Natural Earth Ii

<!--
  示例：Natural Earth II 底图
  说明：用一套离线生成的全球底图包裹球面，无网络也能看到完整地球
  核心逻辑：全球范围 Rectangle → 2048×1024 canvas 绘制海陆 → SingleTileImageryProvider
  依赖：CesiumJS 1.121 · 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>Natural Earth II 底图</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Widgets/widgets.css">
<style>
  html,body{height:100%;margin:0}
  body{background:#0e1116;color:#e6e8ec;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  #c{height:100%}
  .tip{position:absolute;left:12px;top:12px;z-index:5;
       background:rgba(23,28,35,.9);border:1px solid #2a313b;border-radius:6px;
       padding:8px 12px;font-size:12px;color:#a2a9b6;max-width:320px;line-height:1.6}

  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}
</style>
</head>
<body>
<div id="c"></div>
<div class="tip">底图由 canvas 现场绘制，海陆轮廓是示意，不需要任何瓦片服务。</div>
<script src="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Cesium.js"></script>
<script>
(function () {
  'use strict';

  var viewer = new Cesium.Viewer('c', {
    baseLayer: false,
    baseLayerPicker: false, geocoder: false, homeButton: false,
    sceneModePicker: false, navigationHelpButton: false,
    animation: false, timeline: false, fullscreenButton: false,
    infoBox: false, selectionIndicator: false
  });

  var scene = viewer.scene;
  scene.globe.baseColor = Cesium.Color.fromCssColorString('#1c2733');
  scene.backgroundColor = Cesium.Color.fromCssColorString('#0e1116');
  scene.skyBox.show = false;
  scene.sun.show = false;
  scene.moon.show = false;
  if (scene.skyAtmosphere) scene.skyAtmosphere.show = false;

  function worldImage() {
    var W = 2048, H = 1024;
    var c = document.createElement('canvas');
    c.width = W; c.height = H;
    var ctx = c.getContext('2d');

    /* 海洋 */
    ctx.fillStyle = '#173246';
    ctx.fillRect(0, 0, W, H);

    /* 用若干多边形示意大陆 */
    ctx.fillStyle = '#3f6248';
    var blocks = [
      [0.16, 0.28, 0.14, 0.34], [0.22, 0.62, 0.08, 0.22],
      [0.44, 0.22, 0.10, 0.20], [0.46, 0.46, 0.08, 0.32],
      [0.56, 0.28, 0.20, 0.24], [0.72, 0.60, 0.10, 0.16],
      [0.82, 0.30, 0.09, 0.22]
    ];
    blocks.forEach(function (b) {
      ctx.beginPath();
      ctx.ellipse(b[0] * W, b[1] * H, b[2] * W, b[3] * H, 0.3, 0, Math.PI * 2);
      ctx.fill();
    });

    /* 极地冰盖 */
    ctx.fillStyle = 'rgba(226,236,244,0.9)';
    ctx.fillRect(0, 0, W, 46);
    ctx.fillRect(0, H - 54, W, 54);

    return c.toDataURL('image/png');
  }

  viewer.imageryLayers.addImageryProvider(
    new Cesium.SingleTileImageryProvider({
      url: worldImage(),
      rectangle: Cesium.Rectangle.fromDegrees(-180, -90, 180, 90),
      tileWidth: 2048,
      tileHeight: 1024
    })
  );
  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(105, 32, 19500000),
    orientation: { heading: 0, pitch: Cesium.Math.toRadians(-90), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>