#version 300 es
precision highp float;
uniform vec3 iResolution;
uniform float iTime;

out vec4 FragColor;

#define PALETTE vec3(9,4,0)

void mainImage(out vec4 o, vec2 u) {
    float n, i, s, t = iTime * .2, d, v;
    vec3 q, p = iResolution, c;
    u = (u + u - p.xy) / p.y;
    vec2 l = u - (u.yx * .9 + .3 - vec2(-.35, .15));
    for(; i++ < 5e1 && d < 5e1; d += s = min(q.y = .01 + .6 * abs(24. - length(q.xy)), v = max(s, dot(abs(fract(p) - .5), vec3(.04)))), c += (1. + cos(p.z + PALETTE)) / v + d * vec3(5, 2, 1) / q.y / 1e1 + 7. * vec3(3, 4, 1) / length(l)) for(q = p = vec3(u * d, d - 16.), s = length(p) - 8., p.xy *= mat2(cos(t + p.z * .6 + vec4(0, 33, 11, 0))), p += cos(t + p.zxy) + cos(t + p.yzx * s) / s / 4., p += .5 * cos(t + dot(cos(t + p), p) * p), n = .02; n < 2.; n *= 1.6) q.y -= abs(dot(sin(4. * t + .3 * q / n), q - q + n));

    c = mix(c, c.yzx, smoothstep(2., .1, length(u) * 1.));
    o.rgb = tanh(c * c / 6e7 / length(u - .3) + .1 * length(u));
}

void main() {
    mainImage(FragColor, gl_FragCoord.xy);
}