TensorGlyph

VTKExamples/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.

Code

TensorGlyph.cxx

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

int main(int, char *[])
{
    // Setup points
    vtkSmartPointer<vtkPoints> points =
      vtkSmartPointer<vtkPoints>::New();
    points->InsertNextPoint(0.0, 0.0, 0.0);
    points->InsertNextPoint(5.0, 0.0, 0.0);

    vtkSmartPointer<vtkPolyData> polyData = vtkSmartPointer<vtkPolyData>::New();
    polyData->SetPoints(points);

    vtkSmartPointer<vtkDoubleArray> tensors = vtkSmartPointer<vtkDoubleArray>::New();
    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,.7,.7,0,-.7,.7); // column major

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

    vtkSmartPointer<vtkCubeSource> cubeSource = vtkSmartPointer<vtkCubeSource>::New();
    cubeSource->Update();

    vtkSmartPointer<vtkTensorGlyph> tensorGlyph = vtkSmartPointer<vtkTensorGlyph>::New();
    tensorGlyph->SetInputData(polyData);
    tensorGlyph->SetSourceConnection(cubeSource->GetOutputPort());
    tensorGlyph->ColorGlyphsOff();
    tensorGlyph->ThreeGlyphsOff();
    tensorGlyph->ExtractEigenvaluesOff();
    tensorGlyph->Update();

    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputData(tensorGlyph->GetOutput());

    vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);

    vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
    renderer->AddActor(actor);

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

    vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
    interactor->SetRenderWindow( renderWindow );
    renderWindow->Render();
    interactor->Start();

    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(TensorGlyph)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkFiltersGeneral
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingCore
  vtkRenderingFreeType
  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.