// Source: @notargs https://twitter.com/notargs/status/1250468645030858753
uniform float3 iResolution;
uniform float  iTime;

float f(vec3 p) {
    p.z -= iTime * 10.;
    float a = p.z * .1;
    p.xy *= mat2(cos(a), sin(a), -sin(a), cos(a));
    return .1 - length(cos(p.xy) + sin(p.yz));
}

half4 main(vec2 fragcoord) {
    vec3 d = .5 - fragcoord.xy1 / iResolution.y;
    vec3 p=vec3(0);
    for (int i = 0; i < 32; i++) {
      p += f(p) * d;
    }
    return ((sin(p) + vec3(2, 5, 9)) / length(p)).xyz1;
}