标记便签改为 DOM 覆盖层，修复近距离缩放漂移

src/scene/CesiumGlobe.js

@@ -7,10 +7,6 @@ const IMAGERY_URL =
 const TERRAIN_URL =
   'https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer';
 
-// 标记便签的离地高度（米）：抬到高空，使其 bounding 球比城市/国家名更靠相机，
-// 从而在透明通道的深度排序中始终后绘制（盖在标签上层）。
-const MARKER_ALTITUDE = 50000;
-
 // 计算多边形集合的球面面积（km²），用于按国土面积分级国家名字号
 function sphericalAreaKm2(polys) {
   let area = 0;
@@ -96,7 +92,7 @@ function makeStickyNote(text, fontSize, selected = false) {
   ctx.textAlign = 'center';
   ctx.fillText(text, arrowW + bodyW / 2, h / 2 + 1);
 
-  return { canvas: c, scale: 1 / S };
+  return { canvas: c, scale: 1 / S, width: w, height: h };
 }
 
 export class CesiumGlobe {
@@ -235,47 +231,69 @@ export class CesiumGlobe {
   }
 
   _buildMarkers() {
-    const viewer = this.viewer;
-
     ENTRIES.forEach((entry, i) => {
-      // 便签：黄底黑字 + 左侧箭头指向坐标（整张图）
+      const position = Cesium.Cartesian3.fromDegrees(entry.lng, entry.lat);
       const noteNormal = makeStickyNote(entry.name, 19, false);
       const noteSelected = makeStickyNote(entry.name, 19, true);
-
-      const entity = viewer.entities.add({
-        position: Cesium.Cartesian3.fromDegrees(entry.lng, entry.lat, MARKER_ALTITUDE),
-        billboard: {
-          image: noteNormal.canvas,
-          scale: noteNormal.scale,
-          horizontalOrigin: Cesium.HorizontalOrigin.LEFT,
-          verticalOrigin: Cesium.VerticalOrigin.CENTER,
-          pixelOffset: new Cesium.Cartesian2(0, 0),
-          disableDepthTestDistance: Number.POSITIVE_INFINITY,
-          distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 1e7),
-        },
-      });
-      entity.entryIndex = i;
-
-      this.markers.push({ entity, noteNormal, noteSelected, index: i });
+      this.markers.push({ position, noteNormal, noteSelected, index: i });
     });
+    this._initMarkerLayer();
+  }
+
+  // 便签用 DOM 覆盖层渲染：始终在城市/国家名上层，且缩放到最近也不会漂移
+  _initMarkerLayer() {
+    const container = document.getElementById('cesium-container');
+    this._markerLayer = document.createElement('div');
+    this._markerLayer.id = 'marker-layer';
+    container.appendChild(this._markerLayer);
+
+    for (const m of this.markers) {
+      const el = document.createElement('div');
+      el.className = 'marker-note';
+      el.style.width = `${m.noteNormal.width}px`;
+      el.style.height = `${m.noteNormal.height}px`;
+      el.dataset.index = m.index;
+      m.el = el;
+      m.normalUrl = m.noteNormal.canvas.toDataURL();
+      m.selectedUrl = m.noteSelected.canvas.toDataURL();
+      el.style.backgroundImage = `url("${m.normalUrl}")`;
+      el.addEventListener('click', (e) => {
+        e.stopPropagation();
+        this.onPick?.(m.index);
+      });
+      this._markerLayer.appendChild(el);
+    }
+
+    this.viewer.scene.postRender.addEventListener(() => this._updateMarkerLayer());
+  }
+
+  // 每帧更新便签屏幕位置（相机移动/缩放/飞行时跟随）
+  _updateMarkerLayer() {
+    const scene = this.viewer.scene;
+    const camera = scene.camera;
+    const toPos = new Cesium.Cartesian3();
+    for (const m of this.markers) {
+      const el = m.el;
+      if (!el) continue;
+      const win = Cesium.SceneTransforms.worldToWindowCoordinates(scene, m.position);
+      if (!win) { el.style.display = 'none'; continue; }
+      Cesium.Cartesian3.subtract(m.position, camera.positionWC, toPos);
+      if (Cesium.Cartesian3.dot(toPos, camera.directionWC) < 0) {
+        el.style.display = 'none'; // 背对相机不显示
+        continue;
+      }
+      el.style.display = 'block';
+      el.style.left = `${win.x}px`;
+      el.style.top = `${win.y}px`;
+    }
   }
 
   _setupPick() {
     const viewer = this.viewer;
     // 移除 Viewer 默认的单击选中与双击“追踪实体”：否则双击后会锁定相机（定住）
+    // 标记便签已改为 DOM 覆盖层，点击由 DOM 元素自行处理
     viewer.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_CLICK);
     viewer.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
-
-    const handler = new Cesium.ScreenSpaceEventHandler(viewer.scene.canvas);
-    handler.setInputAction((movement) => {
-      const picked = viewer.scene.pick(movement.position);
-      if (Cesium.defined(picked) && picked.id && picked.id.entryIndex !== undefined) {
-        const index = picked.id.entryIndex;
-        this.onPick?.(index);
-        this.flyToEntry(index);
-      }
-    }, Cesium.ScreenSpaceEventType.LEFT_CLICK);
-    this._handler = handler;
   }
 
   // 相机平滑飞至某个标记上空并居中：回到与初始一致的高度与北朝上方向，左键拖拽手感不变
@@ -421,11 +439,10 @@ export class CesiumGlobe {
   setSelected(index) {
     this.selected = index;
     if (!this.viewer) return;
-    this.markers.forEach(({ entity, noteNormal, noteSelected, index: i }) => {
-      const on = i === index;
-      entity.billboard.image = on ? noteSelected.canvas : noteNormal.canvas; // 选中加黑边
+    this.markers.forEach((m) => {
+      const on = m.index === index;
+      if (m.el) m.el.style.backgroundImage = `url("${on ? m.selectedUrl : m.normalUrl}")`;
     });
-    this.viewer.scene.requestRender();
   }
 
   setVisible(visible) {