HAS Fluid Blob

// Smooth-minimum blending for organic merging
float smin(float a, float b, float k) {
  float h = clamp(.5 + .5 * (b - a) / k, 0., 1.);
  return mix(b, a, h) - k * h * (1. - h);
}

float map(vec3 p) {
  vec3 mp = applyModifiers(p);
  float d = 100.;
  for(int i = 0; i < 10; i++) {
    if(i >= u_numBlobs) break;
    float r = (i == 0) ? u_coreR : u_dropR;
    float db = length(mp - applyModifiers(u_blobs[i])) - r;
    if(i == 0) d = db;
    else d = smin(d, db, u_merge);
  }
  return d;
}

// GGX microfacet specular distribution
float ggx(vec3 n, vec3 h, float r) {
  float a2 = r*r*r*r;
  float NdH = max(dot(n, h), 0.);
  float d = NdH*NdH * (a2 - 1.) + 1.;
  return a2 / (3.14159 * d*d + .0001);
}

// Schlick fresnel — metals use albedo as F0
vec3 F0 = mix(vec3(.04), albedo, u_metal);
vec3 schlickF = F0 + (1.-F0) * pow(1.-NdV, 5.);

// Three-light softbox studio
vec3 diff = albedo * (1.-u_metal) * (
  NdL1 * u_keyL  * .5  +   // warm key
  NdL2 * u_fillL * .3  +   // cool fill
  NdL3 * u_rimL  * .25 +   // rim strip
  .15                       // ambient floor
);

// Three-band FFT → visual parameter routing matrix
let audioRoutes = [
  { band: 'bass',  prop: 'size',    amount: 0.5 },
  { band: 'bass',  prop: 'merge',   amount: 0.3 },
  { band: 'mid',   prop: 'drift',   amount: 0.5 },
  { band: 'high',  prop: 'rough',   amount: 0.2 },
  { band: 'bass',  prop: 'fresnel', amount: 0.4 },
];

// Accumulate modulations and clamp to safe ranges
function applyAudioToUniforms() {
  const mods = {};
  audioRoutes.forEach(r => {
    const bv = getBandValue(r.band);
    const cfg = routeProps[r.prop];
    mods[r.prop] = (mods[r.prop] || 0)
      + bv * r.amount * cfg.scale;
  });
}

vec3 applyModifiers(vec3 p) {
  vec3 q = p;
  // Twist — rotate around Y axis by height
  if(u_modTwist != 0.) {
    float tw = q.y * u_modTwist * 2.;
    q = vec3(q.x*cos(tw)-q.z*sin(tw), q.y,
             q.x*sin(tw)+q.z*cos(tw));
  }
  // Squash — flatten Y, expand XZ
  if(u_modSquash != 0.) {
    q.y *= 1. - u_modSquash * .6;
    q.x *= 1. + u_modSquash * .3;
    q.z *= 1. + u_modSquash * .3;
  }
  // Melt — droop by distance from center
  if(u_modMelt != 0.) {
    float dist = length(q.xz);
    q.y -= dist*dist * u_modMelt * .8;
  }
  return q;
}