右键环视限制：左右旋转 ±40°、上下倾角 ±20°，松开归位

src/scene/CesiumGlobe.js

@@ -356,7 +356,7 @@ export class CesiumGlobe {
     viewer.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
   }
 
-  // 右键操作（原生 tilt）松开后自动归位：记录按下前状态，松开时恢复
+  // 右键操作（原生 tilt）松开后自动归位 + 拖动角度限制（左右旋转 ±40°，上下倾角 ±20°）
   _setupRightRestore() {
     const scene = this.viewer.scene;
     const camera = this.viewer.camera;
@@ -368,6 +368,8 @@ export class CesiumGlobe {
         position: Cesium.Cartesian3.clone(camera.position),
         direction: Cesium.Cartesian3.clone(camera.direction),
         up: Cesium.Cartesian3.clone(camera.up),
+        heading: camera.heading,
+        pitch: camera.pitch,
       };
     }, Cesium.ScreenSpaceEventType.RIGHT_DOWN);
 
@@ -382,6 +384,37 @@ export class CesiumGlobe {
     }, Cesium.ScreenSpaceEventType.RIGHT_UP);
 
     this._rightRestoreHandler = handler;
+    this.viewer.scene.postUpdate.addEventListener(() => this._clampLookAngles());
+  }
+
+  // 右键拖拽期间，限制相对起始朝向的旋转/倾角
+  _clampLookAngles() {
+    if (!this._rightRestore) return;
+    const camera = this.viewer.camera;
+    const s = this._rightRestore;
+    const MAX_ROT = (40 * Math.PI) / 180;
+    const MAX_TILT = (20 * Math.PI) / 180;
+
+    let heading = camera.heading;
+    let dh = heading - s.heading;
+    while (dh > Math.PI) dh -= 2 * Math.PI;
+    while (dh < -Math.PI) dh += 2 * Math.PI;
+    const rot = Math.max(-MAX_ROT, Math.min(MAX_ROT, dh));
+
+    const pitch = camera.pitch;
+    const dp = pitch - s.pitch;
+    const tilt = Math.max(-MAX_TILT, Math.min(MAX_TILT, dp));
+
+    if (rot !== dh || tilt !== dp) {
+      camera.setView({
+        destination: camera.position,
+        orientation: {
+          heading: s.heading + rot,
+          pitch: s.pitch + tilt,
+          roll: camera.roll,
+        },
+      });
+    }
   }
 
   // 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