How to sync views even if main camera is up side down?

CesiumJS
1

Hi,

I'm trying to synchronize two views like in the sandcastle example.

While moving the camera up, the heading of the synced view becomes incorrect when I go over the pole (it is still with north up, though it should be south up). I wish the two views to behave the same way and to avoid this.

Can you help with this please?

<code>
// We want our two views to be synced across time, so we create
// a shared clock object that both views share
var clockViewModel = new Cesium.ClockViewModel();
var options3D1 = {
    fullscreenButton : false,
    sceneModePicker : false,
    clockViewModel : clockViewModel
};
var options3D2 = {
    homeButton : false,
    fullscreenButton : false,
    sceneModePicker : false,
    clockViewModel : clockViewModel,
    infoBox : false,
    geocoder : false,
    //sceneMode : Cesium.SceneMode.SCENE2D,
    navigationHelpButton : false,
    animation : false
};
// We create two 3D viewers
// The CSS is set up to place them side by side
var view3D1 = new Cesium.Viewer('view3D', options3D1);
var view3D2 = new Cesium.Viewer('view2D', options3D2);

var worldPosition;
var distance;

function sync2DView() {
    // The center of the view is the point that the 3D camera is focusing on
    var viewCenter = new Cesium.Cartesian2(Math.floor(view3D1.canvas.clientWidth / 2), Math.floor(view3D1.canvas.clientHeight / 2));
    // Given the pixel in the center, get the world position
    var newWorldPosition = view3D1.scene.camera.pickEllipsoid(viewCenter);
    if (Cesium.defined(newWorldPosition)){
        // Guard against the case where the center of the screen
        // does not fall on a position on the globe
        worldPosition = newWorldPosition;
    }
    // Get the distance between the world position of the point the camera is focusing on, and the camera's world position
    distance = Cesium.Cartesian3.distance(worldPosition, view3D1.scene.camera.positionWC);
    // Tell the 2D camera to look at the point of focus. The distance controls how zoomed in the 2D view is
    // (try replacing `distance` in the line below with `1e7`. The view will still sync, but will have a constant zoom)
    view3D2.scene.camera.lookAt(worldPosition, new Cesium.Cartesian3(0.0, 0.0, distance));
}

// Apply our sync function every time the 3D camera view changes
view3D1.camera.changed.addEventListener(sync2DView);
// By default, the `camera.changed` event will trigger when the camera has changed by 50%
// To make it more sensitive, we can bring down this sensitivity
view3D1.camera.percentageChanged = 0.000000001;

// Since the second view follows the first view, we disable any
// camera movement on the second view
view3D2.scene.screenSpaceCameraController.enableRotate = false;
view3D2.scene.screenSpaceCameraController.enableTranslate = false;
view3D2.scene.screenSpaceCameraController.enableZoom = false;
view3D2.scene.screenSpaceCameraController.enableTilt = false;
view3D2.scene.screenSpaceCameraController.enableLook = false;

var main_interval = setInterval(moveup, 10);

function moveup() {
    view3D1.scene.camera.rotate(view3D1.scene.camera.right, 0.001);
}
</code>

Cesium 1.50
Chrome 70

2

That example was written specifically to sync a 3D and a 2D view. You can see how it copies over the position but fixes the offset in this line:

view3D2.scene.camera.lookAt(worldPosition, new Cesium.Cartesian3(0.0, 0.0, distance));

``

If you just want to move the two cameras together, you can just apply the rotation to both of them:

view3D1.scene.camera.rotate(view3D1.scene.camera.right, 0.003);

view3D2.scene.camera.rotate(view3D2.scene.camera.right, 0.003);

``

Here’s a Sandcastle example.

You can also just copy the destination and orientation of the first camera onto the second:

var camera1 = view3D1.scene.camera;

var camera2 = view3D2.scene.camera;

camera1.rotate(camera1.right, 0.003);

camera2.setView({

destination : camera1.position,

orientation : {

heading : camera1.heading,

pitch : camera1.pitch,

roll : camera1.roll,

}

});

``

Here’s a Sandcastle for that.

3

Thanks, that solved my issue.