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# FireFlowDemo

VTKEx/Cxx/VisualizationAlgorithms/FireFlowDemo

### Description

This example adds interaction to FireFlow.

The example uses vtkSliderWidget's to manipulate the center of the vtkPointSource that provides seed for the streamlines. As the X, Y, or Z center corrdiantes change, the streamlines are changed. The range of the x, y, and z coordinates are limited to the bounds of the solution dataset. There is a built in delay of 500 milliseconds to make the animation between selections consistent.

Here's the embedded video
showing the interactive movement of the seeding sphere.

Cite

The solution and geometry data is from the Mayavi project. Mayavi is a python application that provides an easy to use interface to many vtk filters. Both a command-line and GUI interface are provided. If you use the Mayavi data or the Mayavi application, please use the following citation in any published work: Ramachandran, P. and Varoquaux, G., `Mayavi: 3D Visualization of Scientific Data` IEEE Computing in Science & Engineering, 13 (2), pp. 40-51 (2011).

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

FireFlowDemo.cxx

    #include <vtkSmartPointer.h>
    #include <vtkVRMLImporter.h>
    #include <vtkXMLUnstructuredGridReader.h>
    #include <vtkContourFilter.h>
    #include <vtkStreamTracer.h>
    #include <vtkGenericOutlineFilter.h>
    #include <vtkPointSource.h>
    #include <vtkTubeFilter.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkSphereSource.h>

    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkInteractorStyleTrackballCamera.h>

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkProperty.h>
    #include <vtkProperty2D.h>
    #include <vtkPolyDataMapper.h>

    #include <vtkCommand.h>
    #include <vtkSliderWidget.h>
    #include <vtkSliderRepresentation2D.h>

    #include <vtkNamedColors.h>

    #include <array>
    #include <chrono>
    #include <thread>

    namespace
    {
    void MakeXWidget(vtkSmartPointer<vtkSliderWidget> &,
                     vtkSmartPointer<vtkPointSource> &,
                     vtkSmartPointer<vtkSphereSource> &,
                     vtkSmartPointer<vtkRenderer> &,
                     vtkSmartPointer<vtkRenderWindowInteractor> &);
    void MakeYWidget(vtkSmartPointer<vtkSliderWidget> &,
                     vtkSmartPointer<vtkPointSource> &,
                     vtkSmartPointer<vtkSphereSource> &,
                     vtkSmartPointer<vtkRenderer> &,
                     vtkSmartPointer<vtkRenderWindowInteractor> &);
    void MakeZWidget(vtkSmartPointer<vtkSliderWidget> &,
                     vtkSmartPointer<vtkPointSource> &,
                     vtkSmartPointer<vtkSphereSource> &,
                     vtkSmartPointer<vtkRenderer> &,
                     vtkSmartPointer<vtkRenderWindowInteractor> &);
    }

    int main (int argc, char *argv[])
    {
      auto colors =
        vtkSmartPointer<vtkNamedColors>::New();
      vtkColor3d isoSurfaceColor = colors->GetColor3d("WhiteSmoke");
      vtkColor3d sphereColor = colors->GetColor3d("hotpink");
      vtkColor3d backgroundColor = colors->GetColor3d("SlateGray");

      auto renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->UseHiddenLineRemovalOn();

      auto renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);

      auto renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Import the VRML Files that define the geometry
      auto vrmlImport =
        vtkSmartPointer<vtkVRMLImporter>::New();
      vrmlImport->SetRenderWindow(renderWindow);
      vrmlImport->SetFileName(argv[1]);
      vrmlImport->Update();

      // Read the UnstructuredGrid define the solution
      auto solution =
        vtkSmartPointer<vtkXMLUnstructuredGridReader>::New();
      solution->SetFileName(argv[2]);
      solution->Update();

      std::array<double,6> bounds;
      solution->GetOutput()->GetBounds(bounds.data());

      // Create an outline
      auto outline =
        vtkSmartPointer<vtkGenericOutlineFilter>::New();
      outline->SetInputConnection(solution->GetOutputPort());

      // Create Seeds
      auto seeds =
        vtkSmartPointer<vtkPointSource>::New();
      seeds->SetRadius(0.2);
      seeds->SetCenter(3.0, 1.6, 1.25);
      seeds->SetNumberOfPoints(50);

      // Create streamlines
      auto streamTracer =
        vtkSmartPointer<vtkStreamTracer>::New();
      streamTracer->SetIntegrationDirectionToBoth();
      streamTracer->SetInputConnection(solution->GetOutputPort());
      streamTracer->SetSourceConnection(seeds->GetOutputPort());
      streamTracer->SetMaximumPropagation(50);
      streamTracer->SetInitialIntegrationStep(.2);
      streamTracer->SetMinimumIntegrationStep(.01);
      streamTracer->SetIntegratorType(2);
      streamTracer->SetComputeVorticity(1);

      auto tubes =
        vtkSmartPointer<vtkTubeFilter>::New();
      tubes->SetInputConnection(streamTracer->GetOutputPort());
      tubes->SetNumberOfSides(8);
      tubes->SetRadius(.02);
      tubes->SetVaryRadius(0);

      auto mapTubes =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapTubes->SetInputConnection(tubes->GetOutputPort());
      mapTubes->SetScalarRange(solution->GetOutput()->GetScalarRange());

      auto tubesActor =
        vtkSmartPointer<vtkActor>::New();
      tubesActor->SetMapper(mapTubes);

      // Create an Isosurface
      auto isoSurface =
        vtkSmartPointer<vtkContourFilter>::New();
      isoSurface->SetValue(0, 500.0);
      isoSurface->SetInputConnection(solution->GetOutputPort());

      auto isoSurfaceMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      isoSurfaceMapper->SetInputConnection(isoSurface->GetOutputPort());
      isoSurfaceMapper->ScalarVisibilityOff();

      auto isoSurfaceActor =
        vtkSmartPointer<vtkActor>::New();
      isoSurfaceActor->SetMapper(isoSurfaceMapper);
      isoSurfaceActor->GetProperty()->SetOpacity(.5);
      isoSurfaceActor->GetProperty()->SetDiffuseColor(isoSurfaceColor.GetData());

      auto sphere =
        vtkSmartPointer<vtkSphereSource>::New();
      sphere->SetCenter(seeds->GetCenter());
      sphere->SetRadius(seeds->GetRadius());
      sphere->SetThetaResolution(20);
      sphere->SetPhiResolution(11);
      auto sphereMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      sphereMapper->SetInputConnection(sphere->GetOutputPort());

      auto sphereActor =
        vtkSmartPointer<vtkActor>::New();
      sphereActor->SetMapper(sphereMapper);
      sphereActor->GetProperty()->SetOpacity(1.0);
      sphereActor->GetProperty()->SetSpecular(.4);
      sphereActor->GetProperty()->SetSpecularPower(80);
      sphereActor->GetProperty()->SetDiffuseColor(sphereColor.GetData());

      renderer->AddActor(tubesActor);
      renderer->AddActor(sphereActor);
      renderer->AddActor(isoSurfaceActor);

      renderer->SetBackground(backgroundColor.GetData());
      renderWindow->SetSize(640, 512);
      renderWindow->Render();
      renderer->GetActiveCamera()->Azimuth(15.0);
      renderer->GetActiveCamera()->Elevation(15.0);
      renderer->GetActiveCamera()->Dolly(1.25);
      renderer->ResetCameraClippingRange();

      // Create widgets to manipuklate point source center
      auto xWidget =
        vtkSmartPointer<vtkSliderWidget>::New();
      MakeXWidget(xWidget, seeds, sphere, renderer, renderWindowInteractor);
      dynamic_cast<vtkSliderRepresentation2D*>(xWidget->GetRepresentation())->SetMinimumValue(bounds[0]);
      dynamic_cast<vtkSliderRepresentation2D*>(xWidget->GetRepresentation())->SetMaximumValue(bounds[1]);
      auto yWidget =
        vtkSmartPointer<vtkSliderWidget>::New();
      MakeYWidget(yWidget, seeds, sphere, renderer, renderWindowInteractor);
      dynamic_cast<vtkSliderRepresentation2D*>(yWidget->GetRepresentation())->SetMinimumValue(bounds[2]);
      dynamic_cast<vtkSliderRepresentation2D*>(yWidget->GetRepresentation())->SetMaximumValue(bounds[3]);
      auto zWidget =
        vtkSmartPointer<vtkSliderWidget>::New();
      MakeZWidget(zWidget, seeds, sphere, renderer, renderWindowInteractor);
      dynamic_cast<vtkSliderRepresentation2D*>(zWidget->GetRepresentation())->SetMinimumValue(bounds[4]);
      dynamic_cast<vtkSliderRepresentation2D*>(zWidget->GetRepresentation())->SetMaximumValue(bounds[5]);

      renderWindow->Render();
      auto style =
        vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
      renderWindowInteractor->SetInteractorStyle(style);

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

    namespace
    {
    #define DELAY 500
    // These callbacks do the actual work.
    // Callbacks for the interactions
    class SliderCallbackX : public vtkCommand
    {
    public:
      static SliderCallbackX *New()
      {
        return new SliderCallbackX;
      }
      virtual void Execute(vtkObject *caller, unsigned long, void*)
      {
        vtkSliderWidget *sliderWidget =
          reinterpret_cast<vtkSliderWidget*>(caller);
        double value = static_cast<vtkSliderRepresentation2D *>(sliderWidget->GetRepresentation())->GetValue();
        double center[3];
        this->PointSource->GetCenter(center);
        center[0] = value;
        this->PointSource->SetCenter(center);
        SphereSource->SetCenter(center);
        PointSource->Modified();
        PointSource->Update();
        std::this_thread::sleep_for(std::chrono::milliseconds(DELAY));
      }
      SliderCallbackX() = default;
      vtkPointSource *PointSource = nullptr;
      vtkSphereSource *SphereSource = nullptr;
    };

    void
    MakeXWidget(vtkSmartPointer<vtkSliderWidget> &widget,
                vtkSmartPointer<vtkPointSource> &pointSource,
                vtkSmartPointer<vtkSphereSource> &sphereSource,
                vtkSmartPointer<vtkRenderer> &renderer,
                vtkSmartPointer<vtkRenderWindowInteractor> &interactor)
    {
      // Setup a slider widget for each varying parameter
      double tubeWidth(.005);
      double sliderLength(.02);
      double titleHeight(.02);
      double labelHeight(.02);

      auto sliderRepX =
        vtkSmartPointer<vtkSliderRepresentation2D>::New();

      sliderRepX->SetRenderer(renderer);

      sliderRepX->SetMinimumValue(-1000.0);
      sliderRepX->SetMaximumValue( 1000);
      sliderRepX->SetValue(pointSource->GetCenter()[0]);
      sliderRepX->SetTitleText("X");
      sliderRepX->SetRenderer(renderer);
      sliderRepX->GetPoint1Coordinate()->SetValue(0.1, 0.1);
      sliderRepX->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedViewport();
      sliderRepX->GetPoint2Coordinate()->SetValue(0.3, 0.1);
      sliderRepX->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedViewport();

      sliderRepX->SetTubeWidth(tubeWidth);
      sliderRepX->SetSliderLength(sliderLength);
      sliderRepX->SetTitleHeight(titleHeight);
      sliderRepX->SetLabelHeight(labelHeight);
      sliderRepX->SetEndCapLength(tubeWidth*1.5);
      sliderRepX->SetSliderWidth(tubeWidth*1.5);
      sliderRepX->GetSliderProperty()->SetColor(0.0, 0.0, 0.0);
      sliderRepX->BuildRepresentation();

      widget->SetRepresentation(sliderRepX);
      widget->SetAnimationModeToAnimate();
      widget->SetNumberOfAnimationSteps(10);
      widget->SetInteractor(interactor);
      widget->EnabledOn();

      auto callbackX =
        vtkSmartPointer<SliderCallbackX>::New();
      callbackX->PointSource = pointSource;
      callbackX->SphereSource = sphereSource;
      widget->AddObserver(vtkCommand::InteractionEvent,callbackX);
    }

    class SliderCallbackY : public vtkCommand
    {
    public:
      static SliderCallbackY *New()
      {
        return new SliderCallbackY;
      }
      virtual void Execute(vtkObject *caller, unsigned long, void*)
      {
        vtkSliderWidget *sliderWidget =
          reinterpret_cast<vtkSliderWidget*>(caller);
        double value = static_cast<vtkSliderRepresentation2D *>(sliderWidget->GetRepresentation())->GetValue();
        double center[3];
        this->PointSource->GetCenter(center);
        center[1] = value;
        this->PointSource->SetCenter(center);
        this->SphereSource->SetCenter(center);
        PointSource->Modified();
        PointSource->Update();
        std::this_thread::sleep_for(std::chrono::milliseconds(DELAY));
      }
      SliderCallbackY() = default;
      vtkPointSource *PointSource = nullptr;
      vtkSphereSource *SphereSource = nullptr;
    };

    void
    MakeYWidget(vtkSmartPointer<vtkSliderWidget> &widget,
                vtkSmartPointer<vtkPointSource> &pointSource,
                vtkSmartPointer<vtkSphereSource> &sphereSource,
                vtkSmartPointer<vtkRenderer> &renderer,
                vtkSmartPointer<vtkRenderWindowInteractor> &interactor)
    {
      // Setup a slider widget for each varying parameter
      double tubeWidth(.005);
      double sliderLength(.02);
      double titleHeight(.02);
      double labelHeight(.02);

      auto sliderRepY =
        vtkSmartPointer<vtkSliderRepresentation2D>::New();

      sliderRepY->SetRenderer(renderer);

      sliderRepY->SetMinimumValue(-1000.0);
      sliderRepY->SetMaximumValue( 1000);
      sliderRepY->SetValue(pointSource->GetCenter()[1]);
      sliderRepY->SetTitleText("Y");
      sliderRepY->SetRenderer(renderer);
      sliderRepY->GetPoint1Coordinate()->SetValue(0.4, 0.1);
      sliderRepY->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedViewport();
      sliderRepY->GetPoint2Coordinate()->SetValue(0.6, 0.1);
      sliderRepY->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedViewport();

      sliderRepY->SetTubeWidth(tubeWidth);
      sliderRepY->SetSliderLength(sliderLength);
      sliderRepY->SetTitleHeight(titleHeight);
      sliderRepY->SetLabelHeight(labelHeight);
      sliderRepY->SetEndCapLength(tubeWidth*1.5);
      sliderRepY->SetSliderWidth(tubeWidth*1.5);
      sliderRepY->GetSliderProperty()->SetColor(0.0, 0.0, 0.0);
      sliderRepY->BuildRepresentation();

      widget->SetRepresentation(sliderRepY);
      widget->SetAnimationModeToAnimate();
      widget->SetNumberOfAnimationSteps(10);
      widget->SetInteractor(interactor);
      widget->EnabledOn();

      auto callbackY =
        vtkSmartPointer<SliderCallbackY>::New();
      callbackY->PointSource = pointSource;
      callbackY->SphereSource = sphereSource;

      widget->AddObserver(vtkCommand::InteractionEvent,callbackY);
    }

    class SliderCallbackZ : public vtkCommand
    {
    public:
      static SliderCallbackZ *New()
      {
        return new SliderCallbackZ;
      }
      virtual void Execute(vtkObject *caller, unsigned long, void*)
      {
        vtkSliderWidget *sliderWidget =
          reinterpret_cast<vtkSliderWidget*>(caller);
        double value = static_cast<vtkSliderRepresentation2D *>(sliderWidget->GetRepresentation())->GetValue();
        double center[3];
        this->PointSource->GetCenter(center);
        center[2] = value;
        this->PointSource->SetCenter(center);
        this->SphereSource->SetCenter(center);
        PointSource->Modified();
        PointSource->Update();
        std::this_thread::sleep_for(std::chrono::milliseconds(DELAY));
      }
      SliderCallbackZ() = default;
      vtkPointSource* PointSource = nullptr;
      vtkSphereSource* SphereSource = nullptr;
    };

    void
    MakeZWidget(vtkSmartPointer<vtkSliderWidget> &widget,
                vtkSmartPointer<vtkPointSource> &pointSource,
                vtkSmartPointer<vtkSphereSource> &sphereSource,
                vtkSmartPointer<vtkRenderer> &renderer,
                vtkSmartPointer<vtkRenderWindowInteractor> &interactor)
    {
      // Setup a slider widget for each varying parameter
      double tubeWidth(.005);
      double sliderLength(.02);
      double titleHeight(.02);
      double labelHeight(.02);

      auto sliderRepZ =
        vtkSmartPointer<vtkSliderRepresentation2D>::New();

      sliderRepZ->SetRenderer(renderer);

      sliderRepZ->SetMinimumValue(-1000.0);
      sliderRepZ->SetMaximumValue( 1000);
      sliderRepZ->SetValue(pointSource->GetCenter()[2]);
      sliderRepZ->SetTitleText("Z");
      sliderRepZ->SetRenderer(renderer);
      sliderRepZ->GetPoint1Coordinate()->SetValue(0.7, 0.1);
      sliderRepZ->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedViewport();
      sliderRepZ->GetPoint2Coordinate()->SetValue(0.9, 0.1);
      sliderRepZ->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedViewport();

      sliderRepZ->SetTubeWidth(tubeWidth);
      sliderRepZ->SetSliderLength(sliderLength);
      sliderRepZ->SetTitleHeight(titleHeight);
      sliderRepZ->SetLabelHeight(labelHeight);
      sliderRepZ->SetEndCapLength(tubeWidth*1.5);
      sliderRepZ->SetSliderWidth(tubeWidth*1.5);
      sliderRepZ->GetSliderProperty()->SetColor(0.0, 0.0, 0.0);
      sliderRepZ->BuildRepresentation();

      widget->SetRepresentation(sliderRepZ);
      widget->SetAnimationModeToAnimate();
      widget->SetNumberOfAnimationSteps(10);
      widget->SetInteractor(interactor);
      widget->EnabledOn();

      auto callbackZ =
        vtkSmartPointer<SliderCallbackZ>::New();
      callbackZ->PointSource = pointSource;
      callbackZ->SphereSource = sphereSource;

      widget->AddObserver(vtkCommand::InteractionEvent,callbackZ);
    }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(FireFlowDemo)

    find_package(VTK COMPONENTS
      vtkvtkCommonColor
      vtkvtkCommonCore
      vtkvtkCommonDataModel
      vtkvtkFiltersCore
      vtkvtkFiltersFlowPaths
      vtkvtkFiltersGeneric
      vtkvtkFiltersSources
      vtkvtkIOImport
      vtkvtkIOXML
      vtkvtkInteractionStyle
      vtkvtkInteractionWidgets
      vtkvtkRenderingContextOpenGL2
      vtkvtkRenderingCore
      vtkvtkRenderingFreeType
      vtkvtkRenderingGL2PSOpenGL2
      vtkvtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping FireFlowDemo: ${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(FireFlowDemo MACOSX_BUNDLE FireFlowDemo.cxx )
      target_link_libraries(FireFlowDemo PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(FireFlowDemo MACOSX_BUNDLE FireFlowDemo.cxx )
      target_link_libraries(FireFlowDemo PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS FireFlowDemo
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build FireFlowDemo

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

    cd FireFlowDemo/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:

    ./FireFlowDemo

WINDOWS USERS

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