Line Widget

The line widget can be enabled and disabled by the pyvista.Plotter.add_line_widget() and pyvista.Plotter.clear_line_widgets() methods respectively. Unfortunately, PyVista does not have any helper methods to utilize this widget, so it is necessary to pass a custom callback method.

One particularly fun example is to use the line widget to create a source for the pyvista.DataSetFilters.streamlines() filter. Again note the use of the name argument in add_mesh.

import numpy as np

import pyvista as pv
from pyvista import examples

pv.set_plot_theme('document')

mesh = examples.download_kitchen()
furniture = examples.download_kitchen(split=True)

arr = np.linalg.norm(mesh['velocity'], axis=1)
clim = [arr.min(), arr.max()]

p = pv.Plotter()
p.add_mesh(furniture, name='furniture', color=True)
p.add_mesh(mesh.outline(), color='black')
p.add_axes()


def simulate(pointa, pointb):
    streamlines = mesh.streamlines(
        n_points=10, max_steps=100, pointa=pointa, pointb=pointb, integration_direction='forward'
    )
    p.add_mesh(streamlines, name='streamlines', line_width=5, render_lines_as_tubes=True, clim=clim)


p.add_line_widget(callback=simulate, use_vertices=True)
p.show()

And here is a screen capture of a user interacting with this