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#119 ROOT CAUSE: interior-id X-byte collision + player-landblock cache hints = cross-entity batch serving

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The decisive probe (3cf6bcc) caught it live in ONE session: a 43-part
staircase entity (src=0x020003F2, healthy MeshRefs tZ=[0.35..15.15])
drew with cache=hit:3 restZero=3 - THREE batches belonging to a 1-part
entity - then under a different hint the correct hit:119. Two
compounding bugs:

1. interiorIdBase = 0x40000000 | (landblockId & 0x00FFFF00) resolved to
   0x40YYFF00 for landblock keys 0xXXYYFFFF - the landblock X byte
   DISCARDED. Every landblock in a map Y-row shared one id space:
   Holtburg town A9B3's 9th interior stab == the AAB3 tower's spiral
   staircase, both 0x40B3FF09. Fixed to 0x40000000|(lbX<<16)|(lbY<<8)
   (the scenery 0x80XXYY## scheme).

2. The Tier-1 classification cache's #53 tuple key (EntityId,
   LandblockHint) was fed the PLAYER's landblock at bucket-draw time
   (RetailPViewRenderer.DrawEntityBucket fabricates its tuple with
   ctx.PlayerLandblockId), so colliding ids from different landblocks
   shared a key: whichever entity classified first under a hint won,
   and the loser wore its batches all session (static fast path never
   re-classifies). Also: bucket-hinted entries were never swept by
   InvalidateLandblock(owner) - stale entries survived owner unload.
   Fixed: ResolveCacheLandblockHint derives the hint from the entity's
   owning cell (ParentCellId landblock, canonical 0xXXYYFFFF), falling
   back to the tuple id for ownerless paths (outdoor stabs/scenery,
   where the tuple IS the owner).

Explains the session-shaped repro exactly: town-login + run to the
tower hydrates/classifies town interiors first -> the tower staircase
cache-hits the town twin's batches (stairs missing/partial + a wrong
object near the floor - the "water barrel"); login-inside classifies
the tower first -> usually clean. meshMissing=0 / entSeen==entDrawn
both ways (everything draws, wrong batches). Likely also feeds #113's
distance-dependent phantom staircase (the town twin wearing the
tower's staircase batches).

3 new cache tests pin the collision contract + hint derivation.
Suites: App green / Core 1430+2skip / UI 420 / Net 294.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Erik 2026-06-11 21:43:45 +02:00
parent 3cf6bcc219
commit 2163308032
4 changed files with 122 additions and 10 deletions
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21
src/AcDream.App/Rendering/GameWindow.cs
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@ -5514,9 +5514,24 @@ public sealed class GameWindow : IDisposable
(lbY - _liveCenterY) * 192f,
0f);
// Per-landblock id namespace: 0x40000000 | (lbId & 0x00FFFF00) | local_counter.
// Distinct from scenery (0x80000000+) and stabs (ids from LandblockLoader).
uint interiorIdBase = 0x40000000u | (landblockId & 0x00FFFF00u);
// Per-landblock id namespace: 0x40000000 | (lbX << 16) | (lbY << 8) | local_counter —
// the same 0xNNXXYY## scheme scenery uses (0x80XXYY##). Distinct from scenery
// (0x80000000+) and stabs (ids from LandblockLoader).
//
// #119 ROOT-CAUSE FIX (2026-06-11): this used to be
// `0x40000000 | (landblockId & 0x00FFFF00)`, which for landblock keys 0xXXYYFFFF
// resolves to 0x40YYFF00 — the landblock X byte DISCARDED. Every landblock in a
// map Y-row produced the same id base, so interior statics collided across
// landblocks (Holtburg town A9B3's 9th stab == the AAB3 tower's 43-part spiral
// staircase, both 0x40B3FF09). The Tier-1 classification cache then served one
// entity's batches to the other (the cache hint at bucket-draw time was the
// player's landblock, identical for both) — the session-sticky "broken stairs +
// water barrel". Counter overflow past 0xFF still bleeds into the lbY byte (the
// documented #53 scenery-namespace caveat); the cache's (EntityId, owner-derived
// LandblockHint) tuple key disambiguates that residual case.
uint interiorLbX = (landblockId >> 24) & 0xFFu;
uint interiorLbY = (landblockId >> 16) & 0xFFu;
uint interiorIdBase = 0x40000000u | (interiorLbX << 16) | (interiorLbY << 8);
uint localCounter = 0;
uint firstCellId = (landblockId & 0xFFFF0000u) | 0x0100u;