[vtkusers] does returning "vtkPolyData" work?

[KS Jothybasu]

Hi all,

How to use smart pointers with python-VTK?

Jothy

On Mon, Jan 4, 2010 at 11:08 AM, Zein Salah <zeinsalah at gmail.com> wrote:

> Hello everybody,
>
> I used smart pointers everywhere (return value, the lvalue) and it worked
> as supposed to be.
>
> Many Thanks,
> Zein
>
> @Rocco: Vielen Dank :).
>
> On Mon, Jan 4, 2010 at 8:55 AM, Rocco Gasteiger <post at rocco-gasteiger.de>
> wrote:
> > Hello Zein,
> >
> > I have two assumptions according to your smart pointer usage (I'm not
> very
> > familiar with them until yet):
> >
> > 1. Maybe your polydata-pointer "polyData" is not valid outside of your
> > function " MyClass::GenerateCont(...)". Your solution could be in
> returning
> > "cutter->GetOutput()" directly instead of " vtkSmartPointer<vtkPolyData>
> > polyData = cutter->GetOutput(); return polyData;"
> >
> > 2. According to this VTK-Documentation:
> > http://www.vtk.org/Wiki/Smart_Pointers, the return type of your function
> > could not be correct. Maybe you can try "vtkSmartPointer<vtkPolyData>
> > MyClass::GenerateCont(...)" instead, additionally with "return
> > cutter->GetOutput();" (like above) in combination with
> > "vtkSmartPointer<vtkPolyData> MyPolydata = MyClass::GenerateCont(..)".
> >
> > I hope this gives you a little help.
> >
> > Best regards, Rocco
> >
> >
> > -----Original Message-----
> > From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On
> Behalf
> > Of Zein Salah
> > Sent: Sunday, January 03, 2010 5:41 PM
> > To: vtkusers at vtk.org
> > Subject: [vtkusers] does returning "vtkPolyData" work?
> >
> > Hallo ,
> > In my class, I have a function that SHOULD return a vtkPolyData, which is
> > the result of a vtkCutter, as shown below:
> >
> >
> > vtkPolyData* MyClass::GenerateCont(double cntr[], double nrml[])
> > {
> >
> >    vtkSmartPointer<vtkPlane> plane = vtkSmartPointer<vtkPlane>::New();
> >    plane->SetOrigin(cntr[0], cntr[1], cntr[2]);
> >    plane->SetNormal(nrml[0], nrml[1], nrml[2]);
> >
> >    vtkSmartPointer<vtkCutter> cutter = vtkSmartPointer<vtkCutter>::New();
> >
> >    cutter->SetInput(....); // some input vtkpolydata
> >    cutter->SetCutFunction(plane);
> >    cutter->Update();
> >
> >
> >    vtkSmartPointer<vtkPolyData> polyData = cutter->GetOutput();
> >    return polyData;
> > }
> >
> >
> > Now I have an array of struct, cArray, where one field of the struct is
> of
> > type vtkPolyData*. When I call the GenerateCont function on the elements
> > of the array, as follows
> >
> >
> > for (int i= 0; i<num; i++) {
> >     double       cntr[3];      cntr[0] = ...;     cntr[1] = ...;
> >      cntr[2] = ...;
> >     double       zdir[3];      zdir[0] = ...;            zdir[1] =
> > ...;             zdir[2] = ...;
> >
> >     cArray[i].polyData = GenerateCont(cntr, zdir);
> > }
> >
> > I noticed that the cArray is not updated. I.e. calling function
> GenerateCont
> > does not return the supposed vtkPolyData. By testing whether the function
> > GenerateCont works itself, I found that is the vtkCutter generates the
> > output as required, only the output value is not returned.
> >
> > What is wrong I am doing? Is returning a vtkPolyData semantically wrong?
> >
> >
> > Much thanks,
> > Zein
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