Port upstream earcut changes to C# (b68b344) — 2026-06-29

[github-actions]

Upstream Sync Task

@Copilot please port the upstream changes listed below to C# and open a pull request.

New commits have been pushed to mapbox/earcut since the last sync.

Previous synced commit: 018bcc1
New upstream commit: b68b344
Full diff: mapbox/earcut@018bcc1...b68b344

Upstream commits to port

• b68b344 switch to radix sort for z-order hashing
• 4560add simplify earcutLinked
• e452ba0 simplify isEar / isEarHashed checks
• da52dc0 slightly faster isValidDiagonal
• f52d2f3 better filtering for pathological cases
• 337e518 v3.1.0
• f8356be Improve readme (#199)
• 8593b2c fix and edge case with coincident holes, close #147 (#198)
• 5996fff add a note on winding order, close #44 (#197)
• 2cea508 add first-class types (#196)
• 9048fef update readme
• 11fd8c0 remove a few redundant checks
• 72af66d add regression tests over MVT 120k polys fixture
• 4def7cb fix a rare self-tangency issue
• 7d71add fix correctness issue with block index
• dfeb5de add an extensive MVT benchmark (120k polygons)
• 414b2db fix hole point filtering + drop vertex skipping
• 45cafa0 inline point in triangle checks in isEarHashed
• 8f5c3f5 inline reflex check in earcutLinked (6% faster)
• 0a76652 smaller node shape, cleanup
• f0a5baa more steiner field from node shape
• d7bd0c5 fix a correctness issue with block index
• 1363b26 microoptimizations
• 1c38eef switch to flat quicksort for z-order indexing
• e173c18 optimize diagonal search
• fa4b50a speed up hole bridge triangle scan with block index
• 526aefd speed up hole bridge raycast with block index
• de94f53 minor updates
• 962024e upgrade dev deps

What to port

Please port all upstream changes to C# and open a pull request. Follow the PORTING_GUIDE.md for language mapping conventions.

Key files to check in the upstream diff:

• src/earcut.js → port any algorithm changes to src/Earcut/Earcut.cs
• test/fixtures/*.json → copy any new/changed fixtures to test/Earcut.Tests/fixtures/
• test/expected.json → update test/Earcut.Tests/expected.json to match

After porting:

1. Run dotnet test and ensure all tests pass
2. Update PORTING_GUIDE.md if new language patterns were introduced