Artefakt ascii

Build this: a live ASCII particle field that spells a word: GPGPU flow-field particles simulated on the GPU, rendered as a grid of ASCII glyphs that drift and react to the cursor.

The complete, self-contained implementation follows, one file per block. It is framework-agnostic core logic — wire it into your own component and mount it on an element.

### ascii-wordmark/shaders.ts
```ts
export const GPGPU_COMPUTE =  `
uniform float uTime;
uniform float uDeltaTime;
uniform float uFlowFieldInfluence;
uniform float uFlowFieldStrength;
uniform float uFlowFieldFrequency;

uniform vec3  uMouse;
uniform float uMouseStrength;
uniform float uMouseSpeed;

uniform sampler2D uBase;

vec4 permute(vec4 x){return mod(((x*34.0)+1.0)*x, 289.0);}
float permute(float x){return floor(mod(((x*34.0)+1.0)*x, 289.0));}
vec4 taylorInvSqrt(vec4 r){return 1.79284291400159 - 0.85373472095314 * r;}
float taylorInvSqrt(float r){return 1.79284291400159 - 0.85373472095314 * r;}

vec4 grad4(float j, vec4 ip){
  const vec4 ones = vec4(1.0, 1.0, 1.0, -1.0);
  vec4 p,s;
  p.xyz = floor( fract (vec3(j) * ip.xyz) * 7.0) * ip.z - 1.0;
  p.w = 1.5 - dot(abs(p.xyz), ones.xyz);
  s = vec4(lessThan(p, vec4(0.0)));
  p.xyz = p.xyz + (s.xyz*2.0 - 1.0) * s.www;
  return p;
}

float simplexNoise4d(vec4 v){
  const vec2  C = vec2( 0.138196601125010504, 0.309016994374947451);
  vec4 i  = floor(v + dot(v, C.yyyy) );
  vec4 x0 = v -   i + dot(i, C.xxxx);
  vec4 i0;
  vec3 isX = step( x0.yzw, x0.xxx );
  vec3 isYZ = step( x0.zww, x0.yyz );
  i0.x = isX.x + isX.y + isX.z;
  i0.yzw = 1.0 - isX;
  i0.y += isYZ.x + isYZ.y;
  i0.zw += 1.0 - isYZ.xy;
  i0.z += isYZ.z;
  i0.w += 1.0 - isYZ.z;
  vec4 i3 = clamp( i0, 0.0, 1.0 );
  vec4 i2 = clamp( i0-1.0, 0.0, 1.0 );
  vec4 i1 = clamp( i0-2.0, 0.0, 1.0 );
  vec4 x1 = x0 - i1 + 1.0 * C.xxxx;
  vec4 x2 = x0 - i2 + 2.0 * C.xxxx;
  vec4 x3 = x0 - i3 + 3.0 * C.xxxx;
  vec4 x4 = x0 - 1.0 + 4.0 * C.xxxx;
  i = mod(i, 289.0);
  float j0 = permute( permute( permute( permute(i.w) + i.z) + i.y) + i.x);
  vec4 j1 = permute( permute( permute( permute (
             i.w + vec4(i1.w, i2.w, i3.w, 1.0 ))
           + i.z + vec4(i1.z, i2.z, i3.z, 1.0 ))
           + i.y + vec4(i1.y, i2.y, i3.y, 1.0 ))
           + i.x + vec4(i1.x, i2.x, i3.x, 1.0 ));
  vec4 ip = vec4(1.0/294.0, 1.0/49.0, 1.0/7.0, 0.0) ;
  vec4 p0 = grad4(j0,   ip);
  vec4 p1 = grad4(j1.x, ip);
  vec4 p2 = grad4(j1.y, ip);
  vec4 p3 = grad4(j1.z, ip);
  vec4 p4 = grad4(j1.w, ip);
  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;
  p4 *= taylorInvSqrt(dot(p4,p4));
  vec3 m0 = max(0.6 - vec3(dot(x0,x0), dot(x1,x1), dot(x2,x2)), 0.0);
  vec2 m1 = max(0.6 - vec2(dot(x3,x3), dot(x4,x4)            ), 0.0);
  m0 = m0 * m0;
  m1 = m1 * m1;
  return 49.0 * ( dot(m0*m0, vec3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
               + dot(m1*m1, vec2( dot( p3, x3 ), dot( p4, x4 ) ) ) ) ;
}

void main() {
  float time = uTime * 0.2;
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  vec4 particle = texture(uParticles, uv);
  vec4 base = texture(uBase, uv);

  float uRepelStrength = clamp(uMouseSpeed, 0.0, uMouseStrength);
  vec3 particlePos = particle.xyz;
  vec3 dir = normalize(particlePos - uMouse);
  float dist = distance(uMouse, particlePos);
  float repulsionForce = uRepelStrength / (dist * (dist + 1.0));
  vec3 repulsion = dir * repulsionForce * 2.0;
  particle.xyz += repulsion * uRepelStrength;

  if (particle.a >= 1.0) {

    particle.a = mod(particle.a, 1.0);
    particle.xyz = base.xyz;
  } else {

    float strength = simplexNoise4d(vec4(base.xyz, time + 1.0));
    float influence = (uFlowFieldInfluence - 0.5) * (- 2.0);
    strength = smoothstep(influence, 1.0, strength);

    vec3 flowField = vec3(
      simplexNoise4d(vec4(particle.xyz * uFlowFieldFrequency + 0.0, time)),
      simplexNoise4d(vec4(particle.xyz * uFlowFieldFrequency + 1.0, time)),
      simplexNoise4d(vec4(particle.xyz * uFlowFieldFrequency + 2.0, time))
    );
    flowField = normalize(flowField);
    particle.xyz += flowField * uDeltaTime * strength * uFlowFieldStrength;

    particle.a += uDeltaTime * 0.3;
    vec3 toTarget = base.xyz - particle.xyz;
    particle.xyz += toTarget * uDeltaTime * 2.2;
  }

  gl_FragColor = particle;
}
`;

export const PARTICLE_VERT =  `
uniform vec2 uResolution;
uniform float uSize;
uniform float uVisibility;
uniform sampler2D uParticlesTexture;

attribute vec2 aParticlesUv;
attribute float aSize;

varying float vAlpha;

void main() {
  vec4 particle = texture2D(uParticlesTexture, aParticlesUv);

  vec4 modelPosition = modelMatrix * vec4(particle.xyz, 1.0);
  vec4 viewPosition = viewMatrix * modelPosition;
  gl_Position = projectionMatrix * viewPosition;

  vAlpha = uVisibility;
  gl_PointSize = uSize * aSize * uResolution.y * 0.006;
  gl_PointSize *= (1.0 / - viewPosition.z);
}
`;

export const PARTICLE_FRAG =  `
varying float vAlpha;
void main() {

  vec2 c = gl_PointCoord - 0.5;
  float d = length(c);
  if (d > 0.5) discard;
  float a = smoothstep(0.5, 0.15, d) * vAlpha;

  gl_FragColor = vec4(vec3(1.0), a);
}
`;

export const ASCII_VERT =  `
varying vec2 vUv;
void main() {
  vUv = uv;
  gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
}
`;

export const TRAIL_LEN = 24;

export const ASCII_FRAG =  `
uniform sampler2D tDiffuse;
uniform vec2 uResolution;
uniform float uAsciiPixelSize;
uniform sampler2D uAsciiTexture;
uniform vec2 uCharCount;
uniform float uAsciiContrast;
uniform float uAsciiBrightness;
uniform float uAsciiMin;
uniform float uAsciiMax;

uniform float uAspect;
uniform vec3  uInk;
uniform vec2  uTrail[${TRAIL_LEN}];
uniform float uTrailAge[${TRAIL_LEN}];
uniform float uTrailOn;

varying vec2 vUv;

void main() {
  vec2 normalizedPixelSize = uAsciiPixelSize / uResolution;
  vec2 uvPixel = normalizedPixelSize * floor(vUv / normalizedPixelSize);
  vec4 texColor = texture2D(tDiffuse, uvPixel);

  float lumaRGB = dot(vec3(0.2126, 0.7152, 0.0722), texColor.rgb);
  float luma = max(lumaRGB, texColor.a);

  luma = (luma - uAsciiMin) / (uAsciiMax - uAsciiMin);
  luma = clamp(luma, 0.0, 1.0);
  luma = luma + uAsciiBrightness;
  luma = (luma - 0.5) * uAsciiContrast + 0.5;
  luma = clamp(luma, 0.0, 1.0);

  vec2 cellUV = fract(vUv / normalizedPixelSize);
  float charIndex = clamp(
    floor(luma * (uCharCount.x - 1.0)),
    0.0,
    uCharCount.x - 1.0
  );
  vec2 asciiUV = vec2(
    (charIndex + cellUV.x) / uCharCount.x,
    cellUV.y
  );
  float character = texture2D(uAsciiTexture, asciiUV).r;

  vec2 cellCenter = uvPixel + normalizedPixelSize * 0.5;

  vec3 inkDeep = vec3(0.14, 0.16, 0.30);
  vec3 inkLift = vec3(0.20, 0.24, 0.42);
  vec3 baseColor = mix(inkDeep, inkLift, smoothstep(0.0, 1.0, cellCenter.x));

  float trail = 0.0;
  float headness = 0.0;
  for (int i = 0; i < ${TRAIL_LEN}; i++) {
    float age = uTrailAge[i];
    if (age >= 1.0) continue;
    vec2 d = (cellCenter - uTrail[i]) * vec2(uAspect, 1.0);
    float rad = 0.16 + age * 0.10;
    float g = smoothstep(rad, 0.0, length(d)) * (1.0 - age);
    if (g > trail) { trail = g; headness = 1.0 - age; }
  }
  trail *= uTrailOn;

  vec3 trailCool = vec3(0.29, 0.23, 1.0);
  vec3 trailHot  = vec3(1.0, 0.32, 0.68);
  vec3 trailColor = mix(trailCool, trailHot, headness);

  vec3 glyphColor = mix(baseColor, trailColor, clamp(trail, 0.0, 1.0));

  float ink = character * smoothstep(0.015, 0.18, luma);
  ink = min(1.0, ink + trail * character * 0.3);

  gl_FragColor = vec4(glyphColor * ink, ink);
}
`;

```

### ascii-wordmark/atlas.ts
```ts
export const RAMP = " .:-=+*#%VAULT";

export function buildAtlas(ramp = RAMP, cell = 64): HTMLCanvasElement {
  const n = ramp.length;
  const c = document.createElement("canvas");
  c.width = cell * n;
  c.height = cell;
  const ctx = c.getContext("2d")!;
  ctx.clearRect(0, 0, c.width, c.height);
  ctx.fillStyle = "#fff";
  ctx.textAlign = "center";
  ctx.textBaseline = "middle";

  ctx.font = `${Math.floor(cell * 0.74)}px ui-monospace, "SF Mono", Menlo, monospace`;
  for (let i = 0; i < n; i++) {
    const ch = ramp[i];
    if (ch !== " ") ctx.fillText(ch, i * cell + cell / 2, cell / 2 + cell * 0.04);
  }
  return c;
}

```

### ascii-wordmark/word-points.ts
```ts
export interface WordPoints {
  positions: Float32Array;
  count: number;
  aspect: number;
}

export function buildWordPoints(
  word: string,
  size: number,
): WordPoints {
  const count = size * size;

  const W = 1024;
  const H = 320;
  const c = document.createElement("canvas");
  c.width = W;
  c.height = H;
  const ctx = c.getContext("2d", { willReadFrequently: true })!;
  ctx.clearRect(0, 0, W, H);
  ctx.fillStyle = "#fff";
  ctx.textAlign = "center";
  ctx.textBaseline = "middle";

  let fontSize = 240;
  ctx.font = `800 ${fontSize}px ui-sans-serif, system-ui, sans-serif`;
  const margin = 80;
  const measured = ctx.measureText(word).width;
  if (measured > W - margin) {
    fontSize = Math.floor(fontSize * ((W - margin) / measured));
    ctx.font = `800 ${fontSize}px ui-sans-serif, system-ui, sans-serif`;
  }
  ctx.fillText(word, W / 2, H / 2);

  const data = ctx.getImageData(0, 0, W, H).data;

  const lit: [number, number][] = [];
  const stride = 2;
  for (let y = 0; y < H; y += stride) {
    for (let x = 0; x < W; x += stride) {
      const a = data[(y * W + x) * 4 + 3];
      if (a > 128) lit.push([x, y]);
    }
  }

  if (lit.length === 0) {
    for (let i = 0; i < 256; i++) lit.push([W / 2, H / 2]);
  }

  const aspect = W / H;
  const positions = new Float32Array(count * 4);
  for (let i = 0; i < count; i++) {

    const p = lit[(Math.random() * lit.length) | 0];
    const jx = (Math.random() - 0.5) * stride;
    const jy = (Math.random() - 0.5) * stride;
    const nx = ((p[0] + jx) / W - 0.5) * 2 * aspect;
    const ny = -((p[1] + jy) / H - 0.5) * 2;
    const nz = (Math.random() - 0.5) * 0.08;

    positions[i * 4 + 0] = nx;
    positions[i * 4 + 1] = ny;
    positions[i * 4 + 2] = nz;
    positions[i * 4 + 3] = Math.random();
  }

  return { positions, count, aspect };
}

```

### ascii-wordmark/renderer.ts
```ts
import * as THREE from "three";
import { GPUComputationRenderer } from "three/examples/jsm/misc/GPUComputationRenderer.js";
import { EffectComposer } from "three/examples/jsm/postprocessing/EffectComposer.js";
import { RenderPass } from "three/examples/jsm/postprocessing/RenderPass.js";
import { ShaderPass } from "three/examples/jsm/postprocessing/ShaderPass.js";
import {
  GPGPU_COMPUTE,
  PARTICLE_VERT,
  PARTICLE_FRAG,
  ASCII_VERT,
  ASCII_FRAG,
  TRAIL_LEN,
} from "./shaders";
import { buildAtlas, RAMP } from "./atlas";
import { buildWordPoints } from "./word-points";

const FLOW_INFLUENCE = 0.43;
const FLOW_STRENGTH = 1.09;
const FLOW_FREQUENCY = 0.53;
const MOUSE_STRENGTH = 0.08;
const MOUSE_SPEED_GAIN = 1.5;

const IS_TOUCH =
  typeof window !== "undefined" &&
  (window.matchMedia?.("(pointer: coarse)").matches ?? false);

const FBO_SIZE = IS_TOUCH ? 128 : 200;
const MAX_DPR = IS_TOUCH ? 1.5 : 2;
const RENDER_SCALE = 0.5;
const ASCII_CELL_DIVISOR = 100;

export interface AsciiWordmarkOptions {
  word: string;
  inkColor: string;
}

export class AsciiWordmarkRenderer {
  private host: HTMLElement;
  private opts: AsciiWordmarkOptions;

  private renderer!: THREE.WebGLRenderer;
  private scene = new THREE.Scene();
  private camera!: THREE.PerspectiveCamera;
  private composer!: EffectComposer;
  private asciiPass!: ShaderPass;

  private gpgpu!: GPUComputationRenderer;
  private posVar!: ReturnType<GPUComputationRenderer["addVariable"]>;
  private points!: THREE.Points;
  private pointsMat!: THREE.ShaderMaterial;

  private clock = new THREE.Clock();
  private raf = 0;
  private running = false;
  private onScreen = true;
  private disposed = false;

  private mouse = new THREE.Vector3(9999, 9999, 0);
  private prevMouse = new THREE.Vector3(9999, 9999, 0);
  private mouseSpeed = 0;

  private mouseUv = new THREE.Vector2(9999, 9999);
  private onCard = false;

  private trailPos: THREE.Vector2[] = [];
  private trailAge: Float32Array = new Float32Array(TRAIL_LEN).fill(1);
  private trailOn = 0;
  private visibility = 0;
  private wordAspect = 3;
  private readonly WORD_MARGIN = 0.92;

  private io?: IntersectionObserver;
  private ro?: ResizeObserver;

  constructor(host: HTMLElement, opts: AsciiWordmarkOptions) {
    this.host = host;
    this.opts = opts;
  }

  mount(): boolean {
    const { clientWidth: w, clientHeight: h } = this.host;
    const dpr = Math.min(window.devicePixelRatio || 1, MAX_DPR);

    this.renderer = new THREE.WebGLRenderer({
      alpha: true,
      antialias: false,
      powerPreference: "high-performance",
      failIfMajorPerformanceCaveat: false,
    });
    this.renderer.setPixelRatio(dpr);
    this.renderer.setSize(w, h);
    this.renderer.setClearColor(0x000000, 0);
    this.host.appendChild(this.renderer.domElement);
    Object.assign(this.renderer.domElement.style, {
      position: "absolute",
      inset: "0",
      width: "100%",
      height: "100%",
      display: "block",

      touchAction: "pan-y",
      userSelect: "none",
      WebkitUserSelect: "none",
    });

    const { positions, count, aspect } = buildWordPoints(this.opts.word, FBO_SIZE);
    this.wordAspect = aspect;

    this.camera = new THREE.PerspectiveCamera(35, w / h, 0.1, 100);
    this.frameWord(w / h);
    this.camera.lookAt(0, 0, 0);

    if (!this.initGPGPU(positions)) return false;
    this.initPoints(count);
    this.initComposer(w, h, dpr);

    this.bindEvents();
    return true;
  }

  private initGPGPU(positions: Float32Array): boolean {
    this.gpgpu = new GPUComputationRenderer(FBO_SIZE, FBO_SIZE, this.renderer);

    this.gpgpu.setDataType(THREE.HalfFloatType);

    const baseTex = this.gpgpu.createTexture();
    (baseTex.image.data as Float32Array).set(positions);

    const initTex = this.gpgpu.createTexture();
    (initTex.image.data as Float32Array).set(positions);

    this.posVar = this.gpgpu.addVariable("uParticles", GPGPU_COMPUTE, initTex);
    this.gpgpu.setVariableDependencies(this.posVar, [this.posVar]);

    const u = this.posVar.material.uniforms;
    u.uTime = { value: 0 };
    u.uDeltaTime = { value: 0 };
    u.uBase = { value: baseTex };
    u.uFlowFieldInfluence = { value: FLOW_INFLUENCE };
    u.uFlowFieldStrength = { value: FLOW_STRENGTH };
    u.uFlowFieldFrequency = { value: FLOW_FREQUENCY };
    u.uMouse = { value: new THREE.Vector3(9999, 9999, 0) };
    u.uMouseStrength = { value: MOUSE_STRENGTH };
    u.uMouseSpeed = { value: 0 };

    const err = this.gpgpu.init();
    if (err) {

      console.warn("[ascii-wordmark] GPGPU unsupported, skipping:", err);
      return false;
    }
    return true;
  }

  private initPoints(count: number) {
    const geo = new THREE.BufferGeometry();

    const uvs = new Float32Array(count * 2);
    const sizes = new Float32Array(count);
    let i = 0;
    for (let y = 0; y < FBO_SIZE; y++) {
      for (let x = 0; x < FBO_SIZE; x++) {
        uvs[i * 2] = (x + 0.5) / FBO_SIZE;
        uvs[i * 2 + 1] = (y + 0.5) / FBO_SIZE;
        sizes[i] = 0.6 + Math.random() * 0.8;
        i++;
      }
    }

    geo.setAttribute("position", new THREE.BufferAttribute(new Float32Array(count * 3), 3));
    geo.setAttribute("aParticlesUv", new THREE.BufferAttribute(uvs, 2));
    geo.setAttribute("aSize", new THREE.BufferAttribute(sizes, 1));
    geo.setDrawRange(0, count);

    this.pointsMat = new THREE.ShaderMaterial({
      vertexShader: PARTICLE_VERT,
      fragmentShader: PARTICLE_FRAG,
      transparent: true,
      depthWrite: false,
      blending: THREE.AdditiveBlending,
      uniforms: {
        uResolution: { value: new THREE.Vector2() },
        uSize: { value: 4 },
        uVisibility: { value: 0 },
        uParticlesTexture: { value: null },
      },
    });

    this.points = new THREE.Points(geo, this.pointsMat);
    this.points.frustumCulled = false;
    this.scene.add(this.points);
  }

  private initComposer(w: number, h: number, dpr: number) {
    const bw = Math.max(2, Math.round(w * RENDER_SCALE));
    const bh = Math.max(2, Math.round(h * RENDER_SCALE));

    this.composer = new EffectComposer(this.renderer);
    this.composer.setPixelRatio(dpr);
    this.composer.setSize(w, h);
    this.composer.addPass(new RenderPass(this.scene, this.camera));

    const atlas = buildAtlas(RAMP);
    const atlasTex = new THREE.CanvasTexture(atlas);
    atlasTex.minFilter = THREE.LinearFilter;
    atlasTex.magFilter = THREE.LinearFilter;

    const cell = (bw * dpr) / ASCII_CELL_DIVISOR;

    const ink = new THREE.Color(this.opts.inkColor);

    this.trailPos = Array.from({ length: TRAIL_LEN }, () => new THREE.Vector2(9999, 9999));
    this.trailAge = new Float32Array(TRAIL_LEN).fill(1);

    this.asciiPass = new ShaderPass({
      uniforms: {
        tDiffuse: { value: null },
        uResolution: { value: new THREE.Vector2(bw * dpr, bh * dpr) },
        uAsciiPixelSize: { value: cell },
        uAsciiTexture: { value: atlasTex },
        uCharCount: { value: new THREE.Vector2(RAMP.length, 1) },
        uAsciiContrast: { value: 1.4 },
        uAsciiBrightness: { value: 0.12 },
        uAsciiMin: { value: 0.0 },
        uAsciiMax: { value: 1.0 },
        uAspect: { value: w / h },
        uInk: { value: new THREE.Vector3(ink.r, ink.g, ink.b) },
        uTrail: { value: this.trailPos },
        uTrailAge: { value: this.trailAge },
        uTrailOn: { value: 0 },
      },
      vertexShader: ASCII_VERT,
      fragmentShader: ASCII_FRAG,
    });
    this.asciiPass.renderToScreen = true;
    this.composer.addPass(this.asciiPass);

    this.pointsMat.uniforms.uResolution.value.set(w * dpr, h * dpr);
  }

  private bindEvents() {
    const onPointerMove = (e: PointerEvent) => {
      const r = this.host.getBoundingClientRect();

      const nx = ((e.clientX - r.left) / r.width) * 2 - 1;
      const ny = -(((e.clientY - r.top) / r.height) * 2 - 1);
      const v = new THREE.Vector3(nx, ny, 0.5).unproject(this.camera);
      const dir = v.sub(this.camera.position).normalize();
      const dist = -this.camera.position.z / dir.z;
      this.mouse.copy(this.camera.position).add(dir.multiplyScalar(dist));

      this.mouseUv.set((e.clientX - r.left) / r.width, 1 - (e.clientY - r.top) / r.height);
      this.onCard = true;
    };
    const onPointerLeave = () => {
      this.mouse.set(9999, 9999, 0);
      this.mouseUv.set(9999, 9999);
      this.onCard = false;
    };

    this.host.addEventListener("pointermove", onPointerMove);
    this.host.addEventListener("pointerleave", onPointerLeave);
    this.cleanupFns.push(() => {
      this.host.removeEventListener("pointermove", onPointerMove);
      this.host.removeEventListener("pointerleave", onPointerLeave);
    });

    const onVis = () => (document.hidden ? this.stop() : this.maybeStart());
    document.addEventListener("visibilitychange", onVis);
    this.cleanupFns.push(() => document.removeEventListener("visibilitychange", onVis));

    this.io = new IntersectionObserver(
      (es) => {
        this.onScreen = es[0]?.isIntersecting ?? true;
        this.onScreen ? this.maybeStart() : this.stop();
      },
      { threshold: 0.01 },
    );
    this.io.observe(this.host);

    this.ro = new ResizeObserver(() => this.resize());
    this.ro.observe(this.host);
  }

  private cleanupFns: (() => void)[] = [];

  private frameWord(viewportAspect: number) {
    const halfV = THREE.MathUtils.degToRad(this.camera.fov) / 2;
    const tanV = Math.tan(halfV);
    const distForHeight = 1.0 / tanV;
    const distForWidth = this.wordAspect / (tanV * viewportAspect);
    const dist = Math.max(distForHeight, distForWidth) * this.WORD_MARGIN;
    this.camera.position.set(0, 0, dist);
  }

  private resize() {
    if (this.disposed) return;
    const { clientWidth: w, clientHeight: h } = this.host;
    if (w === 0 || h === 0) return;
    const dpr = Math.min(window.devicePixelRatio || 1, MAX_DPR);
    this.renderer.setPixelRatio(dpr);
    this.renderer.setSize(w, h);
    this.composer.setPixelRatio(dpr);
    this.composer.setSize(w, h);
    this.camera.aspect = w / h;
    this.frameWord(w / h);
    this.camera.updateProjectionMatrix();

    const bw = Math.max(2, Math.round(w * RENDER_SCALE));
    const bh = Math.max(2, Math.round(h * RENDER_SCALE));
    this.asciiPass.uniforms.uResolution.value.set(bw * dpr, bh * dpr);
    this.asciiPass.uniforms.uAsciiPixelSize.value = (bw * dpr) / ASCII_CELL_DIVISOR;
    this.asciiPass.uniforms.uAspect.value = w / h;
    this.pointsMat.uniforms.uResolution.value.set(w * dpr, h * dpr);
  }

  start() {
    this.onScreen = true;
    this.maybeStart();
  }

  private maybeStart() {
    if (this.disposed || this.running || !this.onScreen || document.hidden) return;
    this.running = true;
    this.clock.getDelta();
    this.raf = requestAnimationFrame(this.loop);
  }

  stop() {
    this.running = false;
    if (this.raf) cancelAnimationFrame(this.raf);
    this.raf = 0;
  }

  private advanceTrail(dt: number) {
    const TRAIL_LIFE = 0.75;
    for (let i = 0; i < TRAIL_LEN; i++) {
      this.trailAge[i] = Math.min(1, this.trailAge[i] + dt / TRAIL_LIFE);
    }
    if (this.onCard) {

      for (let i = TRAIL_LEN - 1; i > 0; i--) {
        this.trailPos[i].copy(this.trailPos[i - 1]);
        this.trailAge[i] = this.trailAge[i - 1];
      }
      this.trailPos[0].copy(this.mouseUv);
      this.trailAge[0] = 0;
    }

    this.asciiPass.uniforms.uTrailAge.value = this.trailAge;
  }

  private loop = () => {
    if (!this.running) return;
    const dt = Math.min(this.clock.getDelta(), 1 / 30);
    const t = this.clock.elapsedTime;

    this.mouseSpeed = this.mouse.distanceTo(this.prevMouse);
    if (this.mouse.x > 9000) this.mouseSpeed = 0;
    this.prevMouse.copy(this.mouse);

    const cu = this.posVar.material.uniforms;
    cu.uTime.value = t;
    cu.uDeltaTime.value = dt;
    cu.uMouse.value.copy(this.mouse);
    cu.uMouseSpeed.value = this.mouseSpeed * MOUSE_SPEED_GAIN;
    this.gpgpu.compute();

    this.pointsMat.uniforms.uParticlesTexture.value =
      this.gpgpu.getCurrentRenderTarget(this.posVar).texture;

    this.visibility = Math.min(1, this.visibility + dt * 0.9);
    this.pointsMat.uniforms.uVisibility.value = this.visibility;

    const au = this.asciiPass.uniforms;
    this.advanceTrail(dt);

    this.trailOn += ((this.onCard ? 1 : 0) - this.trailOn) * Math.min(1, dt * 6);
    au.uTrailOn.value = this.trailOn;

    this.composer.render();
    this.raf = requestAnimationFrame(this.loop);
  };

  dispose() {
    this.disposed = true;
    this.stop();
    this.cleanupFns.forEach((fn) => fn());
    this.io?.disconnect();
    this.ro?.disconnect();
    this.points?.geometry.dispose();
    this.pointsMat?.dispose();
    this.asciiPass?.uniforms.uAsciiTexture.value?.dispose?.();
    this.gpgpu?.dispose?.();
    this.composer?.dispose?.();
    this.renderer?.dispose();
    this.renderer?.forceContextLoss?.();
    if (this.renderer?.domElement.parentNode) {
      this.renderer.domElement.parentNode.removeChild(this.renderer.domElement);
    }
  }
}

```