Trying to export Birth Number (or ID ?) attributes

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Hi !

I'm currently exporting some scattered sim to get some sim (such as explosions) but with particles. For an example, I make a smoke sim with a sphere and a billowy smoke, and in the pyro_import node, below the DOP Import, I lay down a scatter node and a ROP Output Driver node.
Thanks to this, I can export some scattered sim with their attribute (such as temperature, velocity etc.).

The problem is, I'm trying to have an ID Attribute on this particle. I mean by ID, a unique number which corresponds to a particle, like POP Solver.
I tried a sim with the “Source Particle Emitter” shelf in the “Particles” and it gives me the correct ID as I search.

So I did some test to find how to imitate ID system from Pop Solver but on a Pyro Sim. And I found this : below the DOP Import and the scatter node in my pyro_import node, I lay down a AttribWrangle and I say : “i@id = @ptnum;”. And it works pretty good ! But there is a problem.
When I test this on my POP Solver to compare if my “fake” ID is fair compared to the true ID, we can see a slight different result after 50 frames of sim.



Because particles dies and I don't know how to do in a different way.

Do you guys have ideas about a different workflow ? Or how to fixe that ?

PS : I put some example attached.
PS2 : Sorry guys if my explanations are not very clear, I'm even struggling to explain in my own langage ^^'

Attachments:
POP_Solver_Example.hip (315.8 KB)

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And this is a reply to attached a second file, with a billowy smoke for example
Edited by anon_user_83081268 - Aug. 8, 2016 09:58:14

Attachments:
Smoke_ID_AttribWrangle_Example.hip (620.0 KB)

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A POP id is unique across the whole sim and is assigned by a simple counter of new particles. The ‘gaps’ in your screenshot are caused by particles dying and being removed.

Your fake id is just the raw point number calculated after the sim and is not time dependent. Your scattered points are not related frame-by-frame so the fake id seems meaningless?

Are you perhaps looking to advect points through the pyro sim ( pop advect / vdb advect points ) rather than scattering?
Edited by Aeoll - Aug. 8, 2016 10:33:49
Nick Taylor
http://nicholas-taylor.com/ [nicholas-taylor.com]
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Yeah exactly, they're useless because I seek a way to copy this unique id like POP.

And no I don't know what's a POP Advect and a VDB Advect Points. It does the same job as a scattering ?
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