// [FBP] fbp-web · direction: dream · exact wsp.baby fragment shader
// Source: https://wsp.baby/_next/static/chunks/4783-9515bda8d152c361.js (module 41577)

#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
#else
precision mediump float;
#endif
uniform vec2 uRes;      // canvas size in device px
uniform vec2 uCell;     // cell size in device px
uniform float uTime;
uniform vec2 uMouse;    // device px from the top-left (far away = off)
uniform sampler2D uAtlas;
uniform float uGlyphs;
uniform vec3 uColor;
uniform vec3 uGround;
uniform float uIntensity;
uniform float uFade;    // 1 = fade the bottom half out
uniform float uHeroRows;// rows in the first screen (bars sit at its bottom)
uniform sampler2D uSpec;
uniform float uLevel;   // 0..1 loudness (adaptive)
uniform float uBeatAge; // seconds since the last beat (big = none)
uniform vec2 uBeatPos;  // tap position in device px (far away = none)
uniform float uGlow;    // cursor glow on/off

float hash(vec2 c){ return fract(sin(dot(c, vec2(12.9898, 78.233))) * 43758.5453); }

void main(){
  vec2 px = vec2(gl_FragCoord.x, uRes.y - gl_FragCoord.y);
  vec2 cell = floor(px / uCell);
  vec2 local = fract(px / uCell);
  vec2 grid = floor(uRes / uCell);
  float x = cell.x, y = cell.y;

  // Harmonic wave field with subtle slow vortex drift.
  float cx = grid.x * 0.5 + sin(uTime * 0.22) * grid.x * 0.08;
  float cy = grid.y * 0.42 + cos(uTime * 0.17) * grid.y * 0.06;
  vec2 dv = vec2(x - cx, (y - cy) * 1.85);
  float d = length(dv);
  float ang = atan(dv.y, dv.x);
  float t = uTime;
  float lift = uLevel * 0.35;
  float v = sin(x * 0.055 + t * 0.72)
          + sin(y * 0.13 - t * 0.48)
          + sin((x + y * 1.7) * 0.036 + t * 0.38)
          + sin(d * 0.155 - t * (1.42 + uLevel * 0.6) + sin(ang * 2.0 + t * 0.25) * 0.35) * 1.25;
  v = clamp((v + 4.25 + lift) / 8.5, 0.0, 1.0);
  v = pow(v, 2.05) * uIntensity;

  // Bottom fade (the hero's field runs on past the first screen).
  float fade = 1.0;
  if (uFade > 0.5) { float k = y / grid.y; fade = k < 0.46 ? 1.0 : pow(max(0.0, 1.0 - (k - 0.46) / 0.54), 1.55); }

  // Cursor & touch glow + subtle concentric wake ripple.
  float cursorBoost = 0.0;
  if (uGlow > 0.5) {
    vec2 m = uMouse / uCell;
    vec2 md = vec2(x - m.x, (y - m.y) * 1.85);
    float md2 = dot(md, md);
    float mdLen = sqrt(md2);
    float core = exp(-md2 / 92.0) * 0.92;
    float wake = sin(mdLen * 0.55 - t * 3.8) * exp(-md2 / 260.0) * 0.18;
    cursorBoost = max(0.0, core + wake);
    v = min(1.0, v + cursorBoost);
  }

  // Beat / tap pulse ring radiating out from the tap point, not the center.
  // Distance is measured in cells from uBeatPos so the wave starts at the cursor.
  if (uBeatAge < 1.6) {
    vec2 b = uBeatPos / uCell;
    vec2 bd = vec2(x - b.x, (y - b.y) * 1.85);
    float bdLen = length(bd);
    float r = uBeatAge * 46.0;
    float q = (bdLen - r) / 2.3;
    float ring = exp(-q * q) * (1.0 - uBeatAge / 1.6);
    v = min(1.0, v + ring * 0.38);
  }
  if (uLevel > 0.001) {
    float band = pow(x / grid.x, 0.75);
    float s = texture2D(uSpec, vec2(band, 0.5)).r;
    float top = uHeroRows - s * uHeroRows * 0.22;
    if (y > top && y < uHeroRows + 1.0) {
      float k = 1.0 - (y - top) / max(1.0, uHeroRows - top + 1.0);
      v = max(v, (0.08 + s * 0.32) * (0.5 + 0.5 * k));
    }
  }
  v *= fade;

  // Each cell's letter: brighter cells take denser glyphs; the seed shifts smoothly.
  float h = hash(cell);
  float seed = hash(cell + floor(t * 0.035 + h * 13.0));
  float g = floor(min(uGlyphs - 1.0, (v * 0.9 + seed * 0.14) * uGlyphs));
  float lvl = min(11.0, floor(v * 12.0)) / 11.0;
  vec3 dim = vec3(0.042, 0.038, 0.078);
  vec3 mid = uColor * vec3(1.04, 0.96, 1.08);
  vec3 peak = vec3(0.86, 0.78, 1.0);
  vec3 col = mix(dim, mid, pow(lvl, 1.05));
  col = mix(col, peak, smoothstep(0.68, 1.0, lvl) * 0.52 + cursorBoost * 0.28);
  float a = texture2D(uAtlas, vec2((g + local.x) / uGlyphs, local.y)).a;
  gl_FragColor = vec4(mix(uGround, col, a), 1.0);
}