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Zap thinking particles that are out of shot...

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I'd like to rig some Xpresso which makes sure that thinking particles which have been emitted from a PMatterWaves emitter that drift out of shot (no longer in camera view) are killed off immediately.

I've frequently thought this would be a super useful rig for a number of reasons, not least of which is keeping Alembic bakes (to open up motion blur and depth of field, which otherwise won't function correctly) to more reasonable size. I've a 6Gb cache at the moment that is mostly particles out of shot later in the timeline, and even using Krakatoa to render is dragging on...200 million particles being generated, for a few wispy pixels in the shot 🤣 (only 175,000 particles in the sim. I tell you, Krakatoa is a wonder to work with)

So, yeah.

How to kill off thinking particles in a sim when they are off screen from the active camera view?

Thanks a lot! I'll keep you posted with a few experiments if I get anywhere

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OK, thought:

Better to create a collider, and rig it so particles vanish on collision. Set the collider dimensions just out of shot.

I'll try that 🙂

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Easy peasy


PDeflector node with 'Event only' ticked and use the Boole output from that connected to the 'On' port of PDie.


Voila! A particle killer linked to invisible off-camera geometry in your scene!



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Posted (edited)

I like your thinking there, but I am not sure if merely hiding particles on collision truly kills / removes them from calculation, which I presume is the point of the exercise ? Not a TP expert myself, but just a basic thought that occurred...


Edit: Oh - I see you found a better way 🙂



Edited by Cerbera

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