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fix #137 (mechanism 2): BSP full-hit stubs leaked sliding normals — the corridor absorbing wedge

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The Facility Hub corridor dead-stop's second half: after one seam hit,
every forward resolve returned ok=False hit=no with zero advance. The
body-persisted SlidingNormal (-1,0,0) projected the exactly-anti-parallel
corridor push to zero in AdjustOffset and the step loop aborted at step 0
before any collision test could refresh the state.

Audit (docs/research/2026-07-06-137-sliding-normal-lifecycle-audit.md):
retail's only in-transition sliding-normal writer is validate_transition
(0x0050ac21); the whole sphere/BSP layer writes NONE (grep-verified), and
the body persistence (SetPositionInternal 0x005154c2, SLIDING_TS bit sync
0x005154e1) runs only on transition success. Our BSPQuery Contact-branch
full-hit responses were stubs (SetCollisionNormal + SetSlidingNormal +
return Slid) where retail dispatches the real slide_sphere — so the seam
hit (a SUCCESSFUL full-advance resolve per the live log) persisted the
phantom wall's normal, which retail's lifecycle structurally cannot do.

- BSPQuery Contact foot full-hit fallback + head full-hit now route
  through Transition.SlideSphereInternal (CSphere::slide_sphere
  0x00537440 — in-frame slide, no sliding-normal write; ACE
  BSPTree.cs:202,310-316). The dead stub is rewritten as the faithful
  BSPTREE::slide_sphere wrapper.
- PhysicsEngine sliding writeback gated on ok (retail success-only
  placement; behaviorally latent, removes the failed-frame leak class).
- Register: TS-4 amended (Path-6 steep-tangent sites still write the
  normal — now documented), TS-45 added (SphereCollision's write — same
  leak class, left for a follow-up out of #171's blast radius).
- Pins: Issue137SlidingNormalLifecycleTests — both site pins RED->GREEN,
  plus the retail persist/absorb/clear wall lifecycle (validate-write
  persistence, faithful absorbed anti-parallel frame, oblique escape
  clears the bit). BSPQueryTests full-hit pin updated to the real slide.

Mechanism 1 (PortalSide portal polys solid in the physics set) stays
OPEN - #137 not closed; the corridor re-test rides that session.

Suites: Core 2545 / App 713 / UI 425 / Net 385, 0 failures.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Erik 2026-07-05 18:08:29 +02:00
parent e73e45da54
commit a11df5b8d3
7 changed files with 474 additions and 31 deletions
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29
src/AcDream.Core/Physics/PhysicsEngine.cs
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@ -1085,16 +1085,27 @@ public sealed class PhysicsEngine
body.WalkableVertices = null;
}
if (ci.SlidingNormalValid
&& ci.SlidingNormal.LengthSquared() > PhysicsGlobals.EpsilonSq)
// Retail persists sliding state to the body ONLY on transition
// SUCCESS: CPhysicsObj::SetPositionInternal copies the normal at
// 0x005154c2 and syncs SLIDING_TS (bit 4) from the transition's
// final sliding_normal_valid at 0x005154e1 — and SetPositionInternal
// is unreachable when find_valid_position fails (the transition is
// discarded whole; the body keeps its prior state). #137 mechanism
// 2: an unconditional writeback here could persist a normal retail
// would discard.
if (ok)
{
body.SlidingNormal = ci.SlidingNormal;
body.TransientState |= TransientStateFlags.Sliding;
}
else
{
body.SlidingNormal = Vector3.Zero;
body.TransientState &= ~TransientStateFlags.Sliding;
if (ci.SlidingNormalValid
&& ci.SlidingNormal.LengthSquared() > PhysicsGlobals.EpsilonSq)
{
body.SlidingNormal = ci.SlidingNormal;
body.TransientState |= TransientStateFlags.Sliding;
}
else
{
body.SlidingNormal = Vector3.Zero;
body.TransientState &= ~TransientStateFlags.Sliding;
}
}
// L.4 retail-strict (2026-04-30): apply OBJECTINFO::kill_velocity.