[vtkusers] about vtkStreamer

[Jeff Lee]

Hi Petru,
What you explain below seems correct - you need to intersect the 
streamline with the terminating boundary.  vtkStreamTracer actually 
keeps the last point (if the integration goes outside of the domain) so 
you can intersect the cell boundary with the line containing the last 
successful integration point and the "last-point" from the shoot of the 
integration.  Are you sure that your intersection was successful?
-Jeff

Petru Pau wrote:

> Hi Jeff,
>
> It seems that I forgot to mention the most important thing: Yes, thank
> you, I would very much appreciate your guidance.
>
> I modified the code of vtkStreamTracer, but it seems that the algorithm
> always stops when it reaches the border of the first cell. On that cell,
> constraining the stream line to the surface works OK.
>
> I added some code that computes one more point, by intersecting the 
> line generated
> by the last two computed points with the boundary of the cell. After 
> that, I switch the current
> cell of the vtkInterpolatedVelocityField to the adjacent cell and give 
> the control back
> to the original code. Now it seems that this last point, computed by 
> my code,
> is not detected as belonging to an adjacent cell, and the first call to
> vtkInterpolatedVelocityField's FunctionValues() returns 0.
>
> I intend to add the computation of one extra point, which should be
> in the interior of the adjacent cell (I reckon maybe the algorithm 
> stops because
> VTK does not really like points on edges), and only afterwards pass 
> the control
> back to original code. I am not really satisfied with this, but I 
> don't know what else
> to do to persuade the vtkInterpolatedVelocityField that the point on 
> the edge
> belongs to the cell.
>
> Most probably there is a simpler way to do things: if so, I would be 
> very grateful
> for any help.
>
> Petru
>
>
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-- 
Jeff Lee
Senior Software Engineer
Computational Dynamics North America Ltd
21 Lafayette Street, Suite 230
Lebanon NH 03766 USA
fax:   603 643 9994
phone: 603 643 9993 x109
http://www.cd-adapco.com