Hi Micha,

> Couldn't be possible, that the values of the distance moved
> by the mouse are rounded, if no reference point is used?

Hi Micha, it is possible, but I don't think it would work well in all situations - for example if you are working on something where a value of 10 produces only a small sized result.

Focusing on doing interactive mouse-based modifications by picking points inside the viewport tends to avoid this kind of problem.


> or could be calculated by the viewport scale.

One thing that can tend to be difficult is that a perspective viewport does not have just a single scale factor associated with it. For example, a cylinder of the same height will take up more pixels on the screen if it is closer to the eyepoint, and less pixels if it is far away from the eyepoint. In this case there is no longer a simple universal mapping between pixels and distance like there is in an orthographic viewport.

- Michael