pyvista_cad.topods_to_edges

topods_to_edges(shape, *, linear_deflection=0.1, angular_deflection=0.5, tangent_tol_deg=8.0)

Extract topological edges of shape as a polyline mesh.

Edges are recovered from the existing face triangulation via OCCT’s PolygonOnTriangulation — no extra meshing pass — so the polylines lie exactly on the tessellated facets. Each topological edge becomes a single polyline cell, deduplicated across the faces that share it. Face-less edges (wireframe geometry) fall back to direct 3D curve sampling.

Edges shared by two faces whose surface normals agree to within tangent_tol_deg are dropped: these are smooth/tangent transitions (hidden by convention in CAD viewers) or, for a faceted solid where every triangle is its own planar face, pure tessellation noise. Real sharp edges and open boundaries are kept.

Parameters:

shapeOCP.TopoDS.TopoDS_Shape

Shape to extract edges from. build123d / cadquery wrappers are unwrapped automatically.

linear_deflectionfloat, default: 0.1

Chordal deviation used if shape is not already meshed.

angular_deflectionfloat, default: 0.5

Angular deviation (radians) used if not already meshed.

tangent_tol_degfloat, default: 8.0

Adjacent-face angle below which a shared edge is treated as a tangent/coplanar internal edge and suppressed. Set to 0 to keep every topological edge.

Returns:

pyvista.PolyData

Line-cell mesh. Cell arrays: cad.edge_id (int, per edge) and cad.edge_kind (int code; see field_data ['cad.edge_kind_legend']).

Raises:

pyvista_cad.TessellationError

If OCCT meshing fails.

Parameters:

• shape (Any)

• linear_deflection (float)

• angular_deflection (float)

• tangent_tol_deg (float)

Return type:

PolyData

Examples

Extract feature edges from a build123d box (requires the [step] extra):

>>> import build123d as b3d
>>> from pyvista_cad import topods_to_edges
>>> edges = topods_to_edges(b3d.Box(10, 10, 10).wrapped)
>>> type(edges).__name__
'PolyData'
>>> edges.n_cells
12