# Eye Dome Lighting
# =================

# Eye-Dome Lighting (EDL) is a non-photorealistic, image-based shading technique
# designed to improve depth perception in scientific visualization images.
# It darkens each pixel based on how much nearer its neighbors are in screen
# space, which makes depth ordering readable even on flat-shaded geometry or
# unshaded point clouds. To learn more, see this blog post.
# EDL is most useful when standard Lambertian shading is insufficient, for
# example:
# Point clouds, which have no surface normals to shade from.
# Dense or intertwined geometry where overlapping surfaces collapse into a
# visually flat mass.
# Noisy or raw-scanned meshes with many features at similar depths.

# Dense branching geometry
# ------------------------

# The VTK pine root scan is a classic EDL demonstration dataset: a dense
# tangle of fine branching structures where depth ordering is hard to read
# without extra shading cues.
import pyvista as pv
from pyvista import examples


pine_roots = examples.download_pine_roots()
pine_roots.plot(eye_dome_lighting=True, color='tan')

# Compare EDL shading side by side with standard shading. The left panel
# is rendered with EDL, the right without. EDL reveals which roots lie in
# front of which; without it, they collapse into a flat silhouette.
pl = pv.Plotter(shape=(1, 2), border=False)

pl.subplot(0, 0)
pl.add_mesh(pine_roots, color='tan')
pl.enable_eye_dome_lighting()
pl.add_text('Eye-Dome Lighting', font_size=24)

pl.subplot(0, 1)
pl.add_mesh(pine_roots, color='tan')
pl.add_text('No Eye-Dome Lighting', font_size=24)

pl.link_views()
pl.show()

# Point cloud
# -----------

# EDL was originally motivated by the problem of shading point clouds, which
# have no surface normals for traditional lighting. This Lidar point cloud
# looks ambiguous without shading hints:
point_cloud = examples.download_lidar()

pl = pv.Plotter()
pl.add_mesh(point_cloud, color='lightblue', point_size=5)
pl.show()

# Enable EDL on the renderer via
# `pyvista.Renderer.enable_eye_dome_lighting()` and the terrain structure
# becomes readable.
pl = pv.Plotter()
pl.add_mesh(point_cloud, color='lightblue', point_size=5)
pl.enable_eye_dome_lighting()
pl.show()

# EDL also works alongside scalar coloring:
pl = pv.Plotter()
pl.add_mesh(point_cloud, scalars='Elevation', point_size=5)
pl.enable_eye_dome_lighting()
pl.show()

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