Implement three.js transform controller

[chenkaiC4]

three.js has a nice transform tool kit ui, like:

https://threejs.org/examples/?q=control#misc_controls_transform

will vtk.js support this on the roadmap?
this feature is wonderful

[floryst]

Building that is already possible using vtk.js widgets. However, building a UX similar to that is not on any roadmap I'm aware of.

[daker]

#3280