# FitImplicitFunction

VTKExamples/Cxx/Points/FitImplicitFunction

### Description

Warning

The classes used in this example require vtk 7.1 or later.

### Code

FitImplicitFunction.cxx

    #include <vtkSmartPointer.h>
    #include <vtkFitImplicitFunction.h>
    #include <vtkBoundedPointSource.h>

    #include <vtkSphere.h>
    #include <vtkSphereSource.h>
    #include <vtkGlyph3D.h>
    #include <vtkMath.h>

    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkCamera.h>

    int main (int, char *[])
    {
      vtkMath::RandomSeed(4355412); // for test result consistency

      double radius = 1.0;
      vtkSmartPointer<vtkBoundedPointSource> points =
        vtkSmartPointer<vtkBoundedPointSource>::New();
      points->SetNumberOfPoints(1000000);
      points->SetBounds(-2.0, 2.0, -2.0, 2.0, -2.0, 2.0);

      vtkSmartPointer<vtkSphere> sphere =
        vtkSmartPointer<vtkSphere>::New();
      sphere->SetRadius(radius);

      vtkSmartPointer<vtkFitImplicitFunction> fit =
        vtkSmartPointer<vtkFitImplicitFunction>::New();
      fit->SetInputConnection(points->GetOutputPort());
      fit->SetImplicitFunction(sphere);
      fit->SetThreshold(.01);
      fit->Update();
      std::cout << fit->GetOutput()->GetNumberOfPoints() << " out of "
                << points->GetNumberOfPoints() << " points are within "
                << fit->GetThreshold() << " of the implicit function" << std::endl;

      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetRadius(radius * .05);

      vtkSmartPointer<vtkGlyph3D> glyph3D =
        vtkSmartPointer<vtkGlyph3D>::New();
      glyph3D->SetInputConnection(fit->GetOutputPort());
      glyph3D->SetSourceConnection(sphereSource->GetOutputPort());
      glyph3D->ScalingOff();
      glyph3D->Update();

      vtkSmartPointer<vtkPolyDataMapper> glyph3DMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      glyph3DMapper->SetInputConnection(glyph3D->GetOutputPort());

      vtkSmartPointer<vtkActor> glyph3DActor =
        vtkSmartPointer<vtkActor>::New();
      glyph3DActor->SetMapper(glyph3DMapper);
      glyph3DActor->GetProperty()->SetColor(0.8900, 0.8100, 0.3400);

      // Create graphics stuff
      //
      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();
      ren1->SetBackground(.3, .4, .6);

      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(ren1);
      renWin->SetSize(512,512);

      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);

      // Add the actors to the renderer, set the background and size
      //
      ren1->AddActor(glyph3DActor);

      // Generate an interesting view
      //
      ren1->ResetCamera();
      ren1->GetActiveCamera()->Azimuth(120);
      ren1->GetActiveCamera()->Elevation(30);
      ren1->GetActiveCamera()->Dolly(1.0);
      ren1->ResetCameraClippingRange();

      iren->Initialize();
      iren->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(FitImplicitFunction)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(FitImplicitFunction MACOSX_BUNDLE FitImplicitFunction.cxx )

    target_link_libraries(FitImplicitFunction ${VTK_LIBRARIES})

### Download and Build FitImplicitFunction

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

    cd FitImplicitFunction/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:

    ./FitImplicitFunction

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