Solver value driven by custom attribute

[TheAdmira1]

There is most likely a post about this already (or even help docs), but I cannot seem to phrase the search properly to get the info Im looking for, so I figured I would start another post.

I am trying to drive the "Separation Scale" parameter on the Flip Solver with a custom attribute.

I create the attribute in a sop solver using a volume created by assigning a value to points along a curve, and sourcing that value. The attribute is sticking as I can see it in the details view once I have cached out the particles, but I'm not sure how to push that value to the parameter I want. Im using the same method to move the fluid and to adjust the value of parameters in a vop sop within a sop solver, but that is easy as I can just plug in nodes and pass what I need.

The name of the attribute is "grad_sep" and it is a float value. I have tried putting in grad_sep, GRAD_SEP, $GRAD_SEP, $grad_sep, ${grad_sep}, ${GRAD_SEP}. As you can probably guess, none of these have worked. I am trying to use it the same way I would in pops, but not so much sadly.

Do I need to source it via an hscript call or something? What am I missing here?

TIA!

[eetu]

I think it is just an issue of that parameter being a global value for the solver, and not controllable on a point-by-point basis.

Usually I'd say the parameters on the different solver nodes tend to be global, while the parameters on the physics object nodes are more likely to be controllable with attributes. The controllable attributes are also listed in the help.

[TheAdmira1]

Thanks eetu!

That's kind of what I was assuming, and was afraid someone would confirm.

Going to see if I can get a similar effect from a divergence field.

[old school]

This parameter is referenced by the gasparticleseparate1 Gas Particle Separate DOP micro-solver. The help for the micro-solver indicates that it doesn't take any attributes on the points to apply per-point local changes.

http://www.sidefx.com/docs/houdini12.5/nodes/dop/gasparticleseparate

It's pretty easy to see what parameters at the top level asset are driving. Just open up the Edit Parameter Interface and find that parameter. Then go to the Parameter Description column and see the path in the linked parameter is pointing to and go find that node.

You can use the / or ALT-F hotkeys to open the search window and type the name of the node you are looking for.

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DOPs can take local variables, local to that DOP operator that is and is in the help card for each specific DOP node.

No, you can't pick up geometry attributes with variables in parameter fields as you can in POPs at this time.