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

Robert Kelly isstuff at gmail.com
Thu Dec 4 16:11:28 EST 2008


Here is my solution wrapped up in a VOP simply stick it inside a vopsop and
your off.  I anticipated that there would be more things to do with this
node so I kept it as a small building block but still easy to implement.

http://www.sidefx.com/index.php?option=com_wrapper&Itemid=135

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

> Vex tool could be cool for other stuff.
>
> The attrib transfer sop has some pretty blazingly fast octree code at
> it's heart though, and handles all the kernel stuff already - so you
> might find it's still faster. Lets us know how it goes!
>
> Cheers
>
>
> 2008/12/4 Robert Kelly <isstuff at gmail.com>:
> > 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
> >> >> >> Sidefx-houdini-list at sidefx.com
> >> >> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >> >>
> >> >> > _______________________________________________
> >> >> > 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
> >> >> Sidefx-houdini-list at sidefx.com
> >> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >> >>
> >> > _______________________________________________
> >> > 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
> >> Sidefx-houdini-list at sidefx.com
> >> 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
> =======================================
> _______________________________________________
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