# Types of Shading
# ================

# Comparison of default, flat shading vs. smooth shading.
import pyvista as pv
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
# `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 = pv.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


pl = pv.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()

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