AI CSS Animations

Folded Cortex with Firing Pulses

Brain-like folded ridges turn slowly under soft light while waves of activity race across them. Higher token rates fire the waves faster and brighter along every fold.

Also known as: brain shader, cortex folds, neural activity animation.

HTML + JS

A canvas and a module script, nothing to install. Set canvas.dataset.tps from your stream, or call canvas.token() once per token.

<canvas id="shader-cortex-fold-pulses" data-tps="7" data-color="#b77dff" style="display:block;width:100%;height:240px;border-radius:12px"></canvas>
<script type="module">
  // Set canvas.dataset.tps from your stream, or call canvas.token() per token.
  const canvas = document.getElementById("shader-cortex-fold-pulses");
  const gl = canvas.getContext("webgl2", { alpha: false, antialias: false });
  const fragment = `#version 300 es
precision highp float;
uniform vec3 iResolution;
uniform float iTime;
uniform float uTokens;
uniform float uTps;
uniform vec3 uColor;
out vec4 outColor;
#define TAU 6.28318530718
#define PI 3.14159265359
mat2 rot(float a) { float c = cos(a), s = sin(a); return mat2(c, -s, s, c); }
float hash12(vec2 p) { vec3 q = fract(vec3(p.xyx) * 0.1031); q += dot(q, q.yzx + 33.33); return fract((q.x + q.y) * q.z); }
// a phase in radians that wraps at whole turns, so it stays precise for hours
float turn(float x, float k) { return mod(x * k, TAU); }
vec3 toLin(vec3 c) { return pow(max(c, vec3(0.0)), vec3(2.2)); }
vec3 hueShift(vec3 c, float a) {
  vec3 k = vec3(0.57735);
  float cs = cos(a);
  return max(c * cs + cross(k, c) * sin(a) + k * dot(k, c) * (1.0 - cs), vec3(0.0));
}
// ACES filmic curve, gamma and a tiny dither against banding
vec3 finish(vec3 c, vec2 fc) {
  c = max(c, vec3(0.0));
  c = clamp((c * (2.51 * c + 0.03)) / (c * (2.43 * c + 0.59) + 0.14), 0.0, 1.0);
  c = pow(c, vec3(1.0 / 2.2));
  return c + (hash12(fc) + hash12(fc + 19.19) - 1.0) / 255.0;
}

float gyr(vec3 q) { return dot(sin(q), cos(q.yzx)); }

float folds(vec3 p) {
  vec3 q = p * 12.0;
  q += 1.1 * sin(q.zxy * 0.31 + vec3(0.0, 1.7, 3.1));
  return gyr(q);
}

float sdEll(vec3 p, vec3 r) {
  float k0 = length(p / r);
  float k1 = length(p / (r * r));
  return k0 * (k0 - 1.0) / k1;
}

float map(vec3 p, out float f) {
  vec3 q = p;
  // flatter underneath, fuller at the back
  q.y *= p.y < 0.0 ? 1.35 : 1.0;
  q.y -= 0.06 * q.z;
  float d = sdEll(q, vec3(1.18, 0.74, 0.92));
  // the fissure between the two hemispheres
  d += 0.09 * exp(-p.x * p.x * 90.0) * smoothstep(-0.2, 0.5, p.y);
  f = folds(p);
  float a = abs(f);
  d += 0.024 * (1.0 - smoothstep(0.0, 0.4, a)) - 0.01 * smoothstep(0.4, 1.3, a);
  return d;
}

vec3 toBrain(vec3 p, float yaw) {
  p.xz *= rot(yaw);
  return p;
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
  vec3 acc = toLin(uColor);
  vec3 acc2 = hueShift(acc, -0.7);
  vec3 hot = mix(acc, vec3(1.0), 0.65);
  float e = 1.0 - exp(-uTps / 90.0);
  float yaw = 0.5 + 0.35 * sin(turn(iTime, 0.09));
  float base = fract(iTime * 0.06);

  vec3 ro = vec3(0.0, 0.0, 3.4);
  vec3 rd = normalize(vec3(uv, -1.5));
  ro.yz *= rot(-0.36); rd.yz *= rot(-0.36);
  vec3 col = acc * 0.014 * smoothstep(1.1, 0.0, length(uv));

  float b = dot(ro, rd);
  float h = b * b - dot(ro, ro) + 1.25 * 1.25;
  if (h > 0.0) {
    float t = -b - sqrt(h);
    float tEnd = -b + sqrt(h);
    float dmin = 1e3, tmin = t, f = 0.0;
    for (int i = 0; i < 64; i++) {
      float d = map(toBrain(ro + rd * t, yaw), f);
      if (d < dmin) { dmin = d; tmin = t; }
      if (d < 0.0008 * t || t > tEnd) break;
      t += d * 0.6;
    }
    float pxw = 1.6 * tmin / (1.5 * iResolution.y);
    float cover = 1.0 - smoothstep(0.0, pxw, dmin);
    if (cover > 0.0) {
      vec3 p = toBrain(ro + rd * tmin, yaw);
      float fold;
      map(p, fold);
      vec2 k = vec2(1.0, -1.0) * 0.002;
      float fx;
      vec3 n = normalize(k.xyy * map(p + k.xyy, fx) + k.yyx * map(p + k.yyx, fx) + k.yxy * map(p + k.yxy, fx) + k.xxx * map(p + k.xxx, fx));
      vec3 vd = toBrain(rd, yaw);
      vec3 L = toBrain(normalize(vec3(-0.5, 0.85, 0.45)), yaw);
      float a = abs(fold);
      float groove = smoothstep(0.0, 0.55, a);
      float crest = smoothstep(0.6, 1.3, a);
      float dif = clamp(dot(n, L) * 0.6 + 0.4, 0.0, 1.0);
      float cosv = clamp(-dot(vd, n), 0.0, 1.0);
      float fres = pow(1.0 - cosv, 3.0);
      float spec = pow(clamp(dot(reflect(vd, n), L), 0.0, 1.0), 30.0);

      vec3 tissue = mix(acc * 0.012, mix(acc, acc2, 0.35) * 0.12, dif * dif) * (0.15 + 0.85 * groove);

      // waves of activity spreading along the folds from a few foci
      float fire = 0.0;
      for (int i = 0; i < 3; i++) {
        float fi = float(i);
        vec3 c = normalize(vec3(sin(fi * 2.4 + 0.5), 0.5 + 0.4 * cos(fi * 1.7), cos(fi * 2.4 + 0.5))) * vec3(1.18, 0.74, 0.92);
        float dist = length(p - c);
        float x = fract(dist * 1.6 - base - fract(uTokens * (0.0042 + 0.0006 * fi)) - fi * 0.37);
        fire += smoothstep(0.0, 0.03, x) * exp(-x * 7.0) * exp(-dist * 0.5);
      }
      // the pulses run along the sulci, the fine lines between the folds
      float line = exp(-a * a * 30.0);
      vec3 glow = mix(acc, hot, clamp(fire, 0.0, 1.0)) * line * fire * (0.5 + 3.2 * e);
      glow += acc * line * (0.03 + 0.1 * e);
      vec3 s = tissue + glow + mix(acc, acc2, 0.5) * fres * 0.35 * groove + vec3(1.0) * spec * 0.2 * groove;
      col = mix(col, s, cover);
    }
  }
  fragColor = vec4(finish(col, fragCoord), 1.0);
}

void main() {
  mainImage(outColor, gl_FragCoord.xy);
  outColor.a = 1.0;
}
`;
  const vertex = `#version 300 es
void main() {
  vec2 p = vec2((gl_VertexID << 1) & 2, gl_VertexID & 2);
  gl_Position = vec4(p * 2.0 - 1.0, 0.0, 1.0);
}
`;
  const compile = (type, src) => {
    const s = gl.createShader(type);
    gl.shaderSource(s, src);
    gl.compileShader(s);
    if (!gl.getShaderParameter(s, gl.COMPILE_STATUS)) throw new Error(gl.getShaderInfoLog(s));
    return s;
  };
  const program = gl.createProgram();
  gl.attachShader(program, compile(gl.VERTEX_SHADER, vertex));
  gl.attachShader(program, compile(gl.FRAGMENT_SHADER, fragment));
  gl.linkProgram(program);
  gl.useProgram(program);
  const u = (n) => gl.getUniformLocation(program, n);
  const [res, time, tokens, rate, color] = ["iResolution", "iTime", "uTokens", "uTps", "uColor"].map(u);
  const hex = parseInt((canvas.dataset.color || "#7c5cff").slice(1), 16);
  gl.uniform3f(color, ((hex >> 16) & 255) / 255, ((hex >> 8) & 255) / 255, (hex & 255) / 255);

  // canvas.token(): count real tokens and derive the rate from the last second.
  const stamps = [];
  canvas.token = () => {
    stamps.push(performance.now());
    canvas.dataset.tps = "auto";
  };
  const still = matchMedia("(prefers-reduced-motion: reduce)").matches;
  let count = 0, last = performance.now(), visible = true, frame = 0;
  new IntersectionObserver(([e]) => {
    visible = e.isIntersecting;
    if (visible && !frame) frame = requestAnimationFrame(draw);
  }).observe(canvas);

  function draw(now) {
    frame = 0;
    const dt = Math.min((now - last) / 1000, 0.1);
    last = now;
    while (stamps.length && now - stamps[0] > 1000) stamps.shift();
    const wobble = 1 + 0.25 * Math.sin(now / 588) + 0.15 * Math.sin(now / 233 + 1) + 0.08 * Math.sin(now / 91 + 2);
    const tps = canvas.dataset.tps === "auto" ? stamps.length : Number(canvas.dataset.tps) * wobble;
    count += tps * dt;
    const dpr = Math.min(devicePixelRatio || 1, 2);
    const w = Math.round(canvas.clientWidth * dpr), h = Math.round(canvas.clientHeight * dpr);
    if (canvas.width !== w || canvas.height !== h) { canvas.width = w; canvas.height = h; }
    gl.viewport(0, 0, w, h);
    gl.uniform3f(res, w, h, 1);
    gl.uniform1f(time, still ? 2 : now / 1000);
    gl.uniform1f(tokens, still ? Number(canvas.dataset.tps) * 2 : count);
    gl.uniform1f(rate, tps);
    gl.drawArrays(gl.TRIANGLES, 0, 3);
    if (visible && !still) frame = requestAnimationFrame(draw);
  }
  frame = requestAnimationFrame(draw);
</script>

GLSL for Shadertoy

// Inputs the site passes in, as constants for Shadertoy.
// uTps: tokens per second. uTokens: tokens so far. uColor: the accent.
#define uTps 7.0
#define uTokens (iTime * uTps)
#define uColor vec3(0.718, 0.490, 1.000)

#define TAU 6.28318530718
#define PI 3.14159265359
mat2 rot(float a) { float c = cos(a), s = sin(a); return mat2(c, -s, s, c); }
float hash12(vec2 p) { vec3 q = fract(vec3(p.xyx) * 0.1031); q += dot(q, q.yzx + 33.33); return fract((q.x + q.y) * q.z); }
// a phase in radians that wraps at whole turns, so it stays precise for hours
float turn(float x, float k) { return mod(x * k, TAU); }
vec3 toLin(vec3 c) { return pow(max(c, vec3(0.0)), vec3(2.2)); }
vec3 hueShift(vec3 c, float a) {
  vec3 k = vec3(0.57735);
  float cs = cos(a);
  return max(c * cs + cross(k, c) * sin(a) + k * dot(k, c) * (1.0 - cs), vec3(0.0));
}
// ACES filmic curve, gamma and a tiny dither against banding
vec3 finish(vec3 c, vec2 fc) {
  c = max(c, vec3(0.0));
  c = clamp((c * (2.51 * c + 0.03)) / (c * (2.43 * c + 0.59) + 0.14), 0.0, 1.0);
  c = pow(c, vec3(1.0 / 2.2));
  return c + (hash12(fc) + hash12(fc + 19.19) - 1.0) / 255.0;
}

float gyr(vec3 q) { return dot(sin(q), cos(q.yzx)); }

float folds(vec3 p) {
  vec3 q = p * 12.0;
  q += 1.1 * sin(q.zxy * 0.31 + vec3(0.0, 1.7, 3.1));
  return gyr(q);
}

float sdEll(vec3 p, vec3 r) {
  float k0 = length(p / r);
  float k1 = length(p / (r * r));
  return k0 * (k0 - 1.0) / k1;
}

float map(vec3 p, out float f) {
  vec3 q = p;
  // flatter underneath, fuller at the back
  q.y *= p.y < 0.0 ? 1.35 : 1.0;
  q.y -= 0.06 * q.z;
  float d = sdEll(q, vec3(1.18, 0.74, 0.92));
  // the fissure between the two hemispheres
  d += 0.09 * exp(-p.x * p.x * 90.0) * smoothstep(-0.2, 0.5, p.y);
  f = folds(p);
  float a = abs(f);
  d += 0.024 * (1.0 - smoothstep(0.0, 0.4, a)) - 0.01 * smoothstep(0.4, 1.3, a);
  return d;
}

vec3 toBrain(vec3 p, float yaw) {
  p.xz *= rot(yaw);
  return p;
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
  vec3 acc = toLin(uColor);
  vec3 acc2 = hueShift(acc, -0.7);
  vec3 hot = mix(acc, vec3(1.0), 0.65);
  float e = 1.0 - exp(-uTps / 90.0);
  float yaw = 0.5 + 0.35 * sin(turn(iTime, 0.09));
  float base = fract(iTime * 0.06);

  vec3 ro = vec3(0.0, 0.0, 3.4);
  vec3 rd = normalize(vec3(uv, -1.5));
  ro.yz *= rot(-0.36); rd.yz *= rot(-0.36);
  vec3 col = acc * 0.014 * smoothstep(1.1, 0.0, length(uv));

  float b = dot(ro, rd);
  float h = b * b - dot(ro, ro) + 1.25 * 1.25;
  if (h > 0.0) {
    float t = -b - sqrt(h);
    float tEnd = -b + sqrt(h);
    float dmin = 1e3, tmin = t, f = 0.0;
    for (int i = 0; i < 64; i++) {
      float d = map(toBrain(ro + rd * t, yaw), f);
      if (d < dmin) { dmin = d; tmin = t; }
      if (d < 0.0008 * t || t > tEnd) break;
      t += d * 0.6;
    }
    float pxw = 1.6 * tmin / (1.5 * iResolution.y);
    float cover = 1.0 - smoothstep(0.0, pxw, dmin);
    if (cover > 0.0) {
      vec3 p = toBrain(ro + rd * tmin, yaw);
      float fold;
      map(p, fold);
      vec2 k = vec2(1.0, -1.0) * 0.002;
      float fx;
      vec3 n = normalize(k.xyy * map(p + k.xyy, fx) + k.yyx * map(p + k.yyx, fx) + k.yxy * map(p + k.yxy, fx) + k.xxx * map(p + k.xxx, fx));
      vec3 vd = toBrain(rd, yaw);
      vec3 L = toBrain(normalize(vec3(-0.5, 0.85, 0.45)), yaw);
      float a = abs(fold);
      float groove = smoothstep(0.0, 0.55, a);
      float crest = smoothstep(0.6, 1.3, a);
      float dif = clamp(dot(n, L) * 0.6 + 0.4, 0.0, 1.0);
      float cosv = clamp(-dot(vd, n), 0.0, 1.0);
      float fres = pow(1.0 - cosv, 3.0);
      float spec = pow(clamp(dot(reflect(vd, n), L), 0.0, 1.0), 30.0);

      vec3 tissue = mix(acc * 0.012, mix(acc, acc2, 0.35) * 0.12, dif * dif) * (0.15 + 0.85 * groove);

      // waves of activity spreading along the folds from a few foci
      float fire = 0.0;
      for (int i = 0; i < 3; i++) {
        float fi = float(i);
        vec3 c = normalize(vec3(sin(fi * 2.4 + 0.5), 0.5 + 0.4 * cos(fi * 1.7), cos(fi * 2.4 + 0.5))) * vec3(1.18, 0.74, 0.92);
        float dist = length(p - c);
        float x = fract(dist * 1.6 - base - fract(uTokens * (0.0042 + 0.0006 * fi)) - fi * 0.37);
        fire += smoothstep(0.0, 0.03, x) * exp(-x * 7.0) * exp(-dist * 0.5);
      }
      // the pulses run along the sulci, the fine lines between the folds
      float line = exp(-a * a * 30.0);
      vec3 glow = mix(acc, hot, clamp(fire, 0.0, 1.0)) * line * fire * (0.5 + 3.2 * e);
      glow += acc * line * (0.03 + 0.1 * e);
      vec3 s = tissue + glow + mix(acc, acc2, 0.5) * fres * 0.35 * groove + vec3(1.0) * spec * 0.2 * groove;
      col = mix(col, s, cover);
    }
  }
  fragColor = vec4(finish(col, fragCoord), 1.0);
}

Customizing this shader

  • Speed: uTps is the token rate and uTokens the running count. The standalone runner adds a natural wobble to a fixed rate, the way real streams speed up and slow down.
  • Color: set data-color on the canvas, or change uColor in the Shadertoy version. Currently previewing #b77dff.
  • Size: style the canvas with CSS. It renders at up to twice your screen's pixel density and stops drawing while it is off screen.
  • Reduced motion: the runner draws a single still frame for people who asked their OS for less motion.

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