Re: [opendx-users] Creating a serie from many fields

[Chris Pelkie]

This trick works because Streakline, unlike all other DX modules, uses a special cache for prior results (it actually builds the Series object in this cache, on the fly). This cache can get corrupted, so you should do a Reset Server from time to time; however, once you've got the whole object created and cached, Sequencer will loop nicely and play back the growing streakline(s), so don't Reset unless you are having trouble.

I don't see anything for the first few iterations. Then, after that, the streakline starts to show up and grow longer. Not sure why, though it is possible that the field doesn't change much initially (it's not my data, I'm just the viz guy).

So the presumption is that you have a set of vector fields of the same shape and size stored in .dx files (not sure if this works with .general files, though I don't see why DX should care, once they are Imported and turned into DX fields with vector data). They are logically numbered, like:
'data.001.dx'
'data.002.dx'
etc.

Then, use Sequencer to generate the number series (1,2..), and send to Format ('/path/data.%03d.dx', sequencer_value) to generate each filename. Send this to Import. Send Import's output (should be the vector field) to Streakline 'data' input. You don't need to do anything else to Streakline.

You can provide a set of starting points to Streakline 'start': default is center of first vector field, so you only get one streakline that way (if the vector field doesn't do much at that position, you may not see the line growing). I'm using Grid with parameters (point=origin defined by a Vector interactor, structure="brick", shape={[20 0 0] [0 20 0] [0 0 5]}, density={3, 3, 3}). This gives me 27 starting points distributed in a 40x40x10 volume centered on origin. The output of Grid goes to Streakline 'start' input.

That's all it takes!

On Tuesday, Nov 9, 2004, at 08:46 America/New_York, Emmanuelle Lafont wrote:

I've tried to to send a field with 'series position' attribute, but it
doesn't work.
I didn't found any sample with this method, so I tried with a simple case
but I can't succeed.
Is there samples I didn't found?
Does the frame number must come from the output of the sequencer?

Moreover I don't really understand this method, because at each execution
of the Sequencer, the Streakline module has only one step time...

Could you help me more please?

_______________________________
Chris Pelkie
Scientific Visualization Producer
622 Rhodes Hall, Cornell Theory Center
Ithaca, NY 14853