[Sidefx-houdini-list] POP Collision question

Alex Czetwertynski alex at franktheplumber.com
Mon Aug 16 18:03:35 EDT 2010


That is a great trick! thanks!

Alex

On Aug 16, 2010, at 2:32 PM, Louis Dunlevy wrote:

> 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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>>>>> 
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>>> 
>>> --
>>> =======================================
>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>>> =======================================
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>>> 
>> 
>> 
>> 
>> 
> 
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