恢复绕注视点轨道倾倒，用 ENU 直接求 heading/pitch 修复近天底奇点

src/scene/CesiumGlobe.js

@@ -364,17 +364,64 @@ export class CesiumGlobe {
     viewer.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
   }
 
-  // 右键环视：相机“原地倾倒”（位置不动，只改视线方向）。左右 = 经度方向、上下 = 纬度方向，强制北朝上。
-  // 关键：直接算 heading/pitch 传给 setView，绕过 setView 在近天底处用 up 反推 heading 的奇点——
-  // 否则初期的小角度倾斜会被翻转（表现为“向北平移”）。
+  // 右键环视：绕相机注视点（地形表面）做轨道倾倒。左右 = 经度方向、上下 = 纬度方向，强制北朝上。
+  // 关键：把轨道后的视线方向转到 ENU 后直接求 heading/pitch 传给 setView，
+  // 绕过 setView 在近天底处用 up 反推 heading 的奇点（否则小角度倾斜会被翻转）。
   _setupLookAround() {
     const scene = this.viewer.scene;
     const camera = this.viewer.camera;
     const handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
     this._lookState = null;
+    this._orbitScratch = {
+      offset: new Cesium.Cartesian3(),
+      upAxis: new Cesium.Cartesian3(),
+      eastAxis: new Cesium.Cartesian3(),
+      northAxis: 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(),
+      enu: new Cesium.Matrix4(),
+      invEnu: new Cesium.Matrix4(),
+      localDir: new Cesium.Cartesian3(),
+    };
 
     handler.setInputAction((movement) => {
+      // 旋转中心 = 相机当前注视的屏幕中心点（地形表面），而不是点击点
+      const canvas = scene.canvas;
+      const center = Cesium.Cartesian2.fromElements(
+        canvas.clientWidth / 2,
+        canvas.clientHeight / 2,
+      );
+      const ray = camera.getPickRay(center);
+      let pivot = scene.globe.pick(ray, scene);
+      if (!Cesium.defined(pivot)) {
+        pivot = camera.pickEllipsoid(center, scene.globe.ellipsoid);
+      }
+      if (!Cesium.defined(pivot)) return;
+      const sc = this._orbitScratch;
+      const offset = Cesium.Cartesian3.subtract(camera.position, pivot, sc.offset);
+      const upAxis = Cesium.Cartesian3.normalize(pivot, sc.upAxis);
+      const eastAxis = Cesium.Cartesian3.cross(Cesium.Cartesian3.UNIT_Z, pivot, sc.eastAxis); // 上下拖动（纬度方向）
+      if (Cesium.Cartesian3.magnitudeSquared(eastAxis) < 1e-12) {
+        eastAxis.x = 1;
+        eastAxis.y = 0;
+        eastAxis.z = 0; // 极点退化兜底
+      } else {
+        Cesium.Cartesian3.normalize(eastAxis, eastAxis);
+      }
+      const northAxis = Cesium.Cartesian3.normalize(
+        Cesium.Cartesian3.cross(upAxis, eastAxis, sc.northAxis), // 左右拖动（经度方向）
+        sc.northAxis,
+      );
       this._lookState = {
+        pivot: Cesium.Cartesian3.clone(pivot),
+        startOffset: Cesium.Cartesian3.clone(offset),
+        eastAxis: Cesium.Cartesian3.clone(eastAxis),
+        northAxis: Cesium.Cartesian3.clone(northAxis),
         position: Cesium.Cartesian3.clone(camera.position),
         direction: Cesium.Cartesian3.clone(camera.direction),
         up: Cesium.Cartesian3.clone(camera.up),
@@ -394,7 +441,7 @@ export class CesiumGlobe {
       s.lastY = movement.endPosition.y;
       s.azimuth = Cesium.Math.clamp(s.azimuth + dx * LOOK_RATE, -MAX_LOOK_ROT, MAX_LOOK_ROT);
       s.elevation = Cesium.Math.clamp(s.elevation + dy * LOOK_RATE, -MAX_LOOK_TILT, MAX_LOOK_TILT);
-      this._tiltCamera(s);
+      this._orbitCamera(s);
     }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
 
     handler.setInputAction(() => {
@@ -410,14 +457,32 @@ export class CesiumGlobe {
     this._lookHandler = handler;
   }
 
-  // 原地倾倒：由累计的经度角(azimuth)/纬度角(elevation)直接求 heading/pitch，roll 固定 0（北朝上）
-  _tiltCamera(s) {
-    const el = s.elevation;
-    const az = s.azimuth;
-    const heading = Math.atan2(-Math.cos(el) * Math.sin(az), Math.sin(el));
-    const pitch = Math.asin(-Math.cos(el) * Math.cos(az));
-    this.viewer.camera.setView({
-      destination: s.position,
+  // 轨道倾倒：左右绕南北轴、上下绕东西轴，位置沿轨道移动且始终看向注视点；直接算 heading/pitch 传 setView
+  _orbitCamera(s) {
+    const camera = this.viewer.camera;
+    const sc = this._orbitScratch;
+    Cesium.Quaternion.fromAxisAngle(s.northAxis, s.azimuth, sc.qAz);
+    Cesium.Quaternion.fromAxisAngle(s.eastAxis, s.elevation, sc.qEl);
+    Cesium.Quaternion.multiply(sc.qEl, sc.qAz, sc.q);
+    Cesium.Matrix3.fromQuaternion(sc.q, sc.rotMat);
+    Cesium.Matrix3.multiplyByVector(sc.rotMat, s.startOffset, sc.newOffset);
+    Cesium.Cartesian3.add(s.pivot, sc.newOffset, sc.newPos);
+    const dir = Cesium.Cartesian3.normalize(
+      Cesium.Cartesian3.subtract(s.pivot, sc.newPos, sc.dir),
+      sc.dir,
+    );
+    // 视线方向转到 newPos 处的 ENU，直接求 heading/pitch（避开 setView 近天底用 up 反推 heading 的翻转）
+    Cesium.Transforms.eastNorthUpToFixedFrame(
+      sc.newPos,
+      this.viewer.scene.globe.ellipsoid,
+      sc.enu,
+    );
+    Cesium.Matrix4.inverseTransformation(sc.enu, sc.invEnu);
+    Cesium.Matrix4.multiplyByPointAsVector(sc.invEnu, dir, sc.localDir);
+    const heading = Math.atan2(sc.localDir.x, sc.localDir.y);
+    const pitch = Math.asin(sc.localDir.z);
+    camera.setView({
+      destination: Cesium.Cartesian3.clone(sc.newPos),
       orientation: { heading, pitch, roll: 0 },
     });
   }