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How to apply the transform from an alembic to packed fragments


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Hi all,

I have a hard-surface vehicle animation coming into houdini via alembic (no deformations).

The vehicle needs to be fractured for a RBD sim.

The first frame of the alembic is the vehicle in its rest position. This is where the fracturing is done and the constraints are setup.

Now, how would I apply the animation in the alembic onto the fractured pieces?

The transform pieces SOP only gives me translation. I guess there needs to be some wrangling with intrinsics happening?

I attached a simplified scene with an alembic, maybe somebody can take a look! Thank y'all!


 

 

 

 

cube.anim.v3.abc

transform.frags.w.alembic.hipnc

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So, setting up the constraints for this isnt that easy, I guess because I am now working on deforming geometry.

It is almost working, but broken constraints keep coming back. 

How can I tell the sim to delete constraints that were already broken? 

see file attached

 

constrain.transform.frags.w.alembic_oliver.hipnc

cube.anim.v3.abc

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Lowering the strength of your glue seems to make it break apart, so you can try that! Though since earlier I think you mentioned this is going to be a vehicle, you may want to have a look at cone-twist constraints some time in the future! They allow torque and twisting to happen instead of just an instant break. 

Edit: There's definitely some wonkiness with the constraints though. I tied the activation of the glue to deforming/animated switch and it seems to fix it. 

constrain.transform.frags.w.alembic_jamesr.hipnc

Edited by jamesr
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yes, I will have other constraints, but I am using this simple example to troubleshoot. But your right, I should intrduce other constraints here too, just to make sure I wont get lost in the houdini-rabbit-hole :D

In your file it looks like the constraints are still coming back. 
But I took your idea of the activation frame and built the constraints outside the dopnet on that frame. That seems to work now.

 

 

constrain.transform.frags.w.alembic_oliver.v2.hipnc

cube.anim.v3.abc

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