VoxelForge/Standalone/Research/WorldAssemblerM3/Linux109/REPORT.md

Linux 109 — tunnel floor and shell

Baseline: assembler/world HEAD 95cf8de10723f2dffe7b3dfc116ecf350c7114ae. Candidate source stamp: 9457b9bed7d57a4a387828961f9dd53632ec602eb5ea8f247b087be6ca5cc312 (evaluator v217).

Shape

The per-tile swept tube now uses a horizontal flat floor, a 0.50 m smooth floor-to-wall corner, and a 0.75 m shell. Body floor depth is fixed per passage at the minimum interior radius minus 0.23 m, capped at the local radius. Five-metre cubic blends ramp both mouths into their ground; the lower mouth follows the matching authored native-cave floor where one exists. The route centreline shifts through radius tapers to keep that floor walkable. A small wall relief remains for naturalness.

The passage interiors are unioned first and always win over every passage shell, including at coiled crossings. The shell writes solid only where the host field is air; rock remains unchanged. There is no rock classification. Open-air shell and interior samples pass in the owner audit.

Removed and retained

Removed route support restoration, deferred support after later bores, support columns, mouth-support restoration, and their floor-specific capsule checks and profiling records. Replaced the old open-air/column audit gates with the shell audit and removed the no-long-bridge and rock-column gates, which measured the deleted support mechanism. Walkability, capsule, headroom, grade, mouth, naturalness, and ripple gates remain. Floor-ripple probes fully masked by another passage's interior air are skipped only when the overlap is explicit; capsule walkability still has to pass.

Kept the native Lattice field's explicitly authored below-floor substrate because its spine needs it for walkability; this is part of that native field, not route support restoration. The legacy landmark demo retains its compatibility floor-cap path, which is separate from the resolved route sweep. Native Caves and Lattice fast checks pass.

Performance

Five interleaved L80 pairs per cell, after one warmup for each binary; seconds are median LOD0–2 near-ready / whole-view-ready. Baseline binary is from assembler/world HEAD. Tile counts matched within each cell.

Strate	W8 near	W8 whole	W12 near	W12 whole
SW	0.680 → 0.737 (+8.3%)	1.686 → 1.674 (−0.7%)	0.700 → 0.761 (+8.8%)	1.643 → 1.644 (+0.1%)
FI	1.455 → 0.911 (−37.4%)	2.419 → 1.772 (−26.8%)	1.394 → 0.863 (−38.0%)	2.288 → 1.664 (−27.3%)
TN	1.423 → 0.956 (−32.8%)	2.310 → 1.778 (−23.0%)	1.294 → 0.895 (−30.9%)	2.132 → 1.661 (−22.1%)
VS	1.008 → 0.789 (−21.8%)	1.917 → 1.639 (−14.5%)	0.854 → 0.738 (−13.5%)	1.716 → 1.541 (−10.2%)

There is no broad regression. SW near-ready is about 0.06 s slower; its whole-view time is flat. Measured: SW LOD0–2 skirt triangles rise from 133,894 to 196,602, and summed skirt work rises from 455 to 743 ms at W8 and 650 to 1,044 ms at W12. Inference: the added open-air shell surface and skirts explain the small SW near-ready cost. FI, TN, and VS improve at both readiness marks.

L77 phase census

Two samples per case. Entries are share / estimated worker-s; estimates use weighted L77 samples times WorldAssemblerLODWorker CPU, so they are not direct phase timers.

Case	Base passage	Base support	Candidate passage	Candidate support
FI near	44.62% / 4.108	14.84% / 1.366	22.90% / 1.133	0% / 0
FI whole	29.31% / 4.874	8.08% / 1.344	10.59% / 1.206	0% / 0
TN near	38.57% / 3.318	14.74% / 1.267	19.43% / 1.019	0% / 0
TN whole	24.48% / 3.824	7.59% / 1.186	9.25% / 1.074	0% / 0

The sampled support share disappears. Baseline estimates were 1.19–1.37 worker-s across these cases, below the 1.6–1.9 s expectation.

Audits and determinism

The full-view all-LOD audit passes: 21,425/21,425 canonical passage centreline samples are open. All three interfaces pass capsule and support checks with zero blocked or unsupported samples, zero grade failures, and both mouths bound (2/2). Capsule samples: 266,175 (0–1), 15,120 (1–2), 64,764 (2–3). The shell audit sampled 89,365 floor points, 8,423 wall points, and 10,527 interior points: zero floor, wall, or interior violations; 22,755 open-air shell samples. Naturalness, mouth profile, and ripple summaries pass 3/3, with negative controls detected. Derived floor grade peaks at 14.49°; fast native Caves headroom is 0.30 m and native Lattice headroom is 2.20 m.

Fast tier: PASS, 259 PASS checks plus 5 diagnostics across 80 runs. The Clang/GCC hash matrix matches at W1/W8/W12 for the owner four-strata layout and both two-strata canonical recipes. The v217 canonical pins were written for Surface World style 1 and Floating Islands style 2.

Because Core sources are Unreal-compiled, the Linux VFHostEditor build passed with -NoUBA -MaxParallelActions=4 (27 actions, 67.4 s). Three FI and three SW after arrival traces also passed, each settling its full requested LOD0–2 set. Unreal processes had no prlimit.

Change metrics

LOD0–2 camera mesh windows; “moved” means a shared global lattice crossing displaced by more than 0.01 cm. Coverage is the paired edge-classifier coverage.

Strate	Added	Removed	Moved	Coverage
SW	78,201	14,530	2,758	99.75%
FI	37,810	42,398	78,215	98.31%
TN	44,694	48,925	48,816	98.29%
VS	7,055	7,096	8,790	97.38%

Captures

84 PNGs: before and after, each with both mouths and 25/50/75% stations for all three passages. Each of the nine open-air sections has three views in each set. The capture index lists every image and flags every OPEN AIR view. All 84 source meshes and rendered views contain geometry; minimum visible triangles are 55,420 before and 55,484 after. Six before and seven after images met the pixel floor but were flagged low contrast for review.

Open-air sections (route distance in metres): 0–1: 7.226–10.217, 13.456–17.443, 23.174–24.918, 1036.913–1489.321; 1–2: 101.820–104.499; 2–3: 7.677–34.747, 368.909–376.660, 393.828–396.510, 444.932–447.654.

Failed runs

Early fast runs found a 0.79 m lower-mouth mismatch at native Caves and loss of the native Lattice route substrate; the mouth now matches the authored cave edge floor, and the explicitly authored Lattice floor field is retained. A sentinel check also initially treated the “no native floor” value as support; this was fixed. The first Unreal build stopped before compilation because UnrealBuildTool could not rotate its log under read-only ~/.config; redirecting XDG_CONFIG_HOME to /tmp fixed it. Final audits, timings, hash runs, crossings, captures, build, and six traces passed. No run exceeded 30 minutes.