[vtkusers] How to set the normals for a surface ?

[Konstantinos Kelg]

OK. I found it !
I needed to set myself the normals for each vertex (I had the vertex normal data).
In the following code the "NormP" is a pointer to a float array that contains the normal vector coordinates :
{vertNorm1_x, vertNorm1_y, vertNorm1_z, vertNorm2_x, vertNorm2_y, vertNorm2_z, ...}

vtkFloatArray* arr = vtkFloatArray::New();
arr->SetNumberOfComponents(3);
arr->SetArray((float*)NormP, m_NumOfVertices, 0/*NormP will be deleted by VTK*/);
polyData->GetPointData()->SetNormals(arr);
arr->Delete();

I should call "GetPointData()->SetNormals(..)" to set the vertex normals. I guess the "GetCellData()->SetNormals(..)" sets the normals for each triangle (cell).
Reasonable enough...
Thanks.

--- Στις Πέμ., 02/04/09, ο/η 王君臣 <wangjunchen at gmail.com> έγραψε:

> Από: 王君臣 <wangjunchen at gmail.com>
> Θέμα: Re: [vtkusers] How to set the normals for a surface ?
> Προς: kkelgeor at yahoo.gr, "VTKUserMailLIst" <vtkusers at vtk.org>
> Ημερομηνία: Πέμπτη, 2 Απρίλιος 2009, 11:47
> 2009/4/2 Konstantinos Kelg <kkelgeor at yahoo.gr>
> 
> >
> > Hello,
> >
> >
> > I need to set the normals of a surface.
> > I have 1 normal for each vertex of the mesh.
> > I try this but I get a crash:
> >
> >
> > vtkFloatArray* arr = vtkFloatArray::New();
> > arr->SetNumberOfComponents(3);
> > arr->SetArray((float*)NormP, m_NumOfVertices, 0);
> > polyData->GetCellData()->SetNormals(arr);
> > arr->Delete();
> >
> >
> > I found this piece of code on the web but it's not
> complete:
> >
> > vtkPolyDataNormals *normals =
> vtkPolyDataNormals::New();
> > normals->SetInput(yourData); // Is
> "yourData" the normals per vertex ?
> 
>                                ~~~~~~~yourData is the
> polydata whose vertex
> normal is to be calculated, and the ouput of the
> vtkPolyDataNormals is the
> polydata that contains the normals, you can check the
> instance of the
> vtkPointData or vtkCellData to retrieve the normals
> 
> >
> > normals->ComputeCellNormalsOn();
> > normals->ComputePointNormalsOff();
> > normals->Update();
> >
> > Does anyone know which is the way to do this and how
> do I actually set the
> > vtkPolyDataNormals if I should follow the 2nd way ?
> >
> > Thanks.
> >
> >
> >
> >
> >
> >
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> -- 
> 王君臣


      
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