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gramx

FEM constraints H15

Hi,

I am working on some soft body destruction with FEM, and I wanted a way to constrain some of the geometry around the edges. Not had any luck so far is there a way to do this.

cheers

graham

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There's a few ways using attributes. The help card says:

"The attributes targetP and targetv can be used to specify a target position and velocity for each object point. When you use the Import Target Geometry option on the simulated object, the targetP and targetv will be set automatically every frame. Alternatively, you can create and modify these attributes yourself, using a Multi Solver and a SOP Solver.

This is a way to create soft constraints. You can use the pintoanimation to create hard constraints that make the simulated points follow targetP and targetv exactly."

The target geo method is a little confusing to me, but it seems to be working.  When I point to the Sop solver with the target geo parm, and export targetP or targetv, nothing happens.  When I point to the Sop solver with the target geo parm, and export P or v, it seems to work.  

So I think that on the solid or cloth object, whatever you point the target geo parm to, uses those point positions and point velocities (P and v), and converts them into "targetP" and "targetv".

Anyway, here's a file with those 2 ways. Maybe someone with a better understanding of the target geometry parm, can explain exactly the way it works.

cloth_constrain.hipnc

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Thanks for your help, and the hip :) Your hip file contains a cloth setup rather than FEM soft body but I think it works the same.

I have tried pintoanimation with a FEM object and it does work. hip attached.

I am wondering how you could go about and pin one end to another object to create a floppy tail.

cheers

 

FEM_pin.hipnc

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The reason it wasn't working for you, was you need to convert to tets, and then create @pintoanimation.  When using FEM, your geo has to tets for the sim, and then you convert back to polys after.  Check this hip, I played with a few variations for both @pintoanimation and @targetv/P

FEM_pin_a1.hipnc

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Thanks again this makes sense now. I will post up a few examples when I'm finished. cheers

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