void mainImage(out vec4 fragColor, in vec2 fragCoord)
{
    vec2 uv = fragCoord.xy / iResolution.xy;

    vec2 p = uv * 2.0 - 1.0;

    p.x *= iResolution.x / iResolution.y;

    float t = iTime;

    vec3 color = vec3(0.0);

    for(int i = 0; i < 3; i++)
    {
        vec2 q = p;

        q += sin(q.yx * (4.0 + float(i) * 2.0) + t)
             * (0.12 + float(i) * 0.03);

        float layer =
            0.02 / abs(length(q) - 0.4);

        vec3 layerCol = vec3(
            0.2 + float(i) * 0.3,
            0.4,
            1.0
        );

        color += layerCol * layer;
    }

    fragColor = vec4(color, 1.0);
}