Per-object names round-trip through 3MF

3MF stores one <object> per mesh. When you write a pyvista.MultiBlock, every block name and cad.label is preserved on the way in and on the way out.

This example loads a real multi-part STEP assembly, the NIST AM Bench 2022 build-plate layout (public domain, https://doi.org/10.18434/mds2-2607) with seven named products, writes it to 3MF, and confirms names, units, and per-block metadata survive the round-trip.

from pathlib import Path
import tempfile

import pandas as pd
import pyvista as pv

import pyvista_cad
from pyvista_cad.examples import downloads

Read the real assembly: each part is a named block.

mb_in = pyvista_cad.read_step(downloads.step_assembly_path())
mb_in

MultiBlock (0x7f6faa75f6a0)
  N Blocks:   7
  X Bounds:   4.096e+01, 1.426e+02
  Y Bounds:   -1.994e+01, 8.166e+01
  Z Bounds:   -1.243e-15, 2.203e+01

MultiBlock 7 blocks 284 KiB

Bounds⧉X [4.096e+01, 1.426e+02]Y [-1.994e+01, 8.166e+01]Z [-1.243e-15, 2.203e+01]

• Blocks: (7)
  • AMMT_4x4x0_375_Substrate_TappedPolyData456 pts · 444 cells · 38 KiB
  • AMB2022-01-AMMT-PartCADPolyData690 pts · 436 cells · 44 KiB
  • AMB2022-01-AMMT-PartCADPolyData690 pts · 436 cells · 44 KiB
  • AMB2022-01-AMMT-PartCADPolyData690 pts · 436 cells · 44 KiB
  • AMB2022-01-AMMT-PartCADPolyData690 pts · 436 cells · 44 KiB
  • AMB2022-01-AMMT-RecoaterGuideCADPolyData310 pts · 416 cells · 35 KiB
  • AMB2022-01-AMMT-RecoaterGuideCADPolyData310 pts · 416 cells · 35 KiB

Write to 3MF, then read it back.

out = Path(tempfile.mkdtemp()) / 'amb2022_plate.3mf'
pyvista_cad.write_three_mf(mb_in, out, units='mm')
mb_out = pyvista_cad.read_three_mf(out)

rows = []
for key in mb_out.keys():  # noqa: SIM118
    block = mb_out[key]
    rows.append(
        {
            'key': key,
            'cells': block.n_cells,
            'guid': str(block.field_data['cad.guid'][0])[:8],
        }
    )
pd.DataFrame(rows)

	key	cells	guid
0	AMMT_4x4x0_375_Substrate_Tapped	444	f18ecae3
1	AMB2022-01-AMMT-PartCAD	436	b2c88ef9
2	AMB2022-01-AMMT-PartCAD	436	b2c88ef9
3	AMB2022-01-AMMT-PartCAD	436	b2c88ef9
4	AMB2022-01-AMMT-PartCAD	436	b2c88ef9
5	AMB2022-01-AMMT-RecoaterGuideCAD	416	0444b871
6	AMB2022-01-AMMT-RecoaterGuideCAD	416	0444b871

Render the round-tripped assembly.

pl = pv.Plotter()
pl.add_mesh(mb_out, multi_colors=True, show_edges=True, edge_color='black')
pl.show()

Static Scene

Interactive Scene