Hello, <br><br>    I am fairly new to VTK and am going through the 
Visualizing Toolkit 4th edition text and am hitting a problem in one of 
the examples. When I go to make the pipeline to connect the data with 
the hedgehog function, I do not know what command to use. In the 
example, they use HedgeHog-&gt;SetInputData(SGrid), where HedgeHog and 
Grid are classes definded by the user, but HedgeHog does not have a 
member called SetInputData...I have check the doxygen page and in my 
vtkpython wrapping. Does anyone know how to connect this pipeline then? 
Here is the code I have written for it...the line of interest lies one 
paragraph after the end of the nested for loops. Please no laughing at my code, I am also new to C++ object oriented programming as well.<br>
<br>#include &quot;vtkPoints.h&quot;<br>#include &quot;vtkFloatArray.h&quot;<br>#include &quot;vtkMath.h&quot;<br>#include &quot;vtkPointData.h&quot;<br>#include &quot;vtkPolyDataMapper.h&quot;<br>#include &quot;vtkProperty.h&quot;<br>

#include &quot;vtkStructuredGrid.h&quot;<br>#include &quot;vtkHedgeHog.h&quot;<br>#include &quot;vtkCamera.h&quot;<br>#include &quot;vtkActor.h&quot;<br>#include &quot;vtkRenderer.h&quot;<br>#include &quot;vtkRenderWindowInteractor.h&quot;<br>

#include &quot;vtkRenderWindow.h&quot;<br>#include &quot;<div id=":fr">vtkInteractorStyleTrackballCamera.h&quot;<br><br>int main ()<br>{<br><br>  int i,j,k,kOffset,jOffset,offset;<br>  float x[3],v[3],rMin=0.5,rMax=1.0,deltaRad,deltaZ;<br>

  float radius, theta;<br>  static int dims[3]={13,11,11};<br><br>vtkStructuredGrid *grid = vtkStructuredGrid::New();<br> grid-&gt;SetDimensions(dims);<br><br>vtkPoints *points = vtkPoints::New();<br> points-&gt;Allocate(dims[0]*dims[1]*dims[2]);<br>

<br>vtkFloatArray *vector = vtkFloatArray::New();<br> vector-&gt;SetNumberOfComponents(3);<br> vector-&gt;SetNumberOfTuples(dims[0]*dims[1]*dims[2]);<br><br> deltaZ = 2.0 / (dims[2]-1);<br> deltaRad = (rMax-rMin) / (dims[1]-1);<br>

<br> v[2] = 0.0;<br><br> for (k=0; k&lt;dims[2]; k++)<br>   {<br>     x[2] = -1.0 + k * deltaZ;<br>     kOffset = k * dims[0] * dims[1];<br>     for (j=0; j&lt;dims[1]; j++)<br>       {<br>     radius= rMin + j * deltaRad;<br>

     jOffset= j * dims[0];<br>     for (i=0; i&lt;dims[0]; i++);<br>     {<br>       theta = i * vtkMath::DegreesFromRadians(15.0);<br>       x[0]=radius *cos( theta );<br>       x[1] = radius * sin( theta );<br>       v[0] = -x[1];<br>

       v[1] = x[0];<br>       offset=i + jOffset + kOffset;<br>       points-&gt;InsertPoint( offset,x );<br>       vector-&gt;InsertTuple( offset,v );<br>     }<br>       }<br>   }<br><br> grid-&gt;SetPoints(points);<br>

 grid-&gt;GetPointData()-&gt;SetVectors( vector );<br><br>vtkHedgeHog *hog = vtkHedgeHog::New();<br> hog-&gt;SetVectorMode( vector );<br> hog-&gt;SetScaleFactor( 0.1 );<br><br>vtkPolyDataMapper *mapper = vtkPolyDataMapper::New();<br>

 mapper-&gt;SetInputConnection( hog-&gt;GetOutputPort() );<br><br>vtkActor *actor = vtkActor::New();<br> actor-&gt;SetMapper( mapper );<br> actor-&gt;GetProperty()-&gt;SetColor( 0,0,0 );<br><br>vtkRenderer *ren = vtkRenderer::New();<br>

 ren-&gt;AddActor( actor );<br> ren-&gt;SetBackground( 0.1,0.2,0.4 );<br><br>vtkRenderWindow *renWin = vtkRenderWindow::New();<br> renWin-&gt;AddRenderer( ren );<br> renWin-&gt;SetSize( 500,500 );<br><br>vtkRenderWindowInteractor *wink = vtkRenderWindowInteractor::New();<br>

 wink-&gt;SetRenderWindow( renWin );<br><br>vtkInteractorStyleTrackballCamera *style = vtkInteractorStyleTrackballCamera::New();<br> wink-&gt;SetInteractorStyle( style );<br><br> wink-&gt;Initialize();<br> wink-&gt;Start();<br>

<br> style-&gt;Delete();<br> wink-&gt;Delete();<br> renWin-&gt;Delete();<br> ren-&gt;Delete();<br> actor-&gt;Delete();<br> mapper-&gt;Delete();<br> hog-&gt;Delete();<br> vector-&gt;Delete();<br> points-&gt;Delete();<br> grid-&gt;Delete();<br>

<br>return 0;<br>}<br><br><br>Thank you for your help and support,<br>Luke H</div>