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

[Tim Hutton]

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.

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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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