Entity preserves z value while keeping xy during dragged by mouse

CesiumJS
1

Hi,

Is there a way to keep height of the entities while it is dragged and follows the mouseXY?

I’m wondering if it is about with Camera angle but I have no idea.

image
image720×795 59.4 KB

You might find helpful to show the solution with the bad example below

Any advice is appreciated, thanks.

2

Hi, I am also facing a similar issue.
I am trying to implement drag on x - y axis.
I have a box entity and I placed point entities on its circumference. By dragging each point I would like to resize and rotate the box.

Capture

To achieve the desired behavior I need the point to only move on the plane of the top face of the box.
has anyone achieved a similar behavior?

would appreciate yo hear if you advanced or solved the issue…

thanks

1 Like
3

@roi081295
you can use this function to create a mathematical plane to make the point only movable upon a specific plane.

https://cesium.com/learn/ion-sdk/ref-doc/Plane.html?classFilter=plane

4

Hi @Hiroshi_Yaginuma,

Thank you for your response!
I actually tried using the Plane.FromPointNormal and then use IntersectionTests.rayPlane with the pick ray to get the end point of drag. Do you think this is the right approach?

const normal = ellipsoid.geodeticSurfaceNormal(startGeoPosition);
const plane = Cesium.Plane.fromPointNormal(startGeoPosition, normal);
const ray = viewer.camera.getPickRay(movement.endPosition);
const endGeoPosition = IntersectionTests.rayPlane(ray, plane);

The endGeoPosition is then used to update the dragged point location via a callback property.

Although this does not give the desired result.
In addition, the plane should not curve with the ellipsoid of the earth.

Thank you

5

that is correct approach.
you just need to consider reference frame of the coordinates of the plane. Make sure you transform by correct inverse matrix.

6

Thank you for the reply!
I put togther a sandcastle link showing my use case and problem.
Points are dragabble using Alt.

Could you show mw what you mean?

Thanks again