Glyph3D normal to polygon

Development
1

I’m trying to make a glyph3D normal to a polygon. Maybe I’m misinterpreting the use of normals or my approach is wrong, but I can’t make the glyphs normal to the polygon. This is what I’m getting at the moment.

** EDIT** : I solved the orientation part (The updated code is below). I still looking for a way to show only on normal in the polygon center.

python_TmvepYu8ek
python_TmvepYu8ek933×638 15 KB

This is my function to generate the glyphs.

def create_glyph(actor):

    poly_data = actor.GetMapper().GetInput()
    normals = vtk.vtkPolyDataNormals()

    normals.SetInputData(poly_data)
    normals.ComputePointNormalsOff()
    normals.ComputeCellNormalsOn()
    normals.SplittingOff()
    normals.FlipNormalsOn()
    normals.ConsistencyOn()
    normals.AutoOrientNormalsOn()
    normals.Update()

    arrowSource = vtk.vtkArrowSource()

    glyph3D = vtk.vtkGlyph3D()
    glyph3D.SetSourceConnection(arrowSource.GetOutputPort())
    glyph3D.SetVectorModeToUseNormal()
    glyph3D.SetInputData(normals.GetOutput())
    glyph3D.SetScaleFactor(20)
    glyph3D.OrientOn()
    glyph3D.Update()

    mapper = vtk.vtkPolyDataMapper()
    mapper.SetInputConnection(glyph3D.GetOutputPort())

    actor = vtk.vtkActor()
    actor.SetMapper(mapper)
    actor.GetProperty().SetColor(colores.GetColor3d('Yellow'))

    return actor

I also wanted to ask if it is possible to just make a glyph in the middle of the polygon.

2

For normals at cell centers, you can try running the vtkCellCenters algorithm on your dataset. If you compute cell normals before running vtkCellCenters, the vertices placed at centers should have point normals.