[Sidefx-houdini-list] particle fluid kill plane

François Duchesneau sidefx at trinix.ca
Fri Aug 12 13:50:00 EDT 2016


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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