[Sidefx-houdini-list] particle fluid kill plane

Neil Dickson ndickson at sidefx.com
Fri Aug 12 13:44:36 EDT 2016


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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