[vtkusers] vtkBoxWidget handle size bug?

Berti Krüger berti_krueger at hotmail.com
Wed Feb 7 01:21:55 EST 2018

It seems i am not the only one who doesn't understand the logic behind the
sizing of the vtkBoxWidget handles:



I am using a vtkBoxWidget, and it seems the size of the handles depends on
the ValidPick (to know if handle has been picked or not) (and on the
renderer to. We have to set a current renderer before calling PlaceWidget.)

So, when I am creating the box, ValidPick is 0 because handles have not been
picked yet.
The size of the handles is calculate with:

return (this->HandleSize * factor * this->InitialLength);

But, when we resize the box, ValidPick change to 1 (on
OnLeftButtonDown() (same for middle and right button) ), and the size
is now calculated like this:

return (this->HandleSize * factor *  sqrt(radius) );

InitialLength has been replaced by sqrt(radius) (defined on

But sqrt(radius) is different from InitalLength.

So, when we create a vtkBoxWidget, handles are small, and when we resize it,
handles are bigger.

Is this normal, or it's a bug ?

Thank you.

Am Mon, 5 Feb 2018 10:00:16 +0000
schrieb Berti Krüger <berti_krueger at hotmail.com>:

> Hello Everyone!
> I am currently using a vtkBoxWidget in my project (VTK 8.1). After i
> created the vtkBoxWidget, the size handles (= vtkSphereActors) have not been
> picked yet and are small and nice. 
> But, when I resize the vtkBoxWidget (smaller or larger, it doesn't matter) or
> simply click on it, the handles get bigger (radius increases) and stay this
> way.
> They sometimes tend to get so large that they are piercing the mesh and
> visually adding themselves to it, which is annoying. And they never get
> smaller again, sometimes they get even larger.
> When i zoom out by large amount and then zoom in again, the handles get normal
> ( = small) again.
> Is this the intented behaviour, and if so, what is the purpose of it or is it
> a bug ?
> Thank you very much in advance.
> Berti Krüger
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