RBD plus Flip - passive to active interaction issue - Some help needed!

[Lud83]

Hi everyone,

I recently tried to create a shot with a helicopter crashing into water - its a multi stage sim. No details required as I added a Test setup file regarding this problem. 

To try out interactions between a detailed RBD and a FLIP sim I had to come up with a way to use dummy objects for the bigger RBD pieces, that I want to float and interact with the waves.

so here is a simple test setup with two elements:

1. a static Sphere that will remain static and a participant of the simulation for the first 20 frames (representing the initial crash of the high detailed model with its Volume collider)

2. a rbd-obj Sphere that is born and supposed to start interacting with the waves to get the floating motion (representing the wreckage-dummy for the point-transform for the high detail model)

 

Now i thought it would be as easy as feeding both inputs into the sim, deleting each corresponding to its time frame, and then just use a switch solver (I could find a number of setups on the switch solver).

I got it to work somehow, though the switch solver didn't - nevertheless at Stage (2) the Flip simulation just explodes or rather the rbd-obj get thrown out of the water and i can't figure out why or how to fix it.

 

Any help would be appreciated! Thanks!

 

Lud83

Flip-RBD-Issue.hipnc

[Sean-R]

Hey Ludwig,

I've switched you RBD sphere over to a RBD Packed object as it allows you to use the "active" point attributes. Active defines if the solver should include the object in the sim, a full list of attributes available to you can be found here: http://www.sidefx.com/docs/houdini/nodes/dop/rbdpackedobject

I've set this active attribute in an attribute wrangle to be set to 1 after frame 20. I've also added an assemble sop to pack the object, a RBD Packed object dop to bring the sphere into the dopnet, checked "Overwrite Attributes" so the object references the active attribute made at SOP level and I've switched the rigid solver back to Bullet. Finally, I've adjusted the Density of the object so it floats on the water.

Thanks,

 

Sean

Flip-RBD-Issue_FIX.hipnc