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Particular > Emit particles from edges of layer's alpha

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Dan Kirklin
Particular > Emit particles from edges of layer's alpha
on May 2, 2013 at 6:05:03 pm

Hey,

I have created a roto around my actor using the Rotobrush-Tool and I want to emit particles using Trapcode Particular from the edges of my roto.

I am unable to find a proper way to achieve this.

Many thanks for anyone that can help.


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John Cuevas
Re: Particular > Emit particles from edges of layer's alpha
on May 2, 2013 at 6:37:01 pm

Here's one method, take a copy of your roto'd layer and place it in a precomp. Duplicate the layer and a simple choker to it and adjust it to say 10 pixels(you can change this later). Now change the track matte of the bottom layer to alpha inverted. now you should have a thin outer border of your roto. Bring that into your final comp, create a particular layer and set it to emit from a layer and choose your roto/border layer as the emitter.

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.


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Dan Kirklin
Re: Particular > Emit particles from edges of layer's alpha
on May 4, 2013 at 10:41:53 am

Hey, thanks!

It seems to work rather well. However, some particles (Specifically Sprite-based) seem to show up for one frame and then disappear at certain points. With a high number of sprites emitting from the source, it makes everything "jumpy" instead of smooth, since a the particles appear and disappear without following their life parameter.


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Kyle Ronald
Re: Particular > Emit particles from edges of layer's alpha
on Sep 1, 2017 at 6:38:17 pm

Thought I'd post the answer to this in case anyone is experiencing this same problem in the future. You need to further adjust your settings in the "Layer Emitter" dropdown. Specifically you need to change "Layer Sampling" to "Particle Birth Time" and also change "Layer RGB Usage" to "RGB -XYZ Velocity".

This will make the particles stay true to their life parameter when using the layer emitter in particular and prevent them from disappearing when sourcing a layer that is moving.

Hope this helps!


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