"""
3D depth shading
================

This example shows to to use depth shading in 3D plots to reduce the opacity (increase transparency) of
vertices and edges that are further away from the viewer. This gives a better sense of depth but can be
confusing in some cases, so there are style options to turn it off.
"""

import igraph as ig
import iplotx as ipx

g = ig.Graph.Erdos_Renyi(15, m=20)

layout = g.layout_fruchterman_reingold_3d()

ipx.network(
    g,
    layout,
    vertex_alpha=0.9,
    figsize=(8, 8),
)

# %%
# Notice that depth shading is a 0-1 multiplier on top of the existing alpha value, so no vertex will have
# alpha (opacity) greater than 0.9 in this example, but vertices that are further back will have values
# below 0.9 (the minimum is usually 0.1).
#
# .. tip::
#   To get a better sense of depth shading, use Matplotlib with an interactive backend and rotate the
#   plot using the mouse.
#
# You can turn off depth shading by setting ``depthshade=False`` for vertices and/or edges:

ipx.network(
    g,
    layout,
    vertex_alpha=0.9,
    figsize=(8, 8),
    vertex_depthshade=False,
    edge_depthshade=False,
)

# %%
# In this case all vertices have the same opacity (0.9) regardless of their depth, and all edges have an
# opacity of 1.0 (no transparency).