View Full Version : empty Polygon Selection and generating TParticles

07-24-2012, 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 ?


07-24-2012, 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?


07-24-2012, 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 ?

07-24-2012, 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. :)

07-24-2012, 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 ;)


07-24-2012, 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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