Extrude Trim

Extrude a pyvista.PolyData with a pyvista.Plane() using extrude_trim().

from __future__ import annotations

import pyvista as pv

Generate an Extruded Surface

# Create surface and plane
mesh = pv.ParametricRandomHills(random_seed=2)
plane = pv.Plane(
    center=(mesh.center[0], mesh.center[1], -5),
    direction=(0, 0, -1),
    i_size=30,
    j_size=30,
)

# Perform the extrude trim
extruded_hills = mesh.extrude_trim((0, 0, -1.0), plane)
extruded_hills

PolyData (0x7a71dc596620)
  N Cells:    39600
  N Points:   20000
  N Strips:   0
  X Bounds:   -1.000e+01, 1.000e+01
  Y Bounds:   -2.309e-14, 2.000e+01
  Z Bounds:   -5.000e+00, 7.725e+00
  N Arrays:   0

PolyData 20,000 points 39,600 cells 1.4 MiB

Bounds⧉X [-1.000e+01, 1.000e+01]Y [-2.309e-14, 2.000e+01]Z [-5.000e+00, 7.725e+00]

Cellsfaces 39,600

Plot the Extruded Surface

Plot the resulting pyvista.PolyData.

pl = pv.Plotter(shape=(1, 2))
pl.add_mesh(mesh)
pl.add_text('Original Mesh')

pl.subplot(0, 1)
pl.add_mesh(plane, style='wireframe', color='black')
pl.add_mesh(extruded_hills)
pl.add_text('Extruded Mesh')

pl.link_views()
pl.camera_position = 'iso'
pl.camera.zoom(1.5)
pl.show()

Extruding All Edges

The previous example used the default extrusion='boundary_edges', which only generates faces on the boundary. When using extrusion='all_edges', interior edges are also created.

# Create a triangle.
disc = pv.Disc(c_res=3, r_res=4, inner=0)
plane = pv.Plane(
    center=(disc.center[0], disc.center[1], -1),
    direction=(0, 0, -1),
    i_size=1,
    j_size=1,
)

# extrude with and without the all_edges option
extruded_disc = disc.extrude_trim((0, 0, -1.0), plane)
extruded_disc_all = disc.extrude_trim((0, 0, -1.0), plane, extrusion='all_edges')
print(f'Extrusion has {extruded_disc.n_faces_strict} faces with default boundary_edges')
print(f'Extrusion has {extruded_disc_all.n_faces_strict} faces with all_edges')

Extrusion has 30 faces with default boundary_edges
Extrusion has 72 faces with all_edges

Plot

Show the additional interior faces by plotting with style='wireframe'.

pl = pv.Plotter(shape=(1, 2))
pl.add_mesh(extruded_disc, style='wireframe', line_width=5)
pl.add_text('Extrude with boundary_edges')

pl.subplot(0, 1)
pl.add_mesh(extruded_disc_all, style='wireframe', line_width=5)
pl.add_text('Extrude with all_edges')

pl.link_views()
pl.camera_position = 'iso'
pl.camera.zoom(1.3)
pl.show()

Extrude a Line

You can also extrude lines. Observe that the output from extruded lines is still a pyvista.PolyData.

plane = pv.Plane(
    center=(0, 0, 1), i_size=2, j_size=0.2, direction=[1, 1, 1], j_resolution=1
)
line = pv.Line()
extruded_line = line.extrude_trim((0, 0, 1), plane)
extruded_line

PolyData (0x7a71e0ac9ba0)
  N Cells:    1
  N Points:   4
  N Strips:   0
  X Bounds:   -5.000e-01, 5.000e-01
  Y Bounds:   0.000e+00, 0.000e+00
  Z Bounds:   0.000e+00, 1.500e+00
  N Arrays:   2

PolyData 4 points 1 cells 5 KiB

Bounds⧉X [-5.000e-01, 5.000e-01]Y [0.000e+00, 0.000e+00]Z [0.000e+00, 1.500e+00]

Cellsfaces 1

• Point Data: (2)
  Distance active
  • Texture Coordinates⧉
    2 comp
    float32
    [0.000e+00, 1.000e+00]
    tcoords
  • Distance⧉
    scalar
    float64
    [0.000e+00, 1.000e+00]
    active

Plot the Extruded Line

Note how the scalars are copied to the extruded line.

pl = pv.Plotter()
pl.add_mesh(line, style='wireframe', line_width=20, show_scalar_bar=False, color='r')
pl.add_mesh(plane, style='wireframe', color='black', show_scalar_bar=False)
pl.add_mesh(extruded_line, show_scalar_bar=False, lighting=False)
pl.show()

Static Scene

Interactive Scene

Tags: filter