Bubble Phi Pixelblaze shader

bubble_phi.pbsl.js

// Bubble Phi
// (Sounds like Boba Tea)
//
// Stream of rising bubbles with low discrepancy quasirandom hues
// https://extremelearning.com.au/unreasonable-effectiveness-of-quasirandom-sequences/#quasiperiodic_tiling

// Constants
// IPHI = (sqrt(5) - 1) / 2  // 1 / phi, the golden ratio
IPHI2 = [0.7548776662466927, 0.5698402909980532]

// Tunable parameters
speed = 1
blend = 0.4
twist = 0.6
bubble_density = 1
hue_scale = 384  // hues repeat after this

// UI parameters
var use_fire_hues

export function beforeRender(delta) {

  // t1 - bubble movement
  t1 = time(hue_scale * 0.03 / speed)

  // t2 - hue rotation
  t2 = time(0.05 / speed)
}

export function render3D(index, x, y, z) {

  pix_t1 = hue_scale * t1 - bubble_density * y
  bubble_number = floor(pix_t1)
  bubble_diameter = (wave(pix_t1 - 0.25) + 0.8) / 1.8

  // radius - distance from center Y axis
  cx = 2 * x - 1
  cz = 2 * z - 1
  r = sqrt(cx * cx + cz * cz)

  // mag - distance from color split plane
  if (bubble_number % 2) {
    // twist sunwise
    tty = t2 + twist * y
  } else {
    // twist widdershins
    tty = -t2 - twist * y
  }
  rotx = SQRT2 * (wave(tty + 0.25) - 0.5)
  rotz = SQRT2 * (wave(tty) - 0.5)
  mag = dot(cx, cz, rotx, rotz)
  
  // Hue
  if (use_fire_hues) {
    // cube fire 3D hue calculation
    h = (x + y + z) / 5 + t2
  } else {
    h1 = phi2_hue(bubble_number, 0)
    h2 = phi2_hue(bubble_number, 1)
    h = (mag < 0) ? h2 : h1
  }
  
  // Saturation
  s = 1

  // Value
  v = smoothstep(0.0, 0.15, bubble_diameter - r) * smoothnotch(0, blend, mag)
  
  hsv(h, s, v)
}

export function render2D(index, x, y) {
  // untested
  render3D(index, x, y, 0)
}

export function render(index) {
  // untested
  render3D(index, index / pixelCount, 0, 0)
}

export function toggleFire(isEnabled) {
   use_fire_hues = isEnabled
}

function dot(x0, y0, x1, y1) {
  return x0 * x1 + y0 * y1
}

function phi2_hue(n, i) {
  return frac(0.5 + IPHI2[i] * n)
}

function smoothnotch(center, width, x) {
  hw = width / 2
  return smoothstep(center, center + hw, x) - smoothstep(center - hw, center, x) + 1
}