[vtkusers] vtkCutter->Update doesn't update the vtkCutter->GetOutput()

[Bill Lorensen]

Inside the loop you must disconnect the input to append from the
output of cutter. One way to do that is to use DeepCopy as you
discovered.

Another is to create the cutter inside the loop and Delete it after
adding its output to append If you use SmartPointer's you need not
delete). This should be faster than the DeepCopy, depending on the
size of the models.

If you do not disconnect the input to append, then all of the inputs
will be the same (should be the last cutter output).


On Wed, Nov 3, 2010 at 5:00 AM, nsarrasin <nsarrasin at phenix-systems.com> wrote:
>
> Thanks for your reply,
>
> I followed your advice and used GetOutputPort() but the result stays the
> same.
>
> I post a (light, simple and commented) code which illustrates the problem,
> maybe i'm doing something wrong .
>
> Thanks a lot for helping me.
>
> //slicing of a sphere by a plane. the plane is iteratively rotated all
> around the sphere
>
> #include <vtkSmartPointer.h>
> #include <vtkPolyData.h>
> #include <vtkTransform.h>
> #include <vtkPlane.h>
> #include <vtkCutter.h>
> #include <vtkMath.h>
> #include <vtkAppendPolyData.h>
> #include <vtkPolyDataMapper.h>
> #include <vtkActor.h>
> #include <vtkProperty.h>
> #include <vtkRenderer.h>
> #include <vtkRenderWindow.h>
> #include <vtkRenderWindowInteractor.h>
> #include <vtkSphereSource.h>
> #include <vtkInteractorStyleTrackballCamera.h>
> #include <vector>
>
> int main (int argc, char *argv[])
> {
>        //the object to cut
>        vtkSphereSource* sph = vtkSphereSource::New();
>        sph->SetRadius(25.);
>        sph->SetPhiResolution(50.);
>        sph->SetThetaResolution(50.);
>
>        vtkPolyData *polydata = sph->GetOutput();
>
>        //init the cutting plane
>        double bounds[6], center[3];
>        polydata->GetBounds(bounds);
>        polydata->GetCenter(center);
>
>        vtkPlane* plane = vtkPlane::New();
>        plane->SetOrigin(center);
>        plane->SetNormal(bounds[0]-center[0], bounds[2]-center[1], 0.);
>
>        int nbsections = 10;
>        double angle = 360./(double)nbsections;
>        double normal[3]={0,0,1};
>
>        //init the transformation
>        vtkTransform* transf = vtkTransform::New();
>        transf->RotateWXYZ(angle, normal[0], normal[1], normal[2]);
>
>        vtkMatrix4x4* mat = vtkMatrix4x4::New();
>        transf->GetMatrix(mat);
>
>        vtkAppendPolyData* appdata = vtkAppendPolyData::New();
>        vtkCutter* cutter = vtkCutter::New();
>        cutter->SetInput(polydata);
>        cutter->SetCutFunction(plane);
>
>        double new_normal[4];
>
>        for(int step=0; step<nbsections; step++)
>        {
>                //// Code works but need Update + DeppCopy
>                cutter->Update();
>                vtkPolyData* tmp_result=vtkPolyData::New();
>                tmp_result->DeepCopy( cutter->GetOutput());
>                appdata->AddInput(tmp_result);
>
>                //// Code doesn't update though GetOutputPort()
>                //appdata->AddInputConnection(cutter->GetOutputPort());
>
>                //rotation of the cutting plane around normal
>                mat->MultiplyPoint(plane->GetNormal(), new_normal);
>                plane->SetNormal(new_normal);
>                plane->SetOrigin(center);
>        }
>
>        //visualisation
>        //1. All slices
>        vtkSmartPointer<vtkPolyDataMapper> appmapper =
> vtkSmartPointer<vtkPolyDataMapper>::New();
>        appmapper->SetInput(appdata->GetOutput());
>
>        vtkSmartPointer<vtkActor> appactor = vtkSmartPointer<vtkActor>::New();
>        appactor->SetMapper(appmapper);
>        appactor->GetProperty()->SetColor(1,0,0);
>
>        //2. polydata
>        vtkSmartPointer<vtkPolyDataMapper> teethmapper =
> vtkSmartPointer<vtkPolyDataMapper>::New();
>        teethmapper->SetInput(polydata);
>
>        vtkSmartPointer<vtkActor> teethactor = vtkSmartPointer<vtkActor>::New();
>        teethactor->SetMapper(teethmapper);
>        teethactor->GetProperty()->SetColor(0.8,0.8,0.8);
>
>        // The usual renderer, render window and interactor
>        vtkSmartPointer<vtkRenderer> ren1 =     vtkSmartPointer<vtkRenderer>::New();
>        vtkSmartPointer<vtkRenderWindow> renWin =
> vtkSmartPointer<vtkRenderWindow>::New();
>        vtkSmartPointer<vtkRenderWindowInteractor>      iren =
> vtkSmartPointer<vtkRenderWindowInteractor>::New();
>
>        ren1->SetBackground(.1, .2, .3);
>        renWin->AddRenderer(ren1);
>        iren->SetRenderWindow(renWin);
>
>        ren1->AddActor(appactor);
>        ren1->AddActor(teethactor);
>
>        renWin->Render();
>        iren->Start();
> }
>
> --
> View this message in context: http://vtk.1045678.n5.nabble.com/vtkCutter-Update-doesn-t-update-the-vtkCutter-GetOutput-tp3246712p3248103.html
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