# 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.

Question

### 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();

vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();

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
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
target_link_libraries(TensorGlyph PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS TensorGlyph MODULES${VTK_LIBRARIES}
)
endif ()


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.