#version 450

layout(location = 0) in vec3 fragColor;
layout(location = 1) in vec2 fragPos;

layout(location = 0) out vec4 outColor;

// void main() {
//     outColor = vec4(fragColor, 1.0);
// }
vec3 mandel(vec2 z0) {
    float k = 0.0;
    vec2 z = vec2(0.0);
    for(int i = 0; i < 420; ++i) {
        z = vec2(z.x*z.x-z.y*z.y, z.x*z.y*2.0) + z0;
        if (length(z) > 20.0) break;
        k += 1.0;
    }
    float mu = k + 1.0 - log2(log(length(z)));
    return sin(mu*0.1 + vec3(0.0,0.5,1.0));
}
void main() {
    float ar = fragPos.x / fragPos.y;
    vec2 uv = gl_FragCoord.xy / fragPos.yy - vec2(0.66 * ar, 0.5);
    //uv = uv * 2.0 + vec2(-0.3, 1.0);
    float p = 30.0;
    float t = mod(13.0, p);
    if (t > p/2.0) t = p - t;
    float scale = 0.5 + pow(4.0, t);
    vec2 offset = vec2(-1.36799, .01);
    uv += offset*scale;
    uv /= scale;
    outColor = vec4(mandel(uv), 1.0);
}