#version 410 core

#ifdef GL_ES
precision mediump float;
#endif

out vec4 FragColor; // Output to screen

uniform vec2 u_resolution;  // <-- screen resolution from CPU
uniform float u_time;       // <-- time from CPU
uniform float u_oscilator;      // <-- oscislator from CPU
uniform float u_direction;  // <-- direction from CPU

vec3 hsv2rgb(vec3 c) {
    vec3 rgb = clamp(
        abs(mod(c.x*6.0 + vec3(0.0,4.0,2.0),
        6.0) - 3.0) - 1.0,
        0.0,
        1.0
    );
    return c.z * mix(vec3(1.0), rgb, c.y);
}

vec3 getPaletteColor(float idx, float seed) {
    float baseHue = fract(seed);     // 0..1 base hue
    float sat = 0.9;
    float val = 0.9;

    // Shift hue across palette (idx ensures difference)
    float hue = fract(baseHue + (idx * 0.33));

    return hsv2rgb(vec3(hue, sat, val));
}


vec2 random(vec2 p) {
    return normalize(vec2(
        fract(sin(dot(p, vec2(127.1, 311.7))) * 43758.5453),
        fract(sin(dot(p, vec2(269.5, 183.3))) * 43758.5453)
    ) * 2.0 - 1.0);
}

int randomInt(int x, int y) {
    return int(fract(sin(float(x * 12 + y * 78)) * 43758.5453) * 256.0);
}

float perlinNoise(vec2 st) {
    vec2 i = floor(st);
    vec2 f = fract(st);

    // Corners
    vec2 g00 = random(i + vec2(0.0,0.0));
    vec2 g10 = random(i + vec2(1.0,0.0));
    vec2 g01 = random(i + vec2(0.0,1.0));
    vec2 g11 = random(i + vec2(1.0,1.0));

    // Offsets
    float n00 = dot(g00, f - vec2(0.0,0.0));
    float n10 = dot(g10, f - vec2(1.0,0.0));
    float n01 = dot(g01, f - vec2(0.0,1.0));
    float n11 = dot(g11, f - vec2(1.0,1.0));

    // Interpolation
    vec2 u = f*f*(3.0-2.0*f);
    return mix(mix(n00, n10, u.x), mix(n01, n11, u.x), u.y);
}

mat2 rotate2d(float angle){
    return mat2(cos(angle),-sin(angle),
                sin(angle),cos(angle));
}

void main() {

    vec2 st = gl_FragCoord.xy / u_resolution; // Normalize coordinates
    st += 13.0 + (u_oscilator * 0.001); // Center the coordinates

    vec2 pos = st * (3.0);

    pos = rotate2d(perlinNoise(pos)) * pos;
    pos -= (u_time * (float(u_oscilator) * 0.5) * 0.2);

    float n = perlinNoise(pos);
    vec3 color;

    if (n > 0.4) {
        color = vec3((n + 0.4), (n + 0.4), (n + 0.4));
        // color = getPaletteColor(u_oscilator, (n + 0.5));
    } else if (n > 0.1) {
        color = vec3(n + 0.5, n + 0.1 , 0.0);
        // color = getPaletteColor(u_oscilator + 1, (n + 0.5));
    } else {
        color = vec3(n + 0.05, n + 0.05, n + 0.05);
        // color = getPaletteColor(u_oscilator + 2, (n + 0.5));
        // color = vec3(0.0);
    }
    FragColor = vec4(color, 1.0);
}