"""
.. _shading_example:

Types of Shading
~~~~~~~~~~~~~~~~

Comparison of default, flat shading vs. smooth shading.
"""

# sphinx_gallery_thumbnail_number = 4
from __future__ import annotations

import pyvista
from pyvista import examples

# %%
# PyVista supports two types of shading: flat and smooth shading that uses
# VTK's Phong shading algorithm.
#
# This is a plot with the default flat shading.
mesh = examples.load_nut()
mesh.plot()


# %%
# Here's the same sphere with smooth shading.
mesh.plot(smooth_shading=True)


# %%
# Note how smooth shading makes edges that should be sharp look odd,
# it's because the points of these normals are averaged between two
# faces that have a sharp angle between them.  You can avoid this by
# enabling ``split_sharp_edges``.
#
# .. note::
#    You can configure the splitting angle with the optional
#    ``feature_angle`` keyword argument.
mesh.plot(smooth_shading=True, split_sharp_edges=True)


# %%
# We can even plot the edges that will be split using
# :func:`extract_feature_edges <pyvista.DataSetFilters.extract_feature_edges>`.

# extract the feature edges exceeding 30 degrees
edges = mesh.extract_feature_edges(
    boundary_edges=False,
    non_manifold_edges=False,
    feature_angle=30,
    manifold_edges=False,
)

# plot both the edges and the smoothed mesh
pl = pyvista.Plotter()
pl.enable_anti_aliasing()
pl.add_mesh(mesh, smooth_shading=True, split_sharp_edges=True)
pl.add_mesh(edges, color='k', line_width=5)
pl.show()


# %%
# The ``split_sharp_edges`` keyword argument is compatible with
# physically based rendering as well.

# plot both the edges and the smoothed mesh

# sphinx_gallery_start_ignore
# physically based rendering does not work in interactive plots
PYVISTA_GALLERY_FORCE_STATIC = True
# sphinx_gallery_end_ignore

pl = pyvista.Plotter()
pl.enable_anti_aliasing()
pl.add_mesh(mesh, color='w', split_sharp_edges=True, pbr=True, metallic=1.0, roughness=0.5)
pl.show()
# %%
# .. tags:: plot