A: How to display vertices only as simple 3D-points

[Bill Lorensen]

<x-flowed>It's not a hack. Vertex is a Cell in vtk. Points are coordinates. A Vertex 
has a single point to define its coordinate.

You could use vtkGlyph3D with your points as part of a PolyData. Try 
fly.cxx and change the Source to the Glyph to an instance of vtkPointSource 
with NumberOfPoints=1 and Radius=0. This is what vtkLODActor does to render 
points.

Bill


At 04:46 PM 8/18/99 +0100, Tim Hutton wrote:
>At 16:10 18/08/99 +0200, you wrote:
> >Greetings VTK-gurus!
> >
> >    I am _very_ new to vtk (-> version 2.0) and I would like to figure
> >out how to display a set of about 3000 3D-points just as simple
> >points... a la OpenGL GL_POINTS. All I managed to accomplish sofar, was
> >to alter the fly.cxx demo to display the points. But in this demo the
> >sample points are rendered as spheres. This is way to much geometrical
> >data rendered.
> >
> >    I read in the points with vtkPoints()->InsertNextPoint. But which
> >class do I have to use to make my vtkActor() render itself only as a set
> >of simple 3D-points?
> >
> >Thanks in advance for Your time and kind advice!
>
>I managed to do this as below, bit complicated though.
>
>First create a poly data structure and allocate some space for it:
>
>         vtkPolyData *poly = vtkPolyData::New();
>         poly->Allocate(MAX_POINTS);
>
>Then at the same time you add the point to the vtkPoints structure, add a
>vertex to the poly structure:
>
>                 count = points->InsertNextPoint((float*)vertex);
>                 poly->InsertNextCell(VTK_VERTEX,1,(int*)&count);
>
>Then do this:
>
>         poly->SetPoints(points);
>
>Then you can use a vtkPolyDataMapper to map to a vtkActor and you're away!
>
>The thing is, I'm sure there's a much easier way of doing this, it seems
>like an awful hack, no?. Somebody please tell me how to do this properly.
>
>Hope this helps you, good luck.
>
>Cheers,
>
>Tim.
>
>---------------------------------------------------------------------------
>Tim Hutton, Research Assistant            Email: T.Hutton at eastman.ucl.ac.uk
>MINORI Project                     http://www.eastman.ucl.ac.uk/~dmi/MINORI
>Dental and Medical Informatics                   Tel: [+44] (0171) 915 2344
>Eastman Dental Institute                         Fax: [+44] (0171) 915 2303
>256 Gray's Inn Road, London WC1X 8LD, UK
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