Aurora Curtains

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-aurora-curtains" data-tps="18" data-color="#3cffb4" 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-aurora-curtains");
  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;
// Gradient noise on a lattice that repeats every PER cells. Moving offsets are
// wrapped to whole periods, so the motion loops without a seam.
const float PER = 32.0;
// Octave turn and scale: an integer matrix keeps the lattice periodic.
const mat2 OCT = mat2(2.0, -1.0, 1.0, 2.0);

vec2 grad(vec2 i) {
  i = mod(i, PER);
  vec3 q = fract(vec3(i.xyx) * vec3(0.1031, 0.1030, 0.0973));
  q += dot(q, q.yzx + 33.33);
  return fract((q.xx + q.yz) * q.zy) * 2.0 - 1.0;
}

float noise(vec2 p) {
  vec2 i = floor(p), f = fract(p);
  vec2 u = f * f * f * (f * (f * 6.0 - 15.0) + 10.0);
  float a = dot(grad(i), f);
  float b = dot(grad(i + vec2(1.0, 0.0)), f - vec2(1.0, 0.0));
  float c = dot(grad(i + vec2(0.0, 1.0)), f - vec2(0.0, 1.0));
  float d = dot(grad(i + vec2(1.0, 1.0)), f - vec2(1.0, 1.0));
  return mix(mix(a, b, u.x), mix(c, d, u.x), u.y);
}

// A phase that climbs with x but wraps to the noise period.
float wrapP(float x) { return mod(x, PER); }

// Rotate a colour around the grey axis: hue shifts that follow uColor.
vec3 hue(vec3 c, float a) {
  const vec3 k = vec3(0.57735);
  float ca = cos(a);
  return c * ca + cross(k, c) * sin(a) + k * dot(k, c) * (1.0 - ca);
}

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);
}

// Soft shoulder tone map plus a one step dither against banding.
vec3 finish(vec3 c, vec2 fc) {
  c = 1.0 - exp(-max(c, 0.0));
  return c + (hash12(fc) - 0.5) / 255.0;
}

// One curtain layer: a sheet whose lower edge folds along x, lit from below.
vec3 curtain(vec2 uv, float L, float e, vec2 wf, float wr, float wp) {
  float x = uv.x * (0.9 + 0.25 * L) + L * 3.7;
  float bend = noise(vec2(x * 0.8 + wf.x, L * 5.0 + 0.5));
  float s = x + bend * 0.75;
  // the hem of the sheet swings in deep folds
  float edge = -0.2 + 0.09 * L + 0.32 * noise(vec2(s * 1.1 + wf.y, L * 3.1 + 2.0))
             + 0.06 * noise(vec2(s * 3.0 - wf.x, L * 4.3));
  float d = uv.y - edge;
  // rays: strands along the sheet that slide sideways with the stream
  float rays = 0.12 + 0.88 * smoothstep(-0.25, 0.45, noise(vec2(s * 15.0 + wr, L * 7.0 + 0.3)));
  rays *= mix(1.0, 0.55 + 0.45 * smoothstep(-0.4, 0.5, noise(vec2(s * 41.0 - wr * 2.0, L * 11.0))), 0.4 + 0.6 * e);
  float patchy = smoothstep(-0.18, 0.22, noise(vec2(s * 0.5 + wp, L * 9.0 + 4.0)) + 0.12 * e);
  float rise = 4.2 - 1.8 * e;
  float lit = smoothstep(-0.008, 0.02, d) * exp(-max(d, 0.0) * rise) * 0.8;
  lit += smoothstep(-0.006, 0.006, d) * exp(-max(d, 0.0) * 40.0) * 0.9;
  vec3 low = uColor;
  vec3 high = hue(uColor, 2.1) * 0.75;
  vec3 col = mix(low, high, smoothstep(0.05, 0.4, d));
  return col * lit * rays * patchy / (1.0 + L * 0.45);
}

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 = 1.0 - exp(-uTps / 70.0);

  vec2 wf = vec2(wrapP(uTokens * 0.0036) + wrapP(iTime * 0.03), -wrapP(uTokens * 0.0052) - wrapP(iTime * 0.02));
  float wr = wrapP(uTokens * 0.011) + wrapP(iTime * 0.05);
  float wp = wrapP(uTokens * 0.0021) + wrapP(iTime * 0.01);

  vec3 sky = mix(vec3(0.004, 0.008, 0.02), vec3(0.01, 0.02, 0.045), smoothstep(0.5, -0.4, uv.y));
  // a sparse, steady starfield
  vec2 sc = uv * 70.0;
  vec2 cell = floor(sc);
  float h = hash12(cell);
  vec2 sp = vec2(hash12(cell + 7.1), hash12(cell + 3.3)) * 0.8 + 0.1;
  float star = smoothstep(0.09, 0.0, length(fract(sc) - sp)) * step(0.93, h);
  float tw = 0.7 + 0.3 * sin(mod(iTime * 1.3, 6.2831853) + h * 40.0);
  sky += vec3(0.6, 0.7, 0.9) * star * tw * 0.35 * smoothstep(-0.2, 0.3, uv.y);

  vec3 au = vec3(0.0);
  for (int i = 0; i < 4; i++) au += curtain(uv, float(i), e, wf + float(i) * 1.7, wr, wp);
  vec3 col = sky + au * (0.55 + 1.1 * e);
  // the aurora's own glow on the haze near the horizon
  col += uColor * 0.06 * (0.5 + e) * exp(-abs(uv.y + 0.3) * 6.0);

  // a dark ridge in front, anti aliased by the pixel size
  float ridge = -0.36 + 0.05 * noise(vec2(uv.x * 2.2 + 11.0, 1.0)) + 0.02 * noise(vec2(uv.x * 7.0, 3.0));
  float ground = smoothstep(ridge + px, ridge - px, uv.y);
  col = mix(col, vec3(0.003, 0.005, 0.008) + uColor * 0.01, ground);
  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>

// Inputs the site passes in, as constants for Shadertoy.
// uTps: tokens per second. uTokens: tokens so far. uColor: the accent.
#define uTps 18.0
#define uTokens (iTime * uTps)
#define uColor vec3(0.235, 1.000, 0.706)

// Gradient noise on a lattice that repeats every PER cells. Moving offsets are
// wrapped to whole periods, so the motion loops without a seam.
const float PER = 32.0;
// Octave turn and scale: an integer matrix keeps the lattice periodic.
const mat2 OCT = mat2(2.0, -1.0, 1.0, 2.0);

vec2 grad(vec2 i) {
  i = mod(i, PER);
  vec3 q = fract(vec3(i.xyx) * vec3(0.1031, 0.1030, 0.0973));
  q += dot(q, q.yzx + 33.33);
  return fract((q.xx + q.yz) * q.zy) * 2.0 - 1.0;
}

float noise(vec2 p) {
  vec2 i = floor(p), f = fract(p);
  vec2 u = f * f * f * (f * (f * 6.0 - 15.0) + 10.0);
  float a = dot(grad(i), f);
  float b = dot(grad(i + vec2(1.0, 0.0)), f - vec2(1.0, 0.0));
  float c = dot(grad(i + vec2(0.0, 1.0)), f - vec2(0.0, 1.0));
  float d = dot(grad(i + vec2(1.0, 1.0)), f - vec2(1.0, 1.0));
  return mix(mix(a, b, u.x), mix(c, d, u.x), u.y);
}

// A phase that climbs with x but wraps to the noise period.
float wrapP(float x) { return mod(x, PER); }

// Rotate a colour around the grey axis: hue shifts that follow uColor.
vec3 hue(vec3 c, float a) {
  const vec3 k = vec3(0.57735);
  float ca = cos(a);
  return c * ca + cross(k, c) * sin(a) + k * dot(k, c) * (1.0 - ca);
}

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);
}

// Soft shoulder tone map plus a one step dither against banding.
vec3 finish(vec3 c, vec2 fc) {
  c = 1.0 - exp(-max(c, 0.0));
  return c + (hash12(fc) - 0.5) / 255.0;
}

// One curtain layer: a sheet whose lower edge folds along x, lit from below.
vec3 curtain(vec2 uv, float L, float e, vec2 wf, float wr, float wp) {
  float x = uv.x * (0.9 + 0.25 * L) + L * 3.7;
  float bend = noise(vec2(x * 0.8 + wf.x, L * 5.0 + 0.5));
  float s = x + bend * 0.75;
  // the hem of the sheet swings in deep folds
  float edge = -0.2 + 0.09 * L + 0.32 * noise(vec2(s * 1.1 + wf.y, L * 3.1 + 2.0))
             + 0.06 * noise(vec2(s * 3.0 - wf.x, L * 4.3));
  float d = uv.y - edge;
  // rays: strands along the sheet that slide sideways with the stream
  float rays = 0.12 + 0.88 * smoothstep(-0.25, 0.45, noise(vec2(s * 15.0 + wr, L * 7.0 + 0.3)));
  rays *= mix(1.0, 0.55 + 0.45 * smoothstep(-0.4, 0.5, noise(vec2(s * 41.0 - wr * 2.0, L * 11.0))), 0.4 + 0.6 * e);
  float patchy = smoothstep(-0.18, 0.22, noise(vec2(s * 0.5 + wp, L * 9.0 + 4.0)) + 0.12 * e);
  float rise = 4.2 - 1.8 * e;
  float lit = smoothstep(-0.008, 0.02, d) * exp(-max(d, 0.0) * rise) * 0.8;
  lit += smoothstep(-0.006, 0.006, d) * exp(-max(d, 0.0) * 40.0) * 0.9;
  vec3 low = uColor;
  vec3 high = hue(uColor, 2.1) * 0.75;
  vec3 col = mix(low, high, smoothstep(0.05, 0.4, d));
  return col * lit * rays * patchy / (1.0 + L * 0.45);
}

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 = 1.0 - exp(-uTps / 70.0);

  vec2 wf = vec2(wrapP(uTokens * 0.0036) + wrapP(iTime * 0.03), -wrapP(uTokens * 0.0052) - wrapP(iTime * 0.02));
  float wr = wrapP(uTokens * 0.011) + wrapP(iTime * 0.05);
  float wp = wrapP(uTokens * 0.0021) + wrapP(iTime * 0.01);

  vec3 sky = mix(vec3(0.004, 0.008, 0.02), vec3(0.01, 0.02, 0.045), smoothstep(0.5, -0.4, uv.y));
  // a sparse, steady starfield
  vec2 sc = uv * 70.0;
  vec2 cell = floor(sc);
  float h = hash12(cell);
  vec2 sp = vec2(hash12(cell + 7.1), hash12(cell + 3.3)) * 0.8 + 0.1;
  float star = smoothstep(0.09, 0.0, length(fract(sc) - sp)) * step(0.93, h);
  float tw = 0.7 + 0.3 * sin(mod(iTime * 1.3, 6.2831853) + h * 40.0);
  sky += vec3(0.6, 0.7, 0.9) * star * tw * 0.35 * smoothstep(-0.2, 0.3, uv.y);

  vec3 au = vec3(0.0);
  for (int i = 0; i < 4; i++) au += curtain(uv, float(i), e, wf + float(i) * 1.7, wr, wp);
  vec3 col = sky + au * (0.55 + 1.1 * e);
  // the aurora's own glow on the haze near the horizon
  col += uColor * 0.06 * (0.5 + e) * exp(-abs(uv.y + 0.3) * 6.0);

  // a dark ridge in front, anti aliased by the pixel size
  float ridge = -0.36 + 0.05 * noise(vec2(uv.x * 2.2 + 11.0, 1.0)) + 0.02 * noise(vec2(uv.x * 7.0, 3.0));
  float ground = smoothstep(ridge + px, ridge - px, uv.y);
  col = mix(col, vec3(0.003, 0.005, 0.008) + uColor * 0.01, ground);
  fragColor = vec4(finish(col, fragCoord), 1.0);
}

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