Imported from cdcseacave/halfmesh (src/AGENTS.md). Install upstream with npx skills add cdcseacave/halfmesh --skill src. Copyright stays with the author.

AGENTS.md — src (implementation)

Implementation TUs for the public API. Namespace halfmesh::; file-local helpers go in anonymous namespaces. See root AGENTS.md for conventions.

Numerics are load-bearing. Every formula, threshold and iteration count here is covered by golden fixtures and quality bounds, so BY DEFAULT preserve them and don't casually "improve" numerics. A deliberate change needs the same level of evidence the current value has: golden fixtures regenerated with a reviewed delta report, plus the quality/invariant bounds in tests/ (see tests/AGENTS.md).

TU map

The Mesh class is split across several TUs by concern:

• HalfMesh.cpp — half-edge build/connectivity (flat open-addressing edge pairing), parity-agnostic ConnectBorders, EnumerateHoles, ConnectedComponents, edge collapse (ERemove) + validity predicates, and the in-place face ops FAdd / FAddDisk / FRemoveBulk (undo-log rollback, pinch splitting).
• Mesh.cpp — Mesh core: the representation contract (InvalidateFaces/SyncFaces/ Validate*/pipeline scope), normals, area, AABB, vertex/face adjacency, ListHalfEdges, edit primitives (RemoveFaces/RemoveUnreferencedVertices…).
• MeshIO.cpp — PLY/glTF load/save, texture & texcoord handling, seam export.
• MeshRepair.cpp — RemoveDuplicate/Degenerate faces, FixNonManifold, RemoveSmallComponents, RemoveSpuriousComponents, RemoveSpikes. Repair entry points that work on both representations dispatch to an *Arrays / *HalfEdge arm.
• MeshSimplify.cpp — Mesh::Simplify: QEM edge-collapse decimation (priority/exact mode and the fast threshold-sweep mode; setup is parallelized); the file has explanatory comments on the QEM math, the boundary discontinuity quadric, and the swap-with-last compaction.
• MeshRemesh.cpp — RemeshIsotropic (flip/collapse/relocate/refine + fairing); parallel tangential smoothing, surface queries run on the BVH. Shared helpers in MeshRemeshShared.{h,cpp}.
• MeshHoles.cpp — CloseHoles via Liepa min-weight triangulation (O(n^3) DP) + refine + fairing, and RemoveVerticesAndFill (decimating variant, no refine); holes are filled in parallel and attached with HalfMesh::FAddDisk. Keep the Liepa / pmp-library algorithm attribution comment block at the top of the file.
• MeshSmooth.cpp — Mesh::SmoothHCLaplacian: HC (anti-shrink) Laplacian smoothing (Vollmer'99). Mesh::SmoothTaubin: Taubin'95 lambda|mu band-pass — smooths aggressively at ~zero shrinkage (needs more iterations). Mesh::Smooth(iterations, method): unified dispatcher over both smoothers (Taubin default), each run with its per-function default parameters.
• Parametrize.cpp — UV flattening: per chart (LSCM/Tutte init → SLIM/ARAP), parallelized in dependency-free waves.
• AtlasCharting.cpp — developable D-Charts chart segmentation (SegmentCharts) — cone-Lloyd relaxation + developable merge + flatten-and-bisect flip repair.
• AtlasPacking.cpp — uniform texel-density normalization + the two-tier (skyline min-waste head / shelf tail) first-fit multi-page packer, shared by PackAtlas and the mesh-independent PackRectangles in RectPacking.h.
• TriangleKDTree.cpp — median-split KD-tree (build + nearest-point/ray queries with branch-and-bound pruning); commented.
• TriangleBVH.cpp — binned-SAH BVH build with a bounded traversal stack; nearest-point/ray queries take an optional max_dist bound and NearestPoint a hint_face warm start.
• ParallelFor.h — internal shared parallel-for pool helper (ParallelForPool) used by the parallel phases above.
• ChartFlattenCache.h — internal flip-repair→ParametrizeCharts flatten-artifact bridge (cache keyed by chart face-identity); consumed inside GenerateAtlas / Parametrize only.
• Version.cpp — version strings.
• GltfImageCodec.cpp / .h — the OpenCV-backed GltfLoadImageData / GltfWriteImageData tinygltf callbacks (tinygltf is built with TINYGLTF_NO_STB_IMAGE[_WRITE], so it ships no codec of its own), plus SetGltfImageCodec(), which every tinygltf::TinyGLTF context must call before touching images (MeshIO.cpp and tests/MeshIOTest.cpp do). This is also the single TU that #defines TINYGLTF_IMPLEMENTATION — the two are fused because the writer needs tinygltf helpers that exist only behind that macro.

Conventions specific to src/

• Include own headers as #include <halfmesh/Xxx.h>.
• ASSERT(expr) for invariants (debug-only; no comparison-variant macros).
• After edits, build + run the matching tests/*Test.cpp; the algorithm files also have golden + quality coverage (see tests/AGENTS.md).