Sphere Widget

The sphere widget can be enabled and disabled by the pyvista.WidgetHelper.add_sphere_widget() and pyvista.WidgetHelper.clear_sphere_widgets() methods respectively. This is a very versatile widget as it can control vertex location that can be used to control or update the location of just about anything.

We don’t have any convenient helper methods that utilize this widget out of the box, but we have added a lot of ways to use this widget so that you can easily add several widgets to a scene.

Let’s look at a few use cases that all update a surface mesh.

# sphinx_gallery_thumbnail_number = 3

Example A

Use a single sphere widget

import pyvista as pv
import numpy as np

# Create a triangle surface
surf = pv.PolyData()
surf.points = np.array([[-10,-10,-10],
                    [10,10,-10],
                    [-10,10,0],])
surf.faces = np.array([3, 0, 1, 2])

p = pv.Plotter()

def callback(point):
    surf.points[0] = point

p.add_sphere_widget(callback)
p.add_mesh(surf, color=True)

p.show_grid()
p.show()
sphere widget

Out:

[(27.781683096151145, 32.53341726348856, 23.031683096151145),
 (0.0, 4.751734167337418, -4.75),
 (0.0, 0.0, 1.0)]

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

../../_images/sphere-widget-a.gif

Example B

Use several sphere widgets at once

import pyvista as pv
import numpy as np

# Create a triangle surface
surf = pv.PolyData()
surf.points = np.array([[-10,-10,-10],
                        [10,10,-10],
                        [-10,10,0],])
surf.faces = np.array([3, 0, 1, 2])


p = pv.Plotter()

def callback(point, i):
    surf.points[i] = point

p.add_sphere_widget(callback, center=surf.points)
p.add_mesh(surf, color=True)

p.show_grid()
p.show()
sphere widget

Out:

[(35.317275696613656, 35.317275696613656, 30.317275696613656),
 (0.0, 0.0, -5.0),
 (0.0, 0.0, 1.0)]

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

../../_images/sphere-widget-b.gif

Example C

This one is the coolest - use four sphere widgets to update perturbations on a surface and interpolate between them with some boundary conditions

from scipy.interpolate import griddata
import numpy as np
import pyvista as pv

def get_colors(n):
    """A helper function to get n colors"""
    from itertools import cycle
    import matplotlib
    cycler = matplotlib.rcParams['axes.prop_cycle']
    colors = cycle(cycler)
    colors = [next(colors)['color'] for i in range(n)]
    return colors

# Create a grid to interpolate to
xmin, xmax, ymin, ymax = 0, 100, 0, 100
x = np.linspace(xmin, xmax, num=25)
y = np.linspace(ymin, ymax, num=25)
xx, yy, zz = np.meshgrid(x, y, [0])

# Make sure boundary conditions exist
boundaries = np.array([[xmin,ymin,0],
                   [xmin,ymax,0],
                   [xmax,ymin,0],
                   [xmax,ymax,0]])

# Create the PyVista mesh to hold this grid
surf = pv.StructuredGrid(xx, yy, zz)

# Create some initial perturbations
# - this array will be updated inplace
points = np.array([[33,25,45],
               [70,80,13],
               [51,57,10],
               [25,69,20]])

# Create an interpolation function to update that surface mesh
def update_surface(point, i):
    points[i] = point
    tp = np.vstack((points, boundaries))
    zz = griddata(tp[:,0:2], tp[:,2], (xx[:,:,0], yy[:,:,0]), method='cubic')
    surf.points[:,-1] = zz.ravel(order='F')
    return

# Get a list of unique colors for each widget
colors = get_colors(len(points))
# Begin the plotting routine
p = pv.Plotter()

# Add the surface to the scene
p.add_mesh(surf, color=True)

# Add the widgets which will update the surface
p.add_sphere_widget(update_surface, center=points,
                       color=colors, radius=3)
# Add axes grid
p.show_grid()

# Show it!
p.show()
sphere widget

Out:

[(216.9476807472315, 216.9476807472315, 190.4300322864843),
 (50.0, 50.0, 23.482351539252825),
 (0.0, 0.0, 1.0)]

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

../../_images/sphere-widget-c.gif

Total running time of the script: ( 0 minutes 1.316 seconds)

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