/*{
  "DESCRIPTION": "Signal ID: articulated signs cross a tracked signal field with identification marks and sliced persistent wakes.",
  "INPUTS": [
    { "NAME": "speed", "TYPE": "float", "DEFAULT": 0.55, "MIN": 0.0, "MAX": 2.0 },
    { "NAME": "decay", "TYPE": "float", "DEFAULT": 0.974, "MIN": 0.9, "MAX": 0.999 },
    { "NAME": "energy", "TYPE": "float", "DEFAULT": 0.82, "MIN": 0.0, "MAX": 2.0 },
    { "NAME": "tech", "TYPE": "float", "DEFAULT": 0.62, "MIN": 0.0, "MAX": 1.0 },
    { "NAME": "scale", "TYPE": "float", "DEFAULT": 1.0, "MIN": 0.4, "MAX": 2.4 },
    { "NAME": "focus", "TYPE": "point2D", "DEFAULT": [0.5, 0.5] },
    { "NAME": "colorA", "TYPE": "color", "DEFAULT": [1.0, 0.48, 0.05, 1.0] },
    { "NAME": "colorB", "TYPE": "color", "DEFAULT": [0.04, 0.52, 1.0, 1.0] },
    { "NAME": "seed", "TYPE": "float", "DEFAULT": 3.0, "MIN": 0.0, "MAX": 20.0 }
  ],
  "PASSES": [
    { "TARGET": "ink", "PERSISTENT": true, "FLOAT": true },
    { "TARGET": "echoes", "PERSISTENT": true, "FLOAT": true },
    {}
  ]
}*/

float segmentDistance(vec2 p, vec2 a, vec2 b) {
  vec2 pa = p - a;
  vec2 ba = b - a;
  float h = clamp(dot(pa, ba) / max(dot(ba, ba), 0.00001), 0.0, 1.0);
  return length(pa - ba * h);
}

float hash11(float x) {
  return fract(sin(x * 127.1 + seed * 31.7) * 43758.5453);
}

float glyphDistance(vec2 q, float kind) {
  float d = 10.0;
  if (kind < 1.0) {
    d = min(segmentDistance(q, vec2(-0.055, -0.07), vec2(0.025, 0.0)),
            segmentDistance(q, vec2(0.025, 0.0), vec2(-0.055, 0.07)));
    d = min(d, segmentDistance(q, vec2(-0.005, -0.07), vec2(0.075, 0.0)));
    d = min(d, segmentDistance(q, vec2(0.075, 0.0), vec2(-0.005, 0.07)));
  } else if (kind < 2.0) {
    d = segmentDistance(q, vec2(-0.06, -0.075), vec2(-0.06, 0.075));
    d = min(d, segmentDistance(q, vec2(-0.06, 0.075), vec2(0.055, 0.075)));
    d = min(d, segmentDistance(q, vec2(-0.06, -0.075), vec2(0.055, -0.075)));
    d = min(d, segmentDistance(q, vec2(0.015, -0.045), vec2(0.015, 0.045)));
  } else {
    d = segmentDistance(q, vec2(0.0, -0.085), vec2(0.075, 0.0));
    d = min(d, segmentDistance(q, vec2(0.075, 0.0), vec2(0.0, 0.085)));
    d = min(d, segmentDistance(q, vec2(0.0, 0.085), vec2(-0.075, 0.0)));
    d = min(d, segmentDistance(q, vec2(-0.075, 0.0), vec2(0.0, -0.085)));
    d = min(d, segmentDistance(q, vec2(-0.04, 0.0), vec2(0.04, 0.0)));
  }
  return d;
}

float softKnee(float x) {
  float hot = max(x - 1.0, 0.0);
  return min(x, 1.0) + hot / (1.0 + hot);
}

float boxBorder(vec2 p, vec2 size) {
  vec2 d = abs(p) - size;
  float signedDistance = length(max(d, 0.0)) + min(max(d.x, d.y), 0.0);
  return exp(-abs(signedDistance) * 210.0);
}

void main() {
  vec2 uv = isf_FragNormCoord;
  vec2 px = 1.0 / RENDERSIZE;
  vec2 p = uv - focus;
  p.x *= RENDERSIZE.x / RENDERSIZE.y;
  p /= scale;
  float t = TIME * speed;

  if (PASSINDEX == 0) {
    vec2 flow = vec2(
      0.7 + 0.3 * sin(p.y * 13.0 + t),
      0.55 * sin(p.x * 8.0 - t * 0.8) + 0.22 * cos(p.y * 17.0 + t)
    );
    vec2 previous = IMG_NORM_PIXEL(ink, uv - flow * (0.00135 + energy * 0.00075)).rg;
    vec2 injection = vec2(0.0);

    for (int i = 0; i < 6; i++) {
      float fi = float(i);
      float travel = fract(t * (0.055 + hash11(fi + 2.0) * 0.025) + fi / 6.0 + hash11(fi) * 0.2);
      vec2 center = vec2(mix(-0.58, 0.58, travel), (hash11(fi + 7.0) - 0.5) * 0.58);
      center.y += sin(travel * 12.0 + fi * 2.3 + t * 0.33) * 0.055;
      vec2 q = p - center;
      float angle = (hash11(fi + 12.0) - 0.5) * 1.5 + sin(t * 0.31 + fi) * 0.25;
      q = mat2(cos(angle), -sin(angle), sin(angle), cos(angle)) * q;
      float d = glyphDistance(q, mod(fi, 3.0));
      float stroke = smoothstep(0.015, 0.0045, d);
      float spark = smoothstep(0.035, 0.0, length(q - vec2(0.07, 0.0)));
      if (mod(fi, 2.0) < 1.0) injection.x += stroke + spark * 0.35;
      else injection.y += stroke + spark * 0.35;
    }

    vec2 state = previous * decay + injection * energy * vec2(0.145, 0.13);
    state = vec2(softKnee(state.x), softKnee(state.y));
    gl_FragColor = vec4(clamp(state, 0.0, 6.0), flow * 0.28 + 0.5);
    return;
  }

  if (PASSINDEX == 1) {
    vec3 previous = IMG_THIS_PIXEL(echoes).rgb;
    vec2 fresh = IMG_THIS_PIXEL(ink).rg;
    vec2 tail = IMG_NORM_PIXEL(ink, uv - vec2(px.x * 7.0, 0.0)).rg;
    vec2 splitA = IMG_NORM_PIXEL(ink, uv - vec2(px.x * 13.0, px.y * 3.0)).rg;
    vec2 splitB = IMG_NORM_PIXEL(ink, uv - vec2(px.x * 13.0, -px.y * 3.0)).rg;
    vec3 wake = vec3(fresh.x + tail.x * 0.5, fresh.y + tail.y * 0.5, max(splitA.x, splitB.y));
    vec3 state = max(previous * 0.952, wake * vec3(0.68, 0.7, 0.62));
    state = state / (1.0 + max(state - 1.0, 0.0));
    gl_FragColor = vec4(clamp(state, 0.0, 6.0), 1.0);
    return;
  }

  float sliceBand = floor((p.y + 0.6) * 21.0);
  float sliceEpoch = floor(t * 0.72);
  float sliceRandom = hash11(sliceBand + sliceEpoch * 19.0 + 41.0);
  float sliceActive = step(0.78, sliceRandom) * tech;
  float sliceShift = (sliceRandom - 0.5) * 0.09 * sliceActive;
  vec2 signalUv = clamp(uv + vec2(sliceShift, 0.0), vec2(0.001), vec2(0.999));
  vec2 direct = IMG_NORM_PIXEL(ink, signalUv).rg;
  vec3 echo = IMG_NORM_PIXEL(echoes, signalUv).rgb;
  float structure = direct.x + direct.y;
  float allegiance = clamp(direct.y / (structure + 0.001), 0.0, 1.0);
  vec3 color = mix(colorA.rgb, colorB.rgb, allegiance) * structure * 1.05;
  color += echo.x * colorA.rgb * 0.72 + echo.y * colorB.rgb * 0.68;
  color += echo.z * vec3(0.22, 0.72, 1.0) * 0.38;
  color += pow(max(structure - 0.75, 0.0), 2.0) * vec3(1.0, 0.9, 0.62) * 0.32;

  vec2 gridCoord = (p + vec2(t * 0.008, 0.0)) * vec2(24.0, 18.0);
  vec2 gridEdge = min(fract(gridCoord), 1.0 - fract(gridCoord));
  float grid = 1.0 - smoothstep(0.018, 0.05, min(gridEdge.x, gridEdge.y));
  grid *= smoothstep(0.025, 0.65, structure + echo.z) * 0.13;

  float frames = 0.0;
  float locator = 0.0;
  float crosshairs = 0.0;
  for (int i = 0; i < 6; i++) {
    float fi = float(i);
    float travel = fract(t * (0.055 + hash11(fi + 2.0) * 0.025) + fi / 6.0 + hash11(fi) * 0.2);
    vec2 center = vec2(mix(-0.58, 0.58, travel), (hash11(fi + 7.0) - 0.5) * 0.58);
    center.y += sin(travel * 12.0 + fi * 2.3 + t * 0.33) * 0.055;
    vec2 q = p - center;
    float angle = (hash11(fi + 12.0) - 0.5) * 1.5 + sin(t * 0.31 + fi) * 0.25;
    q = mat2(cos(angle), -sin(angle), sin(angle), cos(angle)) * q;
    float corners = smoothstep(0.055, 0.095, max(abs(q.x), abs(q.y)));
    frames += boxBorder(q, vec2(0.108, 0.112)) * corners;
    locator += smoothstep(0.014, 0.004, length(q - vec2(0.135, -0.112)));
    float dashX = step(0.48, fract((q.x + t * 0.018) * 62.0));
    float dashY = step(0.48, fract((q.y - t * 0.014) * 62.0));
    float horizontal = exp(-abs(q.y) * 210.0) * step(0.058, abs(q.x)) * (1.0 - step(0.16, abs(q.x))) * dashX;
    float vertical = exp(-abs(q.x) * 210.0) * step(0.058, abs(q.y)) * (1.0 - step(0.16, abs(q.y))) * dashY;
    crosshairs += horizontal + vertical;
  }

  float scanY = 0.25 * sin(t * 0.42 + seed) + 0.035 * sin(t * 1.7);
  float scan = exp(-abs(p.y - scanY) * 190.0);
  scan *= step(0.34, fract((p.x + t * 0.08) * 15.0));
  float dataRail = exp(-abs(abs(p.y) - 0.405) * 230.0);
  dataRail *= step(0.72, fract((p.x - t * 0.05 + seed) * 23.0));
  vec2 dotCell = fract((p + vec2(t * 0.006, 0.0)) * vec2(29.0, 21.0)) - 0.5;
  float dotId = hash11(floor((p.x + 0.7) * 29.0) + floor((p.y + 0.7) * 21.0) * 31.0);
  float dots = smoothstep(0.13, 0.045, length(dotCell)) * step(0.68, dotId);
  dots *= smoothstep(0.03, 0.72, structure + echo.z) * 0.28;
  float sliceEdge = exp(-abs(fract((p.y + 0.6) * 21.0) - 0.5) * 90.0) * sliceActive;
  vec3 techColor = mix(colorA.rgb, colorB.rgb, 0.58);
  color += tech * techColor * (grid + frames * 0.23 + locator * 0.42 + crosshairs * 0.18 + dots);
  color += tech * mix(colorA.rgb, vec3(0.85, 0.95, 1.0), 0.65) * (scan * 0.2 + dataRail * 0.16 + sliceEdge * 0.08);
  color = 1.0 - exp(-max(color, 0.0) * 1.25);
  float vignette = smoothstep(0.86, 0.2, length(p));
  gl_FragColor = vec4(color * (0.38 + 0.62 * vignette), 1.0);
}