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Controlling vellum constraints with geo wrangle


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Hey all, 

wondering if anyone can give me any pointers with my setup.  This should be so simple but i've done something wrong here. 

Got a simple vellum cloth pinned at the edges, i'm also adding an animated noise attribute called mask set as a prim attribute on a side branch.  Inside the solver, i'm using a geo wrangle to get the mask value from the geo and using it to modify the restlength.  But it doesn't match the noise attribute being fed in.

To debug it further, i also set the Cd to be the value of the mask in the same geo wrangle.  And then back above if i connect a null to the vellum solver's constraint geo you can see the attribute via colour.  

 

All seems to work but looks like the primitive numbers are being garbled.  I would expect the result of the debug null to have the same pattern as the noise being fed in.

If anyone has any ideas why, would love to know.  Geo wrangles always seem to trip me up.

Thanks

VellumCon_GeoWrangle.hiplc

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Couldn't run your scene because of my ancient Houdini version. However:

I guess the solver won't update the attribute if you're using a wrangle. Try using a vellumconstraintproperty node, instead. This is the proper way to change constraint properties inside a vellum simulation.

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Thanks!  Yeah i've used the vellum constraint property before and its great.

To be honest i'm mostly trying to figure out why geo wrangle doesn't work.  Essentially trying to learn more about vex inside dops.  I can't see why it wouldn't work though, its just setting attributes, and from what i can see it does actually work, its just not reading the attribute correctly from the right prims.

Hmmmmm, will keep looking into it

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