Elevation Band Material

<!--
  示例：高程分层着色
  说明：地形按 60 米一段分成两条色带交替，高处偏暖、低处偏冷
  核心逻辑：globe.material 自定义 fabric → materialInput.height → 分段取色
  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>高程分层着色</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">色带按高程分段，60 米一段，冷色与暖色交替。</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 heightAt(u, v) {
    return 140 * Math.sin(u * 1.8) * Math.cos(v * 1.4) + 40 * Math.sin(u * 5.1);
  }

  var terrain = new Cesium.CustomHeightmapTerrainProvider({
    width: 48, height: 48,
    callback: function (x, y, level) {
      var n = 48, h = new Float32Array(n * n);
      for (var j = 0; j < n; j++) {
        for (var i = 0; i < n; i++) {
          h[j * n + i] = heightAt(x + i / n * 0.03, y + j / n * 0.03);
        }
      }
      return h;
    }
  });
  viewer.terrainProvider = terrain;

  /* 自定义材质：按 materialInput.height 分段取色 */
  scene.globe.material = new Cesium.Material({
    fabric: {
      source: [
        'czm_material czm_getMaterial(czm_materialInput materialInput) {',
        '  czm_material material = czm_getDefaultMaterial(materialInput);',
        '  float h = materialInput.height;',
        '  float band = floor(h / 60.0);',
        '  float odd = mod(band, 2.0);',
        '  vec3 cold = vec3(0.14, 0.33, 0.52);',
        '  vec3 warm = vec3(0.84, 0.63, 0.35);',
        '  vec3 c = mix(cold, warm, odd);',
        '  float fade = smoothstep(0.0, 40.0, h + 200.0);',
        '  material.diffuse = mix(vec3(0.10, 0.14, 0.18), c, fade);',
        '  material.alpha = 1.0;',
        '  return material;',
        '}'
      ].join('\n')
    }
  });
  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.3740, 39.8860, 1000),
    orientation: { heading: Cesium.Math.toRadians(28), pitch: Cesium.Math.toRadians(-14), roll: 0 },
    duration: 0
  });
})();
</script>
</body>
</html>