How to read data in vtkDataArray? - c++

Question

I am ver new to VTK.
This is part of my code:
vtkDataSetReader *rdr = vtkDataSetReader::New();
rdr->SetFileName("proj7b.vtk");
rdr->SetScalarsName("hardyglobal");
rdr->Update();
int dims[3];
vtkRectilinearGrid *rgrid = (vtkRectilinearGrid *) rdr->GetOutput();
rgrid->GetDimensions(dims);
vtkDataArray *dataArray;
dataArray = vtkDoubleArray::New();
dataArray = rgrid->GetPointData()->GetScalars()->GetVoidPointer(0);
for(i=0;i<10;i++)
{
cout<<"here----------"<<endl;
cout<<" "<<dataArray[i]<<" ";
}
I want to read the data into my vtkDataArray. But this code cannot be compile:
proj7b.cxx:525:15: error:
assigning to 'vtkDataArray *' from incompatible type 'void *'
dataArray = rgrid->GetPointData()->GetScalars()->GetVoidPointer(0);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
Is there anyone knows how to read data into vtkDataArray?

Answer 1

Vtk provides the method for it, you don't need to use the "low level" method:
rgrid->GetPointData()->GetArray(0)
or
rgrid->GetPointData()->GetArray("arrayname")
It works the same way for FieldData and CellData ( http://www.vtk.org/doc/release/6.2/html/classvtkFieldData.html)
What you get is a vtkArray, not a simple c++ array, so you will have to read it like:
cout<<" "<<dataArray->GetValue(i) <<" ";
There are a lot of examples in the wiki http://www.vtk.org/Wiki/VTK/Examples/Cxx

Answer 2

please see this page: https://cloud.tencent.com/developer/ask/sof/148655
void doSomething(vtkSmartPointer<vtkDataArray> dataArray)
{
vtkIdType numTuples = dataArray->GetNumberOfTuples();
for (vtkIdType tupleIdx = 0; tupleIdx < numTuples; ++tupleIdx)
{
double* tuple = dataArray->GetTuple(tupleIdx);
for (int j = 0; j < /*¿¿¿???*/; ++j)
{
double var = tuple[j];
// Do something with var
// Carefull don't go out of bounds
}
}
}