[Sidefx-houdini-list] Pop : Limit the number of particles

Larry Giunta larry at gcreativestudios.com
Fri Apr 15 08:39:19 EDT 2016


Thx Tim.

I got sidetracked from this task myself, but will give it a go when I jump back in.

Much appreciated.


> On Apr 4, 2016, at 10:23 AM, Timothy Stam <timothystam at hotmail.com> wrote:
> 
> Have you tried just bringing in one point without using a delete SOP or anything like that?
> I imagine you can use a point wrangle node and use VEX to do an addpoint(), then vary the location of that point based on a variable like @Frame?That way it will always be the same point, only the location of it in space changes. That way you would have one point and one stream.
> I'd test it out before suggesting but don't have time now so I'm just throwing it out there.
> -Timothy
> 
>> From: larry at gcreativestudios.com
>> Date: Fri, 25 Mar 2016 13:55:44 -0400
>> To: sidefx-houdini-list at sidefx.com
>> Subject: Re: [Sidefx-houdini-list] Pop : Limit the number of particles
>> 
>> ahhh … nice thought Olivier.
>> Much appreciated.
>> 
>> ok, I’ll give it a go.
>> 
>> 
>> 
>>> On Mar 25, 2016, at 1:42 PM, Olivier Jeannel <facialdeluxe at gmail.com> wrote:
>>> 
>>> Maybe I'm wrong, but for the falling leaves I'd have them all already birth
>>> at once and later give them some "falling" velocity selected by ptnum or
>>> with an attribute transfer.
>>> Le 25 mars 2016 17:25, "Larry Giunta" <larry at gcreativestudios.com> a écrit :
>>> 
>>>> This is really great Timothy,
>>>> 
>>>> Although I’m still trying to wrap my head around recreating some of the
>>>> functionality from old pops.
>>>> 
>>>> If I try this method to birth just 10 particles it works great.
>>>> However, if I have 10 points scattered on a tube, I tend to get 2
>>>> particles birthing from one point … and then none from others.
>>>> 
>>>> If I jump down to Steve’s suggestion I can set up a delete SOP so I can
>>>> feed one point at a time into the simulation.
>>>> Set emission type to “all points” and it does birth from each points in
>>>> order. Half the battle.
>>>> 
>>>> However, since that only leaves “Impulse Activation” available I have not
>>>> been able to have it birth just one particle per point.
>>>> It still wants to birth a stream at each point.
>>>> 
>>>> I’m need to explore Mike’s detail method further. The answer may lie there.
>>>> 
>>>> In my case I was trying to simulate a specific number of leaves falling
>>>> off a branch.
>>>> Slowly, one at a time. So it’s essential to birth only one particle per
>>>> point as they are introduced into the simulation.
>>>> 
>>>> Thanks,
>>>> Larry
>>>> 
>>>> 
>>>>> On Mar 20, 2016, at 4:22 PM, Timothy Stam <timothystam at hotmail.com>
>>>> wrote:
>>>>> 
>>>>> You're most welcome, glad I could help!
>>>>> 
>>>>>> Date: Sun, 20 Mar 2016 20:37:29 +0100
>>>>>> From: facialdeluxe at gmail.com
>>>>>> To: sidefx-houdini-list at sidefx.com
>>>>>> Subject: Re: [Sidefx-houdini-list] Pop : Limit the number of particles
>>>>>> 
>>>>>> Timothy it is working great !
>>>>>> The npoints just has to reference a Sop node after the Popnet.
>>>>>> If I reference the popnet itself it doesn't work.
>>>>>> if (npoints("/obj/geo1/popnet/") >= 167, 0, 1)
>>>>>> If I reference a Point Sop (point1) which comes after the Popnet it
>>>> works !
>>>>>> if (npoints("/obj/geo1/point1/") >= 167, 0, 1)
>>>>>> And I can compare 2 different sop nodes !
>>>>>> if (npoints("/obj/geo1/point1/") >= npoints("/obj/geo1/sphere1/"), 0, 1)
>>>>>> 
>>>>>> Exactly what I was looking for ! Thank you Thimothy !
>>>>>> 
>>>>>> On Sun, Mar 20, 2016 at 5:45 PM, Timothy Stam <timothystam at hotmail.com>
>>>>>> wrote:
>>>>>> 
>>>>>>> Hi Olivier,
>>>>>>> You can use the following expression in the Impulse Activation
>>>> parameter
>>>>>>> on the popsource node:
>>>>>>> if (npoints("/obj/grid/dopnet1/") >= 500, 0, 1)
>>>>>>> so, if the number of points in dopnet1 exceeds 500, parameter value is
>>>> 0,
>>>>>>> else it is 1.
>>>>>>> You have to reference a SOP node - I think - because in DOPs we use
>>>>>>> particles, not points, where npoints() looks for points.When
>>>> referencing
>>>>>>> any of the DOP nodes it won't work for me.
>>>>>>> This way it stops birthing as soon as I hit 500 particles.
>>>>>>> I hope this is what you were looking for.
>>>>>>> Cheers,
>>>>>>> Timothy Stam
>>>>>>> 
>>>>>>>> From: larry at gcreativestudios.com
>>>>>>>> Date: Sat, 19 Mar 2016 11:05:59 -0400
>>>>>>>> To: sidefx-houdini-list at sidefx.com
>>>>>>>> Subject: Re: [Sidefx-houdini-list] Pop : Limit the number of particles
>>>>>>>> 
>>>>>>>> Olivier,
>>>>>>>> 
>>>>>>>> It would be great if you can follow up on this if you do find a
>>>> suitable
>>>>>>> solution.
>>>>>>>> 
>>>>>>>> I was just trying to tackle this a few months ago for a potential
>>>>>>> project.
>>>>>>>> I never quite got it working exactly as I needed …. but the project
>>>>>>> never happened either.
>>>>>>>> So I just moved on.
>>>>>>>> 
>>>>>>>> But it’s something I’ve had on the list to revisit because it has come
>>>>>>> up a few times now.
>>>>>>>> 
>>>>>>>> Good luck!
>>>>>>>> 
>>>>>>>> Larry
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>>> On Mar 18, 2016, at 5:53 PM, Olivier Jeannel <facialdeluxe at gmail.com
>>>>> 
>>>>>>> wrote:
>>>>>>>>> 
>>>>>>>>> Hey Michael, thank you !
>>>>>>>>> I'll try your solution on monday (weird this is a Detail, I would
>>>> have
>>>>>>> say
>>>>>>>>> "Point" in the first thought)
>>>>>>>>> I was thinking maybe also trying to work with particle states, but
>>>> I'm
>>>>>>> not
>>>>>>>>> sure this (ice) feature exists in Houdini.
>>>>>>>>> 
>>>>>>>>> On Fri, Mar 18, 2016 at 10:40 PM, Michael Dunkley <
>>>> mdunkley at gmail.com>
>>>>>>>>> wrote:
>>>>>>>>> 
>>>>>>>>>> Hey Olivier, the pop source node automatically attaches a detail
>>>>>>>>>> attribute, called "nextid", to pop geometry that describes which
>>>>>>>>>> particle id is next in line to be used.  It's technically possible
>>>> to
>>>>>>>>>> reference this through expressions in your activation parameters.
>>>> So,
>>>>>>>>>> impulse activation could be (for instance):
>>>>>>>>>> 
>>>>>>>>>> detail("$DOPNET:popobject1/Geometry","nextid",0)<100
>>>>>>>>>> 
>>>>>>>>>> Note that you may have to change "popobject1" depending on what your
>>>>>>>>>> particle object is called.  popobject1 is the default name from the
>>>>>>>>>> shelf operations.
>>>>>>>>>> I suspect this is not a hundred percent solution, as that number
>>>> would
>>>>>>>>>> only be updated between cooks.  If you're emitting very slowly, then
>>>>>>>>>> probably everything would be fine.  But if you're emitting 10000
>>>>>>>>>> particles on frame one, it would birth all 10000 particles, then
>>>> stop
>>>>>>>>>> on the next frame (or substep) as "nextid" would then be 10001.
>>>> Might
>>>>>>>>>> work well for efficiency's sake in concert with Steven's delete
>>>>>>>>>> solution, so that you'd be both stopping emission and running
>>>> cleanup.
>>>>>>>>>> 
>>>>>>>>>> mike
>>>>>>>>>> 
>>>>>>>>>> On Fri, Mar 18, 2016 at 5:10 PM, steven ong <steve_nong at pointy.tv>
>>>>>>> wrote:
>>>>>>>>>>> Hi Olivier,
>>>>>>>>>>> 
>>>>>>>>>>> The POP Kill is deleting the particles.
>>>>>>>>>>> 
>>>>>>>>>>> If you're trying to emit particles one after another, you have to
>>>>>>> either
>>>>>>>>>>> delete the points one by one in SOPs and set Emission Type to All
>>>>>>> Points.
>>>>>>>>>>> 
>>>>>>>>>>> However, in the old POPnet, you can put down a grid as a source and
>>>>>>> in
>>>>>>>>>> the
>>>>>>>>>>> Source POP with Emission Type as "Points(ordered)", set Constant
>>>>>>>>>> Emission to
>>>>>>>>>>> $FPS so now you'll get a particle per frame in the sequence of the
>>>>>>> point
>>>>>>>>>>> number order of the grid.
>>>>>>>>>>> 
>>>>>>>>>>> This functionality is missing from the new Source POP in DOPs. :(
>>>>>>>>>>> 
>>>>>>>>>>> Cheers!
>>>>>>>>>>> steven
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> On 03/18/2016 13:55, Olivier Jeannel wrote:
>>>>>>>>>>>> 
>>>>>>>>>>>> Thank you François,
>>>>>>>>>>>> 
>>>>>>>>>>>> But then, in Pop, how do you do you have the particles to move one
>>>>>>> after
>>>>>>>>>>>> the other and not all at once ?
>>>>>>>>>>>> Thank you Steven,
>>>>>>>>>>>> It works very well ! But should I consider that it delete
>>>>>>> particles, or
>>>>>>>>>> is
>>>>>>>>>>>> the emission simply stopped ?
>>>>>>>>>>>> 
>>>>>>>>>>>> Thank's for your help :)
>>>>>>>>>>>> 
>>>>>>>>>>>> On Fri, Mar 18, 2016 at 9:47 PM, steven ong <steve_nong at pointy.tv
>>>>> 
>>>>>>>>>> wrote:
>>>>>>>>>>>> 
>>>>>>>>>>>>> Hi Olivier,
>>>>>>>>>>>>> 
>>>>>>>>>>>>> You can do this very easily with the old POPnet as there is a
>>>> "Max
>>>>>>> # of
>>>>>>>>>>>>> Particles" parameters. If you don't need the new POPnet
>>>>>>> functionality,
>>>>>>>>>>>>> you
>>>>>>>>>>>>> can consider use the old version.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> Else, in a Pop Kill, you can use the following expression under
>>>> the
>>>>>>>>>> Rule
>>>>>>>>>>>>> tab:
>>>>>>>>>>>>> 
>>>>>>>>>>>>> if(@id>999)
>>>>>>>>>>>>> dead=1;
>>>>>>>>>>>>> 
>>>>>>>>>>>>> That should limit the number of particles to 1000. Hope this
>>>> helps.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> Cheers!
>>>>>>>>>>>>> steven
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>>> On 03/18/2016 13:39, Olivier Jeannel wrote:
>>>>>>>>>>>>> 
>>>>>>>>>>>>>> Hi there,
>>>>>>>>>>>>>> A very simple noob question :
>>>>>>>>>>>>>> In  a Popnet, using a PopSource node, I'm using Impulse
>>>>>>> Activation and
>>>>>>>>>>>>>> Impulse Count.
>>>>>>>>>>>>>> I would like the emission to stop when a certain ptnum is
>>>> reached.
>>>>>>>>>>>>>> I tried in Impulse Activation the following expression :
>>>>>>>>>>>>>> if (@id >100, 0, 1)
>>>>>>>>>>>>>> But no luck.
>>>>>>>>>>>>>> I'm sure I've seen it somewhere inside one of the 300 tutorials
>>>>>>> I've
>>>>>>>>>>>>>> watched but I'm too dumb to find it :/
>>>>>>>>>>>>>> 
>>>>>>>>>>>>>> Can someone give me the correct expression ?
>>>>>>>>>>>>>> 
>>>>>>>>>>>>>> Thank you :)
>>>>>>>>>>>>>> _______________________________________________
>>>>>>>>>>>>>> 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
>>>> 
>>> _______________________________________________
>>> 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