[Sidefx-houdini-list] How to control RigidBody instances

Olivier Jeannel facialdeluxe at gmail.com
Wed Nov 29 15:16:08 EST 2017


I have a setup in vop to intrinsic transform. I can share it if you want to
have a look.

2017-11-29 16:25 GMT+01:00 Thomas Volkmann <listmail.3d at gmail.com>:

> Thanks Olivier, I think I stumbled upon that video during a former Houdini
> project. Definitely makes the SI to Houdini transition easier...
> But now to the latest problem....
> I want to replace the rigidbodies with some other object after the
> simulation.
> So I merge the sim-object, use "add" to delete the geo and just keep the
> points (very intuitive) and then I want to use a "copy to points" node.
> By default everything goes haywire, but when I disable "transform using
> point orientations" hte objects end up in the right positions but have a
> static rotation.
> I guess I have to get the intrinsic transforms and apply them to the point
> orientation (or similar) before the copy, but I really can't figure it out
> atm....
> Any ideas?
>
> On Wed, Nov 29, 2017 at 10:44 AM Olivier Jeannel <facialdeluxe at gmail.com>
> wrote:
>
> > If triggers for sims is you're thing, I enjoyed this tut :
> >
> > http://shortandsweet3d.blogspot.fr/2017/01/xsi-to-
> houdini-4-from-states-to-streams.html
> > If you're in pop or dop and want to play it like in ice State
> > Machine, Mikael Pettersén nailed it.
> >
> > 2017-11-29 10:35 GMT+01:00 Olivier Jeannel <facialdeluxe at gmail.com>:
> >
> > > You can use "Attribute Create" if you're in sop.
> > > Otherwise in Vop, "Bind Export".
> > > Checking with the Geometry Spreadsheet to insure every attributes are
> > > there, or hit "x" and click a node to create a temporary vizualizer.
> > >
> > > 2017-11-29 9:29 GMT+01:00 Thomas Volkmann <listmail.3d at gmail.com>:
> > >
> > >> Yep, I found merging and then referencing the input to be the most
> > >> straight
> > >> forward for me. I had the intention to do as much as I can in code,
> but
> > >> obviously my skills are still limited :)
> > >> But on another note:
> > >> Where would you store some global variables that should be referenced
> by
> > >> some other objects (eg. a frame number that should act as a trigger)?
> > >> Atm I just have an object that holds an attribute-wrangle which is
> > working
> > >> fine. Just curious on other approaches...
> > >> The Null-OUT workflow will be incorporated, thanks Michael!
> > >>
> > >> cheers,
> > >> Thomas
> > >>
> > >> On Tue, Nov 28, 2017 at 6:39 PM Ciaran Moloney <
> > moloney.ciaran at gmail.com>
> > >> wrote:
> > >>
> > >> > If you're working in a wrangle node, you could just reference the
> > input
> > >> > port and be done with it.
> > >> >
> > >> > On Tue, Nov 28, 2017 at 4:59 PM, Michael Dunkley <
> mdunkley at gmail.com>
> > >> > wrote:
> > >> >
> > >> > > Hey Thomas - the null thing i mentioned isn't required per se,
> just
> > >> > > best practice and a very common houdini pattern.  Basically the
> idea
> > >> > > is you usually want to reference paths from nulls, if appropriate,
> > so
> > >> > > that if your network graph changes (ie you add more relevant
> > >> > > operations after your wrangle), you don't have to change the
> > >> > > expression.  I guess the idea is that it makes your logic more
> > >> > > agnostic and less reliant on specific nodes.  My personal approach
> > is
> > >> > > to label the nulls in ways that describe the state of the network
> at
> > >> > > that point (eg OUT_sim).   Again, not strictly necessary, just a
> > >> > > little cleaner than referencing workhorse nodes, and also works
> > better
> > >> > > in cases where, for instance, you decide you want to cache the
> > output
> > >> > > of your dop network before referencing it.
> > >> > > For your case i think the network would look something like
> > >> > > dop_import->null, and you'd then reference that null.
> > >> > >
> > >> > > On Tue, Nov 28, 2017 at 11:14 AM, Thomas Volkmann <
> > >> listmail.3d at gmail.com
> > >> > >
> > >> > > wrote:
> > >> > > > Hi Michael, that works great! The shelf tools seem to do the
> > packing
> > >> > > > automatically (copy stamp node).
> > >> > > > What do you mean by pulling from a null sop?
> > >> > > > So far I can point directly to /DopNetwork or use a merge node
> to
> > >> get
> > >> > it
> > >> > > > inside my Geo where I connect it to the wrangle-node (was just
> > >> about to
> > >> > > > test Oliviers approach when your mail came in...thanks Olivier
> > I'll
> > >> > take
> > >> > > a
> > >> > > > look at that approach in due time).
> > >> > > > It's a lot of these 'best practices' that I'm not aware of
> atm....
> > >> > > >
> > >> > > > cheers,
> > >> > > > Thomas
> > >> > > >
> > >> > > > On Tue, Nov 28, 2017 at 4:32 PM Michael Dunkley <
> > mdunkley at gmail.com
> > >> >
> > >> > > wrote:
> > >> > > >
> > >> > > >> Hey Thomas.  So far as your expression goes - P is usually a
> > point
> > >> > > >> attribute, not a detail, the detail function doesn't require
> "op"
> > >> > > >> syntax, and usually doesn't return an array unless you're
> asking
> > >> for
> > >> > > >> an array attribute.
> > >> > > >> The expression you're looking for is probably more along the
> > lines
> > >> of:
> > >> > > >>
> > >> > > >> vector pos = point("/full_or_relative_path/to_node","P",3)
> > >> > > >>
> > >> > > >> where the path is just a normal houdini path, the attribute is
> > >> > > >> expressed as a string (as you had) and the 3 is simply the
> number
> > >> of
> > >> > > >> the rbd you're trying to access.  This is making the assumption
> > >> that
> > >> > > >> you're working with packed rbd's, so that the "point number"
> > you're
> > >> > > >> grabbing actually represents an entire packed piece.  Unpacked
> > >> rbd's
> > >> > > >> would be slightly trickier to grab.  Haven't watched that
> Entagma
> > >> vid,
> > >> > > >> so i don't know which you're actually working with.
> > >> > > >> It would also be good practice to pull from a (null) sop if
> > >> possible
> > >> > > >> (as opposed to dops directly - pulling directly from dops is
> > >> certainly
> > >> > > >> possible, though the syntax is a little screwier and generally
> > not
> > >> > > >> ideal).
> > >> > > >>
> > >> > > >>
> > >> > > >>
> > >> > > >> On Tue, Nov 28, 2017 at 9:05 AM, Olivier Jeannel <
> > >> > > facialdeluxe at gmail.com>
> > >> > > >> wrote:
> > >> > > >> > I personnaly go with vop.
> > >> > > >> > Having the points you're working with in the first port.
> > >> > > >> > And the points you're gathering infos from in the second
> port.
> > >> > > >> > You can either use a PcOpen + Pcfilter (P) if you want to get
> > >> the P
> > >> > > >> > according to the distance.
> > >> > > >> > Or use the Import Point (P) based on the id number.
> > >> > > >> >
> > >> > > >> > Or go the PrimUV route if you want to gather one attribute
> from
> > >> > > polygon
> > >> > > >> > location (same as UV to Location in ICE)
> > >> > > >> >
> > >> > > >> >
> > >> > > >> > 2017-11-28 13:46 GMT+01:00 Thomas Volkmann <
> > >> listmail.3d at gmail.com>:
> > >> > > >> >
> > >> > > >> >> A small follow-up:
> > >> > > >> >> How do I get the position of a certain RigidBody instance in
> > >> > another
> > >> > > >> >> objects pointwrangle?
> > >> > > >> >>
> > >> > > >> >> I'm trying:
> > >> > > >> >> vector pos[] = detail("op:/MyDOP/MyRBD_PackedObject", "P");
> > >> > > >> >>
> > >> > > >> >> Any hints?
> > >> > > >> >> Thanks,
> > >> > > >> >> Thomas
> > >> > > >> >>
> > >> > > >> >> On Mon, Nov 27, 2017 at 2:27 PM Thomas Volkmann <
> > >> > > listmail.3d at gmail.com>
> > >> > > >> >> wrote:
> > >> > > >> >>
> > >> > > >> >> > Excellent, Thanks!
> > >> > > >> >> >
> > >> > > >> >> >
> > >> > > >> >> > On Mon, Nov 27, 2017 at 1:29 PM Matt Estela <
> > >> > matt.estela at gmail.com
> > >> > > >
> > >> > > >> >> wrote:
> > >> > > >> >> >
> > >> > > >> >> >> Grow/shrinking is well covered by this entagma tutorial:
> > >> > > >> >> >>
> > >> > > >> >> >> http://www.entagma.com/scaling-the-bullets-dynamically/
> > >> > > >> >> >>
> > >> > > >> >> >>
> > >> > > >> >> >> On 27 November 2017 at 23:10, Thomas Volkmann <
> > >> > > listmail.3d at gmail.com
> > >> > > >> >
> > >> > > >> >> >> wrote:
> > >> > > >> >> >>
> > >> > > >> >> >> > Hi,
> > >> > > >> >> >> >
> > >> > > >> >> >> > I'm taking another dive into Houdini again and I'm
> > having a
> > >> > very
> > >> > > >> slow
> > >> > > >> >> >> start
> > >> > > >> >> >> > at the moment. It seems I have forgotten some of the
> > basic
> > >> > > >> stuff....
> > >> > > >> >> >> > So if someone could help me out and save me a couple of
> > >> hours
> > >> > it
> > >> > > >> would
> > >> > > >> >> >> be
> > >> > > >> >> >> > much appreciated.
> > >> > > >> >> >> >
> > >> > > >> >> >> > I have a simple RigidBody simulation from some
> instanced
> > >> > > objects.
> > >> > > >> >> >> > Now I would like to do some stuff with some of these,
> > like
> > >> > > select
> > >> > > >> by
> > >> > > >> >> ID
> > >> > > >> >> >> and
> > >> > > >> >> >> > then putting them to sleep at a certain frame or have
> > them
> > >> > > >> >> >> > growing/shrinking over time.
> > >> > > >> >> >> >
> > >> > > >> >> >> > Can I do that stuff all in the same place (some wrangle
> > >> node /
> > >> > > >> where?)
> > >> > > >> >> >> or
> > >> > > >> >> >> > does the scaling has to happen in a sop and the sleep
> in
> > >> the
> > >> > > dop?
> > >> > > >> >> >> > Damn, I really thought I was past that initial
> confusion
> > >> when
> > >> > > >> starting
> > >> > > >> >> >> with
> > >> > > >> >> >> > Houdini, but  a couple of months off seem to be a full
> > >> reset
> > >> > on
> > >> > > my
> > >> > > >> >> >> brain...
> > >> > > >> >> >> >
> > >> > > >> >> >> > Thanks,
> > >> > > >> >> >> > Thomas
> > >> > > >> >> >> > _______________________________________________
> > >> > > >> >> >> > 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
> > >> > > >> >> >>
> > >> > > >> >> >
> > >> > > >> >> _______________________________________________
> > >> > > >> >> 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
> > >> > > >> _______________________________________________
> > >> > > >> 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
> > >> > > _______________________________________________
> > >> > > 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
> > >> >
> > >> _______________________________________________
> > >> 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
> >
> _______________________________________________
> Sidefx-houdini-list mailing list
> Sidefx-houdini-list at sidefx.com
> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>


More information about the Sidefx-houdini-list mailing list