mat2 rot(float a) {
    float s = sin(a);
    float c = cos(a);
    return mat2(c, -s, s, c);
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = fragCoord.xy / iResolution.xy;
    vec2 p = uv * 2.0 - 1.0;
    p.x *= uAspect;

    vec2 m = uPointer * 2.0 - 1.0;
    m.x *= uAspect;

    float t = iTime;

    float bass = uAudioBass;
    float mid = uAudioMid;
    float high = uAudioHigh;
    float level = uAudioLevel;

    vec2 q = p;
    float distMouse = length(q - m);

    q += uPointerDelta * vec2(uAspect, 1.0) * exp(-distMouse * 4.0) * 24.0;
    q *= rot(t * 0.08 + bass * 1.6 + uPointerDown * 0.6);

    float r = length(q);
    float a = atan(q.y, q.x);

    float spiral = sin(a * 6.0 + r * (18.0 + bass * 30.0) - t * (2.5 + level * 8.0));
    float nebula = sin(q.x * (5.0 + mid * 14.0) + t);
    nebula += sin(q.y * (7.0 + high * 22.0) - t * 1.3);
    nebula += sin((q.x + q.y) * 6.0 + spiral * 2.0);
    nebula /= 3.0;

    float field = smoothstep(-0.15, 0.85, nebula);
    float core = 0.035 / max(r, 0.035);
    float mouse = 0.02 / max(distMouse, 0.02);

    vec3 bg = vec3(0.004, 0.008, 0.03);
    vec3 blue = vec3(0.04, 0.22, 1.0);
    vec3 cyan = vec3(0.18, 0.85, 1.0);
    vec3 violet = vec3(0.7, 0.16, 1.0);
    vec3 hot = vec3(1.0, 0.35, 0.75);

    vec3 col = bg;
    col += blue * field * (0.25 + mid);
    col += cyan * core * (0.25 + bass * 1.5);
    col += violet * smoothstep(0.2, 1.0, spiral * 0.5 + 0.5) * (0.2 + high);
    col += hot * level * smoothstep(0.9, 0.0, r);
    col += cyan * mouse * 0.16;

    col *= 1.0 + level * 2.0;
    col *= 1.0 - smoothstep(0.8, 1.7, length(p)) * 0.55;

    col = pow(max(col, 0.0), vec3(0.82));

    fragColor = vec4(col, 1.0);
}