User report: the shadow broke MID-SESSION -- suddenly solid opaque black and
buried on any slope. The session log pinned the trigger: pressing V. The
view toggle (SetViewInside) RELOADS every segment mesh through the object
loader and swaps them into the render tree -- including blh_tshd.bgf -- and
the reload path never called SetIsShadow(1) (only the original tree-build
call site tagged it). Untagged, the entire shadow pipeline disengages: no
translucent TFACTOR state block (solid black), no depth bias (buried), wrong
pass. The damage-swap reloads had the same hole.
Fix: tag *tshd* filenames in LoadObjectBGF itself, next to the existing
all-shadow-material detector (which misses the mech proxy -- plain black
material, not shadow_mtl). Every load path -- build, damage swap, view
toggle -- now yields a tagged object; the drawOps alphaTest routing reads
the flag downstream. User-verified live: the shadow survives repeated V
toggles, translucent and slope-correct.
This also likely explains the RECURRING "shadow vanishes on inclines"
reports: any V toggle silently broke it; every relaunch "fixed" it. KB
(locomotion.md): loader-level tag recorded as co-dependent part 5 of the
shadow arrangement; the vanish-diagnostic note now lists all three causes
(reload untag / gait desync / genuine burial) with check-first guidance.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
User report: the ground shadow painted OVER the mech's feet. Root cause: the
flat quad + big depth-bias (-0.004 ~= 2-4 world units) workaround for slope
burial -- a bias big enough to beat the TERRAIN also beat the FEET in the
depth test, and the shadow drew in the late alpha-blend pass (after the mech),
so z-arbitration was the only layering control.
Fix, four co-dependent parts (user-verified live: feet on top, opaque,
survives inclines/declines):
- TILT (mech.cpp UpdateShadowJoint): apply the SKL's own contract for
jointshadow ("apply terrain angle to pitch and roll") -- quad up aligned to
the surface normal via an orthonormal basis fed to the ENGINE's own
LinearMatrix->EulerAngles conversion. Hand-derived Euler signs are exactly
how the prior tilt attempts "dug into the hillside"; the engine conversion
is convention-proof. ~35 deg cliff-guard cap.
- SAMPLER (mech4.cpp): surface gradient from the collision probes PLUS
BTVisualGroundLift per probe -- the quad hugs the VISIBLE terrain, whose
lift varies across a slope; world->local rotation by the TRUE yaw from
localToWorld, not the drift-prone gDriveHeading mirror (the task-#48 bug
class). BT_SHADOW_LOG traces the normals.
- DRAW ORDER (new PASS_SHADOW, l4d3d.h/L4VIDRND/L4VIDEO): shadows draw
between the STATIC terrain and the DYNAMIC opaque bodies -- the classic
decal order. The mech, drawn after, z-passes over the shadow: the bias
can never paint the shadow over the feet, structurally.
- BIAS pairing (L4D3D.cpp): tilt on (default) -> decal epsilon -0.0008;
BT_SHADOW_TILT=0 flat fallback -> the old -0.004. BT_SHADOW_BIAS overrides.
KB (locomotion.md): the four-part arrangement recorded as co-dependent, with
the gait-desync-symptom diagnostic hint retained.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The shadow report was a desync symptom, not a bias/tilt bug: the ~2-4 unit
depth-bias margin is tight enough that v4's out-of-phase leg pose showing
through could push the flat quad under a slope. No shadow code changed;
both symptoms cleared together. Noted as a diagnostic hint (check
[sync]/BT_SYNC_LOG before touching bias/tilt for this report class).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
User-reported recurrence of "legs stutter and lose sync". Live [sync] showed
advSum/legSum drifting 5->92 during walk-up churn, then locking. Reproduced
headlessly (BT_FORCE_OSC throttle feathering + BT_FORCE_TURN + the new
per-frame BT_SYNC_LOG probe) and root-caused in two parts:
- SEED: the bring-up turn-in-place trigger arms only the LEG channel, so the
walk re-entry lands one frame apart -> a persistent clip phase offset.
- AMPLIFIER: with offset clips the two end-of-clip callbacks fire on different
frames; a demand change landing between them picks DIFFERENT next states
(one channel winds down, the other keeps walking) -> opposite-phase churn
(observed bs=6 ls=7 -- body on walk-R, leg on walk-L).
Under v4 (display+travel = BODY) the out-of-phase LEG pose showed through on
every frame the body didn't write joints (Standing/wind-down) = the visible
stutter/pop.
DISASM GROUND TRUTH (neither Advance fn has a static decomp caller; found by
byte-scanning the CODE section for e8 calls):
- master perf (0x4a9b5c gap) -> AdvanceLegAnimation @0x4aa399 (air @0x4aa388)
-> -dist/dt into localVelocity (+0x1cc): the LEG drives LOCAL travel and
(writing last) the displayed pose;
- IntegrateMotion (0x4ab1c8, body advance @0x4ab312, caller FUN_004ab430 =
the projected-origin updater) -> -dist/dt into projectedVelocity (+0x2a0):
the BODY is the dead-reckoning PROJECTOR -- locally invisible.
v4's reading of FUN_004ab430 as the travel source was wrong.
FIX: advance body FIRST (projection; its writes get overwritten), leg LAST
(displayed pose); travel = legAdv under the two-channel split. Display ==
travel through the LEG by construction -- body-channel drift can no longer
become visible, structurally (not by input-symmetry luck).
Verified: trn+feathering repro clean; straight drive locked (adv==proj);
solo goto=enemy kill chain intact; MP 2-node drive-to-range cross-pod kill
intact (241 hits, DESTROYED); no crashes. KB corrected (locomotion.md roles
+ P3_LOCOMOTION.md v5 entry). New gated instruments: BT_SYNC_LOG,
BT_FORCE_OSC.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
