[vtkusers] Streamlines vs. Lagrangian drifters

[Berk Geveci]

	A few remarks:

	1) A fundamental problem in generating particle paths is that
	vtk has no built-in time support. I am working on this. 

	2) vtkStreamer in vtk 3.1.2 uses 2nd order Runge-Kutta (not
	Euler). However, I changed it so that you can now pass
	an integrator object to it (derived from vtkInitialValueProblemSolver). 
	I also implemented a 4th order Runge-Kutta integrator. To be able to 
	use this functionality, you need to use a nightly built or wait 
	for vtk 3.2 (which I hope, will be out soon). I will, in time,
	implement a 5th order Runge-Kutta with 4th order step-size control.

	3) Although the underlying data object can't,
vtkInitialValueProblemSolver 
	can handle time. Therefore, it is a matter of adding that support
	to the data sets to make vtkStreamer capable of generating streaklines.

	I would appreciate feedback and suggestions on this.

	Berk

christopher moore wrote:
> 
> Those of us who do oceanography or fluid dynamics might benefit from a
> class like vtkStreamer that, instead of rendering streamlines, animates
> the path of a drifting particle.  Perhaps someone has done this already
> that might help us out?  I was hoping for something with an accurate
> time-stepping scheme - perhaps a Runge-Kutta (as opposed to simple
> forward-euler)?  I'm a hack of a developer, but if nobody else has done
> this I'll give it a try.  You'll have to promise not to laugh at my code,
> though....
>