[Sidefx-houdini-list] POP Collision question

Louis Dunlevy louisdunlevy at gmail.com
Mon Aug 16 17:32:23 EDT 2010


The point sop can do lookups by attribute. So if you lock a frame of
your particle system and make the nasty particles red you can pipe that
into the second input of a point sop, toggle "Match by attribute" and
use "id" . Now you can put $CR2 in there to copy the colour of that
locked off frame onto your animated particles and delete them appropriately.

Hope that helps
L

Andrew D Lyons wrote:
> It's a CHOP based thing. The caveat is that it gets pretty heavy for
> big long particle objects. It can delete based on any condition you
> desire. We usually set up an attribute for that condition that uses an
> expression of some sort, and if that condition gets above zero - then
> bam. We usually use it to remove particles that come too near to an
> object - such as the camera or a character, but renegades of all
> varieties are fair game.
>
>
> On 16 August 2010 09:59, Alex Czetwertynski <alex at franktheplumber.com> wrote:
>   
>> That sounds interesting!  What condition are you looking for?  In Houdini's world, if the particle was supposed to collide will it allow you to tag a particle that didn't actually collide?  That would be amazing, a net for rebels.
>>
>> Alex
>> Sent via BlackBerry
>>
>> -----Original Message-----
>> From: Andrew D Lyons <tstexture at gmail.com>
>> Sender: <sidefx-houdini-list-bounces at sidefx.com>
>> Date: Mon, 16 Aug 2010 09:32:29
>> To: <sidefx-houdini-list at sidefx.com>
>> Reply-To: <sidefx-houdini-list at sidefx.com>
>> Subject: Re: [Sidefx-houdini-list] POP Collision question
>>
>> I have a SOP that cleans up this kind of thing. It basically deletes
>> particles that don't meet a certain conditionby ID across their entire
>> life span. It's like they never existed...
>>
>> On 15 August 2010 18:15, Robert Kelly <isstuff at gmail.com> wrote:
>>     
>>> Kill the Rebel element!
>>>
>>> Crush them under your mighty Boot!
>>>
>>> On 14 August 2010 00:21, Sebastian H. Schmidt
>>> <sebastian.h.schmidt at googlemail.com> wrote:
>>>       
>>>> Hi Alex,
>>>>
>>>> are your particles flying very fast ?
>>>> If so you could increase the oversampling on the pop-network but that slows
>>>> down the whole simulation.
>>>> Another thing what you could play with on the collision pop would be the
>>>> collision tolerance parameter.
>>>> That parameter defines 'Distance from geometry at which particle is
>>>> considered to have collided'
>>>>
>>>>
>>>> Seb
>>>>
>>>> On Sat, Aug 14, 2010 at 3:28 AM, Alex Czetwertynski <
>>>> alex at franktheplumber.com> wrote:
>>>>
>>>>         
>>>>> I have a set of particles emitted from a sphere going towards another
>>>>> sphere where they stick and slide along the surface.  The problem I'm having
>>>>> is a series of rogue particles flying away from the sphere even though the
>>>>> majority are properly sticking on it.
>>>>>
>>>>> I tried increasing the radial force in my Point SOP at Geo level, but that
>>>>> doesn't seem to help...
>>>>>
>>>>> Is there anything I can do in the Collision POP to avoid this?
>>>>>
>>>>> Thanks
>>>>> Alex
>>>>> _______________________________________________
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>>>>>
>>>>>           
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>>>       
>>
>> --
>> =======================================
>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>> =======================================
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>>     
>
>
>
>   




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