diff --git a/plan.md b/plan.md
index ceb5c40..feba739 100644
--- a/plan.md
+++ b/plan.md
@@ -33,7 +33,7 @@ Diese Fehler können **nicht** mit Deflection-Parametern behoben werden — auch
## Tasks (in Reihenfolge)
-### Task 1: Dockerfile — `gmsh` installieren
+### [x] Task 1: Dockerfile — `gmsh` installieren
- **Datei**: `render-worker/Dockerfile`
- **Was**: Nach der `trimesh`-Zeile einfügen:
@@ -44,7 +44,7 @@ Diese Fehler können **nicht** mit Deflection-Parametern behoben werden — auch
- **Akzeptanzkriterium**: `docker compose exec render-worker python3 -c "import gmsh; print(gmsh.__version__)"` gibt `4.15.x`.
- **Abhängigkeiten**: keine
-### Task 2: `export_step_to_gltf.py` — CLI-Argument `--tessellation_engine`
+### [x] Task 2: `export_step_to_gltf.py` — CLI-Argument `--tessellation_engine`
- **Datei**: `render-worker/scripts/export_step_to_gltf.py`
- **Was**: In `parse_args()` ein neues Argument:
@@ -57,7 +57,7 @@ Diese Fehler können **nicht** mit Deflection-Parametern behoben werden — auch
- **Akzeptanzkriterium**: `--help` listet `--tessellation_engine`.
- **Abhängigkeiten**: keine
-### Task 3: `export_step_to_gltf.py` — Funktion `_tessellate_with_gmsh()`
+### [x] Task 3: `export_step_to_gltf.py` — Funktion `_tessellate_with_gmsh()`
- **Datei**: `render-worker/scripts/export_step_to_gltf.py`
- **Was**: Neue Funktion vor `main()`. Nimmt den XCAF-Compound und Deflection-Parameter. Strategie:
@@ -120,7 +120,7 @@ Diese Fehler können **nicht** mit Deflection-Parametern behoben werden — auch
- **Abhängigkeiten**: Task 1, Task 2
-### Task 4: Admin-Setting `tessellation_engine`
+### [x] Task 4: Admin-Setting `tessellation_engine`
- **Datei**: `backend/app/api/routers/admin.py`
- **Was**: In `SETTINGS_DEFAULTS` eintragen:
@@ -135,7 +135,7 @@ Diese Fehler können **nicht** mit Deflection-Parametern behoben werden — auch
- **Akzeptanzkriterium**: `GET /api/admin/settings` gibt `tessellation_engine: "occ"` zurück.
- **Abhängigkeiten**: keine
-### Task 5: `export_glb.py` — Setting durchreichen
+### [x] Task 5: `export_glb.py` — Setting durchreichen
- **Datei**: `backend/app/domains/pipeline/tasks/export_glb.py`
- **Was**: In `generate_gltf_geometry_task()` (und `generate_gltf_production_task()` wo der OCC-Befehl aufgebaut wird):
@@ -150,7 +150,7 @@ Diese Fehler können **nicht** mit Deflection-Parametern behoben werden — auch
- **Akzeptanzkriterium**: Admin stellt `tessellation_engine` auf `gmsh` → nächster GLB-Export nutzt GMSH.
- **Abhängigkeiten**: Task 2, Task 4
-### Task 6: Frontend — Dropdown in Admin-Settings
+### [x] Task 6: Frontend — Dropdown in Admin-Settings
- **Datei**: `frontend/src/pages/Admin.tsx`
- **Was**: Im Tessellation-Settings-Abschnitt ein Select-Element für `tessellation_engine`:
diff --git a/render-worker/Dockerfile b/render-worker/Dockerfile
index c0e567b..af3ed26 100644
--- a/render-worker/Dockerfile
+++ b/render-worker/Dockerfile
@@ -64,6 +64,12 @@ RUN pip3 install --no-cache-dir "cadquery>=2.4.0"
# Install trimesh for STL→GLB geometry export (separate layer to avoid cache invalidation)
RUN pip3 install --no-cache-dir "trimesh>=4.2.0"
+# libGLU + libXft required by gmsh's shared library loader
+RUN apt-get update && apt-get install -y --no-install-recommends libglu1-mesa libxft2 && rm -rf /var/lib/apt/lists/*
+
+# GMSH for Frontal-Delaunay tessellation (alternative to OCC BRepMesh)
+RUN pip3 install --no-cache-dir "gmsh>=4.15.0"
+
# Copy render scripts
COPY render-worker/scripts/ /render-scripts/
diff --git a/render-worker/scripts/export_step_to_gltf.py b/render-worker/scripts/export_step_to_gltf.py
index edd42da..e8fdd15 100644
--- a/render-worker/scripts/export_step_to_gltf.py
+++ b/render-worker/scripts/export_step_to_gltf.py
@@ -1,8 +1,8 @@
"""OCC-native STEP → GLB export script.
Reads a STEP file via OCP/XCAF (preserving part names and embedded colors),
-tessellates with BRepMesh, optionally applies per-part hex colors, and writes
-a binary GLB in meters (Y-up, glTF convention).
+tessellates with BRepMesh or GMSH Frontal-Delaunay, optionally applies
+per-part hex colors, and writes a binary GLB in meters (Y-up, glTF convention).
No Blender required. Uses the same OCP bindings that cadquery ships with.
@@ -12,6 +12,7 @@ Usage:
--output_path /path/to/output.glb \
[--linear_deflection 0.1] \
[--angular_deflection 0.5] \
+ [--tessellation_engine occ|gmsh] \
[--color_map '{"RingInner": "#4C9BE8", "RingOuter": "#E85B4C"}']
Exit 0 on success, exit 1 on failure.
@@ -50,6 +51,10 @@ def parse_args() -> argparse.Namespace:
"--sharp_threshold", type=float, default=20.0,
help="Dihedral angle threshold (degrees) for sharp B-rep edge detection. Default 20.0",
)
+ parser.add_argument(
+ "--tessellation_engine", choices=["occ", "gmsh"], default="occ",
+ help="Tessellation backend: 'occ' = BRepMesh (default), 'gmsh' = Frontal-Delaunay",
+ )
return parser.parse_args()
@@ -259,6 +264,169 @@ def _extract_sharp_edge_pairs(shape, sharp_threshold_deg: float = 20.0) -> list:
return sharp_pairs
+def _tessellate_with_gmsh(shape, linear_deflection: float, angular_deflection: float) -> None:
+ """Tessellate an OCC TopoDS_Shape using GMSH Frontal-Delaunay mesher.
+
+ Writes the resulting Poly_Triangulation back to each TopoDS_Face via
+ BRep_Builder.UpdateFace(), so the shape's tessellation data is available
+ to RWGltf_CafWriter exactly like BRepMesh output.
+
+ GMSH surface tags correspond 1:1 to faces in TopExp_Explorer(FACE) order
+ after importShapes() from a .brep file — no coordinate-based matching needed.
+
+ Falls back silently to BRepMesh for any face that GMSH cannot mesh (degenerate
+ geometry, e.g. degenerate poles).
+
+ Args:
+ shape: tessellated in-place (OCC TopoDS_Shape)
+ linear_deflection: controls CharacteristicLengthMax (mm)
+ angular_deflection: controls minimum circle subdivision points (rad)
+ """
+ import math as _math
+ import tempfile
+ import gmsh
+
+ from OCP.BRep import BRep_Builder
+ from OCP.BRepTools import BRepTools
+ from OCP.BRepMesh import BRepMesh_IncrementalMesh
+ from OCP.Poly import Poly_Triangulation, Poly_Array1OfTriangle, Poly_Triangle
+ from OCP.TColgp import TColgp_Array1OfPnt
+ from OCP.TopExp import TopExp_Explorer
+ from OCP.TopAbs import TopAbs_FACE
+ from OCP.TopoDS import TopoDS as _TopoDS
+ from OCP.gp import gp_Pnt
+
+ # Write shape to temporary .brep for GMSH import
+ with tempfile.NamedTemporaryFile(suffix=".brep", delete=False) as tmp:
+ brep_path = tmp.name
+
+ n_faces_gmsh = 0
+ n_faces_fallback = 0
+ n_triangles_total = 0
+
+ try:
+ BRepTools.Write_s(shape, brep_path)
+
+ gmsh.initialize()
+ gmsh.option.setNumber("General.Terminal", 0) # suppress console output
+ gmsh.option.setNumber("Mesh.Algorithm", 6) # Frontal-Delaunay 2D
+ gmsh.option.setNumber("Mesh.RecombineAll", 0) # keep triangles (no quads)
+ # CharacteristicLength controls edge length target in mm
+ gmsh.option.setNumber("Mesh.CharacteristicLengthMin", linear_deflection * 0.5)
+ gmsh.option.setNumber("Mesh.CharacteristicLengthMax", linear_deflection * 3.0)
+ # Angular resolution via circle point count: 2π / angular_deflection
+ min_circle_pts = max(6, int(_math.ceil(2.0 * _math.pi / max(angular_deflection, 0.01))))
+ gmsh.option.setNumber("Mesh.MinimumCirclePoints", min_circle_pts)
+ gmsh.option.setNumber("Mesh.MinimumCurvePoints", 3)
+ # Reduce noise from GMSH warnings
+ gmsh.option.setNumber("General.Verbosity", 1)
+
+ gmsh.model.add("shape")
+ gmsh.model.occ.importShapes(brep_path)
+ gmsh.model.occ.synchronize()
+ gmsh.model.mesh.generate(2)
+
+ # Build lookup: surface tag → list of (node_coords, triangle_node_tags)
+ # GMSH surface tags from importShapes correspond 1:1 to TopExp_Explorer(FACE) order
+ surface_tags = [tag for (_, tag) in gmsh.model.getEntities(2)]
+
+ # Collect per-surface mesh data
+ surface_mesh: dict[int, tuple] = {} # tag → (nodes_xyz, triangles)
+ for stag in surface_tags:
+ try:
+ node_tags, coords, _ = gmsh.model.mesh.getNodes(dim=2, tag=stag, includeBoundary=True)
+ if len(node_tags) == 0:
+ continue
+ # coords is flat [x0,y0,z0, x1,y1,z1, ...]
+ node_map = {} # gmsh tag → 1-based local index
+ pts_xyz = []
+ for i, ntag in enumerate(node_tags):
+ x, y, z = coords[3*i], coords[3*i+1], coords[3*i+2]
+ node_map[ntag] = i + 1 # 1-based
+ pts_xyz.append((x, y, z))
+
+ elem_types, elem_tags, elem_node_tags = gmsh.model.mesh.getElements(dim=2, tag=stag)
+ tris = []
+ for etype, etags, entags in zip(elem_types, elem_tags, elem_node_tags):
+ if etype != 2: # type 2 = triangle
+ continue
+ n_elems = len(etags)
+ for k in range(n_elems):
+ a = node_map.get(entags[3*k])
+ b = node_map.get(entags[3*k+1])
+ c = node_map.get(entags[3*k+2])
+ if a and b and c:
+ tris.append((a, b, c))
+
+ if pts_xyz and tris:
+ surface_mesh[stag] = (pts_xyz, tris)
+ except Exception:
+ continue
+
+ except Exception as _gmsh_err:
+ print(f"WARNING: GMSH failed ({_gmsh_err}), falling back to BRepMesh", file=sys.stderr)
+ # Fallback: full BRepMesh on the whole shape
+ BRepMesh_IncrementalMesh(shape, linear_deflection, False, angular_deflection, True)
+ return
+ finally:
+ try:
+ gmsh.finalize()
+ except Exception:
+ pass
+ try:
+ Path(brep_path).unlink(missing_ok=True)
+ except Exception:
+ pass
+
+ # Map GMSH surface data back to OCC faces via TopExp_Explorer (same order as importShapes)
+ builder = BRep_Builder()
+ explorer = TopExp_Explorer(shape, TopAbs_FACE)
+ face_index = 0 # 0-based → maps to surface_tags[face_index]
+
+ while explorer.More():
+ face = _TopoDS.Face_s(explorer.Current())
+ if face_index < len(surface_tags):
+ stag = surface_tags[face_index]
+ mesh_data = surface_mesh.get(stag)
+ if mesh_data:
+ pts_xyz, tris = mesh_data
+ n_nodes = len(pts_xyz)
+ n_tris = len(tris)
+ try:
+ arr_pts = TColgp_Array1OfPnt(1, n_nodes)
+ for idx, (x, y, z) in enumerate(pts_xyz, 1):
+ arr_pts.SetValue(idx, gp_Pnt(x, y, z))
+
+ arr_tris = Poly_Array1OfTriangle(1, n_tris)
+ for idx, (a, b, c) in enumerate(tris, 1):
+ arr_tris.SetValue(idx, Poly_Triangle(a, b, c))
+
+ tri = Poly_Triangulation(arr_pts, arr_tris)
+ builder.UpdateFace(face, tri)
+ n_faces_gmsh += 1
+ n_triangles_total += n_tris
+ except Exception as _e:
+ # Fallback for this face only
+ BRepMesh_IncrementalMesh(face, linear_deflection, False, angular_deflection, False)
+ n_faces_fallback += 1
+ else:
+ # No GMSH mesh for this surface → BRepMesh fallback for this face
+ BRepMesh_IncrementalMesh(face, linear_deflection, False, angular_deflection, False)
+ n_faces_fallback += 1
+ else:
+ BRepMesh_IncrementalMesh(face, linear_deflection, False, angular_deflection, False)
+ n_faces_fallback += 1
+
+ face_index += 1
+ explorer.Next()
+
+ print(
+ f"GMSH tessellation: {n_faces_gmsh} faces meshed, "
+ f"{n_faces_fallback} BRepMesh fallback, "
+ f"{n_triangles_total} triangles total"
+ )
+
+
def _inject_glb_extras(glb_path: Path, extras: dict) -> None:
"""Patch a GLB binary to add/update scenes[0].extras JSON field.
@@ -337,16 +505,20 @@ def main() -> None:
print(f"Found {free_labels.Length()} root shape(s), tessellating "
f"(linear={args.linear_deflection}mm, angular={args.angular_deflection}rad) …")
+ engine = getattr(args, "tessellation_engine", "occ")
for i in range(1, free_labels.Length() + 1):
shape = shape_tool.GetShape_s(free_labels.Value(i))
if not shape.IsNull():
- BRepMesh_IncrementalMesh(
- shape,
- args.linear_deflection,
- False, # isRelative
- args.angular_deflection,
- True, # isInParallel
- )
+ if engine == "gmsh":
+ _tessellate_with_gmsh(shape, args.linear_deflection, args.angular_deflection)
+ else:
+ BRepMesh_IncrementalMesh(
+ shape,
+ args.linear_deflection,
+ False, # isRelative
+ args.angular_deflection,
+ True, # isInParallel
+ )
# --- Extract sharp B-rep edge pairs (before mm→m scaling so coords are in mm) ---
# Collect all free shapes into one list for the extraction function.