philiprosedale.github.io/ising.html at main · PhilipRosedale/philiprosedale.github.io · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Ising-style vector grid</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.7.0/p5.js"></script>
<style>
  body {
    margin: 0;
    padding: 0;
    overflow: hidden;
    background: #1a1a1a;
  }
  #controls {
    position: fixed;
    top: 12px;
    left: 12px;
    z-index: 10;
    display: flex;
    align-items: center;
    gap: 8px;
    font: 13px/1 system-ui, sans-serif;
    color: #ccc;
    background: rgba(0,0,0,0.55);
    padding: 6px 12px;
    border-radius: 6px;
    user-select: none;
  }
  #controls input[type=range] {
    width: 140px;
    accent-color: #888;
  }
  #controls button {
    background: rgba(255,255,255,0.12);
    border: 1px solid rgba(255,255,255,0.25);
    color: #ccc;
    font: 13px/1 system-ui, sans-serif;
    padding: 4px 10px;
    border-radius: 4px;
    cursor: pointer;
  }
  #controls button:hover {
    background: rgba(255,255,255,0.22);
  }
</style>
</head>
<body>
<div id="controls">
  <label for="contrarianSlider">Contrarian</label>
  <input id="contrarianSlider" type="range" min="0" max="100" value="2">
  <span id="contrarianValue">2%</span>
  <label for="noiseSlider">Noise</label>
  <input id="noiseSlider" type="range" min="0" max="100" value="0">
  <span id="noiseValue">0%</span>
  <button id="resetBtn">Reset</button>
</div>
<script>
// Ising-style vector grid: each cell has a unit vector; each frame many random
// cells update their vector toward the average of their four immediate neighbors.

const CELL_SIZE = 14;
const BLEND_ALPHA = 0.3;
const VECTOR_SCALE = 0.675; // fraction of cell half-size for drawing the vector
const UPDATES_PER_FRAME_SCALE = 1; // updates per frame = scale * (cols * rows)

let cols, rows;
let cells = [];
let contrarianFraction = 0.02;
let noiseAmount = 0;

function setup() {
  createCanvas(windowWidth, windowHeight);
  colorMode(HSB, 360, 100, 100);
  cols = max(1, floor(width / CELL_SIZE));
  rows = max(1, floor(height / CELL_SIZE));

  const slider = document.getElementById('contrarianSlider');
  const label  = document.getElementById('contrarianValue');
  slider.addEventListener('input', () => {
    contrarianFraction = parseInt(slider.value) / 100;
    label.textContent = slider.value + '%';
    initGrid();
  });

  const noiseSlider = document.getElementById('noiseSlider');
  const noiseLabel  = document.getElementById('noiseValue');
  noiseSlider.addEventListener('input', () => {
    noiseAmount = parseInt(noiseSlider.value) / 100;
    noiseLabel.textContent = noiseSlider.value + '%';
  });

  document.getElementById('resetBtn').addEventListener('click', () => initGrid());

  initGrid();
}

function initGrid() {
  cells = [];
  for (let i = 0; i < cols; i++) {
    cells[i] = [];
    for (let j = 0; j < rows; j++) {
      const angle = random(TWO_PI);
      cells[i][j] = {
        vx: cos(angle),
        vy: sin(angle),
        contrarian: random() < contrarianFraction
      };
    }
  }
}

function getNeighborAverage(i, j) {
  const left = (i - 1 + cols) % cols;
  const right = (i + 1) % cols;
  const up = (j - 1 + rows) % rows;
  const down = (j + 1) % rows;

  const sumVx = cells[left][j].vx + cells[right][j].vx + cells[i][up].vx + cells[i][down].vx;
  const sumVy = cells[left][j].vy + cells[right][j].vy + cells[i][up].vy + cells[i][down].vy;

  const len = sqrt(sumVx * sumVx + sumVy * sumVy);
  if (len < 1e-10) return null;
  return { vx: sumVx / len, vy: sumVy / len };
}

function normalize(vx, vy) {
  const len = sqrt(vx * vx + vy * vy);
  if (len < 1e-10) return null;
  return { vx: vx / len, vy: vy / len };
}

function updateOneCell() {
  const i = floor(random(cols));
  const j = floor(random(rows));
  const avg = getNeighborAverage(i, j);
  if (avg === null) return;

  const c = cells[i][j];
  const sign = c.contrarian ? -1 : 1;
  const targetVx = avg.vx * sign;
  const targetVy = avg.vy * sign;
  let vxNew = c.vx + BLEND_ALPHA * (targetVx - c.vx);
  let vyNew = c.vy + BLEND_ALPHA * (targetVy - c.vy);
  if (noiseAmount > 0) {
    const jitter = random(-PI, PI) * noiseAmount;
    const cs = cos(jitter);
    const sn = sin(jitter);
    const rx = vxNew * cs - vyNew * sn;
    const ry = vxNew * sn + vyNew * cs;
    vxNew = rx;
    vyNew = ry;
  }
  const n = normalize(vxNew, vyNew);
  if (n !== null) {
    c.vx = n.vx;
    c.vy = n.vy;
  }
}

function draw() {
  background(0, 0, 12);

  const half = CELL_SIZE * 0.5;
  const len = half * VECTOR_SCALE;

  noStroke();
  for (let i = 0; i < cols; i++) {
    for (let j = 0; j < rows; j++) {
      const c = cells[i][j];
      if (c.contrarian) {
        fill(0, 0, 22);
        rect(i * CELL_SIZE, j * CELL_SIZE, CELL_SIZE, CELL_SIZE);
      }
    }
  }

  for (let i = 0; i < cols; i++) {
    for (let j = 0; j < rows; j++) {
      const cx = (i + 0.5) * CELL_SIZE;
      const cy = (j + 0.5) * CELL_SIZE;
      const c = cells[i][j];

      const angle = atan2(c.vy, c.vx);
      const hue = map(angle, -PI, PI, 0, 360);
      stroke(hue, 70, 95);
      strokeWeight(1.5);
      line(cx, cy, cx + c.vx * len, cy + c.vy * len);
    }
  }

  const numUpdates = max(1, round(UPDATES_PER_FRAME_SCALE * cols * rows));
  for (let k = 0; k < numUpdates; k++) {
    updateOneCell();
  }
}

let dragging = false;
let dragStartX, dragStartY;
let dragCellI, dragCellJ;

function getCellUnderMouse() {
  const i = floor(mouseX / CELL_SIZE);
  const j = floor(mouseY / CELL_SIZE);
  if (i >= 0 && i < cols && j >= 0 && j < rows) return { i, j };
  return null;
}

function mousePressed() {
  if (mouseX < 0 || mouseX > width || mouseY < 0 || mouseY > height) return;
  const cell = getCellUnderMouse();
  if (!cell) return;
  dragging = true;
  dragStartX = mouseX;
  dragStartY = mouseY;
  dragCellI = cell.i;
  dragCellJ = cell.j;
}

function mouseDragged() {
  if (!dragging) return;
  const dx = mouseX - dragStartX;
  const dy = mouseY - dragStartY;
  const len = sqrt(dx * dx + dy * dy);
  if (len < 2) return;
  const c = cells[dragCellI][dragCellJ];
  c.vx = dx / len;
  c.vy = dy / len;
}

function mouseReleased() {
  if (!dragging) return;
  const dx = mouseX - dragStartX;
  const dy = mouseY - dragStartY;
  const len = sqrt(dx * dx + dy * dy);
  if (len >= 2) {
    const c = cells[dragCellI][dragCellJ];
    c.vx = dx / len;
    c.vy = dy / len;
  }
  dragging = false;
}
</script>
</body>
</html>