控制攝像機pitch不到地下 cesium

網上找的控制攝像機pitch的，雖然不太好用 但是能解一下燃眉之急，記錄一下

viewer.clock.onTick.addEventListener(function () {
    if(viewer.camera.pitch > -8)   //角度可以定義，正數是朝上看，負數是朝下看
    {    
        viewer.scene.screenSpaceCameraController.enableTilt = false;   //設置false爲不允許相機傾斜
    }
});

var mousePosition,startMousePosition;
var handler = new Cesium.ScreenSpaceEventHandler(viewer.canvas);
handler.setInputAction(function(movement) {
    mousePosition=startMousePosition= Cesium.Cartesian3.clone(movement.position);
    handler.setInputAction(function(movement) {
        mousePosition = movement.endPosition;
        var y = mousePosition.y - startMousePosition.y;
        if(y>0){
            viewer.scene.screenSpaceCameraController.enableTilt = true;        //鼠標從上往下劃的時候允許傾斜相機
        }
    }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
}, Cesium.ScreenSpaceEventType.MIDDLE_DOWN);

原帖：https://blog.csdn.net/thor027/article/details/82455649