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Sky scraper RBD glue simulation problem


mightcouldb1

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Probably not so much problem as a lack of understanding on my part. I have a very tall object that I am trying to blow up. I have tried various forces... magnets, points, fieldforce, fans, you name it.

It seems as though my object is stuck from simulating.

If I simulate it as a regular RBD fractured object everything works fine. As soon as I make it a glue object, I can't affect it no matter how many zeroes I add to the force scale.

I tried turning off "Glue ignores resting objects" in my RBD solver node, and it starts to give me slightly better results although it seems as though I really have to crank the force up to see something. As soon as the chunk is freed from the from the fracture, it is launched into infinite space somewhere because the magnitude of my force is so high.

Any tips? Could this be because of the weight from the top pieces?

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Probably not so much problem as a lack of understanding on my part. I have a very tall object that I am trying to blow up. I have tried various forces... magnets, points, fieldforce, fans, you name it.

It seems as though my object is stuck from simulating.

If I simulate it as a regular RBD fractured object everything works fine. As soon as I make it a glue object, I can't affect it no matter how many zeroes I add to the force scale.

I tried turning off "Glue ignores resting objects" in my RBD solver node, and it starts to give me slightly better results although it seems as though I really have to crank the force up to see something. As soon as the chunk is freed from the from the fracture, it is launched into infinite space somewhere because the magnitude of my force is so high.

Any tips? Could this be because of the weight from the top pieces?

I dont think you can brake glue with forces.

I might be wrong though, :)

Edited by mawi
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This is most likely because glue does not respond to forces, only impacts. So you can't make glued objects separate through forces alone; you either need to have something impact the glued object (or vice versa), or turn glue off for some subset of the pieces, possibly using group(s) and an RBD State DOP. So you might end up with an invisible "smasher" object that is animated to emulate an outward explosive force.

The reason turning off ""Glue ignores resting objects" works better is because then the glue will look at the resting impacts between the building and the ground plane, which can cause the glue to release. But that's not normally what you'd want.

By the way, you have to look at the Houdini 8 interface (and constraints have changed a bit), but I still think Craig Zerouni's DVD can't be beat if you really want to understand what's going on under the hood with DOPs:

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