{
  "widgettype": "VBox",
  "options": {"width": "100%", "height": "100%", "padding": "10px", "backgroundColor": "#F5F6FA"},
  "subwidgets": [
    {"widgettype": "HBox", "options": {"width": "100%", "gap": "8px", "align": "center"}, "subwidgets": [
      {"widgettype": "Text", "options": {"label": "🎬 实时演示预览", "fontSize": "18px", "fontWeight": "bold"}},
      {"widgettype": "Text", "id": "demo_session_label", "options": {"label": "未开始", "fontSize": "13px", "color": "#FF8800"}},
      {"widgettype": "Button", "options": {"label": "开始演示", "type": "primary"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.startDemo()"}}]},
      {"widgettype": "Button", "options": {"label": "结束演示", "type": "danger"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.stopDemo()"}}]},
      {"widgettype": "Button", "options": {"label": "暂停"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.pauseDemo()"}}]},
      {"widgettype": "Button", "options": {"label": "继续"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.resumeDemo()"}}]},
      {"widgettype": "Button", "options": {"label": "编辑实体"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.editEntity()"}}]},
      {"widgettype": "Button", "options": {"label": "查看属性"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.showAttrs()"}}]},
      {"widgettype": "Button", "options": {"label": "保存脚本(热加载)"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.hotload()"}}]},
      {"widgettype": "Button", "options": {"label": "全屏"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.toggleFullscreen()"}}]}
    ]},
    {"widgettype": "HBox", "options": {"width": "100%", "gap": "8px", "marginTop": "8px"}, "subwidgets": [
      {"widgettype": "Button", "options": {"label": "视角:环绕"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.switchCamera('orbit')"}}]},
      {"widgettype": "Button", "options": {"label": "视角:俯视"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.switchCamera('topdown')"}}]},
      {"widgettype": "Button", "options": {"label": "视角:第一人称"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.switchCamera('firstperson')"}}]},
      {"widgettype": "Button", "options": {"label": "加入多人预览"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.joinPresence()"}}]},
      {"widgettype": "Button", "options": {"label": "离开预览"},
       "binds": [{"wid": "self", "event": "click", "actiontype": "script", "options": {"script": "demoViewer.leavePresence()"}}]}
    ]},
    {"widgettype": "Text", "id": "demo_canvas_container",
     "options": {"label": "3D 预览区（three.js 渲染；未开始演示时显示占位）", "width": "100%", "flex": "1",
                 "height": "100%", "marginTop": "10px", "backgroundColor": "#1A1D26", "color": "#8A93A6",
                 "padding": "10px", "borderRadius": "6px"}}
  ]
}