[Paraview] SafeDownCast to vtkDoubleArray fails

[Burlen Loring]

Natalie Happenhofer wrote:
> Hi!
> Thx a lot, I get now a DataArray using
> getArr = scaldat ->GetArray(0); //I just have one array in my point data
>
> But still the downcast to vtkDoubleArray fails, here is the code I used:
>
> scaldat = input -> GetPointData();
> vtkDataArray *getArr = vtkDataArray::CreateDataArray(VTK_DOUBLE);
> getArr = scaldat -> GetArray(0);
This is going to create a leak, because you ask for a New() an array 
then reassign your pointer to it before you call Delete().

>
>  vtkDoubleArray *scalars = vtkDoubleArray::New();
> scalars = vtkDoubleArray::SafeDownCast(getArr); //this downcast fails, 
> i.e at runtime I get that warning below
Again this results in a leak for same reason.
>  if(!scalars) vtkErrorMacro("SafeDownCast to vtkDoubleArray failed");
>
>
> With the member function "IsTypeOf(char *classname)" I tried to find 
> out if getArr is an array of a subclass of vtkDataArray, but this does 
> not seem to be the case. getArr is just a vtkDataArray. But I need to 
> access the values in it!!!
There are a few reasons why the cast could fail. Do you know for sure 
that getArr is not null? Could you check to be sure the array in 
question is actually a double array? Try getArr->Print(cerr); That 
should give more info. If this happened to me I would open the code in a 
debugger and single step through this portion of the code examining 
variables to see they have the expected values.


>
> thx,
> NH
>
>
>
> > Date: Sun, 21 Sep 2008 11:49:00 -0400
> > From: burlen.loring at kitware.com
> > To: nataliehapp at hotmail.com
> > CC: paraview at paraview.org
> > Subject: Re: [Paraview] SafeDownCast to vtkDoubleArray fails
> >
> > Natalie Happenhofer wrote:
> > > Hi!
> > > I need to cast my Point Data to a vtkDoubleArray, but it fails:
> > >
> > > vtkPointData *scaldat = input -> GetPointData();
> > > vtkDoubleArray *scalars = vtkDoubleArray::New();
> > > scalars = vtkDoubleArray::SafeDownCast(scaldat);
> > > if(!scalars) vtkErrorMacro("SafeDownCast to vtkDoubleArray failed");
> > PointData is not an array, it's a container of arrays. To get one of 
> its
> > arrays see the GetArray methods.
> > 
> http://www.vtk.org/doc/nightly/html/classvtkFieldData.html#888a6492210426d4ba4d358b87ab198f
> >
> > To find this in the documentation you would have to use the inheritance
> > diagrams. PointData "is a" DataSetAttibutes "is a" FieldData and so on.
> >
> > >
> > > and everytime I run the program I get that vtkErrorMacro.
> > > as far as I know from the input files, the PointData should be float,
> > > but casting to vtkFloatArray fails as well. Why? and what can I do
> > > about it?
> > >
> > > thx a lot,
> > > NH
> > >
> > > 
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> > --
> > Burlen Loring
> > Kitware, Inc.
> > R&D Engineer
> > 28 Corporate Drive
> > Clifton Park, NY 12065-8662
> > Phone: 518-371-3971 x137
> >
>
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-- 
Burlen Loring
Kitware, Inc.
R&D Engineer
28 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-371-3971 x137