e7f5c83b49
Survey of about 75 papers on robust predicates, Delaunay tetrahedralization, boundary recovery, quality improvement and hexahedral meshing, with verified DOIs and the licence of every associated code base. Architecture and roadmap now name the chosen methods (robust CDT after Diazzi et al. 2023; octree-dual all-hex first). ADR 0001 adds the licence findings and the test-geometry rule. Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm Co-authored-by: jyviko <[email protected]> Co-authored-by: Claude Opus 5.5 <[email protected]>
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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's kernel, as a git dependency pinned by rev
(solidcraft-kernel, solidcraft-geom; MIT OR Apache-2.0, built on the Apache-2.0 truck
crates). ModelCraft uses its B-rep bodies and its tessellation; it does not read CAD exchange
files itself. Only modelcraft-geometry may depend on it.
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.
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 (per-model Creative Commons licences, authoring tool unrecorded) is pending an owner decision. The default corpus is generated: SolidCraft-built parts 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.