable)[segmentIndex]; // mech+0x300, Wword(0x65)
//
// The segment-tree walk (@0049cad4, re-read 2026-08-02 for #110). The
// binary iterates the mech's segment table (mech+0x300, vtbl+0x34 GetNth)
// to this zone's segment, then walks two lists ON the EntitySegment:
// seg+0xD0 the damage-zone indices ATTACHED to this segment
// seg+0xE8 the CHILD segment indices
// Those are the engine's own EntitySegment::damageZoneTable /
// childIndexTable -- byte-identical offsets (TableOf is 0x18: 0xD0+0x18 =
// 0xE8), populated at stream time by JMOVER.cpp:373 (AddDamageZone) [T0].
// The previous "reconstruction" here walked stub iterators that always
// returned NULL, so the cascade never left this zone: an arm died and the
// gun pod hanging off it kept firing (#110, Lynx + Conn Man's three-chassis
// audit). Element payload = PlugOf<int> (operator int).
//
EntitySegment::SegmentTableIterator segs(my_mech->segmentTable); // mech+0x300
EntitySegment *seg = segs.GetNth(segmentIndex); // vtbl+0x34
if (seg == 0)
return; // (binary derefs blind)
if (destroySiblingsOnDestruction) // Wword(0x68)
{
SegmentIterator sibs(&seg->siblings); // seg+0xd0
for (DZRef *r; (r = sibs.Next()) != 0; ) // slot 0x28
// Other zones on the SAME segment.
EntitySegment::IntegerTableIterator sibs(seg->GetDamageZoneTable()); // seg+0xD0
for (EntitySegment::IntegerPlug *r; (r = sibs.ReadAndNext()) != 0; )
{
Mech__DamageZone *sib = my_mech->Zone(r->index); // inherited damageZones[..], typed
if (sib != this && sib->GetGraphicState() != 1)
Mech__DamageZone *sib = my_mech->Zone((int)*r);
if (sib != 0 && sib != this && sib->GetGraphicState() != 1)
{
sib->RecurseSegmentTable(my_mech);
sib->SetGraphicState(2); // slot 0xc
sib->SetGraphicState(2); // 2 = Gone
}
}
}
if (descendOnDestruction) // Wword(0x67)
{
SegmentIterator kids(&seg->children); // seg+0xe8
for (DZRef *r; (r = kids.Next()) != 0; )
// Every zone on every CHILD segment, recursively -- the arm takes the
// gun with it. The binary's child-zone loop has NO graphic-state
// guard (only the sibling loop has one); reproduced as-is.
EntitySegment::IntegerTableIterator kids(seg->GetChildIndexTable()); // seg+0xE8
for (EntitySegment::IntegerPlug *r; (r = kids.ReadAndNext()) != 0; )
{
SegmentRecord *child = ((SegTableX &)my_mech->segmentTable)[r->index];
SegmentIterator czones(&child->siblings); // child+0xd0
for (DZRef *cr; (cr = czones.Next()) != 0; )
EntitySegment::SegmentTableIterator segs2(my_mech->segmentTable);
EntitySegment *child = segs2.GetNth((int)*r);
if (child == 0)
continue;
EntitySegment::IntegerTableIterator czones(child->GetDamageZoneTable()); // child+0xD0
for (EntitySegment::IntegerPlug *cr; (cr = czones.ReadAndNext()) != 0; )
{
Mech__DamageZone *cz = my_mech->Zone(cr->index);
Mech__DamageZone *cz = my_mech->Zone((int)*cr);
if (cz == 0)
continue;
cz->RecurseSegmentTable(my_mech);
cz->SetGraphicState(2);
}