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Gubkin

Drive Fractured Geo with Particles

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Hello everyone,

 

I am trying to fracture an animated object and control the pieces with particles.
I created a point at the centroid at each piece and also in the POP network created the exact same number of points to be created at the first frame. Then I tried applying those points to the pieces via "transform pieces" node but the pieces are stretching instead of following the points. Any ideas?
 

drive_fractured_geo_with_particles.hip

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Pack the geo with another assemble sop after the first assemble (on the left-hand branch, not down through your group/foreach branch) and it works fine.

 

I think the reason it's stretching is it's mapping each point from your input geo, of which there are much more than 6, to the 6 particles. Once it's gone through the first 6 points, it loops around and starts over again. ie, points 0-5 are "correctly" mapped to particles 0-5 of your animated geometry. Once it gets to point 6 (ie 7, because we start at point 0), it loops and maps it to your 0th particle; point 7 to your 1st particle, etc. etc. If you check the point numbers you'll see this is consistent.

 

Give it the same number of points to work with (ie, pack your geometry) and everything works fine. :)

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That was easy, thank you! :)

 

Could you advice how to procedurally get the number of points in the impulse count? $NPT doesn't work there as in the old pop network..

Edited by Gubkin

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That's because it's a local variable (I think). You can create a detail attribute before it's piped into the popnet with an attribute create, set it's value to $NPT, and then fetch that detail attribute from the node it was created on inside the popnet (ie, detail("../../attribcreate1/","numpts",0)).

 

Or just set the pop source emission type to all points rather than points. Much easier.

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Thank you again!
For some reason when  I do the setup with my animated geometry the points don't inherit the velocity. I tried using the trail sop and also checked the point numbers to make sure they are the same.
Also, If I add to the inherited velocity the pieces follow the points but when I plug a ground plane for collision they don't.. they all just keep the object together as one. And this is not even the motion of the original points which means they are doing completely their own thing.. any idea why this is happening?

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The plane adds additional points and that's why.. Any idea how to remove these specific points?

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Did it with an object from outside the pop network and grouping it and deleting the group after the popnet before plugging it to the "transform pieces"

Edited by Gubkin

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