3D Vector Field — d3 + GSAP ScrollTrigger (Zoom Fix)
        
<!doctype html>
<html>
<head>
  <meta charset="utf-8" />
  <title>3D Vector Field — d3 + GSAP ScrollTrigger (Zoom Fix)</title>
  <style>
    html,body { height:200%; margin:0; background:#080808; color:#ddd; }
    #canvas { display:block; background:#0b0b0b; position: sticky; top: 0; width: 100vw; height: 100vh; }
    .overlay { position:fixed; left:10px; top:10px; color:#ccc; font-family:system-ui; font-size:13px; z-index:10; }
    .hint { position:fixed; right:10px; bottom:10px; color:#999; font-family:system-ui; font-size:13px; z-index:10; }
  </style>
</head>
<body>
  <canvas id="canvas"></canvas>

  <script src="https://unpkg.com/d3@7/dist/d3.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/gsap.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/ScrollTrigger.min.js"></script>
  <script>
  gsap.registerPlugin(ScrollTrigger);

  const cfg = {
    width: Math.min(1200, window.innerWidth - 20),
    height: Math.min(800, window.innerHeight - 20),
    cols: 20,
    rows: 14,
    depthLayers: 10,
    spacing: 48,
    vectorScale: 14,
    perspective: 800,
    rotationSpeed: 0.6,
    // NEW: single zoom factor (1 = normal, >1 = zoomed in)
    zoom: 1
  };

  const canvas = document.getElementById('canvas');
  const ctx = canvas.getContext('2d');

  function resize() {
    cfg.width = Math.min(1200, window.innerWidth - 20);
    cfg.height = Math.min(800, window.innerHeight - 20);
    canvas.width = cfg.width;
    canvas.height = cfg.height;
  }
  resize();
  window.addEventListener('resize', resize);

  const centerFn = () => ({ x: cfg.width/2, y: cfg.height/2 });

  const xOffset = -((cfg.cols - 1) * cfg.spacing) / 2;
  const yOffset = -((cfg.rows - 1) * cfg.spacing) / 2;
  const zOffset = -((cfg.depthLayers - 1) * cfg.spacing) / 2;

  const points = [];
  for (let iz = 0; iz < cfg.depthLayers; iz++) {
    for (let iy = 0; iy < cfg.rows; iy++) {
      for (let ix = 0; ix < cfg.cols; ix++) {
        const x = xOffset + ix * cfg.spacing;
        const y = yOffset + iy * cfg.spacing;
        const z = zOffset + iz * cfg.spacing;
        points.push({x,y,z, ix, iy, iz});
      }
    }
  }

  const depthScale = d3.scaleLinear().domain([zOffset, -zOffset]).range([0,1]);
  const colorScale = d3.scaleLinear().domain([0,1]).range([60,220]);
  const widthScale = d3.scaleLinear().domain([0,1]).range([0.6,2.6]);

  // Projection now uses zoom: we apply zoom by scaling rx, ry relative to center.
  function project(pt, cameraAngle = 0) {
    const cosA = Math.cos(cameraAngle), sinA = Math.sin(cameraAngle);
    const rx = pt.x * cosA + pt.z * sinA;
    const rz = -pt.x * sinA + pt.z * cosA;
    // base perspective scale
    const scale = cfg.perspective / (cfg.perspective - rz);
    const c = centerFn();
    // apply zoom as additional multiplier on projected coordinates around center
    return {
      x: c.x + (rx * scale - 0) * cfg.zoom,
      y: c.y + (pt.y * scale - 0) * cfg.zoom,
      s: scale * cfg.zoom,
      rz
    };
  }

  function circularField(x,y,z,t) {
    const r = Math.hypot(x,y) + 1e-6;
    const omega = cfg.rotationSpeed * (1 + 0.06 * z / cfg.spacing);
    const vx = -y / r, vy = x / r;
    const vz = 0.35 * Math.sin(t * 1.2 + z * 0.02 + x * 0.01);
    const amp = cfg.vectorScale * (1 - 0.18 * Math.tanh(r / (cfg.cols*cfg.spacing*0.5)));
    const ang = omega * t;
    const cos = Math.cos(ang), sin = Math.sin(ang);
    const rx = vx * cos - vy * sin;
    const ry = vx * sin + vy * cos;
    return { vx: rx * amp, vy: ry * amp, vz: vz * amp * 0.6 };
  }

  function drawArrow(x1,y1,x2,y2,lineWidth,color,alpha){
    ctx.save();
    ctx.globalAlpha = alpha;
    ctx.strokeStyle = color; ctx.fillStyle = color; ctx.lineWidth = lineWidth; ctx.lineCap='round';
    ctx.beginPath(); ctx.moveTo(x1,y1); ctx.lineTo(x2,y2); ctx.stroke();
    const headLen = 6 + lineWidth*1.5;
    const angle = Math.atan2(y2-y1, x2-x1);
    ctx.beginPath();
    ctx.moveTo(x2,y2);
    ctx.lineTo(x2 - headLen*Math.cos(angle-Math.PI/6), y2 - headLen*Math.sin(angle-Math.PI/6));
    ctx.lineTo(x2 - headLen*Math.cos(angle+Math.PI/6), y2 - headLen*Math.sin(angle+Math.PI/6));
    ctx.closePath(); ctx.fill();
    ctx.restore();
  }

  d3.timer(function(elapsed){
    const t = elapsed / 1000;
    ctx.fillStyle = "rgba(8,8,10,0.20)";
    ctx.fillRect(0,0,cfg.width,cfg.height);
    const cameraAngle = 0.12 * Math.sin(t * 0.15);
    const projected = points.map(p => ({p, proj: project(p, cameraAngle)}))
                            .sort((a,b) => a.proj.rz - b.proj.rz);
    for (const item of projected){
      const p = item.p, proj = item.proj, scale = proj.s;
      const vec = circularField(p.x,p.y,p.z,t);
      const sx = proj.x, sy = proj.y;
      const end3 = { x: p.x + vec.vx, y: p.y + vec.vy, z: p.z + vec.vz };
      const eproj = project(end3, cameraAngle);
      const ex = eproj.x, ey = eproj.y;
      const depthVal = depthScale(p.z);
      const hue = colorScale(depthVal);
      const brightness = 52 + 28*depthVal;
      const color = `hsl(${hue},85%,${brightness}%)`;
      const lineWidth = widthScale(depthVal) * scale;
      const alpha = 0.28 + 0.72 * depthVal;
      drawArrow(sx,sy,ex,ey,Math.max(0.6,lineWidth),color,alpha);
    }
    // subtle front points
    ctx.save(); ctx.globalAlpha=0.06; ctx.fillStyle="#fff";
    for (const item of projected.slice(-60)){ ctx.beginPath(); ctx.arc(item.proj.x, item.proj.y, 1.2*item.proj.s,0,Math.PI*2); ctx.fill(); }
    ctx.restore();
  });

  // GSAP ScrollTrigger: animate cfg.zoom from 1 -> 2.8 (tune as desired)
  gsap.to(cfg, {
    zoom: 2.8,
    ease: "none",
    scrollTrigger: {
      trigger: document.body,
      start: "top top",
      end: "bottom top",
      scrub: 0.6,
      // markers: true
    }
  });
  </script>
</body>
</html>

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====================

User prompt 1 of 3 - 2/16/2026, 7:22:46 PM:
Generate me 3d vector field in d3js animated in circular motion. HTML + JS only

GPT-5 mini:
## 3D Vector Field (HTML + JS) — Animated Circular Motion (d3.js + Canvas)

Below is a single-file HTML+JS example that uses d3 for scales and animation timing, and an HTML canvas to render a pseudo-3D vector field where vectors circulate around the Z axis (circular motion). The 3D effect is achieved with simple perspective projection. Paste into a file (e.g., index.html) and open in a browser.

```html
<!doctype html>
<html>
<head>
  <meta charset="utf-8" />
  <title>3D Circular Vector Field — d3.js</title>
  <style>
    html,body { height:100%; margin:0; background:#111; color:#ddd; }
    #canvas { display:block; margin:0 auto; background:#0b0b0b; }
    .overlay { position:fixed; left:10px; top:10px; color:#ccc; font-family:system-ui,Segoe UI,Roboto; font-size:13px; }
  </style>
</head>
<body>
  <div class="overlay">3D Circular Vector Field — d3.js</div>
  <canvas id="canvas"></canvas>

  <script src="https://unpkg.com/d3@7/dist/d3.min.js"></script>
  <script>
  // Config
  const cfg = {
    width: Math.min(1200, window.innerWidth - 20),
    height: Math.min(800, window.innerHeight - 20),
    cols: 20,          // grid columns
    rows: 14,          // grid rows
    depthLayers: 10,   // number of z-slices (3D)
    spacing: 48,       // base spacing in x/y
    vectorScale: 14,   // arrow length multiplier
    perspective: 800,  // perspective distance
    rotationSpeed: 0.6 // angular speed (radians per second)
  };

  // Canvas setup
  const canvas = document.getElementById('canvas');
  canvas.width = cfg.width;
  canvas.height = cfg.height;
  const ctx = canvas.getContext('2d');

  // Derived layout
  const centerX = cfg.width / 2;
  const centerY = cfg.height / 2;
  const xOffset = -((cfg.cols - 1) * cfg.spacing) / 2;
  const yOffset = -((cfg.rows - 1) * cfg.spacing) / 2;
  const zOffset = -((cfg.depthLayers - 1) * cfg.spacing) / 2;

  // Build grid points in 3D
  const points = [];
  for (let iz = 0; iz < cfg.depthLayers; iz++) {
    for (let iy = 0; iy < cfg.rows; iy++) {
      for (let ix = 0; ix < cfg.cols; ix++) {
        const x = xOffset + ix * cfg.spacing;
        const y = yOffset + iy * cfg.spacing;
        const z = zOffset + iz * cfg.spacing;
        points.push({x,y,z, ix, iy, iz});
      }
    }
  }

  // d3 scales for color and thickness by depth (near = brighter)
  const depthScale = d3.scaleLinear()
    .domain([zOffset, -zOffset]) // far to near
    .range([0,1]);

  const colorScale = d3.scaleLinear()
    .domain([0,1])
    .range([60, 220]); // hue values for HSL

  const widthScale = d3.scaleLinear()
    .domain([0,1])
    .range([0.6, 2.6]); // line width

  // Projection: simple perspective onto canvas
  function project(pt, cameraAngle = 0) {
    // optionally rotate around Y (cameraAngle) to make it spin camera a bit
    const cosA = Math.cos(cameraAngle), sinA = Math.sin(cameraAngle);
    const rx = pt.x * cosA + pt.z * sinA;
    const rz = -pt.x * sinA + pt.z * cosA; // rotated z
    const scale = cfg.perspective / (cfg.perspective - rz);
    return {
      x: centerX + rx * scale,
      y: centerY + pt.y * scale,
      s: scale,
      rz
    };
  }

  // Vector field function: circular around Z axis with optional time
  // returns vector {vx, vy, vz}
  function circularField(x,y,z, t) {
    // compute radius in XY plane from origin
    const r = Math.hypot(x, y) + 1e-6;
    // angular velocity might vary slightly with z for depth variation
    const omega = cfg.rotationSpeed * (1 + 0.06 * z / cfg.spacing);
    // direction tangent to circle: (-y/r, x/r)  (counterclockwise)
    const vx = -y / r;
    const vy =  x / r;
    // add small vertical component that oscillates with time for 3D motion
    const vz = 0.35 * Math.sin(t * 1.2 + z * 0.02 + x * 0.01);
    // amplitude modulation by radius to keep vectors reasonable
    const amp = cfg.vectorScale * (1 - 0.18 * Math.tanh(r / (cfg.cols*cfg.spacing*0.5)));
    // also rotate vector slowly over time
    const ang = omega * t;
    const cos = Math.cos(ang), sin = Math.sin(ang);
    const rx = vx * cos - vy * sin;
    const ry = vx * sin + vy * cos;
    return { vx: rx * amp, vy: ry * amp, vz: vz * amp * 0.6 };
  }

  // Arrow drawing helper
  function drawArrow(x1,y1,x2,y2, lineWidth, color, alpha) {
    ctx.save();
    ctx.globalAlpha = alpha;
    ctx.strokeStyle = color;
    ctx.fillStyle = color;
    ctx.lineWidth = lineWidth;
    ctx.lineCap = 'round';

    // main shaft
    ctx.beginPath();
    ctx.moveTo(x1,y1);
    ctx.lineTo(x2,y2);
    ctx.stroke();

    // arrowhead
    const headLen = 6 + lineWidth * 1.5;
    const angle = Math.atan2(y2 - y1, x2 - x1);
    ctx.beginPath();
    ctx.moveTo(x2, y2);
    ctx.lineTo(x2 - headLen * Math.cos(angle - Math.PI/6), y2 - headLen * Math.sin(angle - Math.PI/6));
    ctx.lineTo(x2 - headLen * Math.cos(angle + Math.PI/6), y2 - headLen * Math.sin(angle + Math.PI/6));
    ctx.closePath();
    ctx.fill();

    ctx.restore();
  }

  // Animation loop using d3.timer
  const start = Date.now();
  d3.timer(function(elapsed) {
    const t = elapsed / 1000; // seconds

    // clear with slight alpha to create motion trails
    ctx.fillStyle = "rgba(8,8,10,0.20)";
    ctx.fillRect(0,0,cfg.width,cfg.height);

    // optional slow camera spin for nicer 3D perception
    const cameraAngle = 0.12 * Math.sin(t * 0.15);

    // sort points by depth (back to front) for painter's algorithm
    const projected = points.map(p => {
      const proj = project(p, cameraAngle);
      return { p, proj };
    }).sort((a,b) => a.proj.rz - b.proj.rz); // far (more negative rz) first

    // draw grid points vectors
    for (const item of projected) {
      const p = item.p;
      const proj = item.proj;
      const scale = proj.s;

      // compute vector at this 3D point
      const vec = circularField(p.x, p.y, p.z, t);

      // project start and end
      const sx = proj.x;
      const sy = proj.y;

      // project 3D end by adding vector then projecting (approx)
      const end3 = { x: p.x + vec.vx, y: p.y + vec.vy, z: p.z + vec.vz };
      const eproj = project(end3, cameraAngle);

      const ex = eproj.x;
      const ey = eproj.y;

      // color / width / alpha by depth (nearer => brighter / thicker)
      const depthVal = depthScale(p.z);
      const hue = colorScale(depthVal);
      const brightness = 52 + 28 * depthVal;
      const color = `hsl(${hue}, 85%, ${brightness}%)`;
      const lineWidth = widthScale(depthVal) * scale;

      // fade vectors that are very far behind
      const alpha = 0.28 + 0.72 * depthVal;
      drawArrow(sx, sy, ex, ey, Math.max(0.6, lineWidth), color, alpha);
    }

    // optional: draw subtle grid points near front
    ctx.save();
    ctx.globalAlpha = 0.06;
    ctx.fillStyle = "#fff";
    for (const item of projected.slice(-60)) {
      ctx.beginPath();
      ctx.arc(item.proj.x, item.proj.y, 1.2 * item.proj.s, 0, Math.PI*2);
      ctx.fill();
    }
    ctx.restore();

    // done; continue
  });

  // Resize handling
  window.addEventListener('resize', () => {
    cfg.width = Math.min(1200, window.innerWidth - 20);
    cfg.height = Math.min(800, window.innerHeight - 20);
    canvas.width = cfg.width;
    canvas.height = cfg.height;
  });

  </script>
</body>
</html>
```

Usage notes (brief):
- Adjust cfg.cols/rows/depthLayers and spacing for density.
- Change cfg.rotationSpeed, vectorScale, perspective for different visual effects.
- The script uses d3.timer and d3 scales; no DOM-based SVG vectors to keep performance high.

--------------------

User prompt 2 of 3 - 2/16/2026, 7:23:57 PM:
Now add GSAP scroll trigger so when I scroll it zooms in into center of this field.

GPT-5 mini:
## Updated HTML + JS — Add GSAP ScrollTrigger Zoom

Below is the single-file HTML updated to include GSAP with ScrollTrigger. Scrolling the page will animate a smooth zoom into the center of the 3D vector field by adjusting the canvas perspective value and a camera focal offset. Paste into a file and open in a browser.

```html
<!doctype html>
<html>
<head>
  <meta charset="utf-8" />
  <title>3D Circular Vector Field — d3.js + GSAP ScrollTrigger</title>
  <style>
    html,body { height:200%; margin:0; background:#111; color:#ddd; } /* taller page to allow scrolling */
    #canvas { display:block; margin:40vh auto 0; background:#0b0b0b; } /* start canvas mid-page */
    .overlay { position:fixed; left:10px; top:10px; color:#ccc; font-family:system-ui,Segoe UI,Roboto; font-size:13px; z-index:10; }
    .hint { position:fixed; right:10px; bottom:10px; color:#999; font-family:system-ui,Segoe UI,Roboto; font-size:13px; z-index:10; }
  </style>
</head>
<body>
  <div class="overlay">3D Circular Vector Field — d3.js + GSAP ScrollTrigger</div>
  <div class="hint">Scroll to zoom in</div>
  <canvas id="canvas"></canvas>

  <script src="https://unpkg.com/d3@7/dist/d3.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/gsap.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/ScrollTrigger.min.js"></script>

  <script>
  gsap.registerPlugin(ScrollTrigger);

  // Config (kept adjustable)
  const cfg = {
    width: Math.min(1200, window.innerWidth - 20),
    height: Math.min(800, window.innerHeight - 20),
    cols: 20,
    rows: 14,
    depthLayers: 10,
    spacing: 48,
    vectorScale: 14,
    perspective: 800,
    rotationSpeed: 0.6,
    // additional camera params that ScrollTrigger will tween
    camZOffset: 0,       // shift along z for camera (used in projection)
    perspectiveScale: 1  // multiplier applied to perspective for zooming
  };

  // Canvas setup
  const canvas = document.getElementById('canvas');
  canvas.width = cfg.width;
  canvas.height = cfg.height;
  const ctx = canvas.getContext('2d');

  // Derived layout
  const centerX = () => cfg.width / 2;
  const centerY = () => cfg.height / 2;
  const xOffset = -((cfg.cols - 1) * cfg.spacing) / 2;
  const yOffset = -((cfg.rows - 1) * cfg.spacing) / 2;
  const zOffset = -((cfg.depthLayers - 1) * cfg.spacing) / 2;

  // Build grid points in 3D
  const points = [];
  for (let iz = 0; iz < cfg.depthLayers; iz++) {
    for (let iy = 0; iy < cfg.rows; iy++) {
      for (let ix = 0; ix < cfg.cols; ix++) {
        const x = xOffset + ix * cfg.spacing;
        const y = yOffset + iy * cfg.spacing;
        const z = zOffset + iz * cfg.spacing;
        points.push({x,y,z, ix, iy, iz});
      }
    }
  }

  // d3 scales for color and thickness by depth (near = brighter)
  const depthScale = d3.scaleLinear()
    .domain([zOffset, -zOffset])
    .range([0,1]);

  const colorScale = d3.scaleLinear()
    .domain([0,1])
    .range([60, 220]);

  const widthScale = d3.scaleLinear()
    .domain([0,1])
    .range([0.6, 2.6]);

  // Projection: uses cfg.perspective * cfg.perspectiveScale and camZOffset
  function project(pt, cameraAngle = 0) {
    const cosA = Math.cos(cameraAngle), sinA = Math.sin(cameraAngle);
    const rx = pt.x * cosA + pt.z * sinA;
    const rz = -pt.x * sinA + pt.z * cosA + cfg.camZOffset;
    const perspectiveEffective = cfg.perspective * cfg.perspectiveScale;
    const scale = perspectiveEffective / (perspectiveEffective - rz);
    return {
      x: centerX() + rx * scale,
      y: centerY() + pt.y * scale,
      s: scale,
      rz
    };
  }

  // Vector field function: circular around Z axis
  function circularField(x,y,z, t) {
    const r = Math.hypot(x, y) + 1e-6;
    const omega = cfg.rotationSpeed * (1 + 0.06 * z / cfg.spacing);
    const vx = -y / r;
    const vy =  x / r;
    const vz = 0.35 * Math.sin(t * 1.2 + z * 0.02 + x * 0.01);
    const amp = cfg.vectorScale * (1 - 0.18 * Math.tanh(r / (cfg.cols*cfg.spacing*0.5)));
    const ang = omega * t;
    const cos = Math.cos(ang), sin = Math.sin(ang);
    const rx = vx * cos - vy * sin;
    const ry = vx * sin + vy * cos;
    return { vx: rx * amp, vy: ry * amp, vz: vz * amp * 0.6 };
  }

  function drawArrow(x1,y1,x2,y2, lineWidth, color, alpha) {
    ctx.save();
    ctx.globalAlpha = alpha;
    ctx.strokeStyle = color;
    ctx.fillStyle = color;
    ctx.lineWidth = lineWidth;
    ctx.lineCap = 'round';
    ctx.beginPath();
    ctx.moveTo(x1,y1);
    ctx.lineTo(x2,y2);
    ctx.stroke();
    const headLen = 6 + lineWidth * 1.5;
    const angle = Math.atan2(y2 - y1, x2 - x1);
    ctx.beginPath();
    ctx.moveTo(x2, y2);
    ctx.lineTo(x2 - headLen * Math.cos(angle - Math.PI/6), y2 - headLen * Math.sin(angle - Math.PI/6));
    ctx.lineTo(x2 - headLen * Math.cos(angle + Math.PI/6), y2 - headLen * Math.sin(angle + Math.PI/6));
    ctx.closePath();
    ctx.fill();
    ctx.restore();
  }

  // Animation loop using d3.timer
  d3.timer(function(elapsed) {
    const t = elapsed / 1000;
    ctx.fillStyle = "rgba(8,8,10,0.20)";
    ctx.fillRect(0,0,cfg.width,cfg.height);
    const cameraAngle = 0.12 * Math.sin(t * 0.15);
    const projected = points.map(p => ({ p, proj: project(p, cameraAngle) }))
                            .sort((a,b) => a.proj.rz - b.proj.rz);
    for (const item of projected) {
      const p = item.p;
      const proj = item.proj;
      const scale = proj.s;
      const vec = circularField(p.x, p.y, p.z, t);
      const sx = proj.x;
      const sy = proj.y;
      const end3 = { x: p.x + vec.vx, y: p.y + vec.vy, z: p.z + vec.vz };
      const eproj = project(end3, cameraAngle);
      const ex = eproj.x;
      const ey = eproj.y;
      const depthVal = depthScale(p.z);
      const hue = colorScale(depthVal);
      const brightness = 52 + 28 * depthVal;
      const color = `hsl(${hue}, 85%, ${brightness}%)`;
      const lineWidth = widthScale(depthVal) * scale;
      const alpha = 0.28 + 0.72 * depthVal;
      drawArrow(sx, sy, ex, ey, Math.max(0.6, lineWidth), color, alpha);
    }
    ctx.save();
    ctx.globalAlpha = 0.06;
    ctx.fillStyle = "#fff";
    for (const item of projected.slice(-60)) {
      ctx.beginPath();
      ctx.arc(item.proj.x, item.proj.y, 1.2 * item.proj.s, 0, Math.PI*2);
      ctx.fill();
    }
    ctx.restore();
  });

  // GSAP ScrollTrigger: zoom into center while scrolling down the page
  // We'll tween cfg.perspectiveScale (lower => zoom in) and cfg.camZOffset to pull camera forward.
  gsap.to(cfg, {
    perspectiveScale: 0.28,   // smaller perspective => larger apparent zoom
    camZOffset: -200,         // shift camera forward along Z
    ease: "none",
    scrollTrigger: {
      trigger: document.body,
      start: "top top",
      end: "bottom top",
      scrub: 0.6,
      // markers: true, // uncomment for debugging
    },
    onUpdate: () => {
      // no-op; d3.timer reads cfg directly each frame
    }
  });

  // Responsive handling
  function resizeCanvas() {
    cfg.width = Math.min(1200, window.innerWidth - 20);
    cfg.height = Math.min(800, window.innerHeight - 20);
    canvas.width = cfg.width;
    canvas.height = cfg.height;
  }
  window.addEventListener('resize', resizeCanvas);

  // Ensure initial layout (canvas vertically centered area)
  resizeCanvas();

  </script>
</body>
</html>
```

Notes:
- Adjust GSAP target values (perspectiveScale and camZOffset) to tune zoom intensity.
- Set ScrollTrigger markers: true for tuning the scroll range.

--------------------

User prompt 3 of 3 - 2/16/2026, 7:25:00 PM:
It does not zoom in

GPT-5 mini:
Likely cause: the canvas draw uses a fixed center and perspective read from cfg, but the projection math or GSAP target values don't produce a visibly larger scale. I'll give a minimal, corrected HTML+JS where ScrollTrigger clearly zooms by animating a single "zoom" parameter that multiplies projected coordinates (works robustly). Paste this file and open in a browser; scroll to see zoom.

```html
<!doctype html>
<html>
<head>
  <meta charset="utf-8" />
  <title>3D Vector Field — d3 + GSAP ScrollTrigger (Zoom Fix)</title>
  <style>
    html,body { height:200%; margin:0; background:#080808; color:#ddd; }
    #canvas { display:block; margin:30vh auto 0; background:#0b0b0b; }
    .overlay { position:fixed; left:10px; top:10px; color:#ccc; font-family:system-ui; font-size:13px; z-index:10; }
    .hint { position:fixed; right:10px; bottom:10px; color:#999; font-family:system-ui; font-size:13px; z-index:10; }
  </style>
</head>
<body>
  <div class="overlay">3D Vector Field — Scroll to zoom</div>
  <div class="hint">Scroll to zoom in</div>
  <canvas id="canvas"></canvas>

  <script src="https://unpkg.com/d3@7/dist/d3.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/gsap.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.12.2/ScrollTrigger.min.js"></script>
  <script>
  gsap.registerPlugin(ScrollTrigger);

  const cfg = {
    width: Math.min(1200, window.innerWidth - 20),
    height: Math.min(800, window.innerHeight - 20),
    cols: 20,
    rows: 14,
    depthLayers: 10,
    spacing: 48,
    vectorScale: 14,
    perspective: 800,
    rotationSpeed: 0.6,
    // NEW: single zoom factor (1 = normal, >1 = zoomed in)
    zoom: 1
  };

  const canvas = document.getElementById('canvas');
  const ctx = canvas.getContext('2d');

  function resize() {
    cfg.width = Math.min(1200, window.innerWidth - 20);
    cfg.height = Math.min(800, window.innerHeight - 20);
    canvas.width = cfg.width;
    canvas.height = cfg.height;
  }
  resize();
  window.addEventListener('resize', resize);

  const centerFn = () => ({ x: cfg.width/2, y: cfg.height/2 });

  const xOffset = -((cfg.cols - 1) * cfg.spacing) / 2;
  const yOffset = -((cfg.rows - 1) * cfg.spacing) / 2;
  const zOffset = -((cfg.depthLayers - 1) * cfg.spacing) / 2;

  const points = [];
  for (let iz = 0; iz < cfg.depthLayers; iz++) {
    for (let iy = 0; iy < cfg.rows; iy++) {
      for (let ix = 0; ix < cfg.cols; ix++) {
        const x = xOffset + ix * cfg.spacing;
        const y = yOffset + iy * cfg.spacing;
        const z = zOffset + iz * cfg.spacing;
        points.push({x,y,z, ix, iy, iz});
      }
    }
  }

  const depthScale = d3.scaleLinear().domain([zOffset, -zOffset]).range([0,1]);
  const colorScale = d3.scaleLinear().domain([0,1]).range([60,220]);
  const widthScale = d3.scaleLinear().domain([0,1]).range([0.6,2.6]);

  // Projection now uses zoom: we apply zoom by scaling rx, ry relative to center.
  function project(pt, cameraAngle = 0) {
    const cosA = Math.cos(cameraAngle), sinA = Math.sin(cameraAngle);
    const rx = pt.x * cosA + pt.z * sinA;
    const rz = -pt.x * sinA + pt.z * cosA;
    // base perspective scale
    const scale = cfg.perspective / (cfg.perspective - rz);
    const c = centerFn();
    // apply zoom as additional multiplier on projected coordinates around center
    return {
      x: c.x + (rx * scale - 0) * cfg.zoom,
      y: c.y + (pt.y * scale - 0) * cfg.zoom,
      s: scale * cfg.zoom,
      rz
    };
  }

  function circularField(x,y,z,t) {
    const r = Math.hypot(x,y) + 1e-6;
    const omega = cfg.rotationSpeed * (1 + 0.06 * z / cfg.spacing);
    const vx = -y / r, vy = x / r;
    const vz = 0.35 * Math.sin(t * 1.2 + z * 0.02 + x * 0.01);
    const amp = cfg.vectorScale * (1 - 0.18 * Math.tanh(r / (cfg.cols*cfg.spacing*0.5)));
    const ang = omega * t;
    const cos = Math.cos(ang), sin = Math.sin(ang);
    const rx = vx * cos - vy * sin;
    const ry = vx * sin + vy * cos;
    return { vx: rx * amp, vy: ry * amp, vz: vz * amp * 0.6 };
  }

  function drawArrow(x1,y1,x2,y2,lineWidth,color,alpha){
    ctx.save();
    ctx.globalAlpha = alpha;
    ctx.strokeStyle = color; ctx.fillStyle = color; ctx.lineWidth = lineWidth; ctx.lineCap='round';
    ctx.beginPath(); ctx.moveTo(x1,y1); ctx.lineTo(x2,y2); ctx.stroke();
    const headLen = 6 + lineWidth*1.5;
    const angle = Math.atan2(y2-y1, x2-x1);
    ctx.beginPath();
    ctx.moveTo(x2,y2);
    ctx.lineTo(x2 - headLen*Math.cos(angle-Math.PI/6), y2 - headLen*Math.sin(angle-Math.PI/6));
    ctx.lineTo(x2 - headLen*Math.cos(angle+Math.PI/6), y2 - headLen*Math.sin(angle+Math.PI/6));
    ctx.closePath(); ctx.fill();
    ctx.restore();
  }

  d3.timer(function(elapsed){
    const t = elapsed / 1000;
    ctx.fillStyle = "rgba(8,8,10,0.20)";
    ctx.fillRect(0,0,cfg.width,cfg.height);
    const cameraAngle = 0.12 * Math.sin(t * 0.15);
    const projected = points.map(p => ({p, proj: project(p, cameraAngle)}))
                            .sort((a,b) => a.proj.rz - b.proj.rz);
    for (const item of projected){
      const p = item.p, proj = item.proj, scale = proj.s;
      const vec = circularField(p.x,p.y,p.z,t);
      const sx = proj.x, sy = proj.y;
      const end3 = { x: p.x + vec.vx, y: p.y + vec.vy, z: p.z + vec.vz };
      const eproj = project(end3, cameraAngle);
      const ex = eproj.x, ey = eproj.y;
      const depthVal = depthScale(p.z);
      const hue = colorScale(depthVal);
      const brightness = 52 + 28*depthVal;
      const color = `hsl(${hue},85%,${brightness}%)`;
      const lineWidth = widthScale(depthVal) * scale;
      const alpha = 0.28 + 0.72 * depthVal;
      drawArrow(sx,sy,ex,ey,Math.max(0.6,lineWidth),color,alpha);
    }
    // subtle front points
    ctx.save(); ctx.globalAlpha=0.06; ctx.fillStyle="#fff";
    for (const item of projected.slice(-60)){ ctx.beginPath(); ctx.arc(item.proj.x, item.proj.y, 1.2*item.proj.s,0,Math.PI*2); ctx.fill(); }
    ctx.restore();
  });

  // GSAP ScrollTrigger: animate cfg.zoom from 1 -> 2.8 (tune as desired)
  gsap.to(cfg, {
    zoom: 2.8,
    ease: "none",
    scrollTrigger: {
      trigger: document.body,
      start: "top top",
      end: "bottom top",
      scrub: 0.6,
      // markers: true
    }
  });
  </script>
</body>
</html>
```

How this fixes it:
- Introduces a single cfg.zoom applied directly to projected x/y and scale so increasing zoom enlarges the field visually.
- ScrollTrigger tweens cfg.zoom from 1 to 2.8 (adjust that value if you want stronger/weaker zoom).
-->