Randomizing the internal animation timing of particles.

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I have the following POP setup.
Bats flying out of the mouth cave. The cave is just a NURB surface. The bats are particles. The individual bat geometry is very simple polygonal object that is animated by BlendSOP. The BlendSOP is whats being used as an instance. It just animates the flapping of the wings and contorting of the body in relation to wing flap. The geometry is low as they are small in screen space and fly fast past camera.
SourcePOP emmits 225 individuals over course of 15 frames. To randomise the flock distribution I animated the impulse activate and impuylse birth rate. So that some frames emmit losts of members, some frames emit fewer, and some none at all.
The emmision source is a NURBS gridSOP that is facing the mouth of the cave. Emmission occurs on random points on surface.
The swarm members fly towards an attractor.

I noticed that regardless of their birth time, all flock members beat their wings in unison. I thought that a member born in frame #3, would have different beat then member born on frame#1. Meaning that the internal animation of the flock member begins at their birth and be offset by the frame number of their birth. Instead what I see is that internal animation is same across all indivisuals, and only their birth order is different.

What are some of the ways to randomize the internal animation of the instance geometry or to offset their animation channels by frame number of their birth?

Thank you

David Rindner
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Hi David

You're going to want to look into stamping in the copy SOP. Basically it allows you to change parameters upstream of the copy based on attributes in your template.

Put simply, if you're copying an animated bat to a bunch of particles it will allow you to offset the animation based on any particle attribute (rand($ID) is a good place to start)
Take a look in the demo's on the cd, there may be a simple stamping one there. I know the skeleton crowd demo uses stamping to do exactly what you're asking.

Cheers
Marc
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you might actually like this demo instead.

try to find:
$HFS/demo/OPspecific/CHOPs/BatsHover

-k
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Thank you Marc and Kenny. Marc, can you supply the context for the particle operator you described. Into which POP or SOP or VEX does it go? And how?

Thank you

David Rindner
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