# VTK/Examples/Cxx/Visualization/TensorGlyph

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.

## TensorGlyph.cxx

```#include <vtkVersion.h>

#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();
#if VTK_MAJOR_VERSION <= 5
tensorGlyph->SetInput(polyData);
#else
tensorGlyph->SetInputData(polyData);
#endif
tensorGlyph->SetSourceConnection(cubeSource->GetOutputPort());
tensorGlyph->ColorGlyphsOff();
tensorGlyph->ThreeGlyphsOff();
tensorGlyph->ExtractEigenvaluesOff();
tensorGlyph->Update();

vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
mapper->SetInput(tensorGlyph->GetOutput());
#else
mapper->SetInputData(tensorGlyph->GetOutput());
#endif

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;
}
```

# Please try the new VTKExamples website.

## CMakeLists.txt

```cmake_minimum_required(VERSION 2.8)

PROJECT(TensorGlyph)

find_package(VTK REQUIRED)
include(\${VTK_USE_FILE})

if(VTK_LIBRARIES)
else()
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 PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.