[Sidefx-houdini-list] particle fluid kill plane

Alvaro Castaneda varomix at gmail.com
Fri Aug 12 15:25:31 EDT 2016


The POP kill DOP even has a prebuilt expression there for that

// Kill by Condition
dead = (@P.y > 1) ? 1 : 0;

just edit that to
dead = (@P.y < 0) ? 1 : 0;

and they should die during simulation

On Fri, Aug 12, 2016 at 11:56 AM, Jason Johnston <jasonj at pixar.com> wrote:

> I believe all you need to do is put down a pop kill dop and put in this
> code:
>
> if (v at P.y < -4) removepoint(geoself(), @ptnum);
>
>
> -Jason
>
>
> On 08/12/2016 10:50 AM, François Duchesneau wrote:
>
>> I think he's talking about killing particles during the sim inside Dop.
>> This would work only when using a Sop Solver within the simulation.
>>
>> That brings a question. I think at some point there was an overhead when
>> using sop nodes on a simulation through a Sop Solver because the geometry
>> had to be copied again or something like that. Anyone knows if it's still
>> the case? In order words, is using a sop solver on the points of a heavy
>> particle sim slows down the computation apart from the nodes used inside
>> the sop solver of course?
>>
>> Thanks
>>
>> François
>>
>> On 08/12/2016 01:44 PM, Neil Dickson wrote:
>>
>>> The Clip SOP also works on points, so you can just use that if you don't
>>> want to fuss around with VEX or expressions. You can just set the direction
>>> and position with the viewport handles or the parameter pane if you want
>>> them to be exact.
>>>
>>> Cheers,
>>> Neil
>>>
>>> On 12/08/2016 1:14 PM, Mark Elendt wrote:
>>>
>>>> If you have the plane normal, (A, B, C), you can define an equation
>>>> for the plane:
>>>>      A*x + B*y + C*z + D
>>>> where D moves the plane up and down along the normal (from the
>>>> origin).
>>>>
>>>> If you take a point (x,y,z) and plug it into the equation, positive
>>>> values mean the point is above the plane, negative values below.
>>>>
>>>> So, in VEX:
>>>>
>>>>      cvex
>>>>      partitionplane(vector N; float D)
>>>>      {
>>>>     float dist = dot(@P, normalize(N)) + D;
>>>>
>>>>     if (dist > 0)
>>>>         addgroup("dist", @ptnum);
>>>>     else if (dist == 0)
>>>>         addgroup("onplane", @ptnum);
>>>>     else
>>>>         addgroup("below", @ptnum);
>>>>      }
>>>>
>>>>      On Friday Aug 12 at 10:03, Gary Jaeger wrote:
>>>>
>>>>> no that would work. A kill plane is just that. A plane that kills the
>>>>> particles. It can be at any arbitrary angle but generally I use them to
>>>>> kill particles in the Y.
>>>>>
>>>>> I’ll see if I can figure that out :)
>>>>>
>>>>> Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
>>>>> http://corestudio.com <http://corestudio.com/>
>>>>>
>>>>>> On Aug 12, 2016, at 9:53 AM, François Duchesneau <sidefx at trinix.ca>
>>>>>> wrote:
>>>>>>
>>>>>> I've never used Bifrost. What is the kill plane?
>>>>>>
>>>>>> If you're referring to a way of kill particles below a certain value
>>>>>> in Y for example you could use an expression in the Kill Pop but I suspect
>>>>>> what you're after is more sophisticated.
>>>>>>
>>>>>> Francois
>>>>>>
>>>>>> On 08/12/2016 12:35 PM, Gary Jaeger wrote:
>>>>>>
>>>>>>> Noob question. Is there an equivalent to the bifrost kill plane for
>>>>>>> particle fluids?
>>>>>>>
>>>>>>> Gary Jaeger / 650.728.7957 direct / 415.518.1419 mobile
>>>>>>> http://corestudio.com <http://corestudio.com/>
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