RBD Packed Object - Glue + Gravity + Constrain

[bgodoy]

Sorry if this question has been asked before (I've been searching the forums and still can't find an answer) but I have a question about setting up constraints for RBD Packed Objects. In a nutshell, what I'm looking to do is allow my main piece of geometry to "stay in place" while gravity only affects the pieces that are being collided with.

 

I should mention I'm still relatively new to Houdini so I don't really have any idea of how this process has changed over serval versions—I'm on 15—nor do I have an extensive knowlegde of Houdini at this point (unfortunately, but that's why I'm learning).

 

So far the issue I seem to be having is that my gravity is pulling down all of my fractured pieces (which are being held together by a glue constraint) but this geometry is part of a larger building which means I have to make sure it looks as if it is attached to the larger structure.

 

Example image below.

 

Hopefully this all makes sense and is enough to go on because I brought in all of my assets from Maya (alembic). I feel like I'm just missing something really simple here... tried adding a Pin Constraint earlier but realized there is a difference between using constraints with RBD Packed Objects and a regular RBD Object node... now I'm at a loss.

 

Thanks in advance for any advice!

-B

[carlo_c]

If I'm understanding correctly I think you just want to constrain the edge pieces to the building with another glue constraint that cannot be broken so that they will hold the rest in place. 

[bgodoy]

If I'm understanding correctly I think you just want to constrain the edge pieces to the building with another glue constraint that cannot be broken so that they will hold the rest in place. 

Yes, exactly. Thanks for summing it up Carlo haha... I apologize for the long winded description.

 

Any tips or example files would be greatly appreciated

 

If it helps, below is another image that does a better job of describing what I'm after.... Basically, I want the shattered pieces to be affected by gravity while the remaining pieces stay in place.

Edited December 18, 2015 by bgodoy

[kerguestenen]

Sorry for the delay, i'm sure you resolved this already.

I'm working for the firt time with bullet, and from the little i understood, you could just add an "active" attribute on the "border" pieces of your wall (as they are packed, each piece is just a point right?), and set this active attribute to 0;

So they will stay in place, but as they are still glued to the other pieces, all your wall should stay in place.