/*{
  "DESCRIPTION": "Neon KIFS mandala: a polar kaleidoscope folded over an iterated 2D KIFS, drawn as thin glowing orbit-trap laser lines that bloom into a rotating, morphing fractal flower. Real-time, seamless 16s loop.",
  "CREDIT": "glslop agent (Claude)",
  "CATEGORIES": ["fractal", "kifs", "neon", "kaleidoscope"],
  "INPUTS": [
    { "NAME": "speed",     "TYPE": "float", "DEFAULT": 1.0, "MIN": 0.0, "MAX": 3.0 },
    { "NAME": "glow",      "TYPE": "float", "DEFAULT": 1.0, "MIN": 0.3, "MAX": 3.0 },
    { "NAME": "hue",       "TYPE": "float", "DEFAULT": 0.0, "MIN": 0.0, "MAX": 1.0 },
    { "NAME": "morph",     "TYPE": "float", "DEFAULT": 0.5, "MIN": 0.0, "MAX": 1.2 },
    { "NAME": "zoom",      "TYPE": "float", "DEFAULT": 1.0, "MIN": 0.4, "MAX": 2.5 },
    { "NAME": "symmetry",  "TYPE": "long",  "DEFAULT": 6,   "MIN": 3,   "MAX": 12 },
    { "NAME": "iterCount", "TYPE": "long",  "DEFAULT": 14,  "MIN": 4,   "MAX": 20 }
  ]
}*/

#define PI  3.14159265359
#define TAU 6.28318530718

const float PERIOD = 16.0;
const int   MAXI   = 20;

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

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

void main(){
  vec2 uv = (gl_FragCoord.xy - 0.5 * RENDERSIZE.xy) / RENDERSIZE.y;
  uv *= 1.7 / zoom;

  float ph = fract(TIME * speed / PERIOD);
  float th = TAU * ph;

  // kaleidoscope: fold the plane into N mirrored wedges, slowly spinning
  float a = atan(uv.y, uv.x) + th;          // one full spin per loop (seamless)
  float r = length(uv);
  float seg = TAU / float(symmetry);
  a = mod(a, seg);
  a = abs(a - 0.5 * seg);
  vec2 z = vec2(cos(a), sin(a)) * r;

  // iterated Kaliset fold (abs + inversion) -> ornate nested fractal webs;
  // orbit traps drive the thin laser lines.
  mat2 R = rot(0.08 * sin(th));
  vec2 off = vec2(0.74 + 0.10 * morph * sin(th), 0.56 + 0.10 * morph * cos(th));
  float t1 = 1.0e9, t2 = 1.0e9, t3 = 1.0e9;
  for (int i = 0; i < MAXI; i++){
    if (i >= iterCount) break;
    z = abs(z) / (dot(z, z) + 0.0008);     // fold + inversion -> detail at all scales
    z = R * z;
    z -= off;
    t1 = min(t1, dot(z, z));               // nearest approach to origin
    t2 = min(t2, abs(z.x));                // vertical filaments
    t3 = min(t3, length(z - vec2(0.45, 0.18)));
  }

  // thin glowing laser lines from the orbit traps; hue drifts with radius -> rainbow rings
  vec3 col = vec3(0.0);
  col += pal(hue + 0.05 + 0.45 * r) * (0.0060 / (t1 + 0.00060));
  col += pal(hue + 0.42 + 0.45 * r) * (0.0042 / (t2 * t2 + 0.00035));
  col += pal(hue + 0.74 + 0.45 * r) * (0.0050 / (t3 * t3 + 0.00060));
  col *= glow;

  // tone map -> hot cores to white, saturated halos
  col = col / (1.0 + col);
  col = pow(col, vec3(0.80));
  col *= 1.0 - 0.18 * dot(uv, uv) * zoom * zoom;   // soft vignette

  gl_FragColor = vec4(col, 1.0);
}