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
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