Cube Edges w/ Hue Quantization

cube_edges_w_hue_quantization.pbgl, format as .js

// For Evil Genius Labs 8x8x8 LED cube running PixelBlaze

phi = (sqrt(5) + 1) / 2  // golden ratio
hq = 32                  // hue quantization, try integers 3-10 for fun

export function beforeRender(delta) {
  t1 = time(.1)
  t2 = time(.04)
}

function is_at(v, lo, hi) {
  return (v == lo || v == hi) - (v < lo || v > hi)
}

export function render(index) {
  x = floor(index / 8) % 8
  y = index % 8
  z = floor(index / 8 / 8)

  // fn == 1 if pixel on frame of cube n
  f1 = (is_at(x, 0, 7) + is_at(y, 0, 7) + is_at(z, 0, 7)) >= 2
  f2 = (is_at(x, 1, 6) + is_at(y, 1, 6) + is_at(z, 1, 6)) >= 2
  f3 = (is_at(x, 2, 5) + is_at(y, 2, 5) + is_at(z, 2, 5)) >= 2

  v1 = smoothstep(0, .3, wave((x + y + z) / 3 / 8 - t2))
  v2 = smoothstep(0, .4, wave(-(x + y + z) / 2 / 8 - t2))
  v3 = smoothstep(0, .5, wave((x - y + z) / 2 / 8 - t2))

  // d: spatial dither, 2 bits
  d = ((x + y + z) & 3) / 4

  h = t1 + phi * f2 + (2 * phi) * f3
  h = floor(hq * h + d) / hq
  s = 1
  v = f1 * v1 + f2 * v2 + f3 * v3
  hsv(h, s, v)
}