"""
=============================
Billboard vs Geometry Spheres
=============================

This example demonstrates the difference between billboard-based sphere impostors
and traditional geometry-based spheres. Billboard spheres are rendered as textured
quads that always face the camera, making them more efficient for rendering many
spheres at a distance.

"""

import numpy as np

from fury import actor, window

###############################################################################
# Create sphere data with positions, colors, and radii.

centers = np.array([[0, 0, 0], [2, 0, 2], [-1, 0, 0]])
colors = np.array([[1, 0, 0], [0, 1, 0], [0, 0, 1]])
radii = np.array([1.2, 1, 1])

###############################################################################
# Create billboard spheres (shader-based impostors).
# These are rendered as textured quads that face the camera.

billboard_spheres = actor.sphere(
    centers=centers, colors=colors, radii=radii, opacity=1, impostor=True
)

###############################################################################
# Create geometry-based spheres (traditional mesh).
# These are actual 3D mesh spheres with vertices and faces.

geometry_spheres = actor.sphere(
    centers=centers + np.array([[0, -2, 0]]),
    colors=colors,
    radii=radii,
    opacity=1,
    impostor=False,
)

###############################################################################
# Create descriptive text labels to identify each type.

billboard_text = actor.text(
    "Billboard Spheres (Shader-based)",
    position=[-5, 0, 0],
    colors=(1, 1, 1),
    anchor="middle-right",
)

geometry_text = actor.text(
    "Geometry Spheres (Mesh-based)",
    position=[-5, -4, 0],
    colors=(1, 1, 1),
    anchor="middle-right",
)

###############################################################################
# Add ground planes for visual reference.

ground_top = actor.box(
    centers=np.array([[0, 0, 0]]), colors=(0.5, 0.5, 0.5), scales=(7, 0.1, 7)
)

ground_bottom = actor.box(
    centers=np.array([[0, -2, 0]]), colors=(0.5, 0.5, 0.5), scales=(7, 0.1, 7)
)

###############################################################################
# Create scene and add all actors.

scene = window.Scene()
scene.background = (0.1, 0.1, 0.15)

scene.add(billboard_spheres)
scene.add(geometry_spheres)
scene.add(billboard_text)
scene.add(geometry_text)
scene.add(ground_top)
scene.add(ground_bottom)

###############################################################################
# Create and start the ShowManager.

show_m = window.ShowManager(
    scene=scene, size=(800, 600), title="Billboard vs Geometry Spheres"
)
show_m.start()