[vtkusers] Re: Streamlines from a FloatArray

[ursula.goette at philips.com]

Hi Tom,

>oh, now that I think about it those are just the strength of the vector
>field at a point, and perhaps you are asking how VTK is to know WHICH
>point to associate that strength with?
Correct - I think vtk needs to know where the vector is in space, otherwise
it cannot integrate anything in the flow field.

So, I guess it might be useful if you also fill in the Points of the vtkPolyData
and not only the Data of the Points.

Regards,
Ursula



                                                                                                                       
                                                                                                                       
                                                   To:   Ursula Goette/BST/MS/PHILIPS at EMEA2                            
                                                   cc:   vtkusers at vtk.org                                              
                                                   Subject:    Re: [vtkusers] Re: Streamlines from a FloatArray        
                                                                                                                       
               tom fogal                           Classification:                                                     
               <tfogal at apollo.sr.unh.ed                                                                                
               u>                                                                                                      
                                                                                                                       
               Sent by:                                                                                                
               tfogal at apollo.sr.unh.edu                                                                                
                                                                                                                       
               07/07/2004 05:04 PM                                                                                     
                                                                                                                       
                                                                                                                       




<OFBED18E15.1239F85E-ONC1256ECA.001C98F2-C1256ECA.001D805F at diamond.philips.com
> ursula.goette at philips.com writes:
> 1. do you also have a spacing for the vector field (points?)

spacing? I'm not sure I follow you -- are you asking if I have a
rigid format to the field, as in one reading every 2 'x units', etc ?
The floatarray is setup to have groups of 3 tuples like:

x0, y0, z0, x1, y1, z1, x2, y2, z2, ...

oh, now that I think about it those are just the strength of the vector
field at a point, and perhaps you are asking how VTK is to know WHICH
point to associate that strength with?

> 2. do you give the stream line (a) source point(s) to start from?

yes. I've tried the origin and some points around there when I noticed
that in vtkStreamer::Integrate() it would end up multiplying by the
start location =)

> 3. do you set all the other things necessary to create the stream line?
>
> Why don't you check out the example file officeTube.tcl. There you
> can see how to use the filter.

I believe I set everything correctly. I pretty much copied the relevant
sections from the officeTube.tcl and then changed the input to come
from my floatarray -> points -> polydata chain.

Thanks for your help!

-tom