/*{
  "DESCRIPTION": "Iridescent wormhole — neon wireframe rings rushing through a swirling oil-slick film, thin-film interference racing toward a wet vanishing point.",
  "CREDIT": "petrol x hyperspace",
  "CATEGORIES": ["generative"],
  "INPUTS": [
    { "NAME": "sides", "TYPE": "float", "DEFAULT": 12.0, "MIN": 4.0, "MAX": 28.0 },
    { "NAME": "speed", "TYPE": "float", "DEFAULT": 0.7, "MIN": 0.0, "MAX": 3.0 },
    { "NAME": "swirl", "TYPE": "float", "DEFAULT": 1.5, "MIN": 0.0, "MAX": 4.0 },
    { "NAME": "ringDensity", "TYPE": "float", "DEFAULT": 14.0, "MIN": 4.0, "MAX": 30.0 }
  ]
}*/

// iridescent thin-film color
vec3 thinFilm(float t) {
    // approximate thin-film interference
    vec3 col;
    col.r = 0.5 + 0.5 * sin(t * 6.28318 + 0.0);
    col.g = 0.5 + 0.5 * sin(t * 6.28318 + 2.094);
    col.b = 0.5 + 0.5 * sin(t * 6.28318 + 4.188);
    return col;
}

// polygon distance: returns signed distance to a regular polygon outline
float polygonRing(vec2 p, float r, float n, float thickness) {
    float an = 6.28318 / n;
    float bn = mod(atan(p.x, p.y), an) - an * 0.5;
    vec2 q = vec2(cos(bn), sin(bn)) * length(p);
    return abs(length(q) - r) - thickness;
}

void main() {
    vec2 uv = isf_FragNormCoord;
    vec2 res = RENDERSIZE;
    vec2 p = (uv - 0.5) * vec2(res.x / res.y, 1.0);
    
    float t = TIME * speed;
    
    // swirl coordinates
    float r = length(p);
    float a = atan(p.y, p.x);
    a += swirl * (1.0 / (r + 0.15)) * 0.3;
    vec2 sp = vec2(cos(a), sin(a)) * r;
    
    // perspective: depth based on radius
    float depth = 1.0 / (r + 0.08);
    
    // rushing rings
    float ringPhase = depth * ringDensity - t * 3.0;
    float rings = fract(ringPhase);
    
    // wireframe polygon ring
    float n = sides;
    float ringR = 0.0; // we evaluate at current radius
    float polySDF = polygonRing(sp, r, n, 0.0);
    
    // distance to nearest ring boundary
    float dr = abs(rings - 0.5) * 2.0; // 0 at center of band, 1 at edge
    float wire = smoothstep(0.0, 0.15, dr) * (1.0 - smoothstep(0.85, 1.0, dr));
    // Actually let's make thin wires
    float wireIntensity = 1.0 - smoothstep(0.0, 0.08, abs(fract(ringPhase) - 0.5));
    
    // polygon edge falloff
    float an = 6.28318 / n;
    float bn = mod(atan(sp.x, sp.y), an) - an * 0.5;
    float edgeDist = abs(sin(bn)); // 0 at vertices, 1 at edge midpoints
    // Actually for wireframe polygon, we want lines along edges
    
    // Let me reconsider — combine rings + polygon shape
    float polyEdge = abs(cos(bn * n * 0.5)); // pulse at edges
    
    // Combine: rushing rings modulated by polygon angular pattern
    float pattern = wireIntensity * (0.4 + 0.6 * pow(abs(cos(bn * n)), 3.0));
    
    // thin-film iridescence
    float filmT = ringPhase * 0.1 + a * 0.3 + t * 0.05;
    vec3 irid = thinFilm(filmT);
    
    // background oil-slick swirl
    float bgT = r * 8.0 + a * 2.0 + t * 0.3;
    vec3 bgIrid = thinFilm(bgT * 0.15);
    float bgFade = smoothstep(0.0, 0.5, r) * 0.3;
    vec3 bg = bgIrid * bgFade;
    
    // glow
    float glow = pattern * (0.8 + 0.4 * sin(ringPhase * 3.14));
    
    vec3 col = bg + irid * glow * 1.5;
    
    // center vanishing point brightening
    col += vec3(0.3, 0.4, 0.6) * smoothstep(0.15, 0.0, r) * 0.5;
    
    // vignette
    col *= 1.0 - smoothstep(0.6, 1.4, r) * 0.7;
    
    // tone
    col = pow(col, vec3(0.85));
    
    gl_FragColor = vec4(col, 1.0);
}