struct Params {
  time: f32,
  progress: f32,
  aspect: f32,
  padding: f32,
}

@group(0) @binding(0) var<uniform> params: Params;

fn thread(value: f32, width: f32) -> f32 {
  return pow(0.5 + 0.5 * cos(value), width);
}

@fragment
fn fs_main(@location(0) uv: vec2f) -> @location(0) vec4f {
  let p = vec2f(uv.x * params.aspect, uv.y);
  let drift = sin(p.y * 18.0 + params.time * 0.42) * 0.018;
  let warp = thread((p.x + drift) * 310.0, 7.0);
  let weft = thread((p.y + sin(p.x * 13.0) * 0.006) * 280.0, 8.0);
  let crossing = step(0.5, fract(floor(p.x * 49.0) * 0.5 + floor(p.y * 46.0) * 0.5));
  let overUnder = mix(warp * 0.58 + weft, warp + weft * 0.55, crossing);
  let irregularity = sin(p.x * 127.0 + sin(p.y * 31.0)) * 0.025;

  let revealEdge = params.progress + sin(uv.y * 9.0 + params.time * 0.55) * 0.035;
  let woven = 1.0 - smoothstep(revealEdge - 0.15, revealEdge + 0.04, uv.x);
  let looseYarn = thread((p.x + sin(p.y * 8.0 + params.time) * 0.035) * 74.0, 10.0);
  let wovenMask = smoothstep(0.16, 0.72, overUnder + irregularity);
  let looseMask = smoothstep(0.24, 0.78, looseYarn);
  let threadMask = mix(looseMask * 0.72, wovenMask, woven);

  let slider = smoothstep(0.0, 1.0, params.progress);
  let dyed = 1.0 - smoothstep(slider - 0.025, slider + 0.025, uv.x);
  let greige = vec3f(0.69, 0.62, 0.51);
  let madder = vec3f(0.72, 0.24, 0.12);
  let indigo = vec3f(0.08, 0.34, 0.58);
  let dyeColor = mix(madder, indigo, smoothstep(0.15, 0.9, uv.x));
  let threadColor = mix(greige, dyeColor, dyed);
  let shadow = vec3f(0.105, 0.10, 0.082);
  let highlight = mix(vec3f(0.90, 0.84, 0.72), dyeColor * 1.35, dyed);
  var color = mix(shadow, threadColor, threadMask);
  color += highlight * pow(max(warp, weft), 10.0) * 0.14 * woven;

  let vignette = smoothstep(0.82, 0.28, distance(uv, vec2f(0.5)));
  color *= 0.7 + vignette * 0.3;
  return vec4f(color, 1.0);
}