SashegDev
874b6f20c2
Основа — Horizon (MIT). История апстрима не переносится: этот репозиторий ведёт свою.
78 lines
4.1 KiB
Markdown
78 lines
4.1 KiB
Markdown
# Section visibility shortcuts
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The helper in `crates/horizon-client/src/mesher.rs` returns the same 36 face-pair bits
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as the original flood fill. It initializes its visited map with opaque cells,
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resolving state opacity once per cell, and returns directly for fully open or
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fully closed sections. During traversal, touching all six faces ends the fill;
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so does accumulating all pairs across separate completed regions.
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The visited map uses 4 KiB of worker stack instead of a 4 KiB heap allocation.
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Mixed sections still use the original growable traversal stack. There is no
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persistent cache or additional per-section storage. Every call scans all 4096
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interior cells before traversal; cases that previously visited very few open
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cells may benefit less, and their measurements are included below.
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## Reproduction
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From the repository root:
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```sh
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export CARGO_INCREMENTAL=0
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export CARGO_TARGET_DIR=/home/bob/Documents/horizon/target
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cargo test -p horizon-client --lib --profile fast mesher::visibility_tests
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cargo test -p horizon-client --lib --profile fast mesher::visibility_tests::visibility_benchmark -- --ignored --exact --nocapture --test-threads=1
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```
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The ignored test calls the actual production helper with `Padded` sections and
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full-layout `Info` entries. Its reference is the exact helper from main commit
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`73a019967e9665c6b96332988c13cb66679d8477`, with only its name changed. Both receive
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identical inputs, validate equal outputs, and use `black_box` for inputs and
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results. Each case warms up each implementation 200 times, then runs 11 samples
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of 1000 calls each, alternating measurement order. Times are median nanoseconds
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per section; padding construction and state-table construction are excluded.
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No prepared section/assets fixtures were found in the bounded project/cache
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search. These are deterministic synthetic, production-sized 16×16×16 sections
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with a two-block padding border and four state IDs (two of each opacity).
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They cover terrain, isolated cells, sealed and exposed cavities, narrow tunnels,
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disconnected components, and seeded random opacity densities. Independent tests
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also cover all 64 face subsets, all 256 octant masks, and 224 randomized sections.
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The mesher already skips uniform all-air sections before calling this helper.
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The open case describes other fully non-opaque sections and the helper itself.
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These timings do not establish overall meshing, startup, or FPS improvements.
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## Measurements
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Measured 2026-10-15 on AMD Ryzen 5 5600X (6 cores / 12 threads), Linux
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7.2.8-zen1-2-zen, x86_64, rustc 1.99.0 (b940084d7, LLVM 23.1.1). Cargo `fast`
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uses opt-level 3, no LTO, 16 codegen units; incremental compilation was disabled.
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The benchmark runs one test thread. Shared-target Cargo builds were serialized
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with the benchmark by Cargo's build-directory lock.
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| Case | Opaque cells | Before ns | After ns | Speedup |
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| --- | ---: | ---: | ---: | ---: |
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| Fully open | 0 | 27,019.3 | 2,691.6 | 10.04× |
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| Fully closed | 4,096 | 4,823.5 | 2,788.7 | 1.73× |
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| Terrain lower half | 2,048 | 15,274.3 | 14,258.1 | 1.07× |
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| Dividing wall | 256 | 25,006.6 | 24,107.5 | 1.04× |
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| Sealed cavity | 1,352 | 19,953.7 | 17,591.7 | 1.13× |
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| Disconnected all pairs | 3,586 | 7,915.9 | 6,301.4 | 1.26× |
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| Checkerboard | 2,048 | 26,846.5 | 18,697.4 | 1.44× |
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| Six-face tunnel | 4,050 | 5,236.7 | 2,972.3 | 1.76× |
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| Open with sealed cavity | 296 | 26,140.3 | 9,688.8 | 2.70× |
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| Random 1% opaque | 38 | 27,657.9 | 9,061.1 | 3.05× |
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| Random 25% opaque | 1,043 | 24,931.4 | 7,722.5 | 3.23× |
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| Random 50% opaque | 2,050 | 19,811.5 | 5,754.7 | 3.44× |
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| Random 75% opaque | 3,053 | 13,598.2 | 10,474.1 | 1.30× |
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| Random 99% opaque | 4,064 | 5,330.7 | 4,023.7 | 1.32× |
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No case regressed in this run; the 4–7% gains in wall/terrain cases are small
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and more susceptible to timing noise. No distribution-weighted aggregate is
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reported because real-world section frequencies were unavailable.
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Validation passed: the two focused correctness tests, the opt-in benchmark
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(with output equality assertions), `cargo fmt --all -- --check`, and
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`cargo clippy -p horizon-client --lib --tests --profile fast -- -D warnings`.
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The full parity suite and workspace-wide Clippy were not run.
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