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Implement YStripesPointInAreaLocator - #1145

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locationtech:masterfrom
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Implement YStripesPointInAreaLocator#1145
micycle1 wants to merge 1 commit into
locationtech:masterfrom
micycle1:ystripes

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@micycle1

@micycle1 micycle1 commented Aug 29, 2025 •
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A faster point-in-area locator.

It's packaged such that the core polygon algo (YStripesPointInPolygonLocator) is defined in its own non-public class, then the Area variant constructs PolygonLocators for each Polygon in a Geometry, indexed via an STRtree.

The name could be changed too. Of course this too is an indexed PointInAreaLocator, but that exact name is taken.

@grootstebozewolf grootstebozewolf mentioned this pull request Aug 5, 2026
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@grootstebozewolf

grootstebozewolf commented Aug 5, 2026

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Corpus PIP gallery gate against this PR's Y-stripe algorithm (NetTopologySuite.Proofs).

What we checked

Faithful port of YStripesPointInPolygonLocator / YStripesPointInAreaLocator (DD ray-crossing + Y-stripes) run against the Qed-backed gallery in nts-oracle-gallery.md, side-by-side with NTS 2.6 IndexedPointInAreaLocator and SimplePointInAreaLocator.

Write-up + table: jts-1145-pip-lane (corpus PR #451)
Harness: dotnet run --project tests/Discussion839Mre -c Release -- --jts1145

Results (14/14)

Case Point Geometric GT YStripes
Diamond generic (0, 0.5) INTERIOR INTERIOR
Vertex graze (naive parity even) (0, 0) INTERIOR INTERIOR
Horizontal edge (naive parity odd) (−1, 1) on notch EXTERIOR EXTERIOR
Rect interior / edges … INT / BOUNDARY match
Hot-pixel centre / bottom … INT / BOUNDARY match
Spectre interior / reflex pocket (5, 0.5) / (3.5, 0.5) INT / EXT match
Hat interior / pocket (√3 APPROX WKT) … INT / EXT match

Also bit-equal to Indexed and Simple on every row (no locator split).

Suggestion

AbstractPointInRingTest already covers comb / repeated pts / a few robust triangles. Adding the gallery WKT pins (especially diamond graze, horizontal-edge exterior, Spectre pocket) would lock both this locator and IndexedPointInAreaLocator against the classes that pure half-open ray parity gets wrong without special cases.

No objection on soundness from this corpus gate. Port risk residual: Java tip not executed under JVM here (C# line-faithful port + NTS CGAlgorithmsDD).

(Affiliation: NetTopologySuite.Proofs — formal companion, not a JTS committer review.)

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@micycle1 @grootstebozewolf