> ## Documentation Index
> Fetch the complete documentation index at: /llms.txt
> Use this file to discover all available pages before exploring further.

# Halftone Field

> A full-bleed halftone light field: a grid of dots whose size and colour track a slow flowing simplex-noise field, so broad bands of light sweep across a mostly-black frame like a giant LED wall showing a plasma. Built to run under type.

# Halftone Field

A full-bleed halftone light field: a grid of dots whose size and colour track a slow flowing simplex-noise field, so broad bands of light sweep across a mostly-black frame like a giant LED wall showing a plasma. Built to run under type.

**Halftone Field**

```html halftone-field.html
<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=1920, height=1080" />
    <title>Halftone Field</title>
    <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
    <style>
      *,
      *::before,
      *::after {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
      }
      body {
        background: #000;
        overflow: hidden;
      }
      #hlf-root {
        position: relative;
        width: 1920px;
        height: 1080px;
        overflow: hidden;
      }
      #hlf-backdrop {
        position: absolute;
        inset: 0;
        background: #000000;
      }
      #hlf-canvas {
        position: absolute;
        top: 0;
        left: 0;
        width: 1920px;
        height: 1080px;
      }
    </style>
  </head>
  <body>
    <div
      id="hlf-root"
      data-composition-id="halftone-field"
      data-root="true"
      data-width="1920"
      data-height="1080"
      data-start="0"
      data-duration="10"
      data-composition-variables='[
        {"id":"frequency","type":"number","label":"Field frequency","default":2,"min":1,"max":10,"step":0.1},
        {"id":"speed","type":"number","label":"Flow speed","default":5,"min":0,"max":10,"step":0.1},
        {"id":"cellSize","type":"number","label":"Cell size","default":54,"min":1,"max":100,"step":1},
        {"id":"gamma","type":"number","label":"Gamma (midtone crush)","default":12,"min":1,"max":20,"step":0.1},
        {"id":"paletteBias","type":"number","label":"Palette bias","default":2,"min":0,"max":20,"step":0.5},
        {"id":"palette1","type":"color","label":"Palette stop 1 (lows)","default":"#00AAFF"},
        {"id":"palette2","type":"color","label":"Palette stop 2","default":"#C2FF67"},
        {"id":"palette3","type":"color","label":"Palette stop 3","default":"#6600FF"},
        {"id":"palette4","type":"color","label":"Palette stop 4 (crests)","default":"#000000"},
        {"id":"background","type":"color","label":"Background","default":"#000000"},
        {"id":"quantize","type":"boolean","label":"Quantise to 30fps (stepped)","default":false}
      ]'
    >
      <div id="hlf-backdrop"></div>
      <canvas id="hlf-canvas" width="1920" height="1080"></canvas>

      <!-- Driver clip: gives HyperFrames a timed element to own on track 0. -->
      <div
        id="hlf-drv"
        class="clip"
        data-start="0"
        data-duration="10"
        data-track-index="0"
        style="position: absolute; width: 1px; height: 1px; opacity: 0; pointer-events: none"
      ></div>
    </div>

    <script>
      (function () {
        var DUR = 10;
        var W = 1920;
        var H = 1080;

        var V = (window.__hyperframes && window.__hyperframes.getVariables()) || {};
        var CS = getComputedStyle(document.getElementById("hlf-root"));

        // The runtime defines every declared variable as `--<id>` on the root,
        // so a host stylesheet can override one there too. Read the custom
        // property first, fall back to the declared value when it is unset.
        function raw(id) {
          var css = CS.getPropertyValue("--" + id.toLowerCase()).trim();
          return css !== "" ? css : V[id];
        }
        function num(id, fallback) {
          var n = parseFloat(raw(id));
          return isFinite(n) ? n : fallback;
        }
        function bool(id) {
          var v = raw(id);
          return v === true || /^(true|1|on|yes)$/i.test(String(v));
        }
        // #RGB / #RRGGBB -> [r, g, b] in 0..1. Anything else falls back.
        function rgb(id, fallback) {
          var s = String(raw(id) || "").trim();
          var m = /^#([0-9a-f]{3}|[0-9a-f]{6})$/i.exec(s);
          if (!m) s = fallback;
          else s = "#" + m[1];
          var hex = s.slice(1);
          if (hex.length === 3) {
            hex = hex[0] + hex[0] + hex[1] + hex[1] + hex[2] + hex[2];
          }
          var n = parseInt(hex, 16);
          return [((n >> 16) & 255) / 255, ((n >> 8) & 255) / 255, (n & 255) / 255];
        }
        // The reference exposes 1-10 / 1-100 / 1-20 dials and maps them onto
        // the ranges the shader actually wants.
        function mapLinear(x, a1, a2, b1, b2) {
          return b1 + ((x - a1) * (b2 - b1)) / (a2 - a1);
        }

        var FREQ = mapLinear(num("frequency", 2), 1, 10, 0.3, 6);
        var SPEED = num("speed", 5) * 0.05;
        var CELL = mapLinear(num("cellSize", 54), 1, 100, 6, 60);
        var GAMMA = mapLinear(num("gamma", 12), 1, 20, 0.5, 8);
        var BIAS = num("paletteBias", 2) * 0.05;
        var PAL = [
          rgb("palette1", "#00AAFF"),
          rgb("palette2", "#C2FF67"),
          rgb("palette3", "#6600FF"),
          rgb("palette4", "#000000"),
        ];
        var BG = rgb("background", "#000000");
        var QUANTIZE = bool("quantize");

        document.getElementById("hlf-backdrop").style.background =
          "rgb(" +
          BG.map(function (c) {
            return Math.round(c * 255);
          }).join(",") +
          ")";

        var canvas = document.getElementById("hlf-canvas");
        var gl =
          canvas.getContext("webgl", {
            alpha: false,
            antialias: false,
            depth: false,
            stencil: false,
            preserveDrawingBuffer: true,
            powerPreference: "high-performance",
          }) ||
          canvas.getContext("experimental-webgl", {
            alpha: false,
            preserveDrawingBuffer: true,
          });

        var VERT = "attribute vec2 aPos;\nvoid main() { gl_Position = vec4(aPos, 0.0, 1.0); }";

        // Single pass. The reference renders the colour field into a target and
        // samples it at each cell centre, but the field is analytic, so
        // evaluating it at the cell centre here is the same value without the
        // round trip through a texture.
        var FRAG = `
precision highp float;
uniform vec2 uRes;
uniform float uTime;
uniform float uFreq;
uniform float uSpeed;
uniform float uCell;
uniform float uGamma;
uniform float uBias;
uniform vec3 uPal0;
uniform vec3 uPal1;
uniform vec3 uPal2;
uniform vec3 uPal3;
uniform vec3 uBg;

// 3D simplex noise — Ashima Arts / Stefan Gustavson (MIT).
vec3 mod289(vec3 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
vec4 mod289(vec4 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
vec4 permute(vec4 x) { return mod289(((x * 34.0) + 1.0) * x); }
vec4 taylorInvSqrt(vec4 r) { return 1.79284291400159 - 0.85373472095314 * r; }

float snoise(vec3 v) {
  const vec2 C = vec2(1.0 / 6.0, 1.0 / 3.0);
  const vec4 D = vec4(0.0, 0.5, 1.0, 2.0);

  vec3 i = floor(v + dot(v, C.yyy));
  vec3 x0 = v - i + dot(i, C.xxx);

  vec3 g = step(x0.yzx, x0.xyz);
  vec3 l = 1.0 - g;
  vec3 i1 = min(g.xyz, l.zxy);
  vec3 i2 = max(g.xyz, l.zxy);

  vec3 x1 = x0 - i1 + C.xxx;
  vec3 x2 = x0 - i2 + C.yyy;
  vec3 x3 = x0 - D.yyy;

  i = mod289(i);
  vec4 p = permute(permute(permute(
      i.z + vec4(0.0, i1.z, i2.z, 1.0)) +
      i.y + vec4(0.0, i1.y, i2.y, 1.0)) +
      i.x + vec4(0.0, i1.x, i2.x, 1.0));

  float n_ = 0.142857142857;
  vec3 ns = n_ * D.wyz - D.xzx;

  vec4 j = p - 49.0 * floor(p * ns.z * ns.z);

  vec4 x_ = floor(j * ns.z);
  vec4 y_ = floor(j - 7.0 * x_);

  vec4 x = x_ * ns.x + ns.yyyy;
  vec4 y = y_ * ns.x + ns.yyyy;
  vec4 h = 1.0 - abs(x) - abs(y);

  vec4 b0 = vec4(x.xy, y.xy);
  vec4 b1 = vec4(x.zw, y.zw);

  vec4 s0 = floor(b0) * 2.0 + 1.0;
  vec4 s1 = floor(b1) * 2.0 + 1.0;
  vec4 sh = -step(h, vec4(0.0));

  vec4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
  vec4 a1 = b1.xzyw + s1.xzyw * sh.zzww;

  vec3 p0 = vec3(a0.xy, h.x);
  vec3 p1 = vec3(a0.zw, h.y);
  vec3 p2 = vec3(a1.xy, h.z);
  vec3 p3 = vec3(a1.zw, h.w);

  vec4 norm = taylorInvSqrt(vec4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3)));
  p0 *= norm.x;
  p1 *= norm.y;
  p2 *= norm.z;
  p3 *= norm.w;

  vec4 m = max(0.6 - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0);
  m = m * m;
  return 42.0 * dot(m * m, vec4(dot(p0, x0), dot(p1, x1), dot(p2, x2), dot(p3, x3)));
}

// Full-saturation, full-value HSV: only the hue ramp survives.
vec3 hue2rgb(float h) {
  return clamp(abs(mod(h * 6.0 + vec3(0.0, 4.0, 2.0), 6.0) - 3.0) - 1.0, 0.0, 1.0);
}

// Piecewise-linear ramp across the four palette stops.
vec3 ramp(float v) {
  float x = clamp(v, 0.0, 1.0) * 3.0;
  vec3 c = mix(uPal0, uPal1, clamp(x, 0.0, 1.0));
  c = mix(c, uPal2, clamp(x - 1.0, 0.0, 1.0));
  c = mix(c, uPal3, clamp(x - 2.0, 0.0, 1.0));
  return c;
}

void main() {
  // One sample per cell, taken at the cell centre.
  vec2 cell = floor(gl_FragCoord.xy / uCell);
  vec2 centre = (cell + 0.5) * uCell;

  vec2 st = centre / uRes;
  st.x *= uRes.x / uRes.y;

  float hue = abs(snoise(vec3(st * uFreq, uTime * uSpeed)));
  vec3 field = hue2rgb(hue);

  // The gamma is the whole look: it crushes the midtones so most of the frame
  // stays background and only the crests of the field open up.
  float gray = pow(dot(field, vec3(0.2126, 0.7152, 0.0722)), uGamma);
  float v = clamp(gray + uBias, 0.0, 1.0);

  float radius = v * 0.5 * uCell;
  float d = length(gl_FragCoord.xy - centre);
  float mask = 1.0 - smoothstep(radius - 1.0, radius + 1.0, d);

  gl_FragColor = vec4(mix(uBg, ramp(v), mask), 1.0);
}
`;

        var uni = {};
        var ready = false;

        function compile(type, src) {
          var sh = gl.createShader(type);
          gl.shaderSource(sh, src);
          gl.compileShader(sh);
          if (!gl.getShaderParameter(sh, gl.COMPILE_STATUS)) {
            throw new Error("halftone-field shader: " + gl.getShaderInfoLog(sh));
          }
          return sh;
        }

        if (gl) {
          var prog = gl.createProgram();
          gl.attachShader(prog, compile(gl.VERTEX_SHADER, VERT));
          gl.attachShader(prog, compile(gl.FRAGMENT_SHADER, FRAG));
          gl.linkProgram(prog);
          if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
            throw new Error("halftone-field link: " + gl.getProgramInfoLog(prog));
          }
          gl.useProgram(prog);

          var buf = gl.createBuffer();
          gl.bindBuffer(gl.ARRAY_BUFFER, buf);
          gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, 3, -1, -1, 3]), gl.STATIC_DRAW);
          var loc = gl.getAttribLocation(prog, "aPos");
          gl.enableVertexAttribArray(loc);
          gl.vertexAttribPointer(loc, 2, gl.FLOAT, false, 0, 0);

          [
            "uRes",
            "uTime",
            "uFreq",
            "uSpeed",
            "uCell",
            "uGamma",
            "uBias",
            "uPal0",
            "uPal1",
            "uPal2",
            "uPal3",
            "uBg",
          ].forEach(function (n) {
            uni[n] = gl.getUniformLocation(prog, n);
          });

          gl.viewport(0, 0, W, H);
          gl.uniform2f(uni.uRes, W, H);
          gl.uniform1f(uni.uFreq, FREQ);
          gl.uniform1f(uni.uSpeed, SPEED);
          gl.uniform1f(uni.uCell, CELL);
          gl.uniform1f(uni.uGamma, GAMMA);
          gl.uniform1f(uni.uBias, BIAS);
          gl.uniform3f(uni.uPal0, PAL[0][0], PAL[0][1], PAL[0][2]);
          gl.uniform3f(uni.uPal1, PAL[1][0], PAL[1][1], PAL[1][2]);
          gl.uniform3f(uni.uPal2, PAL[2][0], PAL[2][1], PAL[2][2]);
          gl.uniform3f(uni.uPal3, PAL[3][0], PAL[3][1], PAL[3][2]);
          gl.uniform3f(uni.uBg, BG[0], BG[1], BG[2]);
          ready = true;
        }

        // Every frame is computed from t alone — the field is a closed-form
        // function of position and time. No accumulator, no clock, no PRNG.
        // `quantize` snaps t to a 30fps grid for the stepped LED-wall look.
        function draw(t) {
          if (!ready) return;
          gl.uniform1f(uni.uTime, QUANTIZE ? Math.floor(t * 30) / 30 : t);
          gl.drawArrays(gl.TRIANGLES, 0, 3);
          gl.flush();
        }

        window.__timelines = window.__timelines || {};
        var tl = gsap.timeline({ paused: true });

        // The canvas is repainted from a property SETTER, not from onUpdate:
        // gsap's seek(t) suppresses events by default, so an onUpdate callback
        // silently never fires on a scrub and the canvas freezes on frame 0.
        // Tweened values are always written during render, suppressed or not,
        // so this fires on every seek — and hands us the frame time directly.
        var driver = { _t: 0 };
        Object.defineProperty(driver, "t", {
          get: function () {
            return this._t;
          },
          set: function (v) {
            this._t = v;
            draw(v);
          },
        });
        tl.to(driver, { t: DUR, duration: DUR, ease: "none" }, 0);
        window.__timelines["halftone-field"] = tl;

        draw(0);
      })();
    </script>
  </body>
</html>
```

Copy npx hyperframes add halftone-field to the clipboard

That writes one file: `compositions/halftone-field.html`.

## Add it to your video

It runs for 10 seconds at 1920×1080. Paste this into your composition:

```html index.html
<div
  data-composition-id="halftone-field"
  data-composition-src="compositions/halftone-field.html"
  data-start="0"
  data-duration="10"
  data-track-index="1"
  data-width="1920"
  data-height="1080"
></div>
```

Move it in time with `data-start`. Put it on a different timeline row with
`data-track-index`. See [data attributes](/concepts/data-attributes.md) for the rest.

## Change how it looks

Set these CSS variables on the block:

* `--frequency` — Field frequency (1 = broad swells, 10 = fine mottle). Defaults to `2`.
* `--speed` — Flow speed (0 freezes the field). Defaults to `5`.
* `--cellsize` — Cell size (dot pitch, 1 = 6px, 100 = 60px). Defaults to `54`.
* `--gamma` — Gamma: midtone crush, the whole look. Low values flatten it to an even grey dot field. Defaults to `12`.
* `--palettebias` — Palette bias: floor under every dot's size and palette position. 0 lets the darks go fully black. Defaults to `2`.
* `--palette1` — Palette stop 1 (lows). Defaults to `#00AAFF`.
* `--palette2` — Palette stop 2. Defaults to `#C2FF67`.
* `--palette3` — Palette stop 3. Defaults to `#6600FF`.
* `--palette4` — Palette stop 4 (crests). Defaults to `#000000`.
* `--background` — Background. Defaults to `#000000`.
* `--quantize` — Quantise to 30fps for a stepped LED-wall look. Defaults to `false`. Options: `false`, `true`.

## Variables

Every one of these has a default, so the piece works untouched. Set the ones you
want to change on the element:

| Variable | Default | Accepts | What it does |
| - | - | - | - |
| `frequency` | `2` | 1 to 10, step 0.1 | |
| `speed` | `5` | 0 to 10, step 0.1 | |
| `cellSize` | `54` | 1 to 100, step 1 | |
| `gamma` | `12` | 1 to 20, step 0.1 | |
| `paletteBias` | `2` | 0 to 20, step 0.5 | |
| `palette1` | `#00AAFF` | color | |
| `palette2` | `#C2FF67` | color | |
| `palette3` | `#6600FF` | color | |
| `palette4` | `#000000` | color | |
| `background` | `#000000` | color | |
| `quantize` | `false` | boolean | |

Set them with `data-variable-values` on the element that mounts it. These are the
defaults, so this behaves exactly like the preview above until you change one:

```html wrap
<div
  data-composition-id="halftone-field"
  data-composition-src="compositions/halftone-field.html"
  data-variable-values='{"frequency":2,"speed":5,"cellSize":54,"gamma":12,"paletteBias":2,"palette1":"#00AAFF","palette2":"#C2FF67","palette3":"#6600FF","palette4":"#000000","background":"#000000","quantize":false}'
></div>
```

{/* hf:generated-footer */}

Tagged `webgl` `shader` `background` `texture` `halftone`.

## Related topics

* [Browse the complete Catalog](/catalog.md)
* [Add assets and Catalog items in the browser editor](/studio/assets-and-blocks.md)
* [Put blocks together into one video](/concepts/compositions.md)
