//相机绕点飞行

    addCameraFly(){

       const center = Cesium.Cartesian3.fromDegrees(118.08392927033496,36.9440487626934);

       let heading = Cesium.Math.toRadians(50.0);

        const pitch = Cesium.Math.toRadians(-20.0);

        const range = 3000.0;

        let x=50;

        var self=this;

        viewer_g.scene.postRender.addEventListener(function () {

            x+=0.1;

            heading = Cesium.Math.toRadians(x);

            viewer_g.camera.lookAt(center, new Cesium.HeadingPitchRange(heading, pitch, range))           

          }

        });

    },

切换其他场景时，如果又要用到camera.flyTo相机会跳到很高的视角然后在定位，而不是平滑的进入，解决方案

viewer_g.camera.lookAtTransform(Cesium.Matrix4.IDENTITY);