precision highp float;

uniform float u_time;
uniform vec2 u_resolution;
varying vec2 v_texCoord;
varying vec2 v_patternUV;

void main() {
  vec2 fragCoord = gl_FragCoord.xy;
  vec2 iResolution = u_resolution;
  float iTime = u_time * .5;

  float mr = min(iResolution.x, iResolution.y);
  vec2 uv = (fragCoord * 2.0 - iResolution.xy) / mr;

  float d = -iTime * 0.5;
  float a = 0.0;
  for (float i = 0.0; i < 8.0; ++i) {
    a += cos(i - d - a * uv.x);
    d += sin(uv.y * i + a);
  }
  d += iTime * 0.5;
  vec3 col = vec3(cos(uv * vec2(d, a)) * 0.6 + 0.4, cos(a + d) * 0.5 + 0.5);
  col = cos(col * cos(vec3(d, a, 2.5)) * 0.5 + 0.5);
  gl_FragColor = vec4(col, 1.0);
}
Iridescence

Credit
