[vtkusers] strange update problem

[Michael Knopke]

Hello UserGroup,

 

I just stumbled about a very strange occurrence that I can't figure out.

After modifying the elements of a matrix that was retrieved from a
vtkTransform (via ->GetMatrix()) the update pipeline seems not to work
correctly anymore.

Just a simple example:

 

//create a vtkTransform

vtkTransform* transform = vtkTransform::New();

 

//create vtkimagereslice  and set it up to slice a volume, connnect it with
the transform

vtkImageReslice *reslice = vtkImageReslice::New();

reslice->SetSpacing...

reslice->SetTransform(transform);

...

 

//conntect the rest e.g. an imageActor to a renderer 

...

 

 

// now when calling translate and Render everthing is fine

e.g. transform->Translate(0,0,100);

renWin->Render(); //updates the slicer

 

//call identity on the transform just for testing purpose

transform->Identity(); //works

renWin->Render(); //updates the slicer

 

// now when calling translate and Render it still works

e.g. transform->Translate(0,0,100);

renWin->Render(); //updates the slicer

 

 

//BUT when interchanging transform->Identity() with:

 

transform->GetMatrix()->Identity();

 

// it works but then successive calls to translate or rotate will not
trigger an update of the rendering??? 

 

// the does not happen when creating a matrix, modifying the elements and
setting it via transform->SetMatrix(matrix);

 

Does anybody know if this is a bug or am I doing something wrong here?

 

Regards

 

Michael

 

 

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