RBD sim pieces freezing in the air after being added

[Yehbe]

Hello everyone,

 

I'm trying to make a simulation based on the Applied Houdini chain tutorial. One problem I am facing right now is that the pieces that are brought into the simulation through a sopsolver freeze in mid-air. I have changed the sleeping time, but that doesn't work. There does seem to be velocity on the points. But they just freeze in mid-air. Anyone know a solution?

 

BoxChain_RTJ4.hip

 

 

[tamagochy]

I think you should first ask Steven and then coming here ) 

[Librarian]

@Yehbe Can you Please Just Post Final Video From that Training  .Just to see Final Effect .

And those chains react With Audio OR??
 

[nuki]

Since you fracture the chains inside the dopnet, the point count of your dopimport changes every frame (after breakframe).

Your HQ link geometry point count is based on the unfractured chain points (687) and static. Hence theres no way for transformpieces to match the links correctly. Eg. on frame 13, your dopimport has 768 points, on frame 17 its 658. factor in the timeshift -> transformpieces sees different point counts on each of its 3 inputs.

Not quite sure how this fracturing setup is intended to work in conjunction with transformpieces. You'd somehow have to fracture your HQ links in the same fashion and manage the @name attribute.

Edit: I think you are already swapping the breaking pieces to HQ before fracturing, right? So then after your dopimport you'd have to split the 'unbroken' links, which you want to swap out and do the transformpieces on those only. Then import the fractured HQ pieces from the dopnet and merge.

Edited November 24, 2020 by nuki

[Yehbe]

Thanks for your time. I would jump straight to the dopnet, since the error exists in there and is seen in there the best. I will have to figure out all the transformpieces stuff later.

 

Ah yes sorry the speakers are intended to react to audio. I have low-poly proxy geometry for all the chains except for the ones that break. The ones that break get added into the sim with the sopsolver and those are the HQ pieces. I don't swap those already broken pieces since it's just a few pieces overall. The weird thing is that it does work in the tutorial file I did of the setup in the tutorial. So I have to make sure my point count doesn't change?

 

his is the tutorial I am basing my sim on. It's not exactly the same but I hoped a lot was applicable in this scene as well.

T

[nuki]

Just had another look at it, since the problem exists in the dopnet already I would not focus on the transformpieces/pointcount for now. I might be wrong - you pack the newly fractured prims with a different name attribute anyways, so I think that this should work even if the pointcount changes.

The pieces freeze after being replaced by the sop solver, even when copying @v from the unbroken pieces to the new frags. active is set to 1, bullet_sleeping is 0, so they should react to forces (with sleeping they should be woken anyways). They do react to collisions, but snap back into their creation state after the collider has passed.

I'd take a closer look at the object replacement, although I dont see anything really wrong with it at first glance. The collision geo for the broken links looks a bit off tho.

Edited November 24, 2020 by nuki

[Yehbe]

I tried to ignore collisions on them but that doesn't seem to work. I guess the best way to do this is just import the broken pieces in a separate dopnet.