Fps Monitor

<!--
  示例：渲染帧率
  要点：六万个点每六帧更新一次半径，复用数据数组，右上角显示帧率
  依赖：deck.gl 9.0 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>渲染帧率</title>
<style>
  html,body{height:100%;margin:0;background:#0d1117}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif;color:#e6e8ec}
  .bar{position:relative;z-index:5;flex:0 0 auto;padding:8px 12px;background:#161b22;border-bottom:1px solid #252c36;
       display:flex;gap:14px;align-items:center;font-size:12px;color:#8b93a1;flex-wrap:wrap}
  .bar b{color:#58a6ff;font-weight:600}
  .bar label{display:flex;align-items:center;gap:5px;cursor:pointer}
  .bar input[type=checkbox]{accent-color:#4f9ef8}
  .bar input[type=range]{width:150px;accent-color:#4f9ef8}
  .bar button{font:inherit;font-size:12px;padding:3px 10px;border-radius:4px;cursor:pointer;
       border:1px solid #2f3947;background:#1d242e;color:#c9d3e0}
  .bar button:hover{background:#26303d}
  #cv{flex:1 1 auto;min-height:0;width:100%;display:block}
  .fps{position:absolute;right:12px;top:52px;padding:6px 12px;background:rgba(16,22,32,0.88);
       border:1px solid #2c3644;border-radius:6px;font:12px ui-monospace,Consolas,monospace;color:#7fc4ff}
  .wrap{position:relative;flex:1 1 auto;min-height:0}
  .wrap #cv{width:100%;height:100%}
</style>
</head>
<body>
<div class="bar"><span>点数 <b id="n">—</b></span><span>半径每六帧更新一次</span></div>
<div class="wrap">
  <canvas id="cv"></canvas>
  <div class="fps" id="fps">— fps</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/deck.gl@9.0.35/dist.min.js"></script>
<script>
(function () {
  'use strict';

  if (typeof deck === 'undefined') {
    document.body.innerHTML =
      '<div style="padding:24px;color:#ff8c74">deck.gl 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }
  var N = 60000;
  var data = [];
  for (var i = 0; i < N; i++) {
    data.push({
      lng: 104 + Math.random() * 36,
      lat: 22 + Math.random() * 24,
      v: Math.random()
    });
  }

  document.getElementById('n').textContent = N.toLocaleString();

  var phase = 0;

  function makeLayer() {
    return new deck.ScatterplotLayer({
      id: 'points',
      data: data,
      getPosition: function (d) { return [d.lng, d.lat]; },
      getRadius: 1.6 + phase * 0.6,
      radiusUnits: 'pixels',
      radiusMinPixels: 1,
      getFillColor: function (d) {
        var t = d.v;
        return [Math.round(80 + 150 * t), Math.round(180 - 70 * t), Math.round(255 - 120 * t), 165];
      },
      updateTriggers: { getRadius: phase },
      useDevicePixels: false
    });
  }

  var deckgl = new deck.Deck({
    canvas: 'cv',
    width: '100%',
    height: '100%',
    initialViewState: { longitude: 108, latitude: 34, zoom: 3.4, pitch: 30, bearing: 0 },
    controller: true,
    layers: [makeLayer()]
  });

  var frames = 0;
  var mark = performance.now();
  var tick = 0;

  function loop(now) {
    frames++;
    tick++;
    if (tick % 6 === 0) {
      phase = 0.5 + 0.5 * Math.sin(now / 900);
      deckgl.setProps({ layers: [makeLayer()] });
    }
    if (now - mark >= 1000) {
      document.getElementById('fps').textContent = Math.round(frames * 1000 / (now - mark)) + ' fps';
      frames = 0;
      mark = now;
    }
    requestAnimationFrame(loop);
  }
  requestAnimationFrame(loop);
  window.__deck = deckgl;
})();
</script>
</body>
</html>