Interop with build123d

pyvista-cad renders build123d shapes directly. Every build123d shape can be tessellated to a pv.PolyData (or pv.MultiBlock for Compound assemblies) with a single call.

Single shape

import build123d as b3d
import pyvista_cad

solid = b3d.Box(10, 10, 10) - b3d.Cylinder(3, 12)
mesh = pyvista_cad.from_build123d(solid)
mesh.cad.plot()   # CAD-friendly: faces + topological edges

Static Scene

Interactive Scene

The default tessellation uses OCCT’s BRepMesh_IncrementalMesh with linear_deflection=0.1 and angular_deflection=0.5. Tighten both for curved surfaces:

fine = pyvista_cad.from_build123d(
    b3d.Sphere(5.0),
    linear_deflection=0.05,
    angular_deflection=0.2,
)

Compounds become MultiBlocks

A build123d Compound with labelled children round-trips to a pv.MultiBlock whose block names match the labels. Per-block colour and label metadata are written to cad.color / cad.label field data so they survive every downstream PyVista filter.

box = b3d.Box(2, 2, 2)
cyl = b3d.Cylinder(0.8, 2.5)
box.label = 'housing'
cyl.label = 'shaft'
compound = b3d.Compound(children=[box, cyl])

mb = pyvista_cad.from_build123d(compound)
assert mb.keys() == ['housing', 'shaft']

PolyData -> build123d

to_build123d wraps a tessellated pv.PolyData as a faceted TopoDS_Compound re-typed to a build123d Compound. The result is a real build123d object you can hand to its STEP / BREP exporters.

import pyvista as pv

mesh = pv.Cone(resolution=24)
compound = pyvista_cad.to_build123d(mesh)
bbox = compound.bounding_box()

Accessor-style entry point

Construction goes through the module-level functions; the .cad accessor then exposes the per-mesh operations:

mesh = pyvista_cad.from_build123d(solid)
mesh.cad.tessellate(linear_deflection=0.05)

When to use which bridge

You have	Call	You get
build123d.Shape or Compound	from_build123d	PolyData/MultiBlock
cadquery.Workplane	from_cadquery	PolyData
raw TopoDS_Shape (OCP)	from_topods	PolyData
pv.PolyData	to_build123d / to_cadquery / to_topods	shape object