Onion, Halved

// composition: the halved onion at the right thirds crossing, its rings sharing a center that drifts a
// little further off with every ring; flakes of dusty-violet skin fall away toward the lower-left corner.
// layering: translucent sepia discs stacked deepest at the heart, graphite ring lines, papery skin last.
const PALETTE = [
  "#f1e8d3", // ground: parchment
  "#d3b183", // sepia light
  "#b3854e", // sepia mid
  "#8a6a3f", // sepia deep / heart
  "#8e7191", // accent: dusty violet skin
];

function ringShape(cx, cy, r, squash) {
  brush.beginShape(0.75);
  for (let i = 0; i < 12; i++) {
    const a = i * 30;
    const w = 1 + randomGaussian(0, 0.022) + 0.05 * (noise(i * 0.4, r * 0.02) - 0.5);
    brush.vertex(cx + cos(a) * r * w, cy + sin(a) * r * squash * w);
  }
  brush.endShape(true);
}

function skinFlake(cx, cy, s, inner, rot, op, edged) {
  push();
  translate(cx, cy);
  rotate(rot);
  brush.noStroke();
  brush.fillBleed(0.42, "out");
  brush.fillTexture(0.5, 0.55);
  brush.fill("#8e7191", op);
  brush.beginShape(0.6);
  const n = 7;
  for (let i = 0; i <= n; i++) {
    const a = lerp(-15, 150, i / n);
    brush.vertex(cos(a) * s * (1 + randomGaussian(0, 0.025)), sin(a) * s * (1 + randomGaussian(0, 0.025)));
  }
  for (let i = n; i >= 0; i--) {
    const a = lerp(-15, 150, i / n);
    const r = s * (inner + randomGaussian(0, 0.02));
    brush.vertex(cos(a) * r, sin(a) * r);
  }
  brush.endShape(true);
  if (edged) {
    brush.noFill();
    brush.set("2B", "#6d5570", 0.7);
    brush.beginShape(0.6);
    for (let i = 0; i <= n; i++) {
      const a = lerp(-15, 150, i / n);
      brush.vertex(cos(a) * s, sin(a) * s);
    }
    brush.endShape(false);
  }
  pop();
}

function setup() {
  createCanvas(800, 800, WEBGL);
  angleMode(DEGREES);
  brush.scaleBrushes(2.4);
  noLoop();
}

function draw() {
  translate(-width / 2, -height / 2);
  background("#f1e8d3");

  // soft ground shadow, under and left of the section
  brush.noStroke();
  brush.fillBleed(0.55, "out");
  brush.fillTexture(0.5, 0.5);
  brush.fill("#b3854e", 26);
  ringShape(506, 360, 166, 0.6);

  // the section: rings sharing a center that will not hold still
  let cx = 528;
  let cy = 314;
  let r = 156;
  const tones = ["#d3b183", "#c29a62", "#e0c898", "#b3854e"];
  for (let i = 0; i < 10; i++) {
    brush.noStroke();
    brush.fillBleed(0.35, "out");
    brush.fillTexture(0.5, 0.55);
    brush.fill(tones[floor(random(4))], 26 + random(0, 14));
    ringShape(cx, cy, r, 0.94);
    if (random() < 0.75) {
      brush.noFill();
      brush.set(random() < 0.3 ? "pen" : "2B", "#8a6a3f", random(0.5, 0.9));
      ringShape(cx + random(-2, 2), cy + random(-2, 2), r * random(0.985, 1.01), 0.94);
    }
    cx += randomGaussian(-2.4, 2.4);
    cy += randomGaussian(1.6, 2);
    r -= max(7, randomGaussian(13.5, 4.5));
  }
  // the heart
  brush.noStroke();
  brush.fillBleed(0.4, "out");
  brush.fillTexture(0.6, 0.6);
  brush.fill("#8a6a3f", 125);
  ringShape(cx, cy, max(r, 10), 0.9);

  // the papery skin still clinging to the crown
  skinFlake(528, 318, 168, 0.93, 200, 66, true);

  // and the pieces that let go, falling lower-left
  skinFlake(430, 452, 62, 0.68, 205, 96, true);
  skinFlake(348, 528, 47, 0.72, 160, 82, false);
  skinFlake(258, 596, 40, 0.66, 235, 105, true);
  skinFlake(194, 660, 26, 0.7, 185, 70, false);
  skinFlake(150, 706, 13, 0.62, 140, 58, false);

  // root tuft at the base of the section
  brush.set("pen", "#8a6a3f", 0.8);
  brush.line(524, 462, 518, 492);
  brush.line(534, 464, 536, 496);
  brush.line(543, 460, 552, 486);
  brush.line(515, 458, 505, 480);
}