[Sidefx-houdini-list] Best particle references

Ron Schab ron.schab at gmail.com
Sun Oct 30 09:49:14 EDT 2016


Hey mate,

sorry been fairly swamped.  Sending you a quick example *.hip seperately
again in a minute.

Just quickly here, yes P is your pointposition not ur scale.  If you want
to modify that, which of course u can, you probably want to add/multiply/or
whatever your noise to the current pointposition or displace along normals
if you have some.

The advantage of modifying your point attributes after you have done your
particle sim - depending on a few things like complexity of sim, sim frame
range, ... - is that you get pretty much much quicker feedback, where as
let's say you want to see the impact of a pscale change on frame 1345 u
will have to resim 1345 frames before u actually get to see it.

cheers
Ron




Ron Schab
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On Fri, Oct 28, 2016 at 5:51 PM, Gary Jaeger <gary at corestudio.com> wrote:

> Ha, I just realized I was modifying P (position) not pscale. Now just need
> to figure out how to modify pscale (and rotation, etc) inside of the
> pointvop. That’s probably what you were talking about with the bind export.
>
> Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
> http://corestudio.com <http://corestudio.com/>
> > On Oct 27, 2016, at 8:57 PM, Gary Jaeger <gary at corestudio.com> wrote:
> >
> > Thanks Ron. I think I get you. You mean drop a point vop in the
> “source_particles” after the instance node, correct? So the way I’m doing
> it is in the autodop dropping a pop instance after the merge, then in
> source particles I drop the point vop after the instance. Then I do all my
> fancy stuff inside the point vop itself?
> >
> > I think that’s what you mean, though I’ve gotten it to crash a few times
> by just connecting things to see what happens. That shouldn’t be. Also the
> math ops I was playing with seem to affecting the particles in a sort of
> world space, and not locally. For instance why wouldn’t multiplying P x
> Normalized Age cause the particle instances to grow in scale?
> >
> > I also notice that I can do things like pscale *= rand(@id); in the
> popinstance inside of the AutoDopNetwork. What's the advantage of using a
> pointvop over that?
> >
> > thanks much for the help
> >
> > Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
> > http://corestudio.com <http://corestudio.com/>
> >> On Oct 27, 2016, at 1:43 PM, Ron Schab <ron.schab at gmail.com <mailto:
> ron.schab at gmail.com>> wrote:
> >>
> >> Hey Gary,
> >>
> >> you can use the point vop instead now.  It should look very familar to
> what
> >> u've seen done in the old vop sops.
> >>
> >> Advantage setting scale and your other attributes in a point vop after
> you
> >> have done your pop sim being that u don't have to resim each time in
> order
> >> to see your changes.
> >>
> >> In there you can use particle age and/or life (or a normalized age by
> >> dividing age/live with a divide vop) to drive all kinds of attributes.
> >> The attribute you want to export from in there for your scale is pscale
> of
> >> course.  Best to use a bind export for that these days.
> >> You can also add all kinds of randomnessessessessess* via noises,
> patterns
> >> or what ever other function you want to use.
> >> Also you'll have your fit ranges, can set conditions, loops and so
> forth in
> >> there.
> >>
> >> U can add a displacement to current point positions in there as well as
> >> create all kinds of other attributes that u can then use in i.e.
> shaderland
> >> or wherever to drive whatever u need.
> >>
> >> hope that clarifies it a bit more
> >>
> >> cheers
> >> Ron
> >>
> >> Ron Schab
> >> -----------------------------------------------------------------------
> >>
> >> http://www.ronthedon.com <http://www.ronthedon.com/>
> >>
> >>
> >>
> >>
> >> On Thu, Oct 27, 2016 at 6:12 PM, Gary Jaeger <gary at corestudio.com
> <mailto:gary at corestudio.com>> wrote:
> >>
> >>> I’m digging into another project. Ye olde particle instances (cubes,
> >>> spheres, etc) flowing along a path with some randomness. The kind of
> thing
> >>> I can do in Maya and Mash pretty easily but seems like something I
> should
> >>> be able to tackle in houdini. I’ve figured out the emitter flowing
> along
> >>> paths, and finally figured out that I also needed to add a instance
> thing
> >>> underneath the import_location (why is that, btw?) because my
> popinstance
> >>> would show up in the scene but not render. That took a while.
> >>>
> >>> But the things I’m used to being able to bang out quickly - size over
> >>> life, controlled randomness in size and position, assigning random
> shaders,
> >>> etc etc - are all new. Any suggestions on where to go to get up to
> speed on
> >>> those workflows?
> >>>
> >>> One thing I have been finding is that it seems as if Houdini has
> changed
> >>> the way it does things over the years. So some older tutorials contain
> >>> references to things like vop sops that are gone.
> >>>
> >>> Anyway, any suggestions on things to ready and/or watch is appreciated.
> >>>
> >>> Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
> >>> http://corestudio.com <http://corestudio.com/> <http://corestudio.com/
> <http://corestudio.com/>>
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