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ClipUnstructuredGridWithPlane2

vtk-examples/Cxx/UnstructuredGrid/ClipUnstructuredGridWithPlane2


Description

The example uses vtkClipDataSet to clip a vtkUnstructuredGrid. The resulting output and clipped output are presented in yellow and red respectively. To illustrate the clipped interfaces, the example uses a vtkTransform to rotate each output about their centers.

Note that this clipping filter does not retain the original cells if they are not clipped.

After exiting, the example reports the number of each cell type for each output:

The inside dataset contains a
  [vtkUnstructuredGrid](https://www.vtk.org/doc/nightly/html/classvtkUnstructuredGrid.html#details) that has 110148 cells
        Cell type [vtkTetra](https://www.vtk.org/doc/nightly/html/classvtkTetra.html#details) occurs 106998 times.
        Cell type [vtkWedge](https://www.vtk.org/doc/nightly/html/classvtkWedge.html#details) occurs 3150 times.
The clipped dataset contains a
  [vtkUnstructuredGrid](https://www.vtk.org/doc/nightly/html/classvtkUnstructuredGrid.html#details) that has 111824 cells
        Cell type [vtkTetra](https://www.vtk.org/doc/nightly/html/classvtkTetra.html#details) occurs 107420 times.
        Cell type [vtkWedge](https://www.vtk.org/doc/nightly/html/classvtkWedge.html#details) occurs 4404 times.

Compare these results with ClipUnstructuredGridWithPlane (C++) ClipUnstructuredGridWithPlane (Python). Notice that in this example, the original vtkHexahedron in the unclipped regions are converted to vtkTetra. Also, the resulting vtkUnstructuredGrid's have more than 4 times the number of cells.

usage

ClipUnstructuredGridWithPlane2 treemesh.vtk

thanks

Thanks to Bane Sullivan for sharing the treemesh.vtk unstructured grid dataset.

Other languages

See (Python)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

ClipUnstructuredGridWithPlane2.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellTypes.h>
#include <vtkClipDataSet.h>
#include <vtkDataSetMapper.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPlane.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkTransform.h>
#include <vtkUnstructuredGrid.h>
#include <vtkUnstructuredGridReader.h>

#include <iostream>
#include <string>

int main(int argc, char* argv[])
{
  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " filename.vtk e.g. treemesh.vtk"
              << std::endl;
    return EXIT_FAILURE;
  }
  // Create the reader for the data.
  std::string filename = argv[1];
  std::cout << "Loading " << filename.c_str() << std::endl;
  vtkNew<vtkUnstructuredGridReader> reader;
  reader->SetFileName(filename.c_str());
  reader->Update();

  double bounds[6];
  reader->GetOutput()->GetBounds(bounds);
  double center[3];
  reader->GetOutput()->GetCenter(center);

  vtkNew<vtkNamedColors> colors;
  vtkNew<vtkRenderer> renderer;
  renderer->SetBackground(colors->GetColor3d("Wheat").GetData());
  renderer->UseHiddenLineRemovalOn();

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetSize(640, 480);

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);

  double xnorm[3] = {-1.0, -1.0, 1.0};

  vtkNew<vtkPlane> clipPlane;
  clipPlane->SetOrigin(reader->GetOutput()->GetCenter());
  clipPlane->SetNormal(xnorm);

  vtkNew<vtkClipDataSet> clipper;
  clipper->SetClipFunction(clipPlane);
  clipper->SetInputData(reader->GetOutput());
  clipper->SetValue(0.0);
  clipper->GenerateClippedOutputOn();
  clipper->Update();

  vtkNew<vtkDataSetMapper> insideMapper;
  insideMapper->SetInputData(clipper->GetOutput());
  insideMapper->ScalarVisibilityOff();

  vtkNew<vtkActor> insideActor;
  insideActor->SetMapper(insideMapper);
  insideActor->GetProperty()->SetDiffuseColor(
      colors->GetColor3d("banana").GetData());
  insideActor->GetProperty()->SetAmbient(.3);
  insideActor->GetProperty()->EdgeVisibilityOn();

  vtkNew<vtkDataSetMapper> clippedMapper;
  clippedMapper->SetInputData(clipper->GetClippedOutput());
  clippedMapper->ScalarVisibilityOff();

  vtkNew<vtkActor> clippedActor;
  clippedActor->SetMapper(clippedMapper);
  clippedActor->GetProperty()->SetDiffuseColor(
      colors->GetColor3d("tomato").GetData());
  insideActor->GetProperty()->SetAmbient(.3);
  clippedActor->GetProperty()->EdgeVisibilityOn();

  // Create transforms to make a better visualization
  vtkNew<vtkTransform> insideTransform;
  insideTransform->Translate(-(bounds[1] - bounds[0]) * .75, 0, 0);
  insideTransform->Translate(center[0], center[1], center[2]);
  insideTransform->RotateY(-120.0);
  insideTransform->Translate(-center[0], -center[1], -center[2]);
  insideActor->SetUserTransform(insideTransform);

  vtkNew<vtkTransform> clippedTransform;
  clippedTransform->Translate((bounds[1] - bounds[0]) * .75, 0, 0);
  clippedTransform->Translate(center[0], center[1], center[2]);
  clippedTransform->RotateY(60.0);
  clippedTransform->Translate(-center[0], -center[1], -center[2]);
  clippedActor->SetUserTransform(clippedTransform);

  renderer->AddViewProp(clippedActor);
  renderer->AddViewProp(insideActor);

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Dolly(1.4);
  renderer->ResetCameraClippingRange();
  renderWindow->Render();
  renderWindow->SetWindowName("ClipUnstructuredGridWithPlane2");
  renderWindow->Render();

  interactor->Start();

  // Generate a report
  vtkIdType numberOfCells = clipper->GetOutput()->GetNumberOfCells();
  std::cout << "------------------------" << std::endl;
  std::cout << "The inside dataset contains a " << std::endl
            << clipper->GetOutput()->GetClassName() << " that has "
            << numberOfCells << " cells" << std::endl;
  typedef std::map<int, int> CellContainer;
  CellContainer cellMap;
  for (vtkIdType i = 0; i < numberOfCells; i++)
  {
    cellMap[clipper->GetOutput()->GetCellType(i)]++;
  }

  for (auto c : cellMap)
  {
    std::cout << "\tCell type " << vtkCellTypes::GetClassNameFromTypeId(c.first)
              << " occurs " << c.second << " times." << std::endl;
  }

  numberOfCells = clipper->GetClippedOutput()->GetNumberOfCells();
  std::cout << "------------------------" << std::endl;
  std::cout << "The clipped dataset contains a " << std::endl
            << clipper->GetClippedOutput()->GetClassName() << " that has "
            << numberOfCells << " cells" << std::endl;
  typedef std::map<int, int> OutsideCellContainer;
  CellContainer outsideCellMap;
  for (vtkIdType i = 0; i < numberOfCells; i++)
  {
    outsideCellMap[clipper->GetClippedOutput()->GetCellType(i)]++;
  }

  for (auto c : outsideCellMap)
  {
    std::cout << "\tCell type " << vtkCellTypes::GetClassNameFromTypeId(c.first)
              << " occurs " << c.second << " times." << std::endl;
  }
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ClipUnstructuredGridWithPlane2)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  CommonTransforms
  FiltersGeneral
  IOLegacy
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ClipUnstructuredGridWithPlane2: 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(ClipUnstructuredGridWithPlane2 MACOSX_BUNDLE ClipUnstructuredGridWithPlane2.cxx )
  target_link_libraries(ClipUnstructuredGridWithPlane2 PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ClipUnstructuredGridWithPlane2
  MODULES ${VTK_LIBRARIES}
)

Download and Build ClipUnstructuredGridWithPlane2

Click here to download ClipUnstructuredGridWithPlane2 and its CMakeLists.txt file. Once the tarball ClipUnstructuredGridWithPlane2.tar has been downloaded and extracted,

cd ClipUnstructuredGridWithPlane2/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:

./ClipUnstructuredGridWithPlane2

WINDOWS USERS

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