# Plane Widget
# ============

# The plane widget can be enabled and disabled by the
# `pyvista.Plotter.add_plane_widget()` and
# `pyvista.Plotter.clear_plane_widgets()` methods respectively.
# As with all widgets, you must provide a custom callback method to utilize that
# plane. Considering that planes are most commonly used for clipping and slicing
# meshes, we have included two helper methods for doing those tasks.
# Let's use a plane to clip a mesh:
import pyvista as pv
from pyvista import examples

vol = examples.download_brain()

pl = pv.Plotter()
pl.add_mesh_clip_plane(vol)
pl.show()

# After interacting with the scene, the clipped mesh is available as:
pl.widgets.plane_clipped_meshes

# And here is a screen capture of a user interacting with this
# Or you could slice a mesh using the plane widget:
pl = pv.Plotter()
pl.add_mesh_slice(vol)
pl.show()

# After interacting with the scene, the slice is available as:
pl.widgets.plane_sliced_meshes

# And here is a screen capture of a user interacting with this
# Or you could leverage the plane widget for some custom task like glyphing a
# vector field along that plane. Note that we have to pass a `name` when
# calling `add_mesh` to ensure that there is only one set of glyphs plotted
# at a time.
import pyvista as pv
from pyvista import examples

mesh = examples.download_carotid()

pl = pv.Plotter()
pl.add_mesh(mesh.contour(8).extract_largest(), opacity=0.5)


def my_plane_func(normal, origin):
    slc = mesh.slice(normal=normal, origin=origin)
    arrows = slc.glyph(orient='vectors', scale='scalars', factor=0.01)
    pl.add_mesh(arrows, name='arrows')


pl.add_plane_widget(my_plane_func)
pl.show_grid()
pl.add_axes()
pl.show()

# And here is a screen capture of a user interacting with this
# Further, a user can disable the arrow vector by setting the
# `normal_rotation` argument to `False`. For example, here we
# programmatically set the normal vector on which we want to translate the
# plane and we disable the arrow to prevent its rotation.
pl = pv.Plotter()
pl.add_mesh_slice(vol, normal=(1, 1, 1), normal_rotation=False)
pl.show()

# The vector is also forcibly disabled anytime the `assign_to_axis` argument
# is set.
pl = pv.Plotter()
pl.add_mesh_slice(vol, assign_to_axis='z')
pl.show()

# Additionally, users can modify the interaction event that triggers the
# callback functions handled by the different plane widget helpers through the
# `interaction_event` keyword argument when available. For example,
# we can have continuous slicing by using the `InteractionEvent` observer.
import vtk

pl = pv.Plotter()
pl.add_mesh_slice(
    vol, assign_to_axis='z', interaction_event=vtk.vtkCommand.InteractionEvent
)
pl.show()

# And here is a screen capture of a user interacting with this continuously via
# the `InteractionEvent` observer:

# ----------------------------------------------------------------------
# Generated by sphinx-examples-as-code https://github.com/pyvista/sphinx-examples-as-code