fix(prime-random): replace poisson_disk_2d with O(1) poisson_disk#43
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bwyard wants to merge 1 commit into
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fix(prime-random): replace poisson_disk_2d with O(1) poisson_disk#43bwyard wants to merge 1 commit into
bwyard wants to merge 1 commit into
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The old poisson_disk_2d cloned the entire spatial grid (O(cols×rows)) on every accepted point via the pure-fold successors chain. At 500×500 with min_dist=5, that's ~40,000 clones per step — 8.6× slower than necessary. The new poisson_disk uses internal mutation with O(1) grid access while keeping the external contract pure (same seed → same output, always). Signature simplified: seed moved to last arg, no seed returned (pure functions don't thread state out). - Remove BridsonState/BridsonParams/bridson_step infrastructure (fold-only) - Add poisson_disk(width, height, min_dist, max_attempts, seed) -> Vec - Update all unit tests; replace poisson_disk_returns_seed with poisson_disk_empty_on_invalid_input (new guard tested) - Update bench: add 500×500 size, rename group to poisson_disk - Update prime-wasm binding to match new signature Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
poisson_disk_2dcloned the full spatial grid (O(cols×rows)) on every accepted point via the pure-foldsuccessorschain — a hidden performance bug that got worse non-linearly with domain sizepoisson_diskuses internal mutation with O(1) grid access; external contract stays pure (same seed → same output)Benchmark (min_dist=5.0, seed=42, k=30)
Speedup is non-linear because grid clone cost scales with domain area while the fix is O(1).
Test plan
cargo test -p prime-random— 27 tests passcargo build -p prime-wasm— builds cleanpoisson_disk(100.0, 100.0, 10.0, 30, 42)produces same points as oldpoisson_disk_2d(42, 100.0, 100.0, 10.0, 30)🤖 Generated with Claude Code