Custom Shaders Property Textures

<!--
  示例：着色器采样自定义纹理
  说明：用一个 sampler 纹理控制模型颜色，纹理由 canvas 生成
  核心逻辑：TextureUniform(SAMPLER_2D) → texture(u_map, uv) → 改写 diffuse
  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>着色器采样自定义纹理</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">模型表面的色块来自一张程序生成的纹理，不是顶点色。</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 glbBytes(json, bin) {
    var jb = new TextEncoder().encode(JSON.stringify(json));
    var jpad = (4 - jb.length % 4) % 4, bpad = (4 - bin.length % 4) % 4;
    var jl = jb.length + jpad, bl = bin.length + bpad;
    var out = new Uint8Array(12 + 8 + jl + 8 + bl), dv = new DataView(out.buffer);
    dv.setUint32(0, 0x46546c67, true); dv.setUint32(4, 2, true); dv.setUint32(8, out.length, true);
    dv.setUint32(12, jl, true); dv.setUint32(16, 0x4e4f534a, true); out.set(jb, 20);
    for (var i = 0; i < jpad; i++) out[20 + jb.length + i] = 0x20;
    dv.setUint32(20 + jl, bl, true); dv.setUint32(24 + jl, 0x004e4942, true); out.set(bin, 28 + jl);
    return out;
  }

  function boxGlb(w, h, d) {
    var hx = w / 2, hz = d / 2;
    var faces = [
      [[hx, 0, hz], [hx, 0, -hz], [hx, h, -hz], [hx, h, hz], [1, 0, 0]],
      [[-hx, 0, -hz], [-hx, 0, hz], [-hx, h, hz], [-hx, h, -hz], [-1, 0, 0]],
      [[-hx, h, hz], [hx, h, hz], [hx, h, -hz], [-hx, h, -hz], [0, 1, 0]],
      [[-hx, 0, -hz], [hx, 0, -hz], [hx, 0, hz], [-hx, 0, hz], [0, -1, 0]],
      [[-hx, 0, hz], [hx, 0, hz], [hx, h, hz], [-hx, h, hz], [0, 0, 1]],
      [[hx, 0, -hz], [-hx, 0, -hz], [-hx, h, -hz], [hx, h, -hz], [0, 0, -1]]
    ];
    var pos = [], nor = [], idx = [], base = 0;
    faces.forEach(function (f) {
      for (var i = 0; i < 4; i++) { pos.push(f[i][0], f[i][1], f[i][2]); nor.push(f[4][0], f[4][1], f[4][2]); }
      idx.push(base, base + 1, base + 2, base, base + 2, base + 3);
      base += 4;
    });
    var p = new Float32Array(pos), n = new Float32Array(nor), ix = new Uint16Array(idx);
    var pb = p.byteLength, nb = n.byteLength, ib = ix.byteLength;
    var bin = new Uint8Array(pb + nb + ib);
    bin.set(new Uint8Array(p.buffer), 0);
    bin.set(new Uint8Array(n.buffer), pb);
    bin.set(new Uint8Array(ix.buffer), pb + nb);
    var json = {
      asset: { version: '2.0' }, scene: 0, scenes: [{ nodes: [0] }], nodes: [{ mesh: 0 }],
      meshes: [{ primitives: [{ attributes: { POSITION: 0, NORMAL: 1 }, indices: 2, material: 0 }] }],
      materials: [{ pbrMetallicRoughness: {
        baseColorFactor: [0.7, 0.7, 0.7, 1], metallicFactor: 0.05, roughnessFactor: 0.85
      }, doubleSided: true }],
      accessors: [
        { bufferView: 0, componentType: 5126, count: 24, type: 'VEC3', min: [-hx, 0, -hz], max: [hx, h, hz] },
        { bufferView: 1, componentType: 5126, count: 24, type: 'VEC3' },
        { bufferView: 2, componentType: 5123, count: 36, type: 'SCALAR' }
      ],
      bufferViews: [
        { buffer: 0, byteOffset: 0, byteLength: pb, target: 34962 },
        { buffer: 0, byteOffset: pb, byteLength: nb, target: 34962 },
        { buffer: 0, byteOffset: pb + nb, byteLength: ib, target: 34963 }
      ],
      buffers: [{ byteLength: pb + nb + ib }]
    };
    return new Blob([glbBytes(json, bin)], { type: 'model/gltf-binary' });
  }

  /* 纹理：横向色带 + 纵向明暗 */
  function stripes() {
    var c = document.createElement('canvas');
    c.width = 128; c.height = 128;
    var ctx = c.getContext('2d');
    for (var y = 0; y < 128; y += 16) {
      for (var x = 0; x < 128; x += 16) {
        ctx.fillStyle = ((x + y) / 16) % 2 === 0 ? '#3f6f9c' : '#d08a4e';
        ctx.fillRect(x, y, 16, 16);
      }
    }
    ctx.fillStyle = 'rgba(0,0,0,0.35)';
    ctx.fillRect(0, 96, 128, 32);
    return c.toDataURL('image/png');
  }

  var map = new Cesium.TextureUniform({ url: stripes() });

  var shader = new Cesium.CustomShader({
    uniforms: { u_map: { type: Cesium.UniformType.SAMPLER_2D, value: map } },
    fragmentShaderText: [
      'uniform sampler2D u_map;',
      'void fragmentMain(FragmentInput fsInput, inout czm_modelMaterial material) {',
      '  vec2 uv = fsInput.attributes.positionMC.xz / 40.0 + 0.5;',
      '  vec4 tex = texture(u_map, uv);',
      '  material.diffuse = tex.rgb;',
      '  material.roughness = 0.7;',
      '}'
    ].join('\n')
  });

  var enu = Cesium.Transforms.eastNorthUpToFixedFrame(
    Cesium.Cartesian3.fromDegrees(116.3895, 39.9035, 0)
  );

  Cesium.Model.fromGltfAsync({
    url: URL.createObjectURL(boxGlb(60, 90, 60)),
    modelMatrix: enu
  }).then(function (model) {
    model.customShader = shader;
    scene.primitives.add(model);
    viewer.zoomTo(model, new Cesium.HeadingPitchRange(0.5, -0.15, 240));
  });
  /* 相机在模型加载完成后由 zoomTo 设置 */
})();
</script>
</body>
</html>