[vtkusers] about vtkStreamer

[Amy Henderson]

Hi Petru,

vtkStreamTracer is the replacement for vtkStreamer.  See the following 
e-mail from Berk Geveci a few months ago: 
http://public.kitware.com/pipermail/vtkusers/2004-March/072433.html.

- Amy

At 08:27 AM 7/30/2004, Petru Pau wrote:
>I wonder if the people who implemented vtkStreamer are still with us...
>
>...Because I could use some advice.
>
>I needed to generate stream lines on the surfaces of some solid bodies. It is
>known that the initial algorithm allows the streamlines to escape from the 
>surface,
>if the vector field requires it.
>
>So I had to constrain the integration process to the surface of each cell.
>
>There were two problems to be solved:
>- using only the projection of the velocity vector;
>- shifting the integration process to next cell, when a cell boundary is met.
>
>I hacked in the code of vtkStreamer (it seemed to much bother to make a new
>set of classes - a set because it's not enough to modify only vtkStreamer),
>and added some code that works nicely in many cases.
>
>However...
>
>For some situations the algorithm never ends. It is hard to understand 
>why, especially
>considering that the infinite (well...) loop generates points that stay on 
>the same cell.
>
>For other situations the streamline escapes in space. I reckon this is due 
>to a bug.
>
>For other situations, the integration ends when the streamline touches a 
>cell boundary.
>
>Anyway, things work somehow satisfactory. Almost always. Unfortunately not 
>in the
>real situations; the solids for which I need this the integration process 
>generates
>millions of points on streamlines. As always, the exceptional situations 
>tend to be
>"general cases". I was able to detect a few, but not all - after all, I 
>had to guess
>the functionality of the code, in vtkStreamer.
>
>I attach to this message a relevant image. If I change the vectors, there 
>will be other
>lines that go over all three faces.
>
>Petru
>
>
>
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