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dansidi

Varying Wire solver along L-System ?

Hi everyone,

I am still working on a shot where trees bend due to a rocket exhaust. I have tried FEM but I think it will not do what I want (too 'chunky').

I would like to try the Wire solver. What I want is the trunk of the tree to bend very slightly, the branches to bend a bit more and the twigs to bend a twitch a lot - bend angle proportional to branch thickness, basically.

How can I vary the wire deformer strength or bend angle along the length of the L-System branches? I suspect this is a VERY simple thing for a Houdini TD to do, but I am not sure how to approach it. Please help!

I enclose a simple setup where I have a L-system, converted into a Wire sim, with a hard pin constraint on the base of the trunk and I made a Wind force pushing on it.

Many thanks

l-system_wire_test_02.hip

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I can see that you can generate point attributes when the L-System is created, which gives a couple of useful sounding attributes: gen and width.



How would it be possible to feed these into the Wire solver?

Let's say I wanted to multiply Elasticity or Angular Damping by that width attribute. Can that be done? How can I do that?

Any help at all would be very gratefully recieved.

Thanks!

Capture3.PNG

Capture4.PNG

Edited by dansidi
added image

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check out the help card for the wire object. it has all the information you need
"You can create attributes on the wire object’s RestGeometry to influence its behavior. Most of these attributes allow fine-tuning of the wire by scaling values set in this node. Point, primitive, or detail attributes of the same name will be used if the vertex attributes are not present."

if you want to multiply  Angular Damping with that width attrib from the lsystem node, you have to do it before going to dops
like f@dampangular = f@width, then in DOPs set the value to 1 (to use raw attrib data) as you attrib will act as multiplier.
I think you get the idea.

cheers

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