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 3.12 FATAL_ERROR)

project(CellLocator)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "CellLocator: 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(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}
)

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.