How to get vtkboxwidget coordinates - vtk

Question

I set a 3D array image data, render, and show it, and add a vtkboxwidget to it.
I want to get coordinates of each angle of the vtkboxwidget once user rotates, scales the vtkboxwidget. How can i do this. Here is my code.
#include "myrender.h"
#include <vtkInteractorStyleTrackballCamera.h>
// For vtkBoxWidget:
#include "vtkPlanes.h"
#include "vtkBoxWidget.h"
#include "vtkTransform.h"
#include "vtkCommand.h"
#include "vtkProperty.h"
#include "vtkPlane.h"
#include "vtkImageData.h"
#include "vtkExtractVOI.h"
#include "vtkBorderRepresentation.h"
#include "vtkProp3D.h"
class vtkMyCallback : public vtkCommand{
public:
static vtkMyCallback *New() {
return new vtkMyCallback;
}
virtual void Execute(
vtkObject *caller, unsigned long, void* ) {
// Here we use the vtkBoxWidget to transform the underlying coneActor
// (by manipulating its transformation matrix).
vtkSmartPointer<vtkTransform> t =
vtkSmartPointer<vtkTransform>::New();
vtkBoxWidget *widget = reinterpret_cast<vtkBoxWidget*>(caller);
widget->GetTransform( t );
//widget->GetProp3D()->SetUserTransform( t );
double *pos = t->GetPosition();
t->GetMatrix();
std::cout<<"position: "<<pos[0]<<" "<<pos[1]<<" "<<pos[2]<<std::endl;
}};
MyRender::MyRender() {
ROIdata = NULL;
ROI_sz0 = 0;
ROI_sz1 = 0;
ROI_sz2 = 0;
}
MyRender::~MyRender() {
}
void MyRender::setData(unsigned char *ROIdata, int ROI_sz0, int ROI_sz1, int ROI_sz2) {
this->ROIdata = ROIdata;
this->ROI_sz0 = ROI_sz0;
this->ROI_sz1 = ROI_sz1;
this->ROI_sz2 = ROI_sz2;
}
void MyRender::render(vtkSmartPointer<vtkRenderWindow> renWin) {
int width = ROI_sz0;
int height = ROI_sz1;
int depth = ROI_sz2;
/**
* RENDER WHOLE BRAIN DATA AND SHOW.
*/
//Convert the c-style image to a vtkImageData
vtkSmartPointer<vtkImageImport> imageImport = vtkSmartPointer<vtkImageImport>::New();
imageImport->SetImportVoidPointer(ROIdata);
imageImport->SetDataScalarTypeToUnsignedChar();
imageImport->SetNumberOfScalarComponents(1);
imageImport->SetDataSpacing(1.0, 1.0, 1.0);
imageImport->SetDataOrigin(0, 0, 0);
imageImport->SetDataExtent(0, width-1, 0, height-1, 0, depth-1);
imageImport->SetWholeExtent(0, width-1, 0, height-1, 0, depth-1);
imageImport->Update();
int *arr = imageImport->GetOutput()->GetDimensions();
std::cout<<"x size: "<<arr[0]<<" y size: "<<arr[1]<<" z size: "<<arr[2]<<std::endl;
//Create the standard ren, render window, and interactor
vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
//Create transfer mapping scalar value to opacity
vtkSmartPointer<vtkPiecewiseFunction> opacityFunc = vtkSmartPointer<vtkPiecewiseFunction>::New();
opacityFunc->AddPoint(0, 0.0);
opacityFunc->AddPoint(512, 1.0);
opacityFunc->ClampingOff();
//Create transfer mapping scalar value to color
vtkSmartPointer<vtkColorTransferFunction> colorFunc
= vtkSmartPointer<vtkColorTransferFunction>::New();
colorFunc->AddRGBPoint(150, 1.0, 1.0, 1.0);
//The property describes how the data will look
vtkSmartPointer<vtkVolumeProperty> volumeProperty = vtkSmartPointer<vtkVolumeProperty>::New();
volumeProperty->SetColor(colorFunc);
volumeProperty->SetScalarOpacity(opacityFunc);
volumeProperty->ShadeOn();
volumeProperty->SetInterpolationTypeToLinear();
vtkSmartPointer<vtkSmartVolumeMapper> volumeMapper = vtkSmartPointer<vtkSmartVolumeMapper>::New();
volumeMapper->SetInputConnection(imageImport->GetOutputPort());
//The volume holds the mapper and the property and can be used to position/orient the volume
vtkSmartPointer<vtkVolume> volume = vtkSmartPointer<vtkVolume>::New();
volume->SetMapper(volumeMapper);
volume->SetProperty(volumeProperty);
ren->AddVolume(volume);
ren->SetBackground(0, 0, 0);
vtkSmartPointer<vtkBoxWidget> box = vtkSmartPointer<vtkBoxWidget>::New();
box->SetInteractor(renWin->GetInteractor());
box->SetPlaceFactor(1);
box->SetInputConnection(imageImport->GetOutputPort());
box->PlaceWidget();
box->InsideOutOn();
box->SetProp3D(volume);
box->GetOutlineProperty()->SetRepresentationToSurface();
box->GetOutlineProperty()->SetOpacity(1.0);
box->RotationEnabledOff();
vtkSmartPointer<vtkMyCallback> callback = vtkSmartPointer<vtkMyCallback>::New();
box->AddObserver(vtkCommand::InteractionEvent, callback);
box->On();
renWin->AddRenderer(ren);
renWin->Render();
}
How can i get the coodinates of vtkboxwidget in vtkCommand class in real time. Thanks a lot.

Answer 1

From the doc:
void vtkBoxWidget::GetPolyData ( vtkPolyData * pd )
Grab the polydata (including points) that define the box widget.
The polydata consists of 6 quadrilateral faces and 15 points. The first eight points define the eight corner vertices; the next six define the -x,+x, -y,+y, -z,+z face points; and the final point (the 15th out of 15 points) defines the center of the hexahedron. These point values are guaranteed to be up-to-date when either the InteractionEvent or EndInteractionEvent events are invoked. The user provides the vtkPolyData and the points and cells are added to it.
It looks like it is what you are looking for, or not?