[vtkusers] Rotating about the normal in a point

[Van Gasse Kurt]

Hi !

I am having some problems calculating a specific normal of a point on the surface of an object. The goal is to rotate the object about the calculated normal. I have already calculated the normals in order to apply Gouraud-shading, but now I need a normal in a specific point.
Here’s a chunk of the code I wrote : 

  stlreader=vtkSTLReader::New();
  mapper=vtkPolyDataMapper::New();
  pNormals= vtkPolyDataNormals::New();
  motorActor=vtkActor::New();
  vtkNormals *norm=vtkNormals::New();

  stlreader->SetFileName("brol.stl");
  pNormals->SetInput(stlreader->GetOutput());
  mapper->SetInput(pNormals->GetOutput());
  motorActor->SetMapper(mapper);
  motorActor->SetProperty(brolProps);

  this->Props->AddItem(motorActor);

  int pointID;
  vtkDataSet *data;
  data=motorActor->GetMapper()->GetInput();
  pointID=data->FindPoint(78.9994, 73.6264, 197.831);

 float *normal;
 normal=norm->GetNormal(pointID);
 motorActor->RotateWXYZ(90,normal[0],normal[1],normal[2]);

The problem is : the program always return –1 as pointID for the specified point. I’m absolutely sure this point is on the surface of the object. 
Where did it go wrong ? Is there a better way to do this ?
Can you please help me out ?

Cheers,

Kurt