BuildOctree

VTKExamples/Cxx/DataStructures/BuildOctree

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Question

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Code

BuildOctree.cxx

#include <vtkCellArray.h>
#include <vtkDataSetCollection.h>
#include <vtkIdList.h>
#include <vtkOctreePointLocator.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkSmartPointer.h>
#include <vtkXMLPolyDataReader.h>

int main(int, char*[])
{
  // Setup point coordinates
  double x[3]{1.0, 0.0, 0.0};
  double y[3]{0.0, 1.0, 0.0};
  double z[3]{0.0, 0.0, 1.0};

  auto points = vtkSmartPointer<vtkPoints>::New();
  // auto vertices =
  //  vtkSmartPointer<vtkCellArray>::New();

  for (unsigned int i = 0; i < 3; ++i)
  {
    points->InsertNextPoint(x[i], y[i], z[i]);
  }

  std::cout << "There are " << points->GetNumberOfPoints() << " points."
            << std::endl;

  auto polydata = vtkSmartPointer<vtkPolyData>::New();
  polydata->SetPoints(points);

  // Create the tree
  auto octree = vtkSmartPointer<vtkOctreePointLocator>::New();
  octree->SetDataSet(polydata);
  octree->BuildLocator();

  std::cout << "Number of points in tree: "
            << octree->GetDataSet()->GetNumberOfPoints() << std::endl;

  double p[3];
  octree->GetDataSet()->GetPoint(0, p);
  std::cout << "p: " << p[0] << " " << p[1] << " " << p[2] << std::endl;

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BuildOctree)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkIOXML QUIET)
if (NOT VTK_FOUND)
  message("Skipping BuildOctree: ${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(BuildOctree MACOSX_BUNDLE BuildOctree.cxx )
  target_link_libraries(BuildOctree PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(BuildOctree MACOSX_BUNDLE BuildOctree.cxx )
  target_link_libraries(BuildOctree PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS BuildOctree
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build BuildOctree

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

cd BuildOctree/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:

./BuildOctree

WINDOWS USERS

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