Scatterplot

<!--
  示例：deck.gl 散点图层
  要点：不依赖 React、不依赖底图，用 Deck + ScatterplotLayer 直接渲染十万个点
  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>散点图层</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}
  .bar b{color:#58a6ff;font-weight:600}
  #cv{flex:1 1 auto;min-height:0;width:100%}
</style>
</head>
<body>
<div class="bar">
  <span>点数 <b id="n">—</b></span>
  <span>拖拽旋转 · 滚轮缩放</span>
</div>
<canvas id="cv"></canvas>
<script src="https://cdn.jsdelivr.net/npm/deck.gl@9.0.35/dist.min.js"></script>
<script>
(function () {
  'use strict';

  var cv = document.getElementById('cv');

  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;
  }

  /* 生成十万个点，沿几条城市带聚集，接近真实业务的分布形态 */
  var cities = [
    [116.39, 39.90], [121.47, 31.23], [113.26, 23.12],
    [104.06, 30.57], [108.94, 34.34], [114.05, 22.54],
    [126.64, 45.75], [87.61, 43.82]
  ];

  var data = [];
  for (var i = 0; i < 100000; i++) {
    var c = cities[i % cities.length];
    /* 正态感更强的抖动：两次随机取平均 */
    var dx = (Math.random() + Math.random() - 1) * 2.2;
    var dy = (Math.random() + Math.random() - 1) * 1.6;
    data.push({
      lng: c[0] + dx,
      lat: c[1] + dy,
      v: Math.random()
    });
  }

  document.getElementById('n').textContent = data.length.toLocaleString();

  var scatter = new deck.ScatterplotLayer({
    id: 'points',
    data: data,
    getPosition: function (d) { return [d.lng, d.lat]; },
    getRadius: 2.2,
    radiusUnits: 'pixels',
    radiusMinPixels: 1,
    radiusMaxPixels: 4,
    getFillColor: function (d) {
      var t = d.v;
      return [
        Math.round(88 + 140 * t),
        Math.round(166 - 60 * t),
        Math.round(255 - 90 * t),
        170
      ];
    },
    pickable: true,
    antialiasing: true
  });

  var deckgl = new deck.Deck({
    canvas: cv,
    width: '100%',
    height: '100%',
    initialViewState: {
      longitude: 108,
      latitude: 34,
      zoom: 3.4,
      pitch: 35,
      bearing: 0,
      maxPitch: 65
    },
    controller: true,
    layers: [scatter],
    getTooltip: function (info) {
      if (!info.object) return null;
      return info.object.lng.toFixed(3) + ', ' + info.object.lat.toFixed(3);
    }
  });

  /* 留一个入口方便在控制台里试 */
  window.__deck = deckgl;
})();
</script>
</body>
</html>