/*{
  "DESCRIPTION": "Loom of Light — a log-polar mandala woven from interfering line-families that breathe and rotate on a seamless loop. Iridescent filaments cross into a shimmering lattice.",
  "CREDIT": "Claude Opus 4.8",
  "CATEGORIES": ["generative", "abstract", "mandala"],
  "INPUTS": [
    { "NAME": "sectors", "TYPE": "float", "DEFAULT": 8.0, "MIN": 3.0, "MAX": 16.0 },
    { "NAME": "warp",    "TYPE": "float", "DEFAULT": 1.0, "MIN": 0.0, "MAX": 2.0 },
    { "NAME": "glowAmt", "TYPE": "float", "DEFAULT": 1.0, "MIN": 0.2, "MAX": 2.0 }
  ]
}*/

#define PI  3.14159265359
#define TAU 6.28318530718
#define PERIOD 18.0

// iridescent cosine palette
vec3 pal(float t){
  return 0.5 + 0.5 * cos(TAU * (t + vec3(0.0, 0.33, 0.67)));
}

mat2 rot(float a){ float c = cos(a), s = sin(a); return mat2(c, -s, s, c); }

// smooth glowing "line family": bright ridges where sin(x) crosses zero
float family(float x, float w){
  return w / (abs(sin(x)) + w);
}

void main(){
  vec2 uv = (gl_FragCoord.xy - 0.5 * RENDERSIZE.xy) / RENDERSIZE.y;

  // seamless loop phase
  float ph  = fract(TIME / PERIOD);
  float spin = TAU * ph;                 // one full turn per period
  float breath = 0.5 + 0.5 * cos(TAU * ph); // 0..1..0 breathing

  // slow global rotation of the whole field
  uv = rot(spin * 0.25) * uv;

  // ---- log-polar domain ----
  float r = length(uv) + 1e-4;
  float a = atan(uv.y, uv.x);
  float lr = log(r);                      // push domain to larger magnitudes

  // kaleidoscope fold into N mirrored sectors -> mandala symmetry
  float sect = TAU / sectors;
  float af = mod(a, sect);
  af = abs(af - 0.5 * sect);              // mirror each wedge

  // domain warp: gently swirl the folded angle with radius (breathing)
  float wa = af + warp * 0.6 * sin(lr * 3.0 - spin) * (0.5 + 0.5 * breath);

  // ---- three interfering line-families (the "weave") ----
  // radial rings (bands in log-radius) drifting inward
  float f1 = family((lr * 6.0 - spin * 2.0) , 0.06);
  // angular spokes bent by the warp
  float f2 = family((wa * sectors * 2.0)      , 0.05);
  // a diagonal cross-weft = combination of the two coords, rotated in phase
  float f3 = family((lr * 5.0 + wa * sectors * 1.5 + spin), 0.05);

  // weave: multiply pairs so filaments only glow where threads cross,
  // then add a soft union so lone threads still shimmer
  float weave = f1 * f2 + f2 * f3 + f3 * f1;
  float threads = max(f1, max(f2, f3));
  float field = (weave * 1.4 + threads * 0.35) * glowAmt;

  // ---- color ----
  // hue travels along the log-radius and the angle for iridescence
  float hue = lr * 0.35 + af * 0.5 + ph;
  vec3 col = pal(hue) * field;

  // hot cores near where three families meet -> white sparkle
  float core = f1 * f2 * f3;
  col += vec3(1.0, 0.95, 0.85) * pow(core, 1.5) * 1.5;

  // subtle deep-space vignette + radial falloff so center reads as a bright eye
  float vig = smoothstep(1.25, 0.15, r);
  col *= vig;
  col += pal(hue + 0.5) * 0.06 * (1.0 - vig); // cool halo in the dark

  // tone map (soft knee) so hot cores don't blow out flat
  col = col / (1.0 + col);
  col = pow(col, vec3(0.85));               // gentle gamma lift

  gl_FragColor = vec4(col, 1.0);
}