image-seizure-effect.frag

precision highp float;
varying vec2 uv;
uniform float time;
uniform sampler2D img;
vec3 palette( in float t, in vec3 a, in vec3 b, in vec3 c, in vec3 d ) {
  return a + b*cos( 6.28318*(c*t+d) );
}
vec3 color (float t) {
  return palette(
    t,
    vec3(.5),
    vec3(.6 + .1 * cos(.3 * time)),
    vec3(1.),
    vec3(0.22, 0.5, 0.77)
  );
}
void main() {
  float v = 1. - texture2D(img, uv).a;
  v = max(-step(fract(time), 0.5), v);
  gl_FragColor = vec4(
    step(v, 0.) * color(1.6 * (uv.y + time)) +
    step(0., v) * color(sqrt(max(v, 0.)) - 2. * time),
    1.0);
}

image used for https://www.hicetnunc.xyz/objkt/48081 :

https://greweb.me/images/tezos-dist.png