VoxelForge/Standalone/Research/WorldAssemblerM3/Linux98/REPORT.md

L98 — exact passage building blocks

Changes and work counts

Passage setup now prepares per-segment chord endpoints/deltas, squared lengths, radii, Catmull–Rom inputs, and floor-profile samples once per world. Capsule-route and mouth-support callbacks also use prepared segment endpoints and deltas. The scalar expression grouping, divisions, and square roots remain in the same order. Relief interpolation sharing was not added.

Measured preparation per world: 310 passage segments, 313 floor samples, and 32 capsule-route segments; the trace reports 66,296 bytes. The 32 mouth-route segments report another 4,608 bytes. Preparation measured 0.025–0.040 ms in the whole-view hash runs (mouth preparation rounded to 0.000 ms).

The streamed-view counters below are prepared-data reads/uses, not baseline arithmetic counts. They directly confirm the prepared paths were exercised. Avoided recomputations are inferred from the replaced per-sample expressions; the old arithmetic was not separately instrumented.

World	Floor-profile reads	Carve uses	Support/tread uses	Capsule uses	Mouth-support uses
FI	129,382,181	8,255,393	5,131,690	2,693,464	14,773,980
TN	396,540,009	50,346,149	19,176,668	11,657,176	63,632,356
SW	318,412,931	50,093,885	17,065,041	10,323,467	60,102,531
VS	99,874,533	5,141,277	3,142,836	662,072	8,984,390

The XY cache keeps the scalar numerator grouping (qx-ax)*dx + (qy-ay)*dy; clamp, winner, reach, and composition remain per lane. A direct probe exercised 310 z-runs × 8 samples in each world: 2,558 numerator computations and 31,085 cache hits, with zero density mismatches against scalar evaluation. The measured hit fraction was 92.4% of numerator requests. The ordinary streamed view does not call the z-run API, so these XY reuse counts come from the opt-in direct probe, not natural view traffic.

Exactness

Compared rebuilt committed-HEAD baseline to L98 Clang, then L98 Clang to L98 GCC. Density tile hashes aggregate the density sample bit patterns. All comparisons had zero tile-hash mismatches at every LOD, zero LOD0–2 density-tile mismatches, and identical whole-view density, mesh, payload, and topology hashes.

World	Whole-view tiles	LOD0–2 density mismatches	Whole-view density	Mesh	Payload	Topology
FI	2,850	0	40b76d0072a2adcd	8559df0850d4d7f1	7700965ff31ac702	0e7f2a16b4cc71a9
TN	2,249	0	99ca213b21ce86e4	2977525405b79fff	3d7d2efb581710bd	af1916c949224871
SW	2,233	0	8d23c26f5c092be1	15c3aad2e29d9ea0	3d48f68d511c21df	5b1584676884edd8
VS	2,329	0	876b44981d106be3	aaef57cb08bd6845	b19617df9f4acbb1	e8eee991260adff4

The direct XY probe also reported 2,480 sample comparisons and zero mismatches for each world. Hash runs and probe logs are under Saved/Linux/l98/hashes/ and Saved/Linux/l98/reuse-counts/.

L77 passage-share census

Mean near-LOD0–2 passage share, three profile runs per world and binary:

World	HEAD before	L98 after	Change
FI	57.82%	56.74%	−1.08 pp
TN	55.94%	55.70%	−0.24 pp

This is a census comparison, not evidence of a timing gain. Logs and raw run values are in Saved/Linux/l98/census/.

Cold readiness

Median seconds from three interleaved HEAD/L98 pairs per cell. Each binary/stratum/worker-count cell had a warmup. Cold timing includes world/layout setup and passage preparation. The LOD0–2 and whole-view tile counts are included below.

World	LOD0–2 / whole tiles	W8 HEAD → L98 (LOD0–2 / whole s)	W12 HEAD → L98 (LOD0–2 / whole s)
FI	1,408 / 2,850	1.070 / 2.341 → 1.099 / 2.369	1.029 / 2.147 → 1.005 / 2.123
TN	1,216 / 2,249	2.672 / 4.034 → 2.680 / 4.059	2.211 / 3.357 → 2.207 / 3.357
SW	1,344 / 2,233	2.713 / 3.929 → 2.496 / 3.623	2.255 / 3.313 → 2.176 / 3.183
VS	1,344 / 2,329	1.292 / 2.315 → 1.264 / 2.257	1.094 / 2.015 → 1.107 / 2.041

All 48 measured readiness runs completed. Results are close and mixed across worlds; they do not show a broad readiness speedup. Full results and logs are in Saved/Linux/l98/readiness/.

Verification and failed attempts

• Fast tier: PASS (269 pass checks, 5 diagnostic checks), 80 runs, 303.5 s. The first invocation stopped before checks because its output directory had no built headless executable; building it and rerunning passed. Summary: Saved/Linux/l98/verify-fast/fast-summary.json.
• Linux UE build: VFHostEditor Linux Development, -NoUBA -MaxParallelActions=4, succeeded in 36.60 s after timing. The first attempt stopped before compilation when UBT could not rotate its default log in the read-only user config directory. Retry used an explicit log at Saved/Linux/l98/unreal-build-ubt.log; no --as limit was used.
• No measured run exceeded the 30-minute limit. All experiment processes used taskset -c 0-11; headless runs also used the 6 GiB address-space limit.