Autodesk Forge Viewer支持深度展示装配，最大层数限制取决于实际情况。一般情况下，若装配结构合理，深度展示无上限。以下是一个示例代码，展示了如何在Forge Viewer中展示装配结构：

// 初始化Viewer
const viewer = new Autodesk.Viewing.Private.GuiViewer3D(document.getElementById('viewer'));

// 载入装配文件
const documentId = 'urn:mydocumentId';
Autodesk.Viewing.Initializer({ env: 'AutodeskProduction' }, () => {
  const config3d = {
    extensions: ['MyExtension'],
    api: 'derivativeV2',
  };
  viewer.start();
  Autodesk.Viewing.Document.load(documentId, (doc) => {
    const viewables = doc.getRoot().getDefaultGeometry();
    viewer.loadDocumentNode(doc, viewables).then(() => {
      // 调整视角以展示整个装配结构
      viewer.autocam.setHomeViewFrom(viewables);
    });
  }, (err) => {
    console.error(err);
  }, config3d);
});

// 自定义扩展
class MyExtension extends Autodesk.Viewing.Extension {
  constructor(viewer, options) {
    super(viewer, options);
    this.viewer = viewer;
  }
  load() {
    const instanceTree = this.viewer.model.getInstanceTree();
    let rootId = instanceTree.getRootId();
    let depth = 0;

    // 遍历整个装配结构，读取深度信息
    instanceTree.enumNodeChildren(rootId, (childId) => {
      const curDepth = instanceTree.getDepth(childId);
      depth = Math.max(depth, curDepth);
    }, true);

    console.log(`The depth of current assembly is ${depth}.`);
    return true;
  }
  unload() {
    return true;
  }
}

Autodesk.Viewing.theExtensionManager.registerExtension('MyExtension', MyExtension);