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CellLocator

vtk-examples/Cxx/PolyData/CellLocator

Description

This example creates a sphere and then finds the closest point on the sphere to a test point.

Question

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

Code

CellLocator.cxx

#include <vtkCellLocator.h>
#include <vtkNew.h>
#include <vtkSphereSource.h>

int main(int, char*[])
{
  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->Update();

  // Create the tree
  vtkNew<vtkCellLocator> cellLocator;
  cellLocator->SetDataSet(sphereSource->GetOutput());
  cellLocator->BuildLocator();

  double testPoint[3] = {2.0, 0.0, 0.0};

  // Find the closest points to TestPoint
  double closestPoint[3];   // the coordinates of the closest point will be
                            // returned here
  double closestPointDist2; // the squared distance to the closest point will be
                            // returned here
  vtkIdType cellId; // the cell id of the cell containing the closest point will
                    // be returned here
  int subId;        // this is rarely used (in triangle strips only, I believe)
  cellLocator->FindClosestPoint(testPoint, closestPoint, cellId, subId,
                                closestPointDist2);

  std::cout << "Coordinates of closest point: " << closestPoint[0] << " "
            << closestPoint[1] << " " << closestPoint[2] << std::endl;
  std::cout << "Squared distance to closest point: " << closestPointDist2
            << std::endl;
  std::cout << "CellId: " << cellId << std::endl;

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(CellLocator)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping CellLocator: ${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(CellLocator MACOSX_BUNDLE CellLocator.cxx )
  target_link_libraries(CellLocator PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(CellLocator MACOSX_BUNDLE CellLocator.cxx )
  target_link_libraries(CellLocator PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS CellLocator
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build CellLocator

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

cd CellLocator/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:

./CellLocator

WINDOWS USERS

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