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

Olivier Jeannel facialdeluxe at gmail.com
Wed Nov 29 16:40:06 EST 2017


Here is the setup, I added some comments.
https://drive.google.com/open?id=1swFzpbJ34b4mT9cJxneFa6gZuDZZmx20

It shows 2 methods
1/ pointVOP creates classic P and Orient and then turn these into
IntrinsicTransform
2/ pure VOP Intrinsic

I often use these setups,  (once get used to) they are very similar to how
we animated stuff in ice.




2017-11-29 21:16 GMT+01:00 Olivier Jeannel <facialdeluxe at gmail.com>:

> 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/m
>> ailman/listinfo/sidefx-houdini
>> > >> -list
>> > >> > > >> >>
>> > >> > > >> > _______________________________________________
>> > >> > > >> > Sidefx-houdini-list mailing list
>> > >> > > >> > Sidefx-houdini-list at sidefx.com
>> > >> > > >> > https://lists.sidefx.com:443/m
>> ailman/listinfo/sidefx-houdini
>> > >> -list
>> > >> > > >> _______________________________________________
>> > >> > > >> Sidefx-houdini-list mailing list
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>> > >> > > >>
>> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>> > >> > > >>
>> > >> > > > _______________________________________________
>> > >> > > > Sidefx-houdini-list mailing list
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>> > >> > > > 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
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>> > >> >
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>> > >>
>> > >
>> > >
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