地理视图等瓦片加载完再淡入，避免逐块弹出

src/scene/CesiumGlobe.js

@@ -510,6 +510,24 @@ export class CesiumGlobe {
     if (visible && this.viewer) this.viewer.scene.requestRender();
   }
 
+  // 等待当前视图的影像/地形瓦片加载完成（超时兜底），用于切换时“一起出现”
+  waitUntilViewReady(timeout = 4000) {
+    return new Promise((resolve) => {
+      const globe = this.viewer.scene.globe;
+      let done = false;
+      const finish = () => {
+        if (done) return;
+        done = true;
+        globe.tileLoadProgressEvent.removeEventListener(onProgress);
+        resolve();
+      };
+      const onProgress = (remaining) => { if (remaining <= 0) finish(); };
+      globe.tileLoadProgressEvent.addEventListener(onProgress);
+      if (globe.tilesLoaded) finish();
+      setTimeout(finish, timeout);
+    });
+  }
+
   resize() {
     if (this.viewer) this.viewer.resize();
   }