update：雨案例代码的修改

src/examples/weather/rain/rain-function.js

-export function addRain() {
-    const script = document.createElement('script');
-    script.src = 'https://cesium.com/downloads/cesiumjs/releases/1.99/Build/Cesium/Cesium.js';
-    script.onload = () => {
-        window.Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiI3Njg4ZWU5Yi1iZDhiLTRhYmUtOTRiYS04YjM5NmUwNjVmMDMiLCJpZCI6MjI3MzQ3LCJpYXQiOjE3MjA1MjA4Mjh9.E5XW4LnwgfVAaBC-znaYr61m4yK0-j2qEQhi9qwFFPE'
-
-        const viewer = new window.Cesium.Viewer('cesiumContainer', {
-            infoBox: false,
-        });
-
+export function addRain(viewer) {
     viewer.scene.postProcessStages.add(new Cesium.PostProcessStage({
         fragmentShader: `
                 uniform sampler2D colorTexture;
@@ -40,11 +31,4 @@ export function addRain() {
             rainSpeed: 200.0, // 雨速
         },
     }));
-    };
-    document.head.appendChild(script);
-
-    const link = document.createElement('link');
-    link.rel = 'stylesheet';
-    link.href = 'https://cesium.com/downloads/cesiumjs/releases/1.119/Build/Cesium/Widgets/widgets.css';
-    document.head.appendChild(link);
 }

src/examples/weather/rain/rain.vue

 <template>
     <div id="cesiumContainer" class="cesium-container"></div>
 </template>
+
 <script setup>
 import { onMounted } from 'vue';
 import { addRain } from './function';
+
+let viewer;
+
 onMounted(() => {
-    addRain()
+    const script = document.createElement('script');
+    script.src = 'https://cesium.com/downloads/cesiumjs/releases/1.99/Build/Cesium/Cesium.js';
+    script.onload = () => {
+        window.Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiI3Njg4ZWU5Yi1iZDhiLTRhYmUtOTRiYS04YjM5NmUwNjVmMDMiLCJpZCI6MjI3MzQ3LCJpYXQiOjE3MjA1MjA4Mjh9.E5XW4LnwgfVAaBC-znaYr61m4yK0-j2qEQhi9qwFFPE'
+
+        viewer = new window.Cesium.Viewer('cesiumContainer', {
+            infoBox: false,
+        });
+
+        addRain(viewer)
+
+    };
+    document.head.appendChild(script);
+    const link = document.createElement('link');
+    link.rel = 'stylesheet';
+    link.href = 'https://cesium.com/downloads/cesiumjs/releases/1.119/Build/Cesium/Widgets/widgets.css';
+    document.head.appendChild(link);
 });
 </script>
 
 <style>
 .cesium-container {
-width: 100%;
-height: 100vh;
+    width: 100%;
+    height: 100vh;
 }
 </style>
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