[vtkusers] Re: Metaball Simulation

[Goodwin Lawlor]

Hi Randall,

Yeah - exactly. I'd have to look at it closer but an alternative would be a vtkMetaball subclass that just defines one function, then use vtkImplicitBoolean to sum up the functions- I'm not sure this would work... the potential functions maybe coupled,if so- it wont.

Goodwin
  ----- Original Message ----- 
  From: Randall Hand 
  To: Goodwin Lawlor 
  Cc: vtkusers at public.kitware.com 
  Sent: Thursday, January 26, 2006 7:55 PM
  Subject: Re: [vtkusers] Re: Metaball Simulation


  Clever.. so you mean I would derive a vtkMetaballs from vtkImplicitFunction that basically had 1 user function "AddMetaball(float position[3], float radius)".  Then all i'll need is to override the EvaluateFunction and EvaluateGradient to return the correct value, right? 

  wow.. That's nowhere near as complicated as I was expecting to have to do :)  Thanks!


  On 1/26/06, Goodwin Lawlor < goodwin.lawlor at ucd.ie> wrote:
    Randall Hand wrote:
    > I'm curious if there is any way in VTK to do a create a MetaBall-type 
    > dataset.  Example of metaballs can be found here:
    > http://www.corelmag.com/1103/overview/Metaball_Modeling.html
    > < http://www.corelmag.com/1103/overview/Metaball_Modeling.html>
    >
    > Basically I want to be able to define points in 3d-space along with a
    > Radius for each, and then have a vtkPolyData (or something like it) 
    > created from the results of the Metaball surface.  Is there any way to
    > do this in VTK?  I can get a rough approximation by using a vtkGlyph3d
    > and mapping a vtkSphereSource at each point, but that leaves 
    > intersecting geometry without the smooth features that come from a
    > Metaballs type algorithm.

    Hi Randall,

    This looks a job for a vtkImplicitFunction... maybe called vtkMetaballs.
    vtkMetaballs would define a centre, a radius, and a potential function 
    for each metaball you add to the system. Then, just sample it with
    vtkSampleFunction, and create the surface with a vtkContourFilter.

    Have a look at this paper: http://tinyurl.com/7fdox 

    hth

    Goodwin

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  -- 
  Randall Hand
  Visualization Scientist, 
  ERDC-MSRC Vicksburg, MS
  Homepage: http://www.yeraze.com 
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