feat: surface-evaluated normals, GMSH tessellation, draw call batching

USD exporter:
- Compute normals from B-Rep surface via BRepLProp_SLProps at each vertex
  UV parameter — eliminates faceting on curved surfaces (same as Stepper)
- Add GMSH Frontal-Delaunay tessellation engine (opt-in via --tessellation_engine gmsh)
  with per-solid strategy matching export_step_to_gltf.py
- Use vertex normal interpolation instead of faceVarying (6x smaller normals)
- Default engine remains OCC (GMSH has coordinate-space bug with instanced parts)

Frontend:
- Fix faceted shading in InlineCadViewer: only call computeVertexNormals()
  when geometry lacks normals, preserving smooth GLB normals from pipeline
- Add useGeometryMerge hook for draw call batching (merge by material)
- Fix unused import in cadUtils, optional props in ThreeDViewer

Backend:
- Move dataclass import to top of step_processor.py (PEP 8)
- Unified single-read STEP metadata extraction with fallback

Render worker:
- Fix USD import seam/sharp restoration: read primvars via pxr directly
  (Blender's USD importer doesn't expose custom Int2Array primvars)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-03-13 15:14:23 +01:00
parent 6c5873d51f
commit 253f11a945
8 changed files with 977 additions and 166 deletions
+64 -40
View File
@@ -2,8 +2,9 @@
Runs inside Blender's Python environment (bpy available).
Imports a USD stage and restores seam + sharp edges from
schaeffler:*EdgeVertexPairs primvars (mapped as Blender mesh attributes
by Blender's built-in USD importer).
schaeffler:*EdgeVertexPairs primvars. Blender's built-in USD importer does
NOT map arbitrary custom primvars (constant Int2Array) to mesh attributes,
so we read them directly via the pxr module and apply via bmesh.
USD stage convention: mm Y-up, metersPerUnit=0.001.
Blender's USD importer respects metersPerUnit and scales objects to metres.
@@ -21,7 +22,7 @@ def import_usd_file(usd_path: str) -> list | tuple:
Returns a tuple of (parts, material_lookup) where:
- parts: list of imported mesh objects, centred at world origin
- material_lookup: dict mapping blender_object_name → canonical_material_name
(populated from schaeffler:canonicalMaterialName primvars, empty dict if absent)
(populated from schaeffler:canonicalMaterialName customData, empty dict if absent)
USD stage is mm Y-up with metersPerUnit=0.001 — Blender scales to metres.
"""
@@ -38,22 +39,12 @@ def import_usd_file(usd_path: str) -> list | tuple:
_rename_usd_objects(parts)
# Restore seam + sharp edges from primvars mapped to Blender mesh attributes.
# Blender's USD importer converts Int2Array primvars to INT32_2D attributes.
# Attribute names: "schaeffler:sharpEdgeVertexPairs" / "schaeffler:seamEdgeVertexPairs"
restored = 0
for part in parts:
restored += _restore_seam_sharp(part)
if restored:
print(f"[import_usd] restored seam/sharp on {restored} mesh(es)", flush=True)
# Extract material lookup via pxr direct read of the USD file.
# Blender's USD importer does NOT expose STRING primvars or customData as
# Python-accessible properties — but the pxr module (available in render-worker)
# can read them perfectly from the same file.
# Read primvars + customData directly via pxr (Blender's USD importer does
# NOT expose custom primvars or customData as Python-accessible properties).
material_lookup: dict[str, str] = {}
edge_data: dict[str, dict] = {} # part_key → {sharp: [...], seam: [...]}
try:
from pxr import Usd, UsdGeom # type: ignore[import]
from pxr import Usd, UsdGeom, Vt # type: ignore[import]
stage = Usd.Stage.Open(usd_path)
for prim in stage.Traverse():
if prim.GetTypeName() != "Mesh":
@@ -61,16 +52,32 @@ def import_usd_file(usd_path: str) -> list | tuple:
part_key = prim.GetCustomDataByKey("schaeffler:partKey") or ""
mat_name = prim.GetCustomDataByKey("schaeffler:canonicalMaterialName") or ""
if not part_key or not mat_name:
# Also check parent Xform prim (metadata may be on container)
parent = prim.GetParent()
if parent:
part_key = part_key or (parent.GetCustomDataByKey("schaeffler:partKey") or "")
mat_name = mat_name or (parent.GetCustomDataByKey("schaeffler:canonicalMaterialName") or "")
if part_key and mat_name:
# Blender object name = mesh prim leaf name (part_key)
material_lookup[part_key] = mat_name
# Read seam/sharp primvars from USD mesh prim
pvs_api = UsdGeom.PrimvarsAPI(prim)
sharp_pv = pvs_api.GetPrimvar("schaeffler:sharpEdgeVertexPairs")
seam_pv = pvs_api.GetPrimvar("schaeffler:seamEdgeVertexPairs")
sharp_list = []
seam_list = []
if sharp_pv and sharp_pv.HasValue():
raw = sharp_pv.Get()
if raw is not None:
sharp_list = [(int(v[0]), int(v[1])) for v in raw]
if seam_pv and seam_pv.HasValue():
raw = seam_pv.Get()
if raw is not None:
seam_list = [(int(v[0]), int(v[1])) for v in raw]
if sharp_list or seam_list:
# Use part_key as lookup key (matches Blender object name)
edge_data[part_key] = {"sharp": sharp_list, "seam": seam_list}
except Exception as exc:
print(f"[import_usd] WARNING: pxr material lookup failed: {exc}", flush=True)
print(f"[import_usd] WARNING: pxr read failed: {exc}", flush=True)
if material_lookup:
print(f"[import_usd] pxr material lookup: {len(material_lookup)}/{len(parts)} parts",
@@ -79,6 +86,29 @@ def import_usd_file(usd_path: str) -> list | tuple:
print("[import_usd] no schaeffler:canonicalMaterialName metadata found (legacy USD)",
flush=True)
if edge_data:
print(f"[import_usd] pxr edge data: {len(edge_data)} parts with seam/sharp primvars",
flush=True)
# Apply seam + sharp edges to Blender meshes using pxr-read data
restored = 0
for part in parts:
# Match Blender object name to part_key. Blender may add .001 suffixes
# for duplicate names, so try exact match first, then strip suffix.
obj_name = part.name
data = edge_data.get(obj_name)
if data is None:
# Try stripping Blender's .NNN duplicate suffix
base = obj_name.rsplit('.', 1)[0] if '.' in obj_name else obj_name
data = edge_data.get(base)
if data:
restored += _restore_seam_sharp(part, data["sharp"], data["seam"])
if restored:
print(f"[import_usd] restored seam/sharp on {restored} mesh(es)", flush=True)
else:
print("[import_usd] no seam/sharp edges restored (no primvar data or no matches)",
flush=True)
# Centre combined bbox at world origin (same as import_glb convention)
all_corners = []
for p in parts:
@@ -114,21 +144,19 @@ def _rename_usd_objects(parts: list) -> None:
flush=True)
def _restore_seam_sharp(obj) -> int:
"""Apply seam+sharp edges from USD primvars mapped as Blender mesh attributes.
def _restore_seam_sharp(obj, sharp_pairs: list, seam_pairs: list) -> int:
"""Apply seam+sharp edges from pxr-read primvar data via bmesh.
Blender's USD importer maps primvars:schaeffler:sharpEdgeVertexPairs (Int2Array)
to a mesh attribute named "schaeffler:sharpEdgeVertexPairs" with type INT32_2D.
Each attribute element has a .value property returning a 2-tuple (v0, v1).
sharp_pairs / seam_pairs: list of (v0, v1) vertex index pairs read
from the USD file via pxr.UsdGeom.PrimvarsAPI.
Returns 1 if any edge data was applied, 0 otherwise.
"""
mesh = obj.data
sharp_attr = mesh.attributes.get("schaeffler:sharpEdgeVertexPairs")
seam_attr = mesh.attributes.get("schaeffler:seamEdgeVertexPairs")
if not sharp_attr and not seam_attr:
if not sharp_pairs and not seam_pairs:
return 0
mesh = obj.data
# Ensure single-user data block before bmesh edit
if mesh.users > 1:
obj.data = mesh.copy()
@@ -140,22 +168,18 @@ def _restore_seam_sharp(obj) -> int:
n_verts = len(bm.verts)
def _apply_pairs(attr, mark_fn):
def _apply_pairs(pairs, mark_fn):
applied = 0
for elem in attr.data:
v = elem.value # 2-tuple for INT32_2D
if len(v) >= 2 and 0 <= v[0] < n_verts and 0 <= v[1] < n_verts:
edge = bm.edges.get([bm.verts[v[0]], bm.verts[v[1]]])
for v0, v1 in pairs:
if 0 <= v0 < n_verts and 0 <= v1 < n_verts:
edge = bm.edges.get([bm.verts[v0], bm.verts[v1]])
if edge:
mark_fn(edge)
applied += 1
return applied
n_sharp = n_seam = 0
if sharp_attr:
n_sharp = _apply_pairs(sharp_attr, lambda e: setattr(e, 'smooth', False))
if seam_attr:
n_seam = _apply_pairs(seam_attr, lambda e: setattr(e, 'seam', True))
n_sharp = _apply_pairs(sharp_pairs, lambda e: setattr(e, 'smooth', False))
n_seam = _apply_pairs(seam_pairs, lambda e: setattr(e, 'seam', True))
bm.to_mesh(mesh)
bm.free()
@@ -163,4 +187,4 @@ def _restore_seam_sharp(obj) -> int:
if n_sharp or n_seam:
print(f"[import_usd] {obj.name}: {n_sharp} sharp edges, {n_seam} seam edges",
flush=True)
return 1
return 1 if (n_sharp or n_seam) else 0