PolyDataPointNormals
VTKExamples/Cxx/PolyData/PolyDataPointNormals
Description
This demo adds a normal to each point in a polydata.
Code
PolyDataPointNormals.cxx
#include <vtkCellData.h>
#include <vtkCellArray.h>
#include <vtkDoubleArray.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPointData.h>
#include <vtkSmartPointer.h>
int main(int, char *[])
{
///////// Set Point Normals ///////////
// Create 3 points
vtkSmartPointer<vtkPoints> points =
vtkSmartPointer<vtkPoints>::New();
points->InsertNextPoint(1.0, 0.0, 0.0);
points->InsertNextPoint(0.0, 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);
// Set point normals
vtkSmartPointer<vtkDoubleArray> pointNormalsArray =
vtkSmartPointer<vtkDoubleArray>::New();
pointNormalsArray->SetNumberOfComponents(3); //3d normals (ie x,y,z)
pointNormalsArray->SetNumberOfTuples(polydata->GetNumberOfPoints());
// Construct the normal vectors
double pN1[3] = {1.0, 0.0, 0.0};
double pN2[3] = {0.0, 1.0, 0.0};
double pN3[3] = {0.0, 0.0, 1.0};
// Add the data to the normals array
pointNormalsArray->SetTuple(0, pN1) ;
pointNormalsArray->SetTuple(1, pN2) ;
pointNormalsArray->SetTuple(2, pN3) ;
// Add the normals to the points in the polydata
polydata->GetPointData()->SetNormals(pointNormalsArray);
///////// Get Point Normals ///////////
vtkSmartPointer<vtkDoubleArray> pointNormalsRetrieved =
vtkDoubleArray::SafeDownCast(polydata->GetPointData()->GetNormals());
if(pointNormalsRetrieved)
{
std::cout << "There are " << pointNormalsRetrieved->GetNumberOfTuples()
<< " point normals." << std::endl;
for(vtkIdType i = 0; i < pointNormalsRetrieved->GetNumberOfTuples(); i++)
{
double pN[3];
pointNormalsRetrieved->GetTuple(i, pN);
std::cout << "Point normal " << i << ": "
<< pN[0] << " " << pN[1] << " " << pN[2] << std::endl;
}
}//end if(pointNormalsRetrieved)
else
{
std::cout << "No point normals." << std::endl;
}
return EXIT_SUCCESS;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
PROJECT(PolyDataPointNormals)
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
add_executable(PolyDataPointNormals MACOSX_BUNDLE PolyDataPointNormals.cxx)
target_link_libraries(PolyDataPointNormals ${VTK_LIBRARIES})
Download and Build PolyDataPointNormals
Click here to download PolyDataPointNormals and its CMakeLists.txt file. Once the tarball PolyDataPointNormals.tar has been downloaded and extracted,
cd PolyDataPointNormals/build
If VTK is installed:
cmake ..
If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..
Build the project:
make
and run it:
./PolyDataPointNormals
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.