"""
============================
Impostor and Mesh Ellipsoids
============================

This tutorial creates two ellipsoids with the same shape. The left ellipsoid
uses a shader-based impostor; the right one uses a tessellated triangle mesh.
Both represent a 3D ellipsoid, but only the mesh stores its surface as vertices
and faces.

The impostor path warns about its different geometry, tessellation, and picking.
Use ``impostor=False`` when mesh vertices, faces, or face coordinates are needed.

Run this script to open the interactive scene.
"""

import numpy as np

from fury import actor, window

###############################################################################
# Define the shape. ``lengths`` are semi-axis lengths, not diameters: these
# ellipsoids have full axis lengths of 3.0, 1.6, and 1.0. The columns of the
# orientation matrix define the local axis directions; identity aligns them
# with X, Y, and Z.

lengths = (1.5, 0.8, 0.5)
orientation = np.eye(3)
centers = np.array([[0.0, 0.0, 0.0]])

###############################################################################
# Create the impostor ellipsoid on the left. The shader calculates the surface
# analytically instead of generating a dense mesh. ``impostor=True`` is the
# default, but we specify it here to make the comparison explicit.

impostor = actor.ellipsoid(
    centers=centers,
    orientation_matrices=orientation,
    lengths=lengths,
    colors=(0.0, 0.7, 1.0),
    impostor=True,
)
impostor.local.position = (-2.0, 0.0, 0.0)

impostor.add_event_handler(
    lambda event: print(f"Pointer moved in impostor to: {event.x}, {event.y}"),
    "pointer_move",
)

###############################################################################
# Create the mesh ellipsoid on the right. ``phi`` and ``theta`` control its
# tessellation and only affect the mesh branch. Use this branch when you need
# surface vertices and faces or mesh-specific appearance controls.

mesh = actor.ellipsoid(
    centers=centers,
    orientation_matrices=orientation,
    lengths=lengths,
    colors=(1.0, 0.5, 0.0),
    impostor=False,
    phi=32,
    theta=32,
)
mesh.local.position = (2.0, 0.0, 0.0)
mesh.add_event_handler(
    lambda event: print(f"Pointer moved in mesh to: {event.x}, {event.y}"),
    "pointer_move",
)

###############################################################################
# Count the vertices used by each rendering method. Each impostor draws two
# triangles (six generated vertices), but stores only its center and parameters.
# The mesh count comes from its actual position buffer and changes with
# ``phi`` and ``theta``.

impostor_vertices = 6 * impostor.glyph_count
impostor_centers = impostor.geometry.positions.nitems
mesh_vertices = mesh.geometry.positions.nitems

labels = actor.text(
    [
        f"Impostor\n{impostor_vertices} generated vertices\n"
        f"{impostor_centers} stored center",
        f"Mesh\n{mesh_vertices} surface vertices",
    ],
    position=[(-2.0, -1.4, 0.0), (2.0, -1.4, 0.0)],
    colors=(1.0, 1.0, 1.0),
    font_size=0.3,
    anchor="middle-center",
)

scene = window.Scene()
scene.background = (0.05, 0.05, 0.08)
scene.add(impostor, mesh, labels)

###############################################################################
# Open the interactive window when running the script directly.

if __name__ == "__main__":
    show_m = window.ShowManager(
        scene=scene, size=(800, 500), title="Impostor and Mesh Ellipsoids"
    )
    try:
        show_m.start()
    finally:
        show_m.close()