MiscPointData

Description¶

This demo attaches a vector (in this case a float vector of length 1) to each point in a polydata.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

MiscPointData.cxx

#include <vtkFloatArray.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkXMLPolyDataReader.h>

#include <iostream>
#include <string>

int main(int argc, char* argv[])
{
  // Parse command line arguments.
  if (argc != 2)
  {
    std::cout << "Required arguments: Filename e.g. cowHead.vtp" << std::endl;
    return EXIT_FAILURE;
  }

  // Get filename from command line.
  std::string filename = argv[1]; // First command line argument.

  // Read the file
  vtkNew<vtkXMLPolyDataReader> reader;
  std::cout << "Reading " << filename << std::endl;
  reader->SetFileName(filename.c_str());
  reader->Update();

  // Extract the polydata.
  auto polydata = reader->GetOutput();

  // Get the number of points in the polydata.
  vtkIdType idNumPointsInFile = polydata->GetNumberOfPoints();

  // Add distances to each point
  vtkNew<vtkFloatArray> distances;
  distances->SetNumberOfComponents(1);
  distances->SetName("Distances");

  vtkNew<vtkMinimalStandardRandomSequence> rng;
  rng->SetSeed(8775070);
  // rng->SetSeed(0);

  for (vtkIdType i = 0; i < idNumPointsInFile; i++)
  {
    distances->InsertNextValue(rng->GetRangeValue(0.0, 1.0));
    rng->Next();
  }

  polydata->GetPointData()->AddArray(distances);

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(MiscPointData)

find_package(VTK COMPONENTS 
  CommonCore
  CommonDataModel
  IOXML
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "MiscPointData: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(MiscPointData MACOSX_BUNDLE MiscPointData.cxx )
  target_link_libraries(MiscPointData PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS MiscPointData
  MODULES ${VTK_LIBRARIES}
)

Download and Build MiscPointData¶

Click here to download MiscPointData and its CMakeLists.txt file. Once the tarball MiscPointData.tar has been downloaded and extracted,

cd MiscPointData/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:

./MiscPointData

WINDOWS USERS

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