GMSH defaults to single-threaded meshing. Setting General.NumThreads,
Mesh.MaxNumThreads1D and Mesh.MaxNumThreads2D to min(cpu_count, 16) enables
parallel Frontal-Delaunay surface meshing across all available cores.
Benchmark on 121-face assembly (32-core host, capped at 16 threads):
Before: 12.7s total (9.8s in gmsh.model.mesh.generate)
After: 2.8s total (1.1s in gmsh.model.mesh.generate)
Cap at 16 threads — benchmark showed 16 threads (1.1s) matches or beats auto
(1.6s), likely due to NUMA/coordination overhead above that threshold.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Introduces GMSH as an alternative to OCC BRepMesh for STEP→GLB tessellation.
GMSH produces conforming meshes that eliminate fan triangles at cylinder seam
edges — a structural limitation of OCC BRepMesh that cannot be fixed via
deflection parameters.
Changes:
- render-worker/Dockerfile: install gmsh>=4.15.0 + libglu1-mesa + libxft2
- export_step_to_gltf.py: --tessellation_engine occ|gmsh CLI arg +
_tessellate_with_gmsh() using BRep→GMSH→Poly_Triangulation write-back
- admin.py: tessellation_engine setting (SETTINGS_DEFAULTS, SettingsOut,
SettingsUpdate, validation)
- export_glb.py: pass tessellation_engine to export_step_to_gltf.py CLI in
both geometry and production GLB tasks
- Admin.tsx: radio button UI for OCC vs GMSH selection
Tested: 121 faces meshed, 0 BRepMesh fallback, 649K triangles on sample part.
Clean seam edges for UV unwrap — GMSH respects B-rep periodic face boundaries.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Hartmut