precision highp float;
varying vec2 uv0;

// uniform sampler2D BoxTex;
// uniform sampler2D inputImageTexture;

//  uniform float timer;

uniform sampler2D inputImageTexture;

uniform float timer;
uniform float GLITCH;
uniform float swing;
uniform float yStep;
uniform float horzIntensity;
uniform float intensity;
int level = 0;

highp float sat(highp float t) {
  return clamp(t, 0.0, 1.0);
}

highp vec2 sat(highp vec2 t) {
  return clamp(t, 0.0, 1.0);
}

//remaps inteval [a;b] to [0;1]
highp float remap(highp float t, highp float a, highp float b) {
  return sat((t - a) / (b - a));
}

//note: /\ t=[0;0.5;1], y=[0;1;0]
highp float linterp(highp float t) {
  return sat(1.0 - abs(2.0 * t - 1.0));
}

highp vec3 spectrum_offset(highp float t) {
  highp float t0 = 3.0 * t - 1.5;
  return clamp(vec3(-t0, 1.0 - abs(t0), t0), 0.0, 1.0);
}

//note: [0;1]
highp float rand(highp vec2 n) {
  return fract(sin(dot(n.xy, vec2(12.9898, 78.233))) * 43758.5453);
}

//note: [-1;1]
highp float srand(highp vec2 n) {
  return rand(n) * 2.0 - 1.0;
}

highp float mytrunc(highp float x, highp float num_levels) {
  return floor(x * num_levels) / num_levels;
}

highp vec2 mytrunc(highp vec2 x, highp float num_levels) {
  return floor(x * num_levels) / num_levels;
}

// varying highp vec2 textureCoordinate;
// uniform sampler2D inputImageTexture;
// uniform highp float iTime;
highp vec2 inputSize = vec2(720.0, 1280.0);
// uniform sampler2D noiseTexture;

// uniform int isPhoto;


void main() {
  // if (level == 0) {
  //   GLITCH = 0.1;
  // } else if (level == 1) {
  //   GLITCH = 0.2;
  // } else {
  //   GLITCH = 0.2;
  //   swing = 16.0;
  //   yStep = 10.0;
  // }
// float iTime = time;
  highp vec2 iResolution = inputSize;

  highp float aspect = iResolution.x / iResolution.y;
  highp vec2 uv = uv0;
  //uv.y = 1.0 - uv.y;

  highp float ITime = mod(timer, 32.0); // + modelmat[0].x + modelmat[0].z;

  //float rdist = length( (uv - vec2(0.5,0.5))*vec2(aspect, 1.0) )/1.4;
  //GLITCH *= rdist;

  highp float gnm = sat(GLITCH * intensity);
  highp float rnd0 = rand(mytrunc(vec2(ITime, ITime), swing));
  highp float r0 = sat((1.0 - gnm) * 0.7 + rnd0);
  highp float rnd1 = rand(vec2(mytrunc(uv.x, 10.0 * r0), ITime)); //horz
  //float r1 = 1.0f - sat( (1.0f-gnm)*0.5f + rnd1 );
  highp float r1 = 0.5 - 0.5 * gnm + rnd1;
  r1 = 1.0 - max(0.0, ((r1 < 1.0) ? r1 : 0.9999999)); //note: weird ass bug on old drivers
  highp float rnd2 = rand(vec2(mytrunc(uv.y, yStep * r1), ITime)); //vert
  highp float r2 = sat(rnd2);

  highp float rnd3 = rand(vec2(mytrunc(uv.y, 10.0 * r0), ITime));
  highp float r3 = (1.0 - sat(rnd3 + 0.8)) - 0.1;

  highp float pxrnd = rand(uv + ITime);

  highp float ofs = 0.05 * r2 * GLITCH * intensity * (rnd0 > 0.5 ? 1.0 : -1.0);
  ofs += 0.5 * pxrnd * ofs;

  uv.y += 0.1 * r3 * GLITCH * intensity;

  const int NUM_SAMPLES = 10;
  const highp float RCP_NUM_SAMPLES_F = 1.0 / float(NUM_SAMPLES);

  highp vec4 sum = vec4(0.0);
  highp vec3 wsum = vec3(0.0);
  for (int i = 0; i < NUM_SAMPLES; ++i) {
    highp float t = float(i) * RCP_NUM_SAMPLES_F;
    uv.x = sat(uv.x + ofs * horzIntensity * 5. * t);
    highp vec4 samplecol = texture2D(inputImageTexture, uv);
    highp vec3 s = spectrum_offset(t);
    samplecol.rgb = samplecol.rgb * s;
    sum += samplecol;
    wsum += s;
  }
  sum.rgb /= wsum;
  sum.a *= RCP_NUM_SAMPLES_F;

  //fragColor = vec4( sum.bbb, 1.0 ); return;

  gl_FragColor.rgb = sum.rgb; // * outcol0.a;
  gl_FragColor.a = 1.0;
}