[vtk-developers] VtkLineWidget2 InteractionEvent distance

[carlinhos]

Hello,

I'm developing an app to measure the euclidean distance from a 3D point on
the surface of an object to another and show the distance with a line.

To accomplish that, i use *vtkLineWidget2 *with the representation
associated. First time i place it , it shows correctly fit on the surface of
the sphere (or any other object i place into the render window). But when
i'm moving the widget from one of the handler points of the
*vtkLineRepresentation *, it doesn't put the point on the surface of the
sphere.  The method i use sometimes work, sometimes not.

I'm getting the pick every time the *vtkLineWidget2 *throws an Interaction
event, and getting the 3d point of the picked position to set it to the
selected handler of the *vtkLineRepresentation *. Sometimes it works, but
other times, it shows the border of the *vtkLineRepresentation *in a wrong
place (its correctly situated where i picked, but not on the surface of the
object). It seems random to me when it works or not.

I paste the code i call when the Interaction Event of the Widget is thrown.

*///If the selected point is the 1st
				if ( state == vtkLineRepresentation::OnP1 ) {
					this->m_rwi->GetPicker()->Pick(m_rwi->GetLastEventPosition()[0],
					                               m_rwi->GetLastEventPosition()[1],
					                               0,  // always zero.
					                           
					                              
this->m_rwi->GetRenderWindow()->GetRenderers()->GetFirstRenderer());
					double picked[3];

					this->m_rwi->GetPicker()->GetPickPosition(picked);
					lineRepresentation->SetPoint1WorldPosition(picked);
                                 }

//If the selected point is the 2nd
				else if (state == vtkLineRepresentation::OnP2) {

					this->m_rwi->GetPicker()->Pick(m_rwi->GetLastEventPosition()[0],
					                               m_rwi->GetLastEventPosition()[1],
					                               0,
					                              
this->m_rwi->GetRenderWindow()->GetRenderers()->GetFirstRenderer());

					double picked[3];
					this->m_rwi->GetPicker()->GetPickPosition(picked);
					lineRepresentation->SetPoint2WorldPosition(picked);

				}/*

Does anyone know why is not working in all the cases?

Thanks in advance.



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