vtk Motion Callback

[David Gobbi]

Hi Sean,

In C++, the best approach might be to create your own 
vtkInteractorStyle class and override the appropriate
methods.

There used to be a SetTimerMethod in vtkRenderWindowInteractor,
but it was axed when the vtkInteractorStyle class was
created.

 - David

--David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On Wed, 10 Nov 1999, Sean Spicer wrote:

> 
> Jim, David, Others,
> 
> What I really need is to be able to do define a C++ function which gets
> called on every motion event (like an XMotionEvent) and which depends on
> the position of the mouse...so in pseudo code:
> 
> void myButton2Callback(void *arg)
> {
>   vtkRenderWindowInteractor *iren = (vtkRenderWindowInteractor *) arg;
> 
>   int position[2];
> 
>   iren -> GetEventPosition(position)
> 
>   // This function modifies rendering parameters
>   // such that the scene needs to be updated
>   DoSomethingWithThePosition(position);
> 
> }
> 
> 
> void main(void)
> {
>   ... Initialize Vtk and all that jazz ...
> 
>   vtkInteractorStyleTrackball *aStyle;
> 
>   aStyle = (vtkInteractorStyleTrackball *)iren->GetInteractorStyle();
>   aStyle -> SetTrackballModeToTrackball();
>   aStyle -> SetMiddleButtonMotionMethod(myButton2Callback, (void *)iren);
> 
>   ... Get the window interactor started ...
> 
>   iren -> Start();
> 
> }
> 
> I don't see how one can do this with a Timer, mainly because every time
> the timer is triggered, you have to figure out which button is down, and
> react accordingly.  This would foul up the trackball.  Better to override
> the default behavior for one of the buttons (or simply switch to a new
> interactor with modified callbacks)  
> 
> I could do this by descending a class off of vtkInteractorStyleTrackball,
> but that would be an inelegant solution.
> 
> Providing the Motion override functions would be elegant.
> 
> Let me know what you think,
> 
> sean
> 
> ps -- I work entirely in C/C++, so the tcl and python solutions 
>       don't apply.
> 
> ___________________________________________________________________________
> Sean Spicer 	     	          Stanford University Medical Center  
> Biomechanical Engineering         Division of Vascular Surgery, Suite H3642
> Cardiovascular Biomechanics Lab   Stanford CA, 94305 
>                                   Telephone...650.723.1695
>   			          Fax.........650.723.8762
> 
>             http://solvedeath.stanford.edu/~spicer
>  
> 
> 
> 



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