perf(gen): interval propagation -- blocks can finally be PROVEN empty. 1.55s -> 1.21s

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Task 4 ran 11 hours and was killed by system memory pressure before it could file a
report. The work survived, builds clean (0 errors), and is verified faster with
byte-identical output. This commit is my verification, not its summary -- it never
got to write one.

THE STRUCTURAL FIX
0e9df9e established why no block could ever be skipped: OriginSpineOp,
PassageCarveOp and the active seals Lerp/Min/Max against the CURRENT density, so
with an unknown incoming density their supremum is genuinely unbounded. Not a
missing bound -- the operator semantics.

The answer is to propagate a density INTERVAL through the stack, and that is what
landed: FVoxelBoxSdfInterval + PropagateSdfOverBox on the operator interface, an
interval fold through every converter and modifier, interval arithmetic down into
the noise primitives themselves (gradient corners, warp, worm frequencies), and a
BlockSkip lattice the mesher consults per 8^3 block.

Its own guiding comment, which is the right default:
  "no finite interval is a proof. Unknown costs the skip and protects the geometry."

  128^3 TunnelNetwork seed 1337 slot 1, freshly built binary, 3 runs each:
    before  1.515 / 1.554 / 1.569 s
    after   1.213 / 1.258 / 1.171 s     -22.5%, 1.28x -- clears the 17% floor

  Geometry SHA-256 98eaad61..d3c4f IDENTICAL to 0e9df9e. 153,740 triangles either
  way. It skips only provably-empty work; nothing about the world changed.

It also fixed one cause of the 5.6 s empty tiles found in 0e9df9e: an LOD4 tile
legitimately spans 19^3 = 6,859 chunk keys and was rebuilding per-chunk state
thousands of times within a single tile. A shared cache removed that failure mode;
remaining slow empties were LOD0 and are a separate fast-classifier bail, still open.

Partially landed, unfinished when killed: RequestStartCycles on FChunkResult, to
report request-to-ready latency rather than worker generation time. Harmless as is.

⚠️ WHAT KILLED IT, AND IT IS OURS
A single UnrealEditor-Cmd commandlet grew to 19.5 GB, leaving 1.3 GB free on a
32 GB machine, and the OS killed the agent. Freeing it restored 21.6 GB. The owner
said twice that his machine should not be under memory pressure and he was right
both times: first the 411 MiB worker caches, now a 19.5 GB commandlet. A generation
run must not need 19.5 GB. Next task.

Cumulative on this region: 342.2 -> 16.2 -> 2.62 -> 1.49 -> 1.21 s  (~283x).
3,374 insertions / 342 deletions across 12 files. Build 0 errors. Nothing outside
Plugins/VoxelForge; RealtimeMeshComponent untouched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012aheo2crrZmHuYtPpdY2Cb

This commit is contained in:

Fr0zkaandClaude Opus 5 committed 2026-09-09 21:11:13 +02:00

1 parent 0e9df9e5a7

commit d38d4cabef

12 files changed

+3375 -343

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Source/VoxelForge/Private/VoxelDensityOpStack.cpp

+1990 -128

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