vtkPlane and vtkPlaneSource => clippingplane

[Jorrit Schaap]

Dear VTK Users,

In short my question is as folows:

I have:

 vtkPlaneSource *planeSource = vtkPlaneSource::New();

 vtkPolyDataMapper *planeMapper = vtkPolyDataMapper::New();
  planeMapper->SetInput(planeSource->GetOutput());

 vtkActor *planeActor = vtkActor::New();
  planeActor->SetMapper(planeMapper);

after some rotations (done by an interactor) i want to get the normal of
this plane.
Can somebody please give me a hint on how to do that?

Thanks.

Jorrit Schaap.


Here below is my problem in some more detail (for the die-hards)

I am using a clipping plane as follows:

vtkPlane *clippingPlane = vtkPlane::New();
clippingPlane->SetOrigin(x, y, z);
clippingPlane->SetNormal(n1, n2, n3);

aMapper->AddClippingPlane(clippingPlane);   this is some mapper in my
pipeline

this works very good.

Next I tried to make a new vtkInteractorStyle, derived from the
vtkInteractorStyleTrackball, and called it
vtkInteractorStyleClippingPlane.

I overloaded the OnTimer function, and added the functions
TrackballPanClippingPlane and TrackballRotateClippingPlane. In the Pan
function i set the origin of the clippngplane, and this works very nice.

But, in the Rotate function i want to set the normal of the
clippingplane, and i can't figure out how to calculate the new normal
based on the mousemovement.
Here is what i tried: I copied the code from the function
vtkInteractorStyleTrackball::TrackballRotateActor, and replaced the
InterActionActor with a vtkPlaneSource...vtkPolyDataMapper...vtkActor.
(as above) This enables me to rotate the polydata plane.

Now here is my question: how can i get the normal of this polydata
plane?? (so i can use this normal to set the normal of the
clippingPlane).

Thanks again for reading this long story.

Jorrit



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