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Preparing a high resolution object for destruction in Houdini


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Hi all,


Been using Houdini for about a year and destruction is something I'm still trying to grasp properly. Apologies as this is a very simple question but I'd like to get clarification on it before I spend hours working only to find I've messed up.


I have a high resolution Big Ben asset that I'm looking to destroy with shattering, dust and smoke. The object has lots very tiny pieces that I want to include in the RBD simulation of falling down, but not the shattering. What is the best way to specify what objects are going to be shattered and what objects are going to just be included in the RBD simulations?


Again, sorry if this is really simple and I'm missing something obvious!

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Hi Jimmy,


I would personally start with separating each primitive group in the model, drop down a partition and connectivity sops so houdini auto generates groups for each piece, from there u can start selecting and separating apart what you want to fracture and what you do not, merge everything (after uve fractured what you wanted) and pack the rbds, this is a simplified way of doing it, hard to know exactly without the type of destruction / and model in front of me. 


In the case of it being really high res, you'd probably want to start layering sims to keep it efficient and not have crazy bullet glitches, but again, you may not need to do this. 





Edited by amorales
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Thanks for the reply. 


I've put down a connectivity and partition SOP, trying to figure out how to assign a group to a color in the node. I'm still getting to grips with writing expressions, so not sure what to put in. I actually created the separate groups in Maya and they show up properly in Houdini, I just need to figure out the expression.


For now I've been testing the geometry fracturing by using the delete node to specify what I'm destroying. Not a final solution but at least something I can play with. I'm running into a problem when creating an inside surface using the voronoi fracture - the inside surfaces are very messy and are appearing outside the geometry with bad normals. I used a facet node to clean up the normals before the voronoi node, but the new geometry generated from the inside surfaces is causing problems. What is the best way to fix this? I was thinking of applying another facet after the boronoi node to take the new geo into account.

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Are you sure your geo is clean? I've had problems with the inside surfaces created by voronoi before, a fuse node might help but it's hard to say without seeing the error. You mentioned you deleted parts of the geo to specify what to fracture and what not but this could give you errors aswell if it leaves holes in the geo.

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  • 1 month later...

Just a little update on this, I've been fracturing the geometry with voronoi points and am happy enough with what I have so far to test out the RBD sim. I've been using glue adjacent to hold it together and am firing an RBD ball at the fracture point. My problem now is even with the glue strength set to very low, it still doesn't break apart properly as you can see in this video -



I've tried playing around with the density of both objects as well as the velocity with the ball, but can't seem to get a realistic result.

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