Static building/house-wall collision worked on a fresh login to a town but was
lost after logging in elsewhere and PORTALING in: the foot-sphere clipped
straight through walls while server-spawned doors (own collision) still blocked.
Root (capture-confirmed, ACDREAM_PROBE_BUILDING bldOrigin): the building shell
BSP's WorldTransform is computed from the streaming-relative origin
(origin = (lb − _liveCenter)·192) AT CACHE TIME, and CacheBuilding is idempotent
(first-wins per cell). A teleport recenters _liveCenter, but the idempotent guard
never re-bases the cached transform — so the shell sat at a stale world offset
(login Arwic → portal Holtburg: bldOrigin=(-5488,2149), ~5.5 km from the player
at (83,24)), and FindBuildingCollisions never penetrated → result=OK everywhere →
no block. Terrain doesn't suffer this because AddLandblock overwrites its
WorldOffset on every apply.
Fix: clear a landblock's cached buildings at the start of each ApplyLoadedTerrain
(PhysicsDataCache.RemoveBuildingsForLandblock), then let the existing loop
re-populate fresh with the CURRENT origin — the per-apply re-base terrain already
gets, while keeping CacheBuilding's per-cell first-wins within each fresh pass
(retail CSortCell::add_building). Also adds bldOrigin to the [bldg-channel] probe.
Verified on the exact repro (Arwic login → Holtburg portal → walk into wall):
bldOrigin now (107.5,36.0) at the wall (was -5488,2149); channel returns
Collided → Slid (block + wall-slide). Suites green: Core 1568(+2 skip),
App 468(+2 skip), UI 425, Net 317.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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