[Sidefx-houdini-list] transfer attributes from metaballs to geometry?

Robert Kelly isstuff at gmail.com
Thu Dec 4 12:59:14 EST 2008


not a bad idea. But i am inspired by the help document
/vex/functions/metaimport it has some vex code there that may be just what i
need and become a everyday tool.


from the help docs.......

The attributes evaluated are un-premultiplied by the weight of the metaball
at the position and must be multipled for blending. For example, to evaluate
a vector attribute (say color) on metaballs, the following function could be
used:

vector
meta_attribute(string file, attrib_name; vector P)
{
    int        handle;
    vector    result, tmp;
    float    density;

    handle = metastart(file, P);
    result = 0;
    while (metanext(handle))
    {
    if (metaimport(handle, "meta:density", P, density))
    {
        if (metaimport(handle, attrib_name, P, tmp))
        result += density * tmp;
    }
    }
    return result;
}




2008/12/4 Andrew D Lyons <tstexture at gmail.com>

> OK,
>
> Maybe get rid of metaballs and use their centre points with attrib
> transfer.
>
> If you transfer Cd, and Alpha as a radius/weight - then attribTransfer
> "Blend Width" should give you what you are after.
>
> Cheers
>
> 2008/12/4 Robert Kelly <isstuff at gmail.com>:
> > when you tick colours it shows the transform in a colour, probably good
> for
> > doing the difference between the deformed un deformed geometry in the
> > previous trick to find metta weight, but it isnt about transfeing Cd
> > atributes.
> >
> > 2008/12/4 Andrew D Lyons <tstexture at gmail.com>
> >
> >> Oh - I see what you are doing. The magnet SOP is what you want (as
> >> Brian Goodwin suggested). That does colors. Is it not working?
> >>
> >>
> >> 2008/12/4 Robert Kelly <isstuff at gmail.com>:
> >> > hmm attribute transfer only listens to the  attribute and the location
> of
> >> > the center of the metaball, not the weight of the metaball. to test it
> >> you
> >> > make a big strong red metaball and suround it with 4 small weak blue
> ones
> >> > and see what colour the grid listens to. rangi's trick that works on
> one
> >> > atribute is to get a magnet sop and move the geometry in the Y and
> mesure
> >> > the difrence between each points position and that will give you the
> >> > strength of the metaball at each points location. But this dosent get
> you
> >> > the colour.
> >> >
> >> >  Andrew D Lyons methoud works to an extent (the closest to it ) but
> not
> >> at
> >> > the heart of the metaball
> >> >
> >> > I think i will have look into a vex related answer. Unless there is
> some
> >> > more surgestions?
> >> >
> >> > Robert
> >> >
> >> > 2008/12/4 Andrew D Lyons <tstexture at gmail.com>
> >> >
> >> >> Hi,
> >> >>
> >> >> 1 convert-meta
> >> >> 2 attribute transfer SOP.
> >> >>
> >> >> Cheers
> >> >>
> >> >> 2008/12/4 Robert Kelly <isstuff at gmail.com>:
> >> >> > Am I missing something or is ther a simple way to... for example.
> >> >> >
> >> >> > You have a grid, some metaballs of different sizes and weights,
> each
> >> with
> >> >> a
> >> >> > different color in the Cd attribute. the mettaballs are
> intersecting
> >> the
> >> >> > grid. How can i transfer the Cd attribute onto the grid and have it
> >> >> transfer
> >> >> > as you would expect.
> >> >> >
> >> >> > Or do I need to get into writing a vex sop to do this?
> >> >> >
> >> >> > Robert.
> >> >> > _______________________________________________
> >> >> > Sidefx-houdini-list mailing list
> >> >> > Sidefx-houdini-list at sidefx.com
> >> >> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> =======================================
> >> >> Andrew D Lyons | Digital Artist | http://www.tstex.com
> >> >> =======================================
> >> >> _______________________________________________
> >> >> Sidefx-houdini-list mailing list
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> >> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >>
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> >> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >
> >>
> >>
> >>
> >> --
> >> =======================================
> >> Andrew D Lyons | Digital Artist | http://www.tstex.com
> >> =======================================
> >> _______________________________________________
> >> Sidefx-houdini-list mailing list
> >> Sidefx-houdini-list at sidefx.com
> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>
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> >
>
>
>
> --
> =======================================
> Andrew D Lyons | Digital Artist | http://www.tstex.com
> =======================================
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