PolyDataCellNormals
VTKExamples/Cxx/PolyData/PolyDataCellNormals
Description¶
This example shows how to add normals to vertices. This is identical to adding normals to any type of cells. The only difference from [Normals to/from a Polydata]]([Add/Get) is
are changed to
and
Code¶
PolyDataCellNormals.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 /////////// //Setup point coordinates double x[3] = {1.0, 0.0, 0.0}; double y[3] = {0.0, 0.0, 1.0}; double z[3] = {0.0, 0.0, 0.0}; //create 3 points and add a vertex at each point vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New(); vtkSmartPointer<vtkCellArray> vertices = vtkSmartPointer<vtkCellArray>::New(); for ( unsigned int i = 0; i < 3; ++i ) { //Declare a variable to store the index of the point that gets added. This behaves just like an unsigned int. vtkIdType pid[1]; //Add a point to the polydata and save its index, which we will use to create the vertex on that point. pid[0] = points->InsertNextPoint ( x[i], y[i], z[i] ); //create a vertex cell on the point that was just added. vertices->InsertNextCell ( 1,pid ); } //add the points and vertices to a polydata vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New(); polydata->SetPoints(points); polydata->SetVerts(vertices); //set vertex (cell) normals vtkSmartPointer<vtkDoubleArray> normalsArray = vtkSmartPointer<vtkDoubleArray>::New(); normalsArray->SetNumberOfComponents(3); //3d normals (ie x,y,z) normalsArray->SetNumberOfTuples(polydata->GetNumberOfPoints()); //construct the normal vectors double cN1[3] = {1.0, 0.0, 0.0}; double cN2[3] = {0.0, 1.0, 0.0}; double cN3[3] = {0.0, 0.0, 1.0}; //add the data to the normals array normalsArray->SetTuple(0, cN1) ; normalsArray->SetTuple(1, cN2) ; normalsArray->SetTuple(2, cN3) ; //add the normals to the cells in the polydata polydata->GetCellData()->SetNormals(normalsArray); ///////// Get cell normals /////////// vtkSmartPointer<vtkDoubleArray> cellNormalsRetrieved = vtkDoubleArray::SafeDownCast(polydata->GetCellData()->GetNormals()); if(cellNormalsRetrieved) { cout << "There are " << cellNormalsRetrieved->GetNumberOfTuples() << " cell normals." << endl; for(vtkIdType i = 0; i < cellNormalsRetrieved->GetNumberOfTuples(); i++) { double cN[3]; cellNormalsRetrieved->GetTuple(i, cN); cout << "Cell normal " << i << ": " << cN[0] << " " << cN[1] << " " << cN[2] << endl; } } else { cout << "No cell normals." << endl; } return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(PolyDataCellNormals) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(PolyDataCellNormals MACOSX_BUNDLE PolyDataCellNormals.cxx) target_link_libraries(PolyDataCellNormals ${VTK_LIBRARIES})
Download and Build PolyDataCellNormals¶
Danger
The generation of tar files has not been ported to the new VTKExamples. Some tarballs may be missing or out-of-date.
Click here to download PolyDataCellNormals and its CMakeLists.txt file. Once the tarball PolyDataCellNormals.tar has been downloaded and extracted,
cd PolyDataCellNormals/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:
./PolyDataCellNormals
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.