Root cause of the A8.F flap / missing-walls reframed (with the user's help):
the 3rd-person camera EYE passes through walls, and the A8.F renderer keys its
"am I inside?" (PointInCell) and portal side-tests (CameraOnInteriorSide) off
that eye position (camPos = invView translation, GameWindow.cs:7271). Eye clips
a wall -> those decisions flip frame-to-frame -> the flap.
Key finding from camera research (Opus agent + verified against the decomp):
retail's camera does NOT collide with walls either — it fades the player to
translucent (CameraSet::UpdateCamera @ 0x00458ae0 -> SetTranslucencyHierarchical),
which acdream already ports as RetailChaseCamera.ComputeTranslucency. So a
"spring arm that pulls the eye in on a wall hit" is a deliberate divergence from
retail, not a faithful port — needs user sign-off before coding.
Handoff documents: the eye->visibility coupling + flap mechanism, acdream's
current camera (the ported turn/jump input-lag = damping + velocity ring +
mouse filter; no collision), retail's camera (symbols+addresses), the reusable
swept-sphere collision machinery (BSPQuery.FindCollisions vs CellPhysics.BSP),
3 fix options (lead: modern spring arm), open design questions, apparatus, and a
pickup prompt.
Bug A (cellar terrain flood) already fixed + committed in 9417d3c; the
recursive-clip builder works (the prior "Bug B" framing was wrong).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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