Cesium: Option to have user input interrupt camera flight

[puckey]

We are working on a feature where need to have user input override a camera flight tween. Currently all controller input is ignored when a camera flight is active.

I was wondering if we might be up for making this configurable by adding something like interruptable or interruptByInput as a boolean option to Camera.flyTo..

I could propose a PR if this is a welcome addition..

[mramato]

I believe a long long time ago Cesium worked liked this but we took it out for some reason or another. It might be because the Camera object which manages the flight is not the object that handles various input control, so it's an odd connection to make in the lower-level API (but I could be wrong).

I'm not against the idea, but this should also be trivial to implement at the application level by simply calling Camera.cancelFlight if the user does anything that you want to interrupt the flight for. However, if it's equally trivial to add as an option, I'm sure we'll consider taking it.

[puckey]

I used Camera.cancelFlight in a LEFT_DOWN event handler to have clicks/taps cancel flights, but this leaves zoom gestures. I would want a pinch to also interrupt any existing flight, but since zooming gestures are swallowed during flight, I think it is currently impossible at the app level:

https://github.com/AnalyticalGraphicsInc/cesium/blob/d26ccfea38dcf4623cf5da3faca141913c64cfe1/Source/Scene/CameraFlightPath.js#L360

https://github.com/AnalyticalGraphicsInc/cesium/blob/d26ccfea38dcf4623cf5da3faca141913c64cfe1/Source/Scene/ScreenSpaceCameraController.js#L386

[puckey]

Fixed it on app level using the WHEEL input action to also cancel flights. @mramato: Thanks for reminding me to take another look at solving it on the application level!

[mramato]

Glad you got it working!