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TensorGlyph

vtk-examples/Cxx/Visualization/TensorGlyph


Description

This example demonstrates how to apply a rotation+scaling matrix to each point in a data set. We use a cube as the glyph so that simple rotations are easy to interpret. Specifically, we glyph one point with no rotation/scaling, and a second point with a rotation of 45 degrees around the x axis.

Question

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

Code

TensorGlyph.cxx

#include <vtkActor.h>
#include <vtkCellArray.h>
#include <vtkCubeSource.h>
#include <vtkDoubleArray.h>
#include <vtkMath.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPointSource.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkTensorGlyph.h>
#include <vtkVertexGlyphFilter.h>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Setup points
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(5.0, 0.0, 0.0);

  vtkNew<vtkPolyData> polyData;
  polyData->SetPoints(points);

  vtkNew<vtkDoubleArray> tensors;
  tensors->SetNumberOfTuples(2);
  tensors->SetNumberOfComponents(9);

  tensors->InsertTuple9(0, 1, 0, 0, 0, 1, 0, 0, 0, 1);
  tensors->InsertTuple9(1, 1, 0, 0, 0, 0.7, 0.7, 0, -0.7, 0.7); // column major

  polyData->GetPointData()->SetTensors(tensors);

  vtkNew<vtkCubeSource> cubeSource;
  cubeSource->Update();

  vtkNew<vtkTensorGlyph> tensorGlyph;
  tensorGlyph->SetInputData(polyData);
  tensorGlyph->SetSourceConnection(cubeSource->GetOutputPort());
  tensorGlyph->ColorGlyphsOff();
  tensorGlyph->ThreeGlyphsOff();
  tensorGlyph->ExtractEigenvaluesOff();
  tensorGlyph->Update();

  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputData(tensorGlyph->GetOutput());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("LightSalmon").GetData());

  vtkNew<vtkRenderer> renderer;
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("TensorGlyph");

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(TensorGlyph)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkFiltersGeneral
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping TensorGlyph: ${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(TensorGlyph MACOSX_BUNDLE TensorGlyph.cxx )
  target_link_libraries(TensorGlyph PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(TensorGlyph MACOSX_BUNDLE TensorGlyph.cxx )
  target_link_libraries(TensorGlyph PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS TensorGlyph
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build TensorGlyph

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

cd TensorGlyph/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:

./TensorGlyph

WINDOWS USERS

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