void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
  float time = iTime * 1.0;
  vec2 uv = (gl_FragCoord.xy / iResolution.xx - 0.5) * 8.0;
  vec2 uv0 = uv;
  float i0 = 1.0;
  float i1 = 1.0;
  float i2 = 1.0;
  float i4 = 0.0;
  for (int s = 0; s < 7; s++) {
    vec2 r;
    r = vec2(cos(uv.y * i0 - i4 + time / i1), sin(uv.x * i0 - i4 + time / i1)) / i2;
    r += vec2(-r.y, r.x) * 0.3;
    uv.xy += r;

    i0 *= 1.93;
    i1 *= 1.15;
    i2 *= 1.7;
    i4 += 0.05 + 0.1 * time * i1;
  }
  float r = sin(uv.x - time) * 0.5 + 0.5;
  float b = sin(uv.y + time) * 0.5 + 0.5;
  float g = sin((uv.x + uv.y + sin(time * 0.5)) * 0.5) * 0.5 + 0.5;
  fragColor = vec4(r, g, b, 1.0);
}