AI CSS Animations

Comet Trails

Comets sweep across a quiet starfield, each with a curved dust tail and a straight ion tail. Faster tokens send more comets across, quicker, with longer tails.

Also known as: meteor shower, shooting stars.

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-comet-trails" data-tps="70" data-color="#7cc8ff" 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-comet-trails");
  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
uint hu(uint x) { x ^= x >> 16u; x *= 0x7feb352du; x ^= x >> 15u; x *= 0x846ca68bu; x ^= x >> 16u; return x; }
float hf(uint x) { return float(hu(x) >> 8u) * (1.0 / 16777216.0); }
float h1(float a) { return hf(uint(int(floor(a)))); }
float h2(vec2 a) { ivec2 i = ivec2(floor(a)); return hf(uint(i.x) * 0x27d4eb2du ^ hu(uint(i.y) + 0x9e3779b9u)); }
float h3(vec3 a) { ivec3 i = ivec3(floor(a)); return hf(uint(i.x) * 0x27d4eb2du ^ hu(uint(i.y) * 0x165667b1u ^ hu(uint(i.z) + 0x9e3779b9u))); }
float segd(vec2 p, vec2 a, vec2 b, out float t) {
  vec2 pa = p - a, ba = b - a;
  t = clamp(dot(pa, ba) / max(dot(ba, ba), 1e-9), 0.0, 1.0);
  return length(pa - ba * t);
}
vec3 tone(vec3 c) { return 1.0 - exp(-c); }
float dither(vec2 f) { return (h2(f) - 0.5) / 255.0; }
// 0 at idle, about 0.23 at 15 tok/s, 0.46 at 60, 0.7 at 200, 1 at 800
float energy() { return clamp(log2(1.0 + max(uTps, 0.0) / 8.0) / log2(101.0), 0.0, 1.0); }

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
  float px = 1.0 / iResolution.y;
  float e = energy();
  float tk = mod(uTokens, 65536.0);
  float it = mod(iTime, 16384.0);
  float t = mod(iTime, 6000.0);

  vec3 col = vec3(0.003, 0.004, 0.009) + uColor * 0.02 * (0.6 + 0.4 * sin(uv.x * 1.3 + uv.y * 2.0 + 1.0));
  // a quiet starfield behind
  vec2 sg = uv * 34.0;
  vec2 sc = floor(sg);
  float s1 = h2(sc), s2 = h2(sc + 17.0), s3 = h2(sc + 41.0);
  vec2 sp = sc + 0.2 + 0.6 * vec2(s1, s2);
  float sd = length(sg - sp);
  float tw = 0.65 + 0.35 * sin(t * (0.5 + s3) + s3 * TAU);
  col += mix(uColor, vec3(1.0), 0.6) * smoothstep(0.12, 0.0, sd) * pow(s3, 6.0) * tw * 0.9;

  vec3 ionTint = mix(uColor, vec3(1.0), 0.45);
  for (int i = 0; i < 10; i++) {
    float fi = float(i);
    float vis = smoothstep(fi - 1.0, fi + 1.0, 3.0 + 7.0 * e);
    if (vis <= 0.0) break;
    float n = 4.0 + floor(h1(fi * 13.0 + 1.0) * 3.0);
    float q = tk * n / 1024.0 + it * n / 256.0 + h1(fi * 13.0 + 2.0);
    float u = fract(q);
    float cy = mod(floor(q), 64.0);
    float k1 = h3(vec3(fi, cy, 1.0)), k2 = h3(vec3(fi, cy, 2.0)), k3 = h3(vec3(fi, cy, 3.0));
    float k4 = h3(vec3(fi, cy, 4.0)), k5 = h3(vec3(fi, cy, 5.0)), k6 = h3(vec3(fi, cy, 6.0));
    float ang = -0.36 + (k1 - 0.5) * 0.5;
    vec2 dir = vec2(cos(ang), sin(ang));
    vec2 nrm = vec2(-dir.y, dir.x);
    float off = (k2 - 0.5) * 0.9;
    float A = (k3 - 0.5) * 0.2;
    float w = 1.3 + k4 * 1.6;
    float ph = k5 * TAU;
    float X = dot(uv, dir), Y = dot(uv, nrm);
    float Xh = mix(-1.25, 2.35, u);
    float ups = max(uTps, 0.0) * n / 1024.0 + n / 256.0;
    float vel = 3.6 * ups;
    float L = clamp(0.14 + vel * 0.38, 0.14, 1.05);
    float hy = off + A * sin(w * Xh + ph);
    vec2 hp = dir * Xh + nrm * hy;
    float bri = mix(0.55, 1.15, k6) * vis;
    float tt = (Xh - X) / L;
    if (tt > -0.05 && tt < 1.0) {
      float fy = off + A * sin(w * X + ph);
      float fd = A * w * cos(w * X + ph);
      float dY = (Y - fy) * inversesqrt(1.0 + fd * fd);
      float tc = clamp(tt, 0.0, 1.0);
      float wt = 0.003 + 0.03 * tc * sqrt(tc) + px * 0.4;
      float fadeT = pow(1.0 - tc, 1.5) * smoothstep(-0.05, 0.02, tt);
      float dust = fadeT * exp(-dY * dY / (wt * wt)) * (0.009 / (wt + 0.006));
      float wi = 0.0016 + 0.007 * tc + px * 0.3;
      float hs = A * w * cos(w * Xh + ph);
      float dI = ((Y - hy) - hs * (X - Xh)) * inversesqrt(1.0 + hs * hs);
      float ion = pow(1.0 - tc, 2.4) * smoothstep(-0.05, 0.02, tt) * exp(-dI * dI / (wi * wi)) * 0.55;
      col += mix(uColor, vec3(1.0), 0.3 * (1.0 - tc)) * dust * bri;
      col += ionTint * ion * bri;
    }
    float dh = length(uv - hp);
    col += mix(uColor, vec3(1.0), 0.75) * exp(-dh * dh / 0.00009) * 1.6 * bri;
    col += uColor * 0.0012 / (dh * dh + 0.0012) * 0.22 * bri;
  }
  col *= 1.0 - 0.25 * dot(uv * vec2(0.5, 1.0), uv * vec2(0.5, 1.0));
  col = tone(col * 1.25);
  fragColor = vec4(col + dither(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 70.0
#define uTokens (iTime * uTps)
#define uColor vec3(0.486, 0.784, 1.000)

#define TAU 6.28318530718
uint hu(uint x) { x ^= x >> 16u; x *= 0x7feb352du; x ^= x >> 15u; x *= 0x846ca68bu; x ^= x >> 16u; return x; }
float hf(uint x) { return float(hu(x) >> 8u) * (1.0 / 16777216.0); }
float h1(float a) { return hf(uint(int(floor(a)))); }
float h2(vec2 a) { ivec2 i = ivec2(floor(a)); return hf(uint(i.x) * 0x27d4eb2du ^ hu(uint(i.y) + 0x9e3779b9u)); }
float h3(vec3 a) { ivec3 i = ivec3(floor(a)); return hf(uint(i.x) * 0x27d4eb2du ^ hu(uint(i.y) * 0x165667b1u ^ hu(uint(i.z) + 0x9e3779b9u))); }
float segd(vec2 p, vec2 a, vec2 b, out float t) {
  vec2 pa = p - a, ba = b - a;
  t = clamp(dot(pa, ba) / max(dot(ba, ba), 1e-9), 0.0, 1.0);
  return length(pa - ba * t);
}
vec3 tone(vec3 c) { return 1.0 - exp(-c); }
float dither(vec2 f) { return (h2(f) - 0.5) / 255.0; }
// 0 at idle, about 0.23 at 15 tok/s, 0.46 at 60, 0.7 at 200, 1 at 800
float energy() { return clamp(log2(1.0 + max(uTps, 0.0) / 8.0) / log2(101.0), 0.0, 1.0); }

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
  float px = 1.0 / iResolution.y;
  float e = energy();
  float tk = mod(uTokens, 65536.0);
  float it = mod(iTime, 16384.0);
  float t = mod(iTime, 6000.0);

  vec3 col = vec3(0.003, 0.004, 0.009) + uColor * 0.02 * (0.6 + 0.4 * sin(uv.x * 1.3 + uv.y * 2.0 + 1.0));
  // a quiet starfield behind
  vec2 sg = uv * 34.0;
  vec2 sc = floor(sg);
  float s1 = h2(sc), s2 = h2(sc + 17.0), s3 = h2(sc + 41.0);
  vec2 sp = sc + 0.2 + 0.6 * vec2(s1, s2);
  float sd = length(sg - sp);
  float tw = 0.65 + 0.35 * sin(t * (0.5 + s3) + s3 * TAU);
  col += mix(uColor, vec3(1.0), 0.6) * smoothstep(0.12, 0.0, sd) * pow(s3, 6.0) * tw * 0.9;

  vec3 ionTint = mix(uColor, vec3(1.0), 0.45);
  for (int i = 0; i < 10; i++) {
    float fi = float(i);
    float vis = smoothstep(fi - 1.0, fi + 1.0, 3.0 + 7.0 * e);
    if (vis <= 0.0) break;
    float n = 4.0 + floor(h1(fi * 13.0 + 1.0) * 3.0);
    float q = tk * n / 1024.0 + it * n / 256.0 + h1(fi * 13.0 + 2.0);
    float u = fract(q);
    float cy = mod(floor(q), 64.0);
    float k1 = h3(vec3(fi, cy, 1.0)), k2 = h3(vec3(fi, cy, 2.0)), k3 = h3(vec3(fi, cy, 3.0));
    float k4 = h3(vec3(fi, cy, 4.0)), k5 = h3(vec3(fi, cy, 5.0)), k6 = h3(vec3(fi, cy, 6.0));
    float ang = -0.36 + (k1 - 0.5) * 0.5;
    vec2 dir = vec2(cos(ang), sin(ang));
    vec2 nrm = vec2(-dir.y, dir.x);
    float off = (k2 - 0.5) * 0.9;
    float A = (k3 - 0.5) * 0.2;
    float w = 1.3 + k4 * 1.6;
    float ph = k5 * TAU;
    float X = dot(uv, dir), Y = dot(uv, nrm);
    float Xh = mix(-1.25, 2.35, u);
    float ups = max(uTps, 0.0) * n / 1024.0 + n / 256.0;
    float vel = 3.6 * ups;
    float L = clamp(0.14 + vel * 0.38, 0.14, 1.05);
    float hy = off + A * sin(w * Xh + ph);
    vec2 hp = dir * Xh + nrm * hy;
    float bri = mix(0.55, 1.15, k6) * vis;
    float tt = (Xh - X) / L;
    if (tt > -0.05 && tt < 1.0) {
      float fy = off + A * sin(w * X + ph);
      float fd = A * w * cos(w * X + ph);
      float dY = (Y - fy) * inversesqrt(1.0 + fd * fd);
      float tc = clamp(tt, 0.0, 1.0);
      float wt = 0.003 + 0.03 * tc * sqrt(tc) + px * 0.4;
      float fadeT = pow(1.0 - tc, 1.5) * smoothstep(-0.05, 0.02, tt);
      float dust = fadeT * exp(-dY * dY / (wt * wt)) * (0.009 / (wt + 0.006));
      float wi = 0.0016 + 0.007 * tc + px * 0.3;
      float hs = A * w * cos(w * Xh + ph);
      float dI = ((Y - hy) - hs * (X - Xh)) * inversesqrt(1.0 + hs * hs);
      float ion = pow(1.0 - tc, 2.4) * smoothstep(-0.05, 0.02, tt) * exp(-dI * dI / (wi * wi)) * 0.55;
      col += mix(uColor, vec3(1.0), 0.3 * (1.0 - tc)) * dust * bri;
      col += ionTint * ion * bri;
    }
    float dh = length(uv - hp);
    col += mix(uColor, vec3(1.0), 0.75) * exp(-dh * dh / 0.00009) * 1.6 * bri;
    col += uColor * 0.0012 / (dh * dh + 0.0012) * 0.22 * bri;
  }
  col *= 1.0 - 0.25 * dot(uv * vec2(0.5, 1.0), uv * vec2(0.5, 1.0));
  col = tone(col * 1.25);
  fragColor = vec4(col + dither(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 #7cc8ff.
  • 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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