Extrude Rotation

Sweep polygonal data creating “skirt” from free edges and lines, and lines from vertices.

This takes polygonal data as input and generates polygonal data on output. The input dataset is swept around the z-axis to create new polygonal primitives. These primitives form a “skirt” or swept surface. For example, sweeping a line results in a cylindrical shell, and sweeping a circle creates a torus.

import pyvista
import numpy as np

# create a line and rotate it about the Z-axis
resolution = 10
line = pyvista.Line(pointa=(0, 0, 0), pointb=(1, 0, 0), resolution=2)
poly = line.extrude_rotate(resolution=resolution)
poly

Header	Data Arrays
PolyData Information N Cells 2 N Points 33 X Bounds -1.000e+00, 1.000e+00 Y Bounds -9.511e-01, 9.511e-01 Z Bounds 0.000e+00, 0.000e+00 N Arrays 2	Name Field Type N Comp Min Max Texture Coordinates Points float32 2 0.000e+00 1.000e+00 Distance Points float64 1 0.000e+00 1.000e+00

Plot the extruded line

plotter = pyvista.Plotter(shape=(2, 1))
plotter.subplot(0, 0)
plotter.add_text("Line", font_size=24)
plotter.add_mesh(line, color="tan", show_edges=True)
plotter.add_mesh(
    pyvista.PolyData(line.points),
    color="red",
    point_size=10,
    render_points_as_spheres=True,
)
plotter.subplot(1, 0)
plotter.add_text("Extrude Rotated Line", font_size=24)
plotter.add_mesh(poly, color="tan", show_edges=True)
plotter.add_mesh(
    pyvista.PolyData(poly.points),
    color="red",
    point_size=10,
    render_points_as_spheres=True,
)

plotter.show(cpos="xy")

Out:

[(0.0, 0.0, 5.332062506502935),
 (0.0, 0.0, 0.0),
 (0.0, 1.0, 0.0)]

Create a spring

# Create the spring profile (a circle).
plotter = pyvista.Plotter()

vertices = np.array(
    [
        [1.0, 0.0, 0.0],
        [1.0732, 0.0, -0.1768],
        [1.25, 0.0, -0.25],
        [1.4268, 0.0, -0.1768],
        [1.5, 0.0, 0.00],
        [1.4268, 0.0, 0.1768],
        [1.25, 0.0, 0.25],
        [1.0732, 0.0, 0.1768],
    ]
)
faces = np.hstack([[8, 0, 1, 2, 3, 4, 5, 6, 7]])
profile = pyvista.PolyData(vertices, faces)

# Extrude the profile to make a spring.
spring = profile.extrude_rotate(resolution=360, translation=6.0, dradius=1.0, angle=2160.0)
plotter.add_text("Spring", font_size=24)
plotter.add_mesh(spring, color="tan", show_edges=True)

plotter.show(cpos="zx")

Out:

[(0.041666626930236816, 18.26355517249696, 3.0),
 (0.041666626930236816, -0.041666626930236816, 3.0),
 (1.0, 0.0, 0.0)]