[vtkusers] bugs? in widgets

Burlen burlen at apollo.sr.unh.edu
Tue Jul 12 11:29:20 EDT 2005

Hi, I am having some problems re the widgets, specificall the vtkSphereWidget, 
vtkLineWidget, and vtkImplicitPlaneWidget, I am wondering if I have found 
bugs or am just doing something wrong, after posting to the users list I 
didn't recieve an answer so I'm trying here.

first off, I'm using VtkQt http://staff.science.uva.nl/~dshamoni/VtkQt/ , and 
that may be complicating things, I don't know.
second, I can't use SetInput(), or SetProp3D(), but rather need to explicitly 
size the widget and locate them, before turning them on or enabling them.

here are the problems I am experiencing:

1)colors don't change until mouse events fire in interactor....
widgets actors are white by default changing the color to black doesn't affect 
the intial placement into the scene, and I have a white background. I am 
setting the color to balck before turning the widget on, or enabling it, but 
the changes don't take effect until there is some mouse interaction in 

I have experienced this with the outline of the implicit plane widget and the 
"handle" of the sphere widget.

2) vtkSphereWidget intial handle placement...
handle doesn't position itself on the surface of the sphere, instead it shows 
up at the center of the widget, which prevents user interaction, as the 
sphere itself absorbs mouse events. When I zoom inside the sphere, I can then 
click the handle, but as soon as I start to drag, it snaps to the shell of 
the shpere disssapear from the view. There is no SetHandlePosition(x,y,z), so 
I assume that the widget should auytomatically place the handle somewhere on 
the shell of the sphere, and not at the center, where it is inaccessable. 

3) linewidget handle resizing, implicit plane widget handle resizing ...
when I have a line widget, or implicit plane widget in the scene, and I change 
the camera, location zoom in or out, the line widgets don't change size, but 
as soon as I click on the widget, the handles resize. This produces some 
weird behavior, like while zooming in the handles can get relatively large 
taking up most of the scene, then when you select the widget they shrink like 
75%. looks bad, and I can't use it like this. I need to find a way so that 
the handles resizes as the camera manipulation takes place, so that the 
widget handles are always the same relative size in the scene. It seems like 
what ever code that is resizing the handles when they get selected should 
fire each time the camera moves...

If these are bugs then I guess I am out of luck using these widgets in my app,  
but any ideas for work arounds are welcome!

Thanks, Burlen

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