PolyDataPointNormals

VTKExamples/Cxx/PolyData/PolyDataPointNormals

Description¶

This demo adds a normal to each point in a polydata.

Question

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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 =
dynamic_cast<vtkDoubleArray*>(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 3.3 FATAL_ERROR)

project(PolyDataPointNormals)

find_package(VTK COMPONENTS
vtkCommonCore
vtkCommonDataModel QUIET)
if (NOT VTK_FOUND)
message("Skipping PolyDataPointNormals: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(PolyDataPointNormals MACOSX_BUNDLE PolyDataPointNormals.cxx ) target_link_libraries(PolyDataPointNormals PRIVATE${VTK_LIBRARIES})
else ()
# include all components
add_executable(PolyDataPointNormals MACOSX_BUNDLE PolyDataPointNormals.cxx )
target_link_libraries(PolyDataPointNormals PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS PolyDataPointNormals MODULES${VTK_LIBRARIES}
)
endif ()


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

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.