"""
.. _glyph_example:

Plotting Glyphs (Vectors or PolyData)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use vectors in a dataset to plot and orient glyphs/geometric objects.
"""

import math

import numpy as np

# sphinx_gallery_thumbnail_number = 4
import pyvista as pv
from pyvista import examples

# %%
# Glyphying can be done via the :func:`pyvista.DataSetFilters.glyph` filter

mesh = examples.download_carotid().threshold(145, scalars='scalars')
mask = mesh['scalars'] < 210
mesh['scalars'][mask] = 0  # null out smaller vectors

# Make a geometric object to use as the glyph
geom = pv.Arrow()  # This could be any dataset

# Perform the glyph
glyphs = mesh.glyph(orient='vectors', scale='scalars', factor=0.003, geom=geom)

# plot using the plotting class
pl = pv.Plotter()
pl.add_mesh(glyphs, show_scalar_bar=False, lighting=False, cmap='coolwarm')
pl.camera_position = pv.CameraPosition(
    position=(146.53, 91.28, 21.70),
    focal_point=(125.00, 94.45, 19.81),
    viewup=(-0.086, 0.007, 0.996),
)  # view only part of the vector field
cpos = pl.show(return_cpos=True)


# %%
# Another approach is to load the vectors directly to the mesh object and then
# access the :attr:`pyvista.DataSet.arrows` property.

sphere = pv.Sphere(radius=math.pi)

# make cool swirly pattern
vectors = np.vstack(
    (
        np.sin(sphere.points[:, 0]),
        np.cos(sphere.points[:, 1]),
        np.cos(sphere.points[:, 2]),
    ),
).T

# add and scale
sphere['vectors'] = vectors * 0.3
sphere.set_active_vectors('vectors')

# plot just the arrows
sphere.arrows.plot()

# %%
# Plot the arrows and the sphere.

pl = pv.Plotter()
pl.add_mesh(sphere.arrows, lighting=False, scalar_bar_args={'title': 'Vector Magnitude'})
pl.add_mesh(sphere, color='grey', ambient=0.6, opacity=0.5, show_edges=False)
pl.show()


# %%
# Subset of Glyphs
# ++++++++++++++++
#
# Sometimes you might not want glyphs for every node in the input dataset. In
# this case, you can choose to build glyphs for a subset of the input dataset
# by using a merging tolerance. Here we specify a merging tolerance of five
# percent which equates to five percent of the bounding box's length.

# Example dataset with normals
mesh = examples.load_random_hills()

# create a subset of arrows using the glyph filter
arrows = mesh.glyph(scale='Normals', orient='Normals', tolerance=0.05)

pl = pv.Plotter()
pl.add_mesh(arrows, color='black')
pl.add_mesh(mesh, scalars='Elevation', cmap='terrain', smooth_shading=True)
pl.show()
# %%
# .. tags:: filter
