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OneCAD-Simulation/docs/adr/0001-libraries.md
T
e7f5c83b49 docs: meshing literature survey and the tet/hex pipeline it chooses (#1)
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]>
2026-10-13 14:11:15 -04:00

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4.0 KiB
Markdown

# 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.