Imagery Adjust

<!--
  示例：影像图层的亮度、对比度、饱和度与伽马调整
  要点：ImageryLayer 上的 brightness/contrast/saturation/gamma 是逐图层生效的显示参数
  依赖：CesiumJS 1.121 · jsDelivr CDN，两层底图均由 canvas 生成
-->
<!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>影像调色</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%}
  .hud{position:absolute;left:12px;top:12px;z-index:5;background:rgba(23,28,35,.92);
       border:1px solid #2a313b;border-radius:6px;padding:9px 12px;font-size:12px;
       color:#a2a9b6;width:236px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:7px}
  input[type=range]{width:100%}
  .hud button{font:inherit;font-size:12px;padding:3px 9px;border-radius:4px;cursor:pointer;
       border:1px solid #343b46;background:#1d232b;color:#cfd6e2;margin-top:8px}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}
</style>
</head>
<body>
<div id="c"></div>
<div class="hud">
  <div><b>影像调色</b></div>
  <div class="row">亮度 <span id="bVal">1.00</span></div>
  <div class="row"><input id="b" type="range" min="0.2" max="2" step="0.05" value="1"></div>
  <div class="row">对比度 <span id="cVal">1.00</span></div>
  <div class="row"><input id="c" type="range" min="0.2" max="2" step="0.05" value="1"></div>
  <div class="row">饱和度 <span id="sVal">1.00</span></div>
  <div class="row"><input id="s" type="range" min="0" max="2" step="0.05" value="1"></div>
  <div class="row">伽马 <span id="gVal">1.00</span></div>
  <div class="row"><input id="g" type="range" min="0.3" max="3" step="0.05" value="1"></div>
  <div class="row"><button id="reset">恢复默认</button></div>
</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('#16202c');
  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;

  var RECT = Cesium.Rectangle.fromDegrees(115.8, 39.5, 117.0, 40.3);

  /* 底图：深色地形感 */
  function drawBase() {
    var c = document.createElement('canvas');
    c.width = 1024; c.height = 640;
    var ctx = c.getContext('2d');
    var g = ctx.createLinearGradient(0, 0, 0, 640);
    g.addColorStop(0, '#16222f');
    g.addColorStop(1, '#0d1620');
    ctx.fillStyle = g;
    ctx.fillRect(0, 0, 1024, 640);

    ctx.strokeStyle = 'rgba(70,96,124,0.5)';
    ctx.lineWidth = 1;
    for (var x = 0; x < 1024; x += 80) {
      ctx.beginPath(); ctx.moveTo(x, 0); ctx.lineTo(x, 640); ctx.stroke();
    }
    for (var y = 0; y < 640; y += 80) {
      ctx.beginPath(); ctx.moveTo(0, y); ctx.lineTo(1024, y); ctx.stroke();
    }
    return c.toDataURL('image/png');
  }

  /* 叠加层：彩色色块，方便观察调色效果 */
  function drawOverlay() {
    var c = document.createElement('canvas');
    c.width = 1024; c.height = 640;
    var ctx = c.getContext('2d');
    ctx.clearRect(0, 0, 1024, 640);

    var blocks = [
      ['#4d9bff', 80, 80], ['#5fd0a8', 380, 90], ['#ffb13d', 680, 80],
      ['#e35d6a', 100, 360], ['#9b7bff', 400, 350], ['#3f86e0', 700, 360]
    ];
    blocks.forEach(function (b) {
      ctx.fillStyle = b[0];
      ctx.fillRect(b[1], b[2], 220, 170);
    });

    ctx.fillStyle = 'rgba(255,255,255,0.9)';
    ctx.font = '600 34px "Microsoft YaHei", sans-serif';
    ctx.fillText('调色测试层', 80, 300);

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

  viewer.imageryLayers.addImageryProvider(new Cesium.SingleTileImageryProvider({
    url: drawBase(), rectangle: RECT
  }));

  var overlay = viewer.imageryLayers.addImageryProvider(new Cesium.SingleTileImageryProvider({
    url: drawOverlay(), rectangle: RECT
  }));
  overlay.alpha = 0.9;

  var sliderIds = ['b', 'c', 's', 'g'];
  var valueIds = ['bVal', 'cVal', 'sVal', 'gVal'];

  function apply() {
    overlay.brightness = parseFloat(document.getElementById('b').value);
    overlay.contrast = parseFloat(document.getElementById('c').value);
    overlay.saturation = parseFloat(document.getElementById('s').value);
    overlay.gamma = parseFloat(document.getElementById('g').value);
    sliderIds.forEach(function (id, i) {
      document.getElementById(valueIds[i]).textContent =
        parseFloat(document.getElementById(id).value).toFixed(2);
    });
  }

  sliderIds.forEach(function (id) {
    document.getElementById(id).addEventListener('input', apply);
  });

  document.getElementById('reset').addEventListener('click', function () {
    sliderIds.forEach(function (id) {
      document.getElementById(id).value = 1;
    });
    apply();
  });

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.4, 39.2, 420000),
    orientation: {
      heading: 0,
      pitch: Cesium.Math.toRadians(-78),
      roll: 0
    },
    duration: 0
  });
})();
</script>
</body>
</html>