previous_sim_position in FLIP

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hi,

I noticed that in FLIP simulations, after caching, there is point attribute called previous_sim_position. So I assume, that it stores position of particle from previous step.

When I look at those values in Detail view, current position P, and previous are the same. Do I have to check somewhere in solver to store this value, I couldnt find anything like that.

Do you guys have the same experience ?

thanks
Michal Tas Maciejewski @ www.vfxtricks.com
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Just found out that i get this point attribute only if i collide fluid with objects (static object->static solver)

but still, i cannot find any info about this attr.
Michal Tas Maciejewski @ www.vfxtricks.com
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As you've found, that attribute is used for more accurate particle collisions, basically storing the previous position so it can do some interpolation to avoid interpenetration.

If you switch the Collision Detection to Move Outside Collision that attribute will not be created, and collisions with moving or deforming geometry will be less accurate (but they will be faster!)
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