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* mesh: exact predicates (Shewchuk adaptive orient/incircle/insphere), symbolic perturbation, indirect LPI/TPI predicates Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm * mesh: predicate benchmark (filter hit rate, CAD-degenerate inputs); record the predicate decision Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm * mesh: simplify predicates (destructuring over fallbacks, shared-minor exact insphere, cheaper expansion product) Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm --------- Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com> Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
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ADR 0001: Libraries and licences
Status: accepted (2026-10-13)
Context
ModelCraft is MIT OR Apache-2.0. Everything it links must allow that, and the meshing and solver algorithms, where the obvious open-source implementations are GPL-family, must come from papers.
Decision
Geometry: SolidCraft, as git dependencies pinned by rev (solidcraft-kernel,
solidcraft-geom, solidcraft-doc, solidcraft-io; MIT OR Apache-2.0, built on the Apache-2.0
truck crates). SolidCraft is the primary geometry source: ModelCraft opens SolidCraft designs and
meshes from SolidCraft's tessellation, and reads face-tagged meshes SolidCraft exports. Other CAD
exchange files (STEP, which SolidCraft's kernel already reads) can be added as secondary inputs
through the same crate. Only modelcraft-geometry may depend on SolidCraft.
Meshing: our own, implemented from published papers (docs/meshing/literature.md).
Robust predicates follow Shewchuk's adaptive-precision arithmetic (the paper; his reference
predicates.c is public domain). A permissive crate may be adopted instead after review; record
it here. Decided 2026-10-13: our own implementation, modelcraft_mesh::predicates, written from
Shewchuk 1997, Devillers–Teillaud 2011 and Attene 2020 (no unsafe, deterministic, wasm-safe, a
validated coordinate domain instead of Shewchuk's overflow/underflow caveat, and indirect
predicates that robust lacks). robust (georust, MIT OR Apache-2.0) and num-bigint /
num-rational / num-traits (MIT OR Apache-2.0) are dev-dependencies only: differential test
oracles, never linked into ModelCraft.
Linear algebra: to be decided in the solver task, among permissively licensed pure-Rust
crates (for example faer, MIT). Record the choice here.
Allowed: MIT, BSD-2/3, Apache-2.0, ISC, Zlib, Unicode, MPL-2.0 (as an unmodified dependency), CC0 and public domain.
Rejected — never read, copy or link:
| Project | Licence | Would have offered |
|---|---|---|
| TetGen | AGPL-3.0 | constrained Delaunay tetrahedralization |
| CGAL | GPL-3.0 / LGPL-3.0 | Delaunay, mesh generation |
| Gmsh | GPL-2.0+ | tet and hex meshing |
| Netgen | LGPL-2.1 | tet meshing |
| CalculiX | GPL-2.0 | implicit solver, Abaqus-like input |
| Code_Aster | GPL-3.0 | implicit solver |
| OpenRadioss | AGPL-3.0 | explicit solver |
| Elmer | GPL-2.0 / LGPL-2.1 | multiphysics solver |
| deal.II, FreeFEM, Salome | LGPL | FE libraries, pre-processing |
| OpenCASCADE | LGPL-2.1 | B-rep kernel |
| Attene's CDT, Indirect_Predicates, VolumeMesher | GPL / LGPL | robust CDT, indirect predicates (implement from the papers) |
| TetWild (original), Evocube, robustPolycube, ultimaille, invertible-maps | GPL-3.0 / AGPL-3.0 | tet meshing, polycube, injective maps |
| libHexEx, libHexHex, QGP3D, MC3D, CoMISo, Graphite | GPL | integer-grid-map hex extraction, quantization |
| Shewchuk's Triangle | non-commercial only | 2D meshing |
geogram third_party/tetgen, third_party/triangle and their wrappers |
AGPL / non-commercial | (the rest of geogram is BSD-3 and readable) |
libigl copyleft/ modules |
GPL | (libigl core is MPL-2.0 and readable) |
| OpenVolumeMesh, CGoGN | believed LGPL, unverified | treat as forbidden until checked |
Repositories without a licence are all rights reserved: never read them (for example Gao
2019's octree hex code, LoopyCuts). Readable references for the meshing work (re-implement from
the paper, note anything adapted in ATTRIBUTION.md): Shewchuk's predicates.c (public domain),
georust/robust (Apache-2.0), geogram (BSD-3, exclusions above), fTetWild (MPL-2.0), CinoLib,
Gen-Adapt-Ref, HexaLab, robust_hex_dominant_meshing (MIT), quartet (ISC). The full table with
sources is in docs/meshing/literature.md.
Test geometry follows the same rule as test data: nothing produced with a commercial CAD or CAE product. That excludes ABC (Onshape), MAMBO (files from commercial translators) and the HexMe models that come from ABC, GrabCAD or Siemens NX; HexMe's Gmsh-made models are allowed (CC-BY-4.0). Thingi10K is not used either (owner decision 2026-10-13: authoring tools unrecorded). The test corpus is our own: parts built with SolidCraft (scripts or designs authored in SolidCraft, committed as their recipes so the geometry is regenerated, not stored) and analytic shapes.
Commercial products (Abaqus, Nastran, LS-DYNA, LS-PrePost, HyperMesh, ANSA, Femap, Patran, ANSYS) are never run, scripted or used as a source of data. Deck formats come from the vendors' public reference manuals, described in our own words with our own examples.
Consequences
- The tet and hex meshers are significant original work; the literature survey decides the order and the methods.
- SolidCraft and ModelCraft move together: bumping the pinned rev bumps the repeated
[patch.crates-io]entries in the same commit.