# PointInsideObject

VTKExamples/Cxx/PolyData/PointInsideObject

### Description

This example creates a cube at the origin with side 1. Then it checks if the points are inside the cube. There is one point inside, one in the border and one outside. The answer for the first one should be yes, and for the other two, no. Then render the cube and the points to see the result.

### Code

PointInsideObject.cxx

    #include <vtkPolyData.h>
    #include <vtkPointData.h>
    #include <vtkCubeSource.h>
    #include <vtkSmartPointer.h>
    #include <vtkSelectEnclosedPoints.h>
    #include <vtkIntArray.h>
    #include <vtkDataArray.h>
    #include <vtkVertexGlyphFilter.h>
    #include <vtkProperty.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkVertexGlyphFilter.h>

    int main(int, char *argv[])
    {
      //cube centered in origin, 1cm side.
      vtkSmartPointer<vtkCubeSource> cubeSource =
        vtkSmartPointer<vtkCubeSource>::New();
      cubeSource->Update();

      vtkPolyData* cube = cubeSource->GetOutput();

      double testInside[3] = {0.0, 0.0, 0.0};
      double testOutside[3] = {0.7, 0.0, 0.0};
      double testBorderOutside[3] = {0.5, 0.0, 0.0};
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(testInside);
      points->InsertNextPoint(testOutside);
      points->InsertNextPoint(testBorderOutside);

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

      //Points inside test
      vtkSmartPointer<vtkSelectEnclosedPoints> selectEnclosedPoints =
        vtkSmartPointer<vtkSelectEnclosedPoints>::New();
      selectEnclosedPoints->SetInputData(pointsPolydata);
      selectEnclosedPoints->SetSurfaceData(cube);
      selectEnclosedPoints->Update();

      for(unsigned int i = 0; i < 2; i++)
      {
        std::cout << "Point " << i << ": " << selectEnclosedPoints->IsInside(i) << std::endl;
      }

      vtkDataArray* insideArray =
        dynamic_cast<vtkDataArray*>(selectEnclosedPoints->GetOutput()->GetPointData()->GetArray("SelectedPoints"));

      for(vtkIdType i = 0; i < insideArray->GetNumberOfTuples(); i++)
      {
        std::cout << i << " : " << insideArray->GetComponent(i,0) << std::endl;
      }

      //RENDERING PART

      //Cube mapper, actor
      vtkSmartPointer<vtkPolyDataMapper> cubeMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      cubeMapper->SetInputConnection(cubeSource->GetOutputPort());

      vtkSmartPointer<vtkActor> cubeActor =
        vtkSmartPointer<vtkActor>::New();
      cubeActor->SetMapper(cubeMapper);
      cubeActor->GetProperty()->SetOpacity(0.5);

      //Points mapper, actor
      //First, apply vtkVertexGlyphFilter to make cells around points, vtk only render cells.
      vtkSmartPointer<vtkVertexGlyphFilter> vertexGlyphFilter =
      vtkSmartPointer<vtkVertexGlyphFilter>::New();
      vertexGlyphFilter->AddInputData(pointsPolydata);
      vertexGlyphFilter->Update();

     vtkSmartPointer<vtkPolyDataMapper> pointsMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      pointsMapper->SetInputConnection(vertexGlyphFilter->GetOutputPort());

      vtkSmartPointer<vtkActor> pointsActor =
        vtkSmartPointer<vtkActor>::New();
      pointsActor->SetMapper(pointsMapper);
      pointsActor->GetProperty()->SetPointSize(5);
      pointsActor->GetProperty()->SetColor(0.0,0.0,1);

      //Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Add the actor to the scene
      renderer->AddActor(cubeActor);
      renderer->AddActor(pointsActor);
      renderer->SetBackground(.0, 1,.0);

      // Render and interact
      renderWindow->SetWindowName(argv[0]);
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(PointInsideObject)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersGeneral
      vtkFiltersModeling
      vtkFiltersSources
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping PointInsideObject: ${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(PointInsideObject MACOSX_BUNDLE PointInsideObject.cxx )
      target_link_libraries(PointInsideObject PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(PointInsideObject MACOSX_BUNDLE PointInsideObject.cxx )
      target_link_libraries(PointInsideObject PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS PointInsideObject
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build PointInsideObject

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

    cd PointInsideObject/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:

    ./PointInsideObject

WINDOWS USERS

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