The improvement objective was the smallest dihedral sine, which misses
needles: every dihedral angle fine while a corner is nearly flat, so
the corpus meshes had scaled Jacobians down to 0.01-0.07. The objective
is now the smaller of the dihedral sine and the scaled Jacobian at the
worst corner (the measure analysts check, Knupp 2001), weighted so a
Jacobian of 0.3 (the skill's limit) counts as a 30 degree dihedral
angle (the schedule's target): the Jacobian decides only near that
limit. The existing edge removal, multi-face removal, smoothing and
insertion then remove the needles.
Skill tet10 min SJ: sphere-on-plate 0.092 -> 0.335, filleted-bracket
0.021 -> 0.318 (both pass, nothing marked). Default-size tet10:
thin-ribs 0.240, shallow-groove 0.321, rounded-box 0.311.
The strong-relaxation test relaxes below 0.45: nothing is left below
0.3. Literature note in docs/meshing/literature.md.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
The platform maths libraries' atan2 and cbrt differ in the last bits
between macOS and glibc, so the dihedral angles and the shape measure a
mesh reports did too. The crate's own versions use + - * / and sqrt
only (correctly rounded everywhere) and agree with the platform's to a
few ulps.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
The end-to-end demo met a raw-CDT sliver that the validity gate accepted (exactly positive) and
the solver refused. Now:
- One validity criterion, `fieldcraft_model::admissible_jacobian` (normalized Jacobian above
1e-12), used by the implicit solver (fem `positive_inverse`), the explicit tet4/hex8
kinematics and the mesh gate, which proves it on the whole element (tet4: the solvers' own
Jacobian; curved kinds: a Bernstein floor), so whatever passes the gate passes the solvers.
- CDT rounding repaired by flips on the rounded mesh (Diazzi et al. 2023 §5.1) instead of the
±2-ulp nudge.
- `fieldcraft-mesh::tet`: a mutable tetrahedral complex whose every change is a checked
replacement (positive and admissible tetrahedra, faces matched with opposite orientation) with
an exact undo log; edge removal (Klincsek), multi-face removal, Delaunay insertion with
boundary faces, edge collapse; a curvature- and thickness-graded size field; constrained
Delaunay refinement with encroachment splits; ODT smoothing; the Klingner–Shewchuk schedule;
boundary vertices moved onto the exact B-rep surfaces at the end; tet10 with mid-edge nodes on
the geometry.
- `mesh.tet.generate` gains size, order, quality, quality_target, curvature_angle, grading,
max_passes, max_points and reports the CDT's and the mesh's quality; `solve.probe` takes a set
and reports its largest von Mises stress.
- Oracle cases filleted-bracket-fillet-stress(-coarse): the fillet's peak von Mises stress on
tet10 meshes of 2k and 13.5k elements, 213.3 MPa (a four-level study stays within 1.8%); the
CDT cases keep the raw tetrahedralization.
- Corpus quality columns: all 20 valid parts mesh and pass the gate.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm
