地表附近支持右键环视（以点击点为球心，松开归位）

src/scene/CesiumGlobe.js

@@ -114,6 +114,10 @@ function makeStickyNote(text, fontSize, selected = false) {
   return { canvas: c, scale: 1 / S, width: cw, height: ch, tipX: B, tipY: B + h / 2 };
 }
 
+// 右键“环视”手势：放大到地表附近时，右键拖动以点击点为球心环视，松开归位
+const LOOK_GROUND_MAX_HEIGHT = 1e6; // 相机高度低于 1000 km 才启用
+const LOOK_RATE = 0.005; // 每像素旋转弧度
+
 export class CesiumGlobe {
   constructor({ onPick } = {}) {
     this.onPick = onPick;
@@ -250,6 +254,7 @@ export class CesiumGlobe {
 
     this._buildMarkers();
     this._setupPick();
+    this._setupLookAround();
     this._loadBoundaries();
     this._buildCityLabels();
 
@@ -350,6 +355,98 @@ export class CesiumGlobe {
     viewer.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
   }
 
+  // 右键环视：地表附近右键拖动，以点击点为球心调整视角，松开归位
+  _setupLookAround() {
+    const viewer = this.viewer;
+    const scene = viewer.scene;
+    const camera = viewer.camera;
+    this._lookState = null;
+    this._orbitScratch = {
+      offset: new Cesium.Cartesian3(),
+      up: new Cesium.Cartesian3(),
+      right: new Cesium.Cartesian3(),
+      qAz: new Cesium.Quaternion(),
+      qEl: new Cesium.Quaternion(),
+      q: new Cesium.Quaternion(),
+      rotMat: new Cesium.Matrix3(),
+      newOffset: new Cesium.Cartesian3(),
+      newPos: new Cesium.Cartesian3(),
+      dir: new Cesium.Cartesian3(),
+      upProj: new Cesium.Cartesian3(),
+    };
+
+    const handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
+
+    handler.setInputAction((movement) => {
+      if (camera.positionCartographic.height > LOOK_GROUND_MAX_HEIGHT) return;
+      const position =
+        scene.pickPosition(movement.position) ||
+        camera.pickEllipsoid(movement.position, scene.globe.ellipsoid);
+      if (!Cesium.defined(position)) return;
+      this._lookState = {
+        pivot: Cesium.Cartesian3.clone(position),
+        position: Cesium.Cartesian3.clone(camera.position),
+        direction: Cesium.Cartesian3.clone(camera.direction),
+        up: Cesium.Cartesian3.clone(camera.up),
+        lastX: movement.position.x,
+        lastY: movement.position.y,
+      };
+    }, Cesium.ScreenSpaceEventType.RIGHT_DOWN);
+
+    handler.setInputAction((movement) => {
+      if (!this._lookState) return;
+      const s = this._lookState;
+      const dx = movement.position.x - s.lastX;
+      const dy = movement.position.y - s.lastY;
+      s.lastX = movement.position.x;
+      s.lastY = movement.position.y;
+      this._orbitAroundPivot(s.pivot, dx * LOOK_RATE, dy * LOOK_RATE);
+    }, Cesium.ScreenSpaceEventType.RIGHT_DRAG);
+
+    handler.setInputAction(() => {
+      if (!this._lookState) return;
+      const s = this._lookState;
+      camera.setView({
+        destination: s.position,
+        orientation: { direction: s.direction, up: s.up },
+      });
+      this._lookState = null;
+    }, Cesium.ScreenSpaceEventType.RIGHT_UP);
+
+    this._lookHandler = handler;
+  }
+
+  // 围绕 pivot 旋转相机（水平=方位角，垂直=俯仰角）
+  _orbitAroundPivot(pivot, dAzimuth, dElevation) {
+    const camera = this.viewer.camera;
+    const s = this._orbitScratch;
+    const offset = Cesium.Cartesian3.subtract(camera.position, pivot, s.offset);
+    const up = Cesium.Cartesian3.normalize(pivot, s.up); // 球心在原点，pivot 方向即法线
+    const right = Cesium.Cartesian3.normalize(
+      Cesium.Cartesian3.cross(camera.direction, camera.up, s.right),
+      s.right,
+    );
+    Cesium.Quaternion.fromAxisAngle(up, -dAzimuth, s.qAz);
+    Cesium.Quaternion.fromAxisAngle(right, -dElevation, s.qEl);
+    Cesium.Quaternion.multiply(s.qEl, s.qAz, s.q);
+    Cesium.Matrix3.fromQuaternion(s.q, s.rotMat);
+    Cesium.Matrix3.multiplyByVector(s.rotMat, offset, s.newOffset);
+    Cesium.Cartesian3.add(pivot, s.newOffset, s.newPos);
+    const dir = Cesium.Cartesian3.normalize(
+      Cesium.Cartesian3.subtract(pivot, s.newPos, s.dir),
+      s.dir,
+    );
+    const zDotDir = dir.z;
+    s.upProj.x = -dir.x * zDotDir;
+    s.upProj.y = -dir.y * zDotDir;
+    s.upProj.z = 1 - zDotDir * zDotDir;
+    Cesium.Cartesian3.normalize(s.upProj, s.upProj);
+    camera.setView({
+      destination: s.newPos,
+      orientation: { direction: dir, up: s.upProj },
+    });
+  }
+
   // 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
   flyToEntry(index) {
     const entry = ENTRIES[index];