A Tribute to Phenomena

// ╔═════════════╦════════════════╗
// ║ Marco Gomez ║ https://mgz.me ║
// ╚═════════════╩════════════════╝
precision highp float;

uniform vec2 resolution;
uniform float time;

#define t time * 0.7
const int starsPerPlane = 30;
const int planes = 4;
const float barSize = 0.12;
const float barsAng = 1.4;
vec2 barPos;
vec3 barCol;
vec3 cp;

float rand (vec2 uv) {
  return fract(sin(dot(uv, vec2(12.4124, 48.4124))) * 48512.41241);
}

float noise (vec2 uv) {
  vec2 b = floor(uv);
  return mix(
    mix(rand(b), rand(b + vec2(1.0, 0.0)), 0.5),
    mix(rand(b + vec2(0.0, 1.0)), rand(b + vec2(1.0, 1.0)), 0.5),
    0.5
  );
}

vec3 mixCol(float val, float r, float g, float b) {
  return vec3(val * r, val * g, val * b);
}

void bar(float pos, float r, float g, float b) {
  if (
    (barPos.y <= pos + barSize) &&
    (barPos.y >= pos - barSize)
  ) {
    barCol = mixCol(1.0 - abs(pos - barPos.y) / barSize, r, g, b);
  }
}


vec3 twist(vec3 p) {
  float f = sin(t / 3.0) * 1.45;
  float c = cos(f * p.y);
  float s = sin(f / 2.0 * p.y);
  mat2 m = mat2(c, -s, s, c);
  return vec3(m * p.xz, p.y);
}

float cube(vec3 p) {
  p = twist(p);
  cp.x = sin(-t);
  cp.y = cos(-t);
  mat2 m = mat2(cp.y, -cp.x, cp.x, cp.y);
  p.xy *= m; p.xy *= m; p.yz *= m;
  p.zx *= m; p.zx *= m; p.zx *= m;
  cp = p;
  return length(max(abs(p) - vec3(0.4), 0.0)) - 0.08;
}

float face(vec2 uv) {
  uv.y = mod(uv.y, 1.0);
  return (uv.y < uv.x != 1.0 - uv.y < uv.x) ? 1.0 : 0.0;
}

vec3 getNormal(vec3 p) {
  vec2 e = vec2(0.005, -0.005);
  return normalize(
    e.xyy * cube(p + e.xyy) +
    e.yyx * cube(p + e.yyx) +
    e.yxy * cube(p + e.yxy) +
    e.xxx * cube(p + e.xxx)
  );
}

void main(void) {
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  vec2 suv = uv;
  uv = uv * 2.0 - 1.0;
  float ar = resolution.x / resolution.y;
  uv.x *= ar;
  uv *= 1.2;
  float x = gl_FragCoord.x;
  float stp = 1.0;
  float dist = 0.0;
  float near = -1.0;
  float far = -1.0;
  vec3 lightPos = vec3(1.5, 0.5, 1.0);
  float hitdist = -1.0;
  float ay = max(0.1, 0.5 - t / 6.0);
  vec3 ro = vec3(0.0, 0.0, 2.1);
  vec3 rd = normalize(vec3(uv, -2.0));
  for (int i = 0; i < 128; i++) {
    stp = cube(ro + rd * dist);
    dist += stp * 0.5;
    if (dist > 4.0) { break; }
    if (stp < 0.01) {
      far = (
        face(+cp.yx) +
        face(-cp.yx) +
        face(+cp.xz) +
        face(-cp.xz) +
        face(+cp.zy) +
        face(-cp.zy)
      );
      if (hitdist < 0.0) { hitdist = dist; }
      if (near < 0.0) { near = far; }
      dist += 0.05;
    }
  }
  const float speed = 42.0;
  const int layers = 12;
  float stars = 0.0;
  float fl, s;
  for (int layer = 0; layer < layers; layer++) {
    fl = float(layer);
    s = (500.0 - fl * 30.0);
    stars += step(
      0.1,
      pow(
        abs(noise(mod(vec2(suv.x * s + time * speed - fl * 100.0, suv.y * s), resolution.x))),
        21.0
      )
    ) * (fl / float(layers));
  }
  barPos = uv;
  barCol = vec3(stars);
  bar(sin(time                      ), 1.0, 0.0, 0.0);
  bar(sin(time + barsAng / 6.0      ), 1.0, 1.0, 0.0);
  bar(sin(time + barsAng / 6.0 * 2.0), 0.0, 1.0, 0.0);
  bar(sin(time + barsAng / 6.0 * 3.0), 0.0, 1.0, 1.0);
  bar(sin(time + barsAng / 6.0 * 4.0), 0.5, 0.0, 1.0);
  bar(sin(time + barsAng / 6.0 * 5.0), 1.0, 0.0, 1.0);
  vec3 col = barCol;
  if (near > 0.0) {
    vec3 sp = ro + rd * hitdist;
    vec3 ld = lightPos - sp;
    float lDist = max(length(ld), 0.001);
    ld /= lDist;
    float atten = 1.0 / (1.0 + lDist * 0.2 + lDist * 0.1);
    float ambience = 0.5;
    vec3 sn = getNormal(sp);
    float diff = min(0.3, max(dot(sn, ld), 0.0));
    float spec = pow(max(dot(reflect(-ld, sn), -rd), 0.0), 32.0);
    col = mix(
      vec3(0.12, 0.0, 0.3),
      vec3(1.0, 1.0, 1.0),
      vec3((near * 0.45 + far * far * 0.04))
    );
    col = col * (diff + ambience) + vec3(0.78, 0.5, 1.0) * spec / 1.5;
  }
  float gs = 2.0;
  float grid = (
    (mod(floor((suv.x) * resolution.x / gs), 2.0) == 0.0 ? 1.0 : 0.0) *
    (mod(floor((suv.y) * resolution.y / gs), 2.0) == 0.0 ? 1.0 : 0.0)
  );
  gl_FragColor = vec4(col * grid, 1.0);
}