Difference between revisions of "VTK/Examples/Cxx/PolyData/Casting"
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Revision as of 08:37, 11 August 2010
This example creates a polydata object with 3 points and attaches a distance value to each point. To retrieve the array from the polydata, we have to use a SafeDownCast to the type that we want. This is necessary because to keep things as general as possible the polydata will return an abstract array class.
Casting.cxx
#include <vtkSmartPointer.h>
#include <vtkDoubleArray.h>
#include <vtkIntArray.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPointData.h>
int main(int, char *[])
{
//create points
vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
unsigned int numberOfPoints = 3;
points->InsertNextPoint ( 0.0, 0.0, 0.0 );
points->InsertNextPoint ( 1.0, 0.0, 0.0 );
points->InsertNextPoint ( 0.0, 1.0, 0.0 );
//add the points to a polydata
vtkSmartPointer<vtkPolyData> polydata =
vtkSmartPointer<vtkPolyData>::New();
polydata->SetPoints ( points );
//add distances to each point
vtkSmartPointer<vtkDoubleArray> distances =
vtkSmartPointer<vtkDoubleArray>::New();
distances->SetNumberOfComponents ( 1 );
distances->SetName ( "Distances" );
distances->InsertNextValue ( 1.1 );
distances->InsertNextValue ( 2.2 );
distances->InsertNextValue ( 3.3 );
polydata->GetPointData()->AddArray ( distances );
//get the distances from the polydata
vtkDoubleArray* array = vtkDoubleArray::SafeDownCast ( polydata->GetPointData()->GetArray ( "Distances" ) );
if ( array )
{
for ( unsigned int i = 0; i < numberOfPoints; i++ )
{
double dist;
dist = array->GetValue ( i );
std::cout << "Distance: " << dist << std::endl;
}
}
//cast the double distances to ints
vtkDoubleArray* doubleDistances = vtkDoubleArray::SafeDownCast ( polydata->GetPointData()->GetArray ( "Distances" ) );
vtkIntArray* intDistances = vtkIntArray::SafeDownCast ( doubleDistances );
if ( intDistances )
{
for ( unsigned int i = 0; i < numberOfPoints; i++ )
{
int dist;
dist = intDistances->GetValue ( i );
std::cout << "Distance: " << dist << std::endl;
}
}
else
{
std::cout << "invalid cast." << std::endl;
}
return EXIT_SUCCESS;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.6)
PROJECT(Casting)
FIND_PACKAGE(VTK REQUIRED)
INCLUDE(${VTK_USE_FILE})
ADD_EXECUTABLE(Casting Casting.cxx)
TARGET_LINK_LIBRARIES(Casting vtkHybrid)