vtkStreamPoints weirdness?

[Gene Greger]

Hi Folks,

   I'm getting some (at least to me) odd behavior from the vtkStreamPoints
class and was wondering if anyone had some insights.  I create an instance
of the class and set the time step and propagation time:

   vtkStreamPoints *streampoints = vtkStreamPoints::New();
   streampoints->SetInput(plot3D_reader->GetOutput());
   streampoints->SetTimeIncrement(0.05);
   streampoints->SetMaximumPropagationTime(0.5);

Later on in the program, I set the start position, do an update,
and query the output:

   streampoints->SetStartPosition(position);
   streampoints->Update();

   vtkPolyData *dataset = streampoints->GetOutput();
   int num_points = dataset->GetNumberOfPoints();

    for (int p = 0; p < np; p++)
       dataset->GetPoint(p, point);

Based upon the values given for the time increment and maximum propagation
times, I would expect to get 10 stream point values.  However,  I get
anywhere from 10 to 31 points, depending on the start position.

Also, the first point generated by the vtkStreamPoints class is sometimes
exactly equivalent to the start position, and other times not.  I would 
expect this to be consistently one case or the other (for a non-zero velocity
of course.)

Any thoughts? 

			- Gene Greger

----------------------------
Gene Greger
RayTech Systems
gene at world.std.com
----------------------------


-----------------------------------------------------------------------------
This is the private VTK discussion list.  Please keep messages on-topic.
Check the FAQ at: <http://www.automatrix.com/cgi-bin/vtkfaq>
To UNSUBSCRIBE, send message body containing "unsubscribe vtkusers" to
<majordomo at gsao.med.ge.com>.  For help, send message body containing
"info vtkusers" to the same address.     Live long and prosper.
-----------------------------------------------------------------------------