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Rudra

Random Start

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Hi! I'm trying to do random emission start time(look attachment). I try to randomize start time at popnet sop or at source pop. But nothing happens. The result is the same. Emission is begin at the same moment.

Thanks

starttime.hipnc

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Emission is begin at the same moment.

I think in this case it might be a good approach to sim one of your spheres (or a bunch of it with different settings) and write them as bgeo to disk.

You can use the copySOP to read the animated geo back in and copy it to the grid.

Georg

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Hi, rdg! Yes, this is a good approach, but I can't understand, why I cant' do this by stamp or attribute, which defined at sops!

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but I can't understand, why I cant' do this by stamp or attribute, which defined at sops!

POPs aren't that stamp-able as you might think.

I'd guess it's the way simulations work.

The POPnet would need to exist n-times and as it is not history-independent like SOPs the system cannot 'fast-forward or rewind' to a given state.

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but why I can't randomize start time or preroll time on each copy by modifying popnet sop attribute?

Edited by Rudra

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It's like RDG said "...it's the way simulations work". Particle sims are little more than cached geometry. And each POP Network is just a cache-- and you (sadly) can't copy stamp over a cache, it would overwrite itself.

An alternative solution would be to have several popnetworks, and use the opdigits() expression to change start time, preroll, seed, etc.

For example:

popnet0

--Preroll = opdigits('.')

popnet1

--Preroll = opdigits('.')

popnet2

--Preroll = opdigits('.')

You'd then have 3 popnetworks with prerolls being 0, 1, or 2 seconds. Simply copy and pasting one of your popnetworks would give you another sim with 3 seconds of preroll.

If you want random preroll for each sim, try: rand(opdigits('.'))

Long live opdigits()!

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Ok! That's cool stuff! And what about geometry-random velocity attribute?? That's not comfortable managing of lots of random attributes

Edited by Rudra

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