Fr0zka 8043a613c3 perf(opstack): drop the redundant column test, and measure WHICH primitive class blocks the box
The worm fix worked -- attribution now reads "AllSolid killed by:
RoomGraphSource x40", with WormFieldSource gone from the list. The blocker moved
one operator upstream.

And my own warning is now the thing to distrust. It said "if it names
RoomGraphSource, the tiles genuinely straddle cave", which is a hypothesis
wearing the costume of a conclusion -- the same mistake as the previous warning,
one level down. RoomGraphSource has four primitive classes behind it whose
bounds differ enormously in quality. No third guess.

PROVED, not guessed: the columns test is removed. It treated columns as infinite
cylinders in Z (the cache gives them no vertical bound), so a box hundreds of
voxels below the owning room answered Both over a shared XY circle. It was
REDUNDANT rather than conservative: columns are read by exactly one operator,
FRoomColumnMod, whose Eval opens with VF_NearCaveSurface(InOut.Sdf, ...). In a
box no room/tunnel/pit/chimney reaches, Sdf stays FLT_MAX everywhere, so no
column can execute wherever it sits in XY. Removing it tightens the verdict
without touching correctness.

THE INSTRUMENT: EffectOverBox no longer early-outs on the first hit, it counts
all four classes -- stopping at the first gives the right verdict and no
information, which is exactly why "RoomGraphSource x40" was unactionable.
Free at the scale that matters: BuildChunkCache has just run and dwarfs a walk
over ~100 structs, and the verdict is memoised so the walk happens once per box.

GetLastRoomBoxDiagnostic reads back what the operator computed rather than
letting the test re-derive the criterion. The test could replay it -- and that
second definition would drift from the real one and lie on the day it was
believed. Same reason VF_BuildOpStackForChunk exists.

The hypothesis it exists to kill or confirm: a tunnel is culled per voxel by its
BOUNDING SPHERE, an enormous over-estimate for a long thin capsule, while a
room's cull sphere is a fair fit. Tunnels >> rooms would mean the box test is
losing to capsule bounding spheres rather than to real cave.

NOT done deliberately: tightening tunnels to a true capsule test is not free
correctness -- the per-voxel cull IS the bounding sphere, so a capsule test would
be tighter than the cull and would break the stated criterion. Making it sound
needs "no primitive can bring Sdf below max(Blend, SDFBlendRadius*3,
WormNetworkRange)", which needs a bound on how far SmoothMin of N primitives dips
below min. Real 0.2 design work, and doing it blind before knowing whether
tunnels are even the problem is the C10 mistake verbatim.

Unbuilt.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-07-28 18:16:23 +02:00
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