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danhprt

H18 SOP Level RBD - Glue two material fracture objects together

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Posted (edited)

Really having trouble with this / understanding the new workflow. If I have a fractured sphere and a static box what is the correct way to create glue constraints between each object and have them work with the new sop level solver? Seems like I am only able to create constraints that work by breaking objects. What if I just want to glue two shapes together?

 

Any help will be hugely appreciated.

Edited by danhprt

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You can use the various RBD Constraints SOPs to create additional constraints between objects, and RBD Constraint Properties configures the attributes of those constraints. You'd probably want the static box to be part of the same geometry as the fractured sphere, just with i@active set to 0 for the packed prim.

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11 minutes ago, cwhite said:

You can use the various RBD Constraints SOPs to create additional constraints between objects, and RBD Constraint Properties configures the attributes of those constraints. You'd probably want the static box to be part of the same geometry as the fractured sphere, just with i@active set to 0 for the packed prim.

This is sort of what I've tried but It doesn't seem to be working. I've attached a quick example hip file. I'm sure I'm probably just missing a few details or maybe doing something in the wrong order. Just can't figure out whats wrong, I'm trying to drag the fractured sphere using a glue constraint connected to the cube.

geo-1.hipnc

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23 hours ago, danhprt said:

This is sort of what I've tried but It doesn't seem to be working. I've attached a quick example hip file. I'm sure I'm probably just missing a few details or maybe doing something in the wrong order. Just can't figure out whats wrong, I'm trying to drag the fractured sphere using a glue constraint connected to the cube.

geo-1.hipnc

You generally don't want to pack before fracturing, which is what RBD configure does. I think the other issue is that you ended up having some pieces that don't have names

There are simpler ways for this exact scenario, but here's an example that shows a more general approach for separately fracturing objects and then combining them together to add additional constraints. Also note that you'd want to apply / transfer any animation after fracturing for efficiency

geo-1.hipnc

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19 hours ago, cwhite said:

You generally don't want to pack before fracturing, which is what RBD configure does. I think the other issue is that you ended up having some pieces that don't have names

There are simpler ways for this exact scenario, but here's an example that shows a more general approach for separately fracturing objects and then combining them together to add additional constraints. Also note that you'd want to apply / transfer any animation after fracturing for efficiency

geo-1.hipnc

I'm still a bit confused, I've tried to create the same desired effect with your scene and I still get the same issues. I don't understand why creating glue constraints between the two objects using rbdconstraintsfromrules disables the simulation. 

If you're able to show me a simpler setup I'd be so grateful, It seems using constraints on fractured or single objects is straightforward but anything outside of that never wants to work. I've got my head around most of this but its driving me crazy that I still haven't found a way to how to take this fractured sphere and glue it to the animated cube while maintaining the original constraint setup.

geo-2.hipnc

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Did you ever solve this? I am trying to do the same thing (constraining RBD to animated geo).

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Can anyone else assist with this and maybe share a .hip file with the correct usage for the RBD Configure SOP? I can't even figure out where in my chain it should be instanced. I assume after my RBDMaterialFracture node, but before the RBDSolver node? SideFX Documentation isn't particularly clear and I can't seem to find any tutorials.

Any assistance on this would be greatly appreciated!

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here...all I can say the best thing about this so far is....it's bloody finicky !!!

- in secret sauce, try disabling it...won't work....even fracture it with 1 fracture point, ie. no actual break, won't work...you have to do an actual dummy break with 2 points...must be something under the hood.

after that, controls are at best.......finicky.

 

balldragger.gif

vu_ballPuller.hiplc

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