View Full Version : empty Polygon Selection and generating TParticles

07 July 2012, 02:49 PM
quick xpresso quest.

I'm generating TParticles on a Polygon Selection. All fine.
Now, when my Polygon Selection is empty the following occurs :
instead of NOT generating any Particles, the Particles start emitting from Polygon 0.

So, the Particle Generator thinks : if Polygon Selection isNull, use Polygon with Index 0.

Since my Polygon Selection can change over time, based on Collision for example, I need a way to deal with this unwanted behavior.
An exception/ rule like : If Polygon Selection isNull = stop generating Particles.

This has puzzled me before in a number of variations, and maybe there's a common workaround that i'm too stupid to produce.
How do you deal with this ?


07 July 2012, 03:30 PM
I've just tried this out because I wanted to make sure X-Particles didn't do the same (it doesn't).

So then I tried TP and I can't duplicate the problem. If I have an empty selection tag, there are no particles emitted. This is using the TP surface emitter preset, BTW.

Are you sure that the selection is empty?


07 July 2012, 05:42 PM
Press Play and check out particle emission on Polygon 0 when there's no contact.

How would you guys deal with this ?

07 July 2012, 05:48 PM
I would use a Selection Node (Iterator Group)
and compare if the selection count is above zero
and then trigger the Emitter with that. :)

07 July 2012, 05:55 PM
yep. works just fine indeed.
thanks for making me feel stupid again, trying to make it a lot harder than it actually needs to be ;)


07 July 2012, 05:59 PM
No worries mate, I had the same problem a couple of times
and keyframed just the Emitter, your question motivated me
for a more elegant solution...

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07 July 2012, 05:59 PM
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