SashegDev
874b6f20c2
Основа — Horizon (MIT). История апстрима не переносится: этот репозиторий ведёт свою.
44 lines
2.4 KiB
Markdown
44 lines
2.4 KiB
Markdown
# Structure terrain-adaptation density
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`horizon_core::density::Beardifier` implements the pinned Java Edition **26.3**
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structure-density sampler from supplied ordered rigid pieces, jigsaw junctions
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and an affected bounding box. It supports `NONE`, `BURY`, `BEARD_THIN`, `BEARD_BOX`
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and `ENCAPSULATE` adjustments. Live structure discovery, filtering and placement
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remain separate work.
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The sampler retains float accumulation order, wrapped coordinate arithmetic,
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ground-level deltas, the 24-by-24-by-24 kernel and vanilla's inverse-square-root
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approximation. Its kernel is computed once from the formula. No extracted vanilla
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kernel data is stored in the source tree. The immutable sampler can be attached
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to `WorldField::Beardifier` and shared between worker contexts.
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Scalar reads return zero outside the affected box. Bulk reads clear the entire
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output, including an oversized tail, then scan the clipped strided volume.
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Vanilla floors the lower clipping index rather than rounding it upward, so a
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first bulk sample can be outside the scalar bounds. Horizon preserves this
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scalar/bulk distinction. A missing affected box produces zero even if component
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lists are nonempty. Bounds supplied to the Rust constructor must already be
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normalized; short output buffers return a typed error before mutation.
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Run:
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```sh
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python3 tools/test_structure_density_parity.py
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```
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The [local report](../benchmarks/rust-structure-density-2026-10-06/scoped-parity.json)
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records **1,360,095 matching output lines per reference JAR** across **183 fixtures**,
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**28,093 scalar queries** and **339 volumes**. The original Java adapter calls the
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actual `Beardifier` constructor and samplers. Cases include every adjustment mode,
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the full junction kernel neighborhood, ground offsets, overlapping components,
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reversed accumulation order, null/empty bounds, floor clipping, output tails and
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extreme wrapped coordinates. Float outputs are compared by raw bits with
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canonical NaNs.
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The report records the authenticated JARs, source and fixture hashes. Raw outputs
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stay private under `.local`. CI runs the comparison on its configured platforms;
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the local `Math.pow`-derived kernel check does not establish cross-platform math
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parity. The [noise-fill comparison](terrain-filling.md) also checks supplied structure
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density through final-density and aquifer graphs. Structure-start selection,
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invalid-box repair and complete structure terrain generation remain pending.
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