[vtkusers] Why vtkplane and vtkplanesource display at different position?

[Yongqiang]

Hi all,

 

I meet the following question:

I get the normal of the plane and a point on the plane.

 

vtkPlaneSource plane = vtkPlaneSource::New();

plane->SetCenter(pointposition);

plane->SetNormal(normal);  

 

The position of plane is what I expected.

 

Then I use myPlane to cut polydata. But after cutting, it seems that the
myPlane is parallel to plane, but its position is not what I expect.

 

vtkPlane *myPlane = vtkPlane::New();

myPlane->setOrigin(pointposition);

myPlane->setNormal(normal);

 

The only difference between these two setting is SetCenter and SetOrigin

 

In the vtk document, 

vtkPlane->SetOrigin : Set point through which plane passes.

vtkPlaneSource->SetCenter: Set the center of the plane

 

To define a plane, just need normal and a point at the plane. From the
document, I think these two functions are same. They just set a point
position.

 

So why myPlane is not at the position where plane stays?

Is my understanding wrong or other reasons?

 

Thanks for any help!!

 

___________________________________________

Yongqiang

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