Hi everyone!

I was doing the ‘quick start’ tutorial from sidefx.com. I had to make some columns and a sphere (wich would later be used to chrash into the columns) RBD. I put a groundplane just beneath the colomns, so that they shouldn't be able to fall down. But instead of standing on the groundplane, the columns fall right through the groundplane whereas the sphere does actually collide with the groundplane… When I change the RBD solver engine from Bullet (the default) to RBD, I don't have this problem.. I attached the scene file, maybe I did something I shoulnd't have done. Every little help is appreciated!

Felix

Hi Felix,

What version of Houdini did you start the file in? I opened your file (using 12.0.587), and couldn't fix the problem, though using that same version of Houdini, I started the tutorial up to step 14, then I created the Column RBD Point Object and Ground Plane, and the columns stay just fine.

Also, I noticed that there were lots of extra DOP operators, so I'm guessing that as you were creating/deleting nodes, something got altered along the way, if it wasn't some houdini version problem.

Chris

**Edit**
Oh, and as a general bullet tip, under the Collisions Tab on your RBD Object Sphere, click on the Bullet Data tab, and change the Geometry Representation to Sphere, instead of As Is. You can also optimize the scene a bit more, by un-checking the Use Volume Based Collision Detection parameter (this is necessary for using the RBD Solver Type, but not for Bullet)

**Edit 2**
Found someone with issues you'll probably encounter here on the forums: http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=25540&highlight=Bullet [sidefx.com]

Cheers!

Hi Chris,

Thanks for taking the time to overlook my scene file! I started this file in Houdini 12. I guess I'll have to redo this tutorial, because of the wrong nodes you mentioned. Thanks!

Felix

I did a similar mistake, i messed up one of my PolygonSplit operations, the result was the same, the collision didn't work properly on the column.
I backtracked every node in the column tree with bypassing them until i found my bad node…

Maybe i could just have rebuilt the entire thing faster, but i learned something from it.