VelocityProfile

VTKExamples/Cxx/VisualizationAlgorithms/VelocityProfile


Description

This example shows shows warped planes in a structured grid dataset. The planes are warped according to flow momentum. The relative back and forward flow are clearly visible in the deformation of the planes.

Other Languages

See (Python)

Question

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Code

VelocityProfile.cxx

// Translated from velProf.tcl.

#include <vtkActor.h>
#include <vtkAppendPolyData.h>
#include <vtkCamera.h>
#include <vtkLookupTable.h>
#include <vtkMultiBlockDataSet.h>
#include <vtkMultiBlockPLOT3DReader.h>
#include <vtkNamedColors.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyDataNormals.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkStructuredGrid.h>
#include <vtkStructuredGridGeometryFilter.h>
#include <vtkStructuredGridOutlineFilter.h>
#include <vtkWarpVector.h>

#include <array>
#include <string>

int main(int argc, char* argv[])
{
//   auto Scale = [](std::vector<double>& v, double scale) {
//     std::transform(std::begin(v), std::end(v), std::begin(v),
//                    [=](double const& n) { return n / scale; });
//     return;
//   };

  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " filename1 filename2" << std::endl;
    std::cout << "where: filename1 is combxyz.bin and filename2 is combq.bin."
              << std::endl;
    std::cout << "Produces figure 6-14(b) Flow momentum from the VTK Textbook."
              << std::endl;
    return EXIT_FAILURE;
  }

  std::string fileName1 = argv[1];
  std::string fileName2 = argv[2];

  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  std::array<unsigned char , 4> bkg{{65, 99, 149}};
    colors->SetColor("BkgColor", bkg.data());

  // Read a vtk file
  //
  vtkSmartPointer<vtkMultiBlockPLOT3DReader> pl3d =
    vtkSmartPointer<vtkMultiBlockPLOT3DReader>::New();
  pl3d->SetXYZFileName(fileName1.c_str());
  pl3d->SetQFileName(fileName2.c_str());
  pl3d->SetScalarFunctionNumber(100); // Density
  pl3d->SetVectorFunctionNumber(202); // Momentum
  pl3d->Update();

  vtkStructuredGrid* pl3dOutput =
    dynamic_cast<vtkStructuredGrid*>(pl3d->GetOutput()->GetBlock(0));

  // What do we know about the data?
  // Get the extent of the data: imin,imax, jmin,jmax, kmin,kmax
  int extent[6] = {0, 0, 0, 0, 0, 0};
  pl3dOutput->GetExtent(extent);
  double scalarRange[2] = {0.0, 0.0};
  pl3dOutput->GetScalarRange(scalarRange);

  // Planes are specified using a imin,imax, jmin,jmax, kmin,kmax coordinate
  // specification. Min and max i,j,k values are clamped to 0 and maximum value.
  // See the variable named extent for the values.
  //
  vtkSmartPointer<vtkStructuredGridGeometryFilter> plane =
    vtkSmartPointer<vtkStructuredGridGeometryFilter>::New();
  plane->SetInputData(pl3dOutput);
  plane->SetExtent(10, 10, 1, extent[3], 1, extent[5]);

  vtkSmartPointer<vtkStructuredGridGeometryFilter> plane2 =
    vtkSmartPointer<vtkStructuredGridGeometryFilter>::New();
  plane2->SetInputData(pl3dOutput);
  plane2->SetExtent(30, 30, 1, extent[3], 1, extent[5]);

  vtkSmartPointer<vtkStructuredGridGeometryFilter> plane3 =
    vtkSmartPointer<vtkStructuredGridGeometryFilter>::New();
  plane3->SetInputData(pl3dOutput);
  plane3->SetExtent(45, 45, 1, extent[3], 1, extent[5]);

  // We use an append filter because that way we can do the warping, etc. just
  // using a single pipeline and actor.
  //
  vtkSmartPointer<vtkAppendPolyData> appendF =
    vtkSmartPointer<vtkAppendPolyData>::New();
  appendF->AddInputConnection(plane->GetOutputPort());
  appendF->AddInputConnection(plane2->GetOutputPort());
  appendF->AddInputConnection(plane3->GetOutputPort());

  // Warp
  vtkSmartPointer<vtkWarpVector> warp = vtkSmartPointer<vtkWarpVector>::New();
  warp->SetInputConnection(appendF->GetOutputPort());
  warp->SetScaleFactor(0.005);
  warp->Update();

  vtkSmartPointer<vtkPolyDataNormals> normals =
    vtkSmartPointer<vtkPolyDataNormals>::New();
  normals->SetInputData(warp->GetPolyDataOutput());
  normals->SetFeatureAngle(45);

  vtkSmartPointer<vtkPolyDataMapper> planeMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  planeMapper->SetInputConnection(normals->GetOutputPort());
  planeMapper->SetScalarRange(scalarRange);

  vtkSmartPointer<vtkActor> planeActor = vtkSmartPointer<vtkActor>::New();
  planeActor->SetMapper(planeMapper);

  // The outline provides context for the data and the planes.
  vtkSmartPointer<vtkStructuredGridOutlineFilter> outline =
    vtkSmartPointer<vtkStructuredGridOutlineFilter>::New();
  outline->SetInputData(pl3dOutput);

  vtkSmartPointer<vtkPolyDataMapper> outlineMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  outlineMapper->SetInputConnection(outline->GetOutputPort());

  vtkSmartPointer<vtkActor> outlineActor = vtkSmartPointer<vtkActor>::New();
  outlineActor->SetMapper(outlineMapper);
  outlineActor->GetProperty()->SetColor(colors->GetColor3d("Black").GetData());

  // Create the RenderWindow, Renderer and both Actors
  //
  vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renWin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renWin->AddRenderer(ren);

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

  // Add the actors to the renderer, set the background and size
  //
  ren->AddActor(planeActor);
  ren->AddActor(outlineActor);
  ren->SetBackground(colors->GetColor3d("BkgColor").GetData());
  renWin->SetSize(512, 512);

  iren->Initialize();

  renWin->Render();

  ren->GetActiveCamera()->SetPosition(19.8562, -31.8912, 47.0755);
  ren->GetActiveCamera()->SetFocalPoint(8.255, 0.147815, 29.7631);
  ren->GetActiveCamera()->SetViewUp(-0.0333325, 0.465756, 0.884285);
  ren->GetActiveCamera()->SetClippingRange(17.3078, 64.6375);
  renWin->Render();

  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(VelocityProfile)

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

Download and Build VelocityProfile

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

cd VelocityProfile/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:

./VelocityProfile

WINDOWS USERS

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