[vtkusers] trouble rotating from new Origin vtkProp3D

[Sergio Aguirre]

Hi everyone

I am trying to set the origin (the point about which all rotations take
place)
of a vtkActor through a vtkProp3D pointer.

My actor is generated from a series of images containing binary segmentation
masks
that I use to construct a surface through the pipeline below.

As I understand, because the vtkActor surface comes from ImageData whose
origin
are a corner of an image (x,y) and a image slice (z); when I rotate or
translate
the vtkActor it always rotates/translates from that point.

However, I would rather apply rotations/translations from a center of the
vtkActor
surface determined from its bounding box - which I use to calculate a center
and set
that point as a new origin for the actor. However, it has no effect and the
rotations
still apply from the original vtkImageData origin.

Is there a way to set the origin of the vtkActor surface? or do I need to
construct
a new copy surface actor independent of the vtkImageData to be able to set
an
origin at the center of its bounding box?

Any suggestions are appreciated.

Sergio

//// building the vtkActor from images

vtiReader = vtkXMLImageDataReader::New();
    vtiReader->SetFileName("C:/code/epxZCTC_Demo/Debug/demo_103.vti");
    vtiReader->WholeSlicesOff();
    vtiReader->Update();

Image = vtkImageData::New();
    Image->DeepCopy(vtiReader->GetOutput());
 sgauss = vtkImageGaussianSmooth::New();
      sgauss->SetInput(Image);
      sgauss->SetDimensionality(3);
      sgauss->SetStandardDeviation(0.25, 0.25, 0.25);
      sgauss->SetRadiusFactor(1);

Cubes = vtkMarchingCubes::New();
      Cubes->SetInputConnection(sgauss->GetOutputPort());
      Cubes->SetNumberOfContours(1);
      Cubes->ComputeScalarsOff();
      Cubes->ComputeGradientsOff();
      Cubes->ComputeNormalsOff();
      Cubes->SetValue(0,255);

smoother = vtkSmoothPolyDataFilter::New();
smoother->SetInputConnection(Cubes->GetOutputPort());
      smoother->SetNumberOfIterations(300);
      smoother->SetRelaxationFactor(0.01);
      smoother->SetFeatureAngle(60);
      smoother->FeatureEdgeSmoothingOff();
      smoother->BoundarySmoothingOff();
      smoother->SetConvergence(0);

normals  = vtkPolyDataNormals::New();
      normals->SetInputConnection(Cubes->GetOutputPort());
      normals->FlipNormalsOn();

strips  = vtkStripper::New();
      strips->SetInputConnection(smoother->GetOutputPort());

Mapper = vtkPolyDataMapper::New();
      Mapper->SetInputConnection(strips->GetOutputPort());
      Mapper->ScalarVisibilityOff();

Actor = vtkActor::New();
    Actor->SetMapper(colonMapper);
    Actor->GetProperty()->SetDiffuseColor(1.0, 0.65, 0.65);
    Actor->GetProperty()->SetDiffuse(0.70);
    Actor->GetProperty()->SetSpecular(0.3);
    Actor->GetProperty()->SetSpecularPower(10);

// setting a new origin for rotations
vtkProp3D* picked_object = (vtkProp3D*) propList->GetItemAsObject(object);
 double tip[3], bounds[6], icenter[3], center[3], trans[3];
UpdateLaser(styPoseE, tip); // get Tip - new position for translation

picked_object->GetBounds(bounds); // picked_object get bounds

icenter[0] = (bounds[1]-bounds[0])/2; // initial center
icenter[1] = (bounds[3]-bounds[2])/2;
icenter[2] = (bounds[5]-bounds[4])/2;

picked_object->SetOrigin(icenter); // set origin to initial center
picked_object->SetPosition(icenter);

center[0] = tip[0]-icenter[0];
center[1] = tip[1]-icenter[1];
center[2] = tip[2]-icenter[2];

trans[0] = center[0]+icenter[0]; // translation delta
trans[1] = center[1]+icenter[1];
trans[2] = center[2]+icenter[2];

objMtx = vtkMatrix4x4::New();
picked_object->GetMatrix(objMtx); // store picked_object current position +
rotation
objMtx->SetElement(0,3, 0.0);
objMtx->SetElement(1,3, 0.0);
objMtx->SetElement(2,3, 0.0);
objMtx->SetElement(3,3, 1.0);

rotMtx = vtkMatrix4x4::New();
rotMtx->Identity();
rotMtx->SetElement(0,0, 0.9961); // rotation matrix to apply
rotMtx->SetElement(0,2, 0.0871);
rotMtx->SetElement(2,0, -0.0871);
rotMtx->SetElement(2,2, 0.9961);

 t = vtkTransform::New();
t->Identity();
t->Translate(trans[0], trans[1], trans[2]);
t->Concatenate(objMtx); // concatenate current obj transformation matrix
t->Concatenate(rotMtx); // concatenate rotation delta
t->Translate(-icenter[0], -icenter[1], -icenter[2]);

nMtx = vtkMatrix4x4::New();
nMtx->DeepCopy(t->GetMatrix());

picked_object->PokeMatrix(nMtx);

this->RenWin->Render();
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