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borbs727

How to retime a dynamically fractured RBD simulation cache?

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I've found a few threads on this topic, but I haven't seen any concrete solutions or explanations that I can understand.  I've followed the DT course on how to control your fractures to start, but now I'm getting pretty stuck with what I'm trying to accomplish (explained below). I still have a lot to learn about Houdini, so please let me know if my process if 

 

Goal:

To cache out a sim of a solid object that fractures a little bit when in the air, then shatters even more when it impacts the ground.  I'd then like to take this cached out sim and retime it.

 

My Process:

- Make a base object called geo_orig and fracture it with a voronoi fracture sop

- Make the geo_orig a packed "RBD fractured object"

- Use "glue adjacent" on geo_orig so I can control where the in-air shattering occurs by deleting unwanted constraints. 

- Then I go into the RBD packed object and hit "make breakable" and cache out the sim with a ROP output driver.

- I make a new geometry called geo_read_sim and drop a file node within to read the cached sim

- I append the time blend and time shift sops within the geo_read_sim node and that's when the problems start

 

The Problems:

- When I play the retimed sim, the geometry freaks out the moment a shatter happens.  I think this is due to new points being generated on impact?)

- Shattering related, retime unrelated: I can see shattered geometry coming out of unshattered geometry.  Like the original geometry stays behind while a duplicate geometry shatters off and penetrates through the old.  Any thoughts on why this might be occuring?

 

Research:

I've looked at the hip on here, but this deals with retiming a simulation, not a cached one.

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=22492&view=previous&sid=89f08de40a51517484edd04e850202a6

 

This one deals mostly with volume retiming. 

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=118869&sid=b2c7bc6e940c50c42208fa380d53f641

 

This is the best one.  It says on the 1st post of the 2nd page that changing the rbd solver from bullet to rbd and messing with the FPS works... but every time i turn the rbd solver on, I lose the fracturing on impact and glue constraint work.

https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=25640&postdays=0&postorder=asc&start=25&sid=353a937f6b8da5898b0a29f9eb1ec0c4

 

 

Any help or pointers would really be appreciated.

fracture_retime.hiplc

post-13135-0-81068100-1440803555_thumb.j

Edited by borbs727

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