Bug 1 — Missing parts (mirror/repeated instances):
- id(solid.TShape()) is unreliable in OCP: each call creates a new
Python wrapper, so id() always differs even for the same TShape.
Replaced with IsSame() for correct TShape-pointer deduplication.
- TopExp_Explorer(SOLID) misses free shells/faces in assemblies.
Fix: run BRepMesh baseline on full root compound first (catches all
face types), then GMSH overrides per unique solid for better seam
topology. REVERSED solids keep BRepMesh to avoid inverted Jacobians.
Bug 2 — GLB 7× too large (21 MB vs OCC 3 MB):
- CharacteristicLengthMax = linear_deflection × 50 (was ×15)
matches OCC effective edge length on curved surfaces (~5 mm).
- MinimumCirclePoints = min(12, ...) (was min(20, ...))
- Result: GMSH 91% of OCC file size (target ≤120% ✓)
Verified on rolling bearing STEP: same 4 skipped nodes as OCC,
25 unique GMSH tessellations (IsSame deduplication), no OOM.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Per-solid iteration prevents OOM on multi-part assemblies (25-part bearing:
2.3GB RAM when processing compound → ~100MB per solid with per-solid approach)
- Fix CharacteristicLengthMax multiplier 5× → 15× and cap MinimumCirclePoints
at 20 (prevents 63-pts/circle on angular_deflection=0.1rad → 231MB → 21MB)
- Geometry task timeout 120s → 600s for large assemblies
- Production task: reuse _geometry.glb when GMSH enabled (no re-tessellation)
and cache _production_geom.glb for OCC (mtime vs STEP check)
- Viewer now prefers production GLB when available (shows correct GMSH mesh)
- GMSH OpenMP multithreading (min(cpu_count,16)) for 4.4× speedup
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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