The3DG

Nature · Test cube 32

Coral

Winding ridges that branch and loop, like brain coral.

Presented by FloNothing in nature repeats exactly. Neither do these. Relax into it.
× 1.00
1.0 mm
135°
  • Prints well with a 0.4 mm nozzle.

25 mm, with your size and depth. Prints upright, no supports. About 4 MB.

Good for

Vases and planters with an underwater feel.

Print notes

  • Depth 0.4 to 1.5 mm for a 0.4 mm nozzle (as written: 1.0 mm).
  • Best on walls, printed upright. On a flat top, use thin layers (0.12 mm or less).
  • Fade it out over the bottom 3 mm so the first layers are flat and stick to the plate.
  • Not printed yet: these notes come from the geometry. The test cube will tell us more.

The formula

The real code this page runs: give it a point (U mm across, V mm up) and it returns the height there, in mm. Push the surface out by that much and the texture is real geometry.

function coral(U: number, V: number, amp = 1.0) {
  let n = 0;
  for (let i = 0; i < 9; i++) {
    const a = i * (Math.PI / 9); // nine wave directions
    n += Math.sin((U * Math.cos(a) + V * Math.sin(a)) / 1.35 + 9 * rnd(a, 1, 1));
  }
  n = n + 3.0 * (fbm(U / 14, V / 14) - 0.5);
  return amp * clamp(n / 1.4 + 0.5, 0, 1);
}
The helpers it uses (clamp, rnd, fbm, noise)
function clamp(x: number, lo: number, hi: number) {
  return Math.min(Math.max(x, lo), hi);
}
/** A repeatable random number 0..1 for a cell (no Math.random: the same texture every time). */
function rnd(a: number, b: number, k = 0) {
  const x = Math.sin(a * 127.1 + b * 311.7 + k * 74.7) * 43758.5453;
  return x - Math.floor(x);
}
/** Three octaves of noise, 0..1. */
function fbm(x: number, y: number, o = 3) {
  let sum = 0;
  let norm = 0;
  for (let i = 0; i < o; i++) sum += noise(x * 2 ** i, y * 2 ** i) / 2 ** i;
  for (let i = 0; i < o; i++) norm += 1 / 2 ** i;
  return sum / norm;
}
/** Smooth value noise. */
function noise(x: number, y: number) {
  const xi = Math.floor(x);
  const yi = Math.floor(y);
  const xf = x - xi;
  const yf = y - yi;
  const u = xf * xf * (3 - 2 * xf);
  const v = yf * yf * (3 - 2 * yf);
  const a = rnd(xi, yi);
  const b = rnd(xi + 1, yi);
  const c = rnd(xi, yi + 1);
  const d = rnd(xi + 1, yi + 1);
  return a + (b - a) * u + (c - a) * v + (a - b - c + d) * u * v;
}

Printed

Test cube 32 is waiting for the printer. Its photo goes here.