Radiolarian

"""A Haeckel radiolarian as a specimen plate: a spined shell pierced by a spherical Voronoi lattice of pores, its central capsule lit through them in stepped flat tones."""

import math

import numpy as np
from numpy.typing import NDArray
from scipy.spatial import SphericalVoronoi

from walldye import (
    ACCENT,
    ACCENT_4,
    BG,
    BG_ALT,
    UI,
    UI_ALT,
    Canvas,
    P,
    Vec,
    design,
    ladder,
    mix,
    polar,
)

R = 210  # shell radius
PORE = 27  # pore pitch on the sphere surface
STRUT = 0.8  # pore scale inside its Voronoi cell; the rest is shared strut
SPINES = 14
LONG, SHORT = 180, 105  # spine lengths beyond the shell, alternating
HALF = math.degrees(5 / R)  # half the angle a spine's base spans at the shell
BRISTLES = 6 * SPINES
CAPSULE = 0.55 * R  # radius of the glow seen through the pores
DIM = 385  # drop of the dimension line below the centre
GLOW = ladder((BG, ACCENT_4, ACCENT), 18)  # rung 0 is the unlit shell and is never drawn

type Pore = tuple[NDArray[np.float64], float]


def pores(c: Vec) -> list[Pore]:
    """The pores on the visible hemisphere of the shell centred on `c`, as (outline, distance of
    the cell's centre from `c`) pairs, projected straight onto the screen."""
    n = round(4 * math.pi * R * R / (PORE * PORE * 0.866))
    i = np.arange(n) + 0.5
    z = 1 - 2 * i / n  # toward the viewer
    rho = np.sqrt(1 - z * z)
    a = i * math.pi * (3 - math.sqrt(5))  # a Fibonacci lattice: near-even sites, mostly hexagons
    sites = np.stack([rho * np.cos(a), rho * np.sin(a), z], 1)
    sv = SphericalVoronoi(sites)
    sv.sort_vertices_of_regions()
    out: list[Pore] = []
    for site, region in zip(sites, sv.regions, strict=True):
        if site[2] < 0.14:  # cells on the limb would poke through the silhouette
            continue
        v = site + (sv.vertices[region] - site) * STRUT
        out.append((c + R * v[:, :2], R * math.hypot(site[0], site[1])))
    return out


@design(aspects="any")
def draw(s: Canvas) -> None:
    # right of centre on a landscape screen; centred across a portrait one, above the middle
    c = s.pick(landscape=(0.625, 0.486), portrait=(0.5, 0.4))

    # specimen-plate construction: centre lines and one dimension across the shell
    guide = P().M(c + (-R - 230, 0)).H(c.x + R + 230).M(c + (0, -R - 150)).V(c.y + R + 150)
    s.stroke(guide, UI, 1.2, dash=(36, 6, 4, 6))
    y = c.y + DIM
    dim = P().M(c.x - R, y).H(c.x + R)
    for x in (c.x - R, c.x + R):
        dim.M(x, c.y + 12).V(y + 14).M(x - 7, y + 7).L(x + 7, y - 7)
    s.stroke(dim, UI, 1.2)

    # spines and bristles sit behind the shell
    spines, ribs, bristles = P(), P(), P()
    for i in range(SPINES):
        b = i * 360 / SPINES
        tip = R + (LONG if i % 2 == 0 else SHORT)
        spines.poly(
            [
                polar(c, R - 10, bearing=b - HALF),
                polar(c, tip, bearing=b),
                polar(c, R - 10, bearing=b + HALF),
            ],
            closed=True,
        )
        ribs.M(polar(c, R, bearing=b)).L(polar(c, tip - 26, bearing=b))
    for i in range(BRISTLES):
        b = (i + 0.5) * 360 / BRISTLES
        bristles.M(polar(c, R, bearing=b)).L(polar(c, R + (15 if i % 3 == 1 else 9), bearing=b))
    s.stroke(bristles, UI, 1.3)
    s.fill(spines, UI)
    s.stroke(ribs, UI_ALT, 1.2)

    # the shell: a shaded disc with every pore cut through it
    holes = pores(c)
    frame = P().circle(c, R)
    for pts, _ in holes:
        frame.poly(pts, closed=True)
    shade = s.radial_gradient([(0, BG_ALT), (0.7, BG_ALT), (1, mix(BG_ALT, BG, 0.7))], c, R)
    s.fill(P().circle(c, R), BG)  # hides the guides behind the pores
    s.fill(frame, shade, rule="evenodd")

    # the capsule glows through the pores: each pore takes one flat rung by its distance
    with s.buckets(GLOW, "fill") as lit:
        for pts, d in holes:
            if (k := GLOW.rung(1 - d / CAPSULE)) > 0:
                lit[k].poly(pts, closed=True)
    s.stroke(P().circle(c, R), UI_ALT, 2)