spectral_zucconi6.js

// spectral_zucconi6 by Alan Zucconi rewritten from GLSL to JS by Kazik Pogoda
// GLSL: https://www.shadertoy.com/view/ls2Bz1

const ONE_IN_3D = [1, 1, 1];
const c1 = [3.54585104, 2.93225262, 2.41593945];
const x1 = [0.69549072, 0.49228336, 0.27699880];
const y1 = [0.02312639, 0.15225084, 0.52607955];
const c2 = [3.90307140, 3.21182957, 3.96587128];
const x2 = [0.11748627, 0.86755042, 0.66077860];
const y2 = [0.84897130, 0.88445281, 0.73949448];
const saturate = (x) => Math.min(Math.max(x, 0), 1);
const to3d = (x) => [x, x, x];
const add3d = (x, y) => [x[0] + y[0], x[1] + y[1], x[2] + y[2]];
const subtract3d = (x, y) => [x[0] - y[0], x[1] - y[1], x[2] - y[2]];
const multiply3d = (x, y) => [x[0] * y[0], x[1] * y[1], x[2] * y[2]];
const pow23d = (x) => multiply3d(x, x);
const saturate3d = (x) => [saturate(x[0]), saturate(x[1]), saturate(x[2])];
const bump3y = (x, yoffset) => saturate3d(subtract3d(subtract3d(ONE_IN_3D, pow23d(x)), yoffset));
const spectral_zucconi6 = (x) => add3d(bump3y(multiply3d(c1, subtract3d(to3d(x), x1)), y1), bump3y(multiply3d(c2, subtract3d(to3d(x), x2)), y2));